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Implant Survivorship and Complication Rates After Total Knee Arthroplasty With a Third-Generation Cemented System: 15-Year Follow-Up
ABSTRACT
This work is a retrospective cohort study evaluating patients who had undergone third-generation cemented total knee arthroplasty (TKA) with prostheses (NexGen, Zimmer Biomet) utilizing posterior-stabilized (PS) and cruciate-retaining (CR) designs at a single center at their 15-year follow-up.
The purpose of this study is to determine the functional knee scores, reoperations, and long-term survivorship for patients with the NexGen Zimmer Biomet Knee system at the 15-year follow-up. In total, 99 patients who had undergone primary TKA were followed for 15 years.
At the 15-year follow-up, survivorship in both study groups was similar: 98% for PS TKAs and 100% for CR TKAs. The 2 groups also showed similar functionality: 80% of the PS implants and 89% of the CR implants were associated with no or mild pain (P = .40). Reoperation rates were 2% for the PS group and 0% for the CR group (P = .38). No differences in any of the outcomes analyzed were observed between patients who had CR TKA and those who had undergone PS TKA.
Our study found no significant differences in functional outcomes between PS and CR NexGen knee implants. Patients treated by both methods showed excellent longevity and survivorship at the 15-year follow-up.
Continue to: Total knee arthroplasty...
Total knee arthroplasty (TKA) is an orthopedic procedure with increasing demand.1 Over the past 2 decades, a surge in TKA implants has been observed. Of the available prosthetic designs, only a few implants with long-term follow-up have been reported.2-9 The NexGen TKA system (Zimmer Biomet) has been shown to have excellent clinical and radiographic results at an intermediate follow-up term of 8 years.10 This system is a third-generation prosthetic design that was developed to improve problems seen with its predecessors, such as the Miller-Galante II system (Zimmer Biomet), the Insall-Burstein II system (Zimmer Biomet), and the Constrained Condylar Knee (Zimmer Biomet), which were mainly for patellar maltracking.11-17 The NexGen TKA system is a fixed-bearing system designed to include an anatomic femoral trochlea with the option of cruciate-retaining (CR), posterior-stabilized (PS), or more constrained implants. This study evaluates the long-term success of the CR and PS NexGen TKA systems. Outcomes measured include functional knee scores and reoperation rates at the 15-year follow-up. Based on the measured outcomes, potential differences between the PS and CR implants from this system are cited.
MATERIAL AND METHODS
Between July 1995 and July 1997, 334 consecutive primary TKAs were performed on 287 patients at our institution. In total, 167 patients (186 knees) underwent posterior CR TKAs with the NexGen CR prosthesis (Zimmer Biomet), and 120 patients (148 knees) underwent PS TKAs using the NexGen Legacy PS prosthesis (Zimmer Biomet). This retrospective double cohort study was reviewed and approved by our Institutional Review Board. At the 15-year postoperative follow-up, 99 patients were available (Figure 1).
The CR and PS implants were used with similar frequencies by the surgeons who performed the procedures. Patients were not randomized into either the PS- or CR-implant teams; the final decision on implant selection was left to the operating surgeon’s discretion. However, in addition to standard indications for TKA (pain and disability associated with severe arthritic change seen on radiographs and refractory to conservative measures), absolute contraindications to the CR implant included severe combined deformity (flexion contraction >30° combined with a varus or valgus deformity >20°) or posterior cruciate ligament insufficiency (often associated with inflammatory arthritis).
The surgical technique for the CR and PS designs was identical, and included a median parapatellar approach, femoral rotational alignment perpendicular to the transepicondylar axis, measured resection of the flexion and extension gaps, intramedullary femoral alignment, and extramedullary tibial alignment. All components were cemented, and the patella of each patient was resurfaced. All patients received preoperative antibiotics that were continued for 48 hours postoperatively, and 4 weeks of anticoagulation with dose-adjusted warfarin to maintain an international normalized ratio of 1.5 to 2.0.
Patients were observed postoperatively at the 5- to 8-year and 15-year time points. The 5-year data were previously published in 2005 by Bozic and colleagues.10 Patients available for follow-up at the 15-year time-point were evaluated using the 100-point Hospital for Special Surgery (HSS) knee scoring system, which assigns up to 30 points for pain, 22 points for function, 18 points for range of motion, and 10 points each for quadricep strength, deformity, and instability. In addition, common medical conditions limiting patient activity were assessed; these included joint replacement; arthritis in another joint, the back, or spine; weakness or fatigue; breathing or heart ailments; and others.
Continue to: At the 15-year follow-up...
At the 15-year follow-up, patients were contacted via telephone to obtain their HSS knee scores. If patients were unavailable/unable to answer the questions asked, knee score information was collected from a first-degree relative or caretaker. Patients that could not be contacted by phone were sent a HSS knee score survey to their last known address. The online Social Security Death Index was queried for confirmation of death. If deceased, a first-degree relative was contacted for confirmation.
Survivorship was evaluated using revision for any reason and revision for aseptic loosening as separate endpoints via the Kaplan-Meier product-limit method, and the CR and PS TKA groups were compared using the log-rank test. The power of the study for detecting differences between the TKA groups was determined to be 80%, based on a moderate hazard ratio of 1.5, using the log-rank test. Differences between PS and CR TKAs were assessed using the Pearson chi-square test for knee pain and functional outcomes, Fisher’s exact test for patient limitations, such as joint replacement, and the non-parametric Mann Whitney U-test for median pain scores (Table 1). Spearman correlations between the patients’ self-reported knee scores (as a percentage of normal) and physician-based knee scores were performed to assess whether self-reported knee scores were significantly correlated with physician-based knee scores. Kaplan-Meier analysis was performed to evaluate time-related freedom from reoperation at 95% confidence intervals. Statistical analysis was conducted using IBM SPSS Statistics (version 21.0, IBM). Two-tailed P < .05 was considered statistically significant.
RESULTS
Of the 287 patients (334 knees) who had primary TKAs, 99 patients (121 knees; 75 CR and 46 PS) were available at the 15-year follow-up. A total of 155 patients (171 knees) died before the 15-year follow-up, and 33 (42 knees) were lost to follow-up (Figure 1). The functional status of the knees of patients who were lost to follow-up or who had died since the previous follow-up data were published is unknown.
Demographic and outcome data for the cohort of 121 TKAs (99 patients) are summarized in Table 2. The median age at surgery was 64 years, and 71% of the cohort was female.
At the 15-year follow-up, survivorship in both groups was similar: 98% for PS TKAs and 100% for CR TKAs. The 2 groups were also similar functionally: 80% of the PS implants and 89% of the CR implants were associated with no or mild pain (P = .40). Approximately half of the patients in both groups (52% PS; 50% CR; P = .88) required walking support (canes or walkers) and nearly half of both groups (46% PS; 48% CR; P = .62) could walk <5 blocks or only short distances in their homes. In addition, 46% of the patients in both groups reported needing arm assistance to functionally rise from a chair (P = .43); 91% of the patients in both groups could also walk up and down stairs (P = .77). No statistical difference in the medical conditions limiting the patients in the 2 groups was found: joint replacement (2% PS; 6% CR; P = .71), arthritis in another joint (43% PS; 45% CR; P = .84), back or spine arthritis (31% PS; 33% CR; P = 1.00), weakness or fatigue (24% PS; 25% CR; P = 1.00), breathing or heart ailments (11% PS; 20% CR; P = .40), and other reasons (27% PS; 25% CR; P = 1.00). In addition, median self-reported knee scores were 95 and 93 points for the PS and CR groups, respectively (P = .55).
Continue to: Patients reported 2 complications...
Patients reported 2 complications since the previous 5- to 8-year follow-up, 1 in each group. The first case underwent a PS TKA that required open reduction internal fixation for a bilateral supracondylar peri-prosthesis femur fracture following a fall, which was subsequently complicated with infection and ultimately led to above-the-knee amputation. In the second case, a CR TKA patient experienced persistent swelling and knee instability. The patient followed up with a local orthopaedist, but to date, no reoperations on the knee have been reported.
Spearman correlations between the patients’ self-reported knee scores (as a percentage of normal) and physician-based knee scores were moderately correlated with physician-based knee scores (rs = 0.42; P < .001).
Reoperation rates were 2% for PS and 0% for CR (P = .38). Kaplan-Meier analysis was performed to evaluate time-related freedom from reoperation and no significance difference between the PS and CR groups was revealed (log-rank test = 1.40, P = .24, Figure 2).
DISCUSSION
The success of TKA in pain relief and restoration of function has led to increased demands for this surgery.1 Such demand has enabled the introduction of a new joint replacement prosthesis to the market.18 Considering the increased incidence of osteoarthritis in the younger population (<55 years of age), critically reviewing the longevity and durability of TKA implant designs is of great importance. Compared with other TKA implant designs, the NexGen Zimmer Biomet Knee system has shown excellent longevity at the 15-year follow-up.5,6,9,11-15 Our study began with 136 patients, and, after eliminating the deceased, those lost to follow-up, and non-responders, a total of 99 patients were available for the 15-year follow-up. At this time-point, 80% of the PS implants and 89% of the CR implants were associated with no or mild pain. Survivorship at the 15-year follow-up was similar in both groups: 98% for PS TKAs and 100% for CR TKAs. The reoperation rate was low in both groups, and no evidence of aseptic loosening was found. Based on our results, the NexGen Zimmer Biomet Knee system can be concluded to show excellent longevity and functional outcomes at the 15-year follow-up.
Our study includes several limiting factors that were taken into consideration during the analysis of the results. One of the main limitations of this work is that it required a 15-year follow-up of predominantly elderly patients; many of the participants may be expected to be deceased at this time-point. In our study, a total of 7 patients were confirmed to be deceased by a first-degree relative or the Social Security Death Index. In addition, unlike Bozic and colleagues’10 previous 5-year follow-up study, radiographic imaging data were not collected at the 15-year follow-up. However, given that this study aimed to assess the functional knee scores and reoperation rates of the PS and CR NexGen Zimmer Biomet Knee system, radiographic information did not appear to be necessary.
CONCLUSION
This study found no significant differences in functional outcomes between the PS and CR NexGen knee implants. Patients who received these implants showed excellent longevity and survivorship at their 15-year follow-up.
1. Lützner J, Hübel U, Kirschner S, Günther KP, Krummenauer F. Langzeitergebnisse in der Knieendoprothetik. Chirurg. 2011;82(7):618-624. doi:10.1007/s00104-010-2001-8.
2. Font-Rodriguez DE, Scuderi GR, Insall J. Survivorship of cemented total knee arthroplasty. Clin Orthop Relat Res. 1997;345:79-86.
3. Rodriguez JA, Bhende H, Ranawat CS. Total condylar knee replacement: a 20-year followup study. Clin Orthop Relat Res. 2001;388:10-17.
4. Van Loon CJM, Wisse MA, de Waal Malefijt MC, Jansen RH, Veth RPH. The kinematic total knee arthroplasty. Arch Orth Traum Surg. 2000;120(1-2):48-52. doi:10.1007/PL00021215.
5. Buechel FFS. Long-term followup after mobile-bearing total knee replacement. Clin Orthop Relat Res. 2002;404:40-50.
6. Ito J, Koshino T, Okamoto R, Saito T. 15-year follow-up study of total knee arthroplasty in patients with rheumatoid arthritis. J Arthroplasty. 2003;18(8):984-992. doi:10.1016/S0883-5403(03)00262-6.
7. Dixon MC, Brown RR, Parsch D, Scott RD. Modular fixed-bearing total knee arthroplasty with retention of the posterior cruciate ligament. J Bone Joint Surg. 2005;87(3):598-603. doi:10.2106/JBJS.C.00591.
8. Duffy GP, Crowder AR, Trousdale RR, Berry DJ. Cemented total knee arthroplasty using a modern prosthesis in young patients with osteoarthritis. J Arthroplasty. 2007;22(6 Suppl 2):67-70. doi:10.1016/j.arth.2007.05.001.
9. Baker PN, Khaw FM, Kirk LMG, Esler CNA, Gregg PJ. A randomised controlled trial of cemented versus cementless press-fit condylar total knee replacement: 15-year survival analysis. J Bone Joint Surg. 2007;89-B(12):1608-1614. doi:10.1302/0301-620x.89b12.19363.
10. Bozic KJ, Kinder J, Menegini M, Zurakowski D, Rosenberg AG, Galante JO. Implant survivorship and complication rates after total knee arthroplasty with a third-generation cemented system: 5 to 8 years followup. Clin Orthop Relat Res. 2005;430:117-124. doi:10.1097/01.blo.0000146539.23869.14.
11. Effenberger H, Berka J, Hilzensauer G, Ramsauer T, Dorn U, Kißlinger E. Miller-Galante total knee arthroplasty: the importance of material and design on the revision rate. Int Orthop. 2001;25(6):378-381. doi:10.1007/s002640100294.
12. Kirk PG, Rorabeck CH, Bourne RB. Clinical comparison of the Miller Galante I and AMK total knee systems. J Arthroplasty. 1994;9(2):131-136. doi:10.1016/0883-5403(94)90061-2.
13. Kobori M, Kamisato S, Yoshida M, Kobori K. Revision of failed metal-backed patellar component of Miller/Galante-I total knee prosthesis. J Orthop Sci. 2000;5(5):436-438. doi:10.1007/s007760070020.
14. Larson CM, Lachiewicz PF. Patellofemoral complications with the insall-burstein II posterior-stabilized total knee arthroplasty. J Arthroplasty. 1999;14(3):288-292. doi:http://dx.doi.org/10.1016/S0883-5403(99)90053-0.
15. Matsuda S, Miura H, Nagamine R, Urabe K, Hirata G, Iwamoto Y. Effect of femoral and tibial component position on patellar tracking following total knee arthroplasty: 10-year follow-up of Miller-Galante I knees. Am J Knee Surg. 2001;14(3):152-156.
16. Miyagi T, Matsuda S, Miura H, Nagamine R, Urabe K. Changes in patellar tracking after total knee arthroplasty: 10-year follow-up of Miller-Balante I knees. Orthopedics. 2002;25(8):811-813. doi:10.3928/0147-7447-20020801-10.
17. Rao AR, Engh GA, Collier MB, Lounici S. Tibial interface wear in retrieved total knee components and correlations with modular insert motion. J Bone Joint Surg. 2002;84(10):1849-1855.
18. Anand R, Graves SE, de Steiger RN, et al. What is the benefit of introducing new hip and knee prostheses? J Bone Joint Surg. 2011;93(3):51-54. doi:10.2106/JBJS.K.00867.
ABSTRACT
This work is a retrospective cohort study evaluating patients who had undergone third-generation cemented total knee arthroplasty (TKA) with prostheses (NexGen, Zimmer Biomet) utilizing posterior-stabilized (PS) and cruciate-retaining (CR) designs at a single center at their 15-year follow-up.
The purpose of this study is to determine the functional knee scores, reoperations, and long-term survivorship for patients with the NexGen Zimmer Biomet Knee system at the 15-year follow-up. In total, 99 patients who had undergone primary TKA were followed for 15 years.
At the 15-year follow-up, survivorship in both study groups was similar: 98% for PS TKAs and 100% for CR TKAs. The 2 groups also showed similar functionality: 80% of the PS implants and 89% of the CR implants were associated with no or mild pain (P = .40). Reoperation rates were 2% for the PS group and 0% for the CR group (P = .38). No differences in any of the outcomes analyzed were observed between patients who had CR TKA and those who had undergone PS TKA.
Our study found no significant differences in functional outcomes between PS and CR NexGen knee implants. Patients treated by both methods showed excellent longevity and survivorship at the 15-year follow-up.
Continue to: Total knee arthroplasty...
Total knee arthroplasty (TKA) is an orthopedic procedure with increasing demand.1 Over the past 2 decades, a surge in TKA implants has been observed. Of the available prosthetic designs, only a few implants with long-term follow-up have been reported.2-9 The NexGen TKA system (Zimmer Biomet) has been shown to have excellent clinical and radiographic results at an intermediate follow-up term of 8 years.10 This system is a third-generation prosthetic design that was developed to improve problems seen with its predecessors, such as the Miller-Galante II system (Zimmer Biomet), the Insall-Burstein II system (Zimmer Biomet), and the Constrained Condylar Knee (Zimmer Biomet), which were mainly for patellar maltracking.11-17 The NexGen TKA system is a fixed-bearing system designed to include an anatomic femoral trochlea with the option of cruciate-retaining (CR), posterior-stabilized (PS), or more constrained implants. This study evaluates the long-term success of the CR and PS NexGen TKA systems. Outcomes measured include functional knee scores and reoperation rates at the 15-year follow-up. Based on the measured outcomes, potential differences between the PS and CR implants from this system are cited.
MATERIAL AND METHODS
Between July 1995 and July 1997, 334 consecutive primary TKAs were performed on 287 patients at our institution. In total, 167 patients (186 knees) underwent posterior CR TKAs with the NexGen CR prosthesis (Zimmer Biomet), and 120 patients (148 knees) underwent PS TKAs using the NexGen Legacy PS prosthesis (Zimmer Biomet). This retrospective double cohort study was reviewed and approved by our Institutional Review Board. At the 15-year postoperative follow-up, 99 patients were available (Figure 1).
The CR and PS implants were used with similar frequencies by the surgeons who performed the procedures. Patients were not randomized into either the PS- or CR-implant teams; the final decision on implant selection was left to the operating surgeon’s discretion. However, in addition to standard indications for TKA (pain and disability associated with severe arthritic change seen on radiographs and refractory to conservative measures), absolute contraindications to the CR implant included severe combined deformity (flexion contraction >30° combined with a varus or valgus deformity >20°) or posterior cruciate ligament insufficiency (often associated with inflammatory arthritis).
The surgical technique for the CR and PS designs was identical, and included a median parapatellar approach, femoral rotational alignment perpendicular to the transepicondylar axis, measured resection of the flexion and extension gaps, intramedullary femoral alignment, and extramedullary tibial alignment. All components were cemented, and the patella of each patient was resurfaced. All patients received preoperative antibiotics that were continued for 48 hours postoperatively, and 4 weeks of anticoagulation with dose-adjusted warfarin to maintain an international normalized ratio of 1.5 to 2.0.
Patients were observed postoperatively at the 5- to 8-year and 15-year time points. The 5-year data were previously published in 2005 by Bozic and colleagues.10 Patients available for follow-up at the 15-year time-point were evaluated using the 100-point Hospital for Special Surgery (HSS) knee scoring system, which assigns up to 30 points for pain, 22 points for function, 18 points for range of motion, and 10 points each for quadricep strength, deformity, and instability. In addition, common medical conditions limiting patient activity were assessed; these included joint replacement; arthritis in another joint, the back, or spine; weakness or fatigue; breathing or heart ailments; and others.
Continue to: At the 15-year follow-up...
At the 15-year follow-up, patients were contacted via telephone to obtain their HSS knee scores. If patients were unavailable/unable to answer the questions asked, knee score information was collected from a first-degree relative or caretaker. Patients that could not be contacted by phone were sent a HSS knee score survey to their last known address. The online Social Security Death Index was queried for confirmation of death. If deceased, a first-degree relative was contacted for confirmation.
Survivorship was evaluated using revision for any reason and revision for aseptic loosening as separate endpoints via the Kaplan-Meier product-limit method, and the CR and PS TKA groups were compared using the log-rank test. The power of the study for detecting differences between the TKA groups was determined to be 80%, based on a moderate hazard ratio of 1.5, using the log-rank test. Differences between PS and CR TKAs were assessed using the Pearson chi-square test for knee pain and functional outcomes, Fisher’s exact test for patient limitations, such as joint replacement, and the non-parametric Mann Whitney U-test for median pain scores (Table 1). Spearman correlations between the patients’ self-reported knee scores (as a percentage of normal) and physician-based knee scores were performed to assess whether self-reported knee scores were significantly correlated with physician-based knee scores. Kaplan-Meier analysis was performed to evaluate time-related freedom from reoperation at 95% confidence intervals. Statistical analysis was conducted using IBM SPSS Statistics (version 21.0, IBM). Two-tailed P < .05 was considered statistically significant.
RESULTS
Of the 287 patients (334 knees) who had primary TKAs, 99 patients (121 knees; 75 CR and 46 PS) were available at the 15-year follow-up. A total of 155 patients (171 knees) died before the 15-year follow-up, and 33 (42 knees) were lost to follow-up (Figure 1). The functional status of the knees of patients who were lost to follow-up or who had died since the previous follow-up data were published is unknown.
Demographic and outcome data for the cohort of 121 TKAs (99 patients) are summarized in Table 2. The median age at surgery was 64 years, and 71% of the cohort was female.
At the 15-year follow-up, survivorship in both groups was similar: 98% for PS TKAs and 100% for CR TKAs. The 2 groups were also similar functionally: 80% of the PS implants and 89% of the CR implants were associated with no or mild pain (P = .40). Approximately half of the patients in both groups (52% PS; 50% CR; P = .88) required walking support (canes or walkers) and nearly half of both groups (46% PS; 48% CR; P = .62) could walk <5 blocks or only short distances in their homes. In addition, 46% of the patients in both groups reported needing arm assistance to functionally rise from a chair (P = .43); 91% of the patients in both groups could also walk up and down stairs (P = .77). No statistical difference in the medical conditions limiting the patients in the 2 groups was found: joint replacement (2% PS; 6% CR; P = .71), arthritis in another joint (43% PS; 45% CR; P = .84), back or spine arthritis (31% PS; 33% CR; P = 1.00), weakness or fatigue (24% PS; 25% CR; P = 1.00), breathing or heart ailments (11% PS; 20% CR; P = .40), and other reasons (27% PS; 25% CR; P = 1.00). In addition, median self-reported knee scores were 95 and 93 points for the PS and CR groups, respectively (P = .55).
Continue to: Patients reported 2 complications...
Patients reported 2 complications since the previous 5- to 8-year follow-up, 1 in each group. The first case underwent a PS TKA that required open reduction internal fixation for a bilateral supracondylar peri-prosthesis femur fracture following a fall, which was subsequently complicated with infection and ultimately led to above-the-knee amputation. In the second case, a CR TKA patient experienced persistent swelling and knee instability. The patient followed up with a local orthopaedist, but to date, no reoperations on the knee have been reported.
Spearman correlations between the patients’ self-reported knee scores (as a percentage of normal) and physician-based knee scores were moderately correlated with physician-based knee scores (rs = 0.42; P < .001).
Reoperation rates were 2% for PS and 0% for CR (P = .38). Kaplan-Meier analysis was performed to evaluate time-related freedom from reoperation and no significance difference between the PS and CR groups was revealed (log-rank test = 1.40, P = .24, Figure 2).
DISCUSSION
The success of TKA in pain relief and restoration of function has led to increased demands for this surgery.1 Such demand has enabled the introduction of a new joint replacement prosthesis to the market.18 Considering the increased incidence of osteoarthritis in the younger population (<55 years of age), critically reviewing the longevity and durability of TKA implant designs is of great importance. Compared with other TKA implant designs, the NexGen Zimmer Biomet Knee system has shown excellent longevity at the 15-year follow-up.5,6,9,11-15 Our study began with 136 patients, and, after eliminating the deceased, those lost to follow-up, and non-responders, a total of 99 patients were available for the 15-year follow-up. At this time-point, 80% of the PS implants and 89% of the CR implants were associated with no or mild pain. Survivorship at the 15-year follow-up was similar in both groups: 98% for PS TKAs and 100% for CR TKAs. The reoperation rate was low in both groups, and no evidence of aseptic loosening was found. Based on our results, the NexGen Zimmer Biomet Knee system can be concluded to show excellent longevity and functional outcomes at the 15-year follow-up.
Our study includes several limiting factors that were taken into consideration during the analysis of the results. One of the main limitations of this work is that it required a 15-year follow-up of predominantly elderly patients; many of the participants may be expected to be deceased at this time-point. In our study, a total of 7 patients were confirmed to be deceased by a first-degree relative or the Social Security Death Index. In addition, unlike Bozic and colleagues’10 previous 5-year follow-up study, radiographic imaging data were not collected at the 15-year follow-up. However, given that this study aimed to assess the functional knee scores and reoperation rates of the PS and CR NexGen Zimmer Biomet Knee system, radiographic information did not appear to be necessary.
CONCLUSION
This study found no significant differences in functional outcomes between the PS and CR NexGen knee implants. Patients who received these implants showed excellent longevity and survivorship at their 15-year follow-up.
ABSTRACT
This work is a retrospective cohort study evaluating patients who had undergone third-generation cemented total knee arthroplasty (TKA) with prostheses (NexGen, Zimmer Biomet) utilizing posterior-stabilized (PS) and cruciate-retaining (CR) designs at a single center at their 15-year follow-up.
The purpose of this study is to determine the functional knee scores, reoperations, and long-term survivorship for patients with the NexGen Zimmer Biomet Knee system at the 15-year follow-up. In total, 99 patients who had undergone primary TKA were followed for 15 years.
At the 15-year follow-up, survivorship in both study groups was similar: 98% for PS TKAs and 100% for CR TKAs. The 2 groups also showed similar functionality: 80% of the PS implants and 89% of the CR implants were associated with no or mild pain (P = .40). Reoperation rates were 2% for the PS group and 0% for the CR group (P = .38). No differences in any of the outcomes analyzed were observed between patients who had CR TKA and those who had undergone PS TKA.
Our study found no significant differences in functional outcomes between PS and CR NexGen knee implants. Patients treated by both methods showed excellent longevity and survivorship at the 15-year follow-up.
Continue to: Total knee arthroplasty...
Total knee arthroplasty (TKA) is an orthopedic procedure with increasing demand.1 Over the past 2 decades, a surge in TKA implants has been observed. Of the available prosthetic designs, only a few implants with long-term follow-up have been reported.2-9 The NexGen TKA system (Zimmer Biomet) has been shown to have excellent clinical and radiographic results at an intermediate follow-up term of 8 years.10 This system is a third-generation prosthetic design that was developed to improve problems seen with its predecessors, such as the Miller-Galante II system (Zimmer Biomet), the Insall-Burstein II system (Zimmer Biomet), and the Constrained Condylar Knee (Zimmer Biomet), which were mainly for patellar maltracking.11-17 The NexGen TKA system is a fixed-bearing system designed to include an anatomic femoral trochlea with the option of cruciate-retaining (CR), posterior-stabilized (PS), or more constrained implants. This study evaluates the long-term success of the CR and PS NexGen TKA systems. Outcomes measured include functional knee scores and reoperation rates at the 15-year follow-up. Based on the measured outcomes, potential differences between the PS and CR implants from this system are cited.
MATERIAL AND METHODS
Between July 1995 and July 1997, 334 consecutive primary TKAs were performed on 287 patients at our institution. In total, 167 patients (186 knees) underwent posterior CR TKAs with the NexGen CR prosthesis (Zimmer Biomet), and 120 patients (148 knees) underwent PS TKAs using the NexGen Legacy PS prosthesis (Zimmer Biomet). This retrospective double cohort study was reviewed and approved by our Institutional Review Board. At the 15-year postoperative follow-up, 99 patients were available (Figure 1).
The CR and PS implants were used with similar frequencies by the surgeons who performed the procedures. Patients were not randomized into either the PS- or CR-implant teams; the final decision on implant selection was left to the operating surgeon’s discretion. However, in addition to standard indications for TKA (pain and disability associated with severe arthritic change seen on radiographs and refractory to conservative measures), absolute contraindications to the CR implant included severe combined deformity (flexion contraction >30° combined with a varus or valgus deformity >20°) or posterior cruciate ligament insufficiency (often associated with inflammatory arthritis).
The surgical technique for the CR and PS designs was identical, and included a median parapatellar approach, femoral rotational alignment perpendicular to the transepicondylar axis, measured resection of the flexion and extension gaps, intramedullary femoral alignment, and extramedullary tibial alignment. All components were cemented, and the patella of each patient was resurfaced. All patients received preoperative antibiotics that were continued for 48 hours postoperatively, and 4 weeks of anticoagulation with dose-adjusted warfarin to maintain an international normalized ratio of 1.5 to 2.0.
Patients were observed postoperatively at the 5- to 8-year and 15-year time points. The 5-year data were previously published in 2005 by Bozic and colleagues.10 Patients available for follow-up at the 15-year time-point were evaluated using the 100-point Hospital for Special Surgery (HSS) knee scoring system, which assigns up to 30 points for pain, 22 points for function, 18 points for range of motion, and 10 points each for quadricep strength, deformity, and instability. In addition, common medical conditions limiting patient activity were assessed; these included joint replacement; arthritis in another joint, the back, or spine; weakness or fatigue; breathing or heart ailments; and others.
Continue to: At the 15-year follow-up...
At the 15-year follow-up, patients were contacted via telephone to obtain their HSS knee scores. If patients were unavailable/unable to answer the questions asked, knee score information was collected from a first-degree relative or caretaker. Patients that could not be contacted by phone were sent a HSS knee score survey to their last known address. The online Social Security Death Index was queried for confirmation of death. If deceased, a first-degree relative was contacted for confirmation.
Survivorship was evaluated using revision for any reason and revision for aseptic loosening as separate endpoints via the Kaplan-Meier product-limit method, and the CR and PS TKA groups were compared using the log-rank test. The power of the study for detecting differences between the TKA groups was determined to be 80%, based on a moderate hazard ratio of 1.5, using the log-rank test. Differences between PS and CR TKAs were assessed using the Pearson chi-square test for knee pain and functional outcomes, Fisher’s exact test for patient limitations, such as joint replacement, and the non-parametric Mann Whitney U-test for median pain scores (Table 1). Spearman correlations between the patients’ self-reported knee scores (as a percentage of normal) and physician-based knee scores were performed to assess whether self-reported knee scores were significantly correlated with physician-based knee scores. Kaplan-Meier analysis was performed to evaluate time-related freedom from reoperation at 95% confidence intervals. Statistical analysis was conducted using IBM SPSS Statistics (version 21.0, IBM). Two-tailed P < .05 was considered statistically significant.
RESULTS
Of the 287 patients (334 knees) who had primary TKAs, 99 patients (121 knees; 75 CR and 46 PS) were available at the 15-year follow-up. A total of 155 patients (171 knees) died before the 15-year follow-up, and 33 (42 knees) were lost to follow-up (Figure 1). The functional status of the knees of patients who were lost to follow-up or who had died since the previous follow-up data were published is unknown.
Demographic and outcome data for the cohort of 121 TKAs (99 patients) are summarized in Table 2. The median age at surgery was 64 years, and 71% of the cohort was female.
At the 15-year follow-up, survivorship in both groups was similar: 98% for PS TKAs and 100% for CR TKAs. The 2 groups were also similar functionally: 80% of the PS implants and 89% of the CR implants were associated with no or mild pain (P = .40). Approximately half of the patients in both groups (52% PS; 50% CR; P = .88) required walking support (canes or walkers) and nearly half of both groups (46% PS; 48% CR; P = .62) could walk <5 blocks or only short distances in their homes. In addition, 46% of the patients in both groups reported needing arm assistance to functionally rise from a chair (P = .43); 91% of the patients in both groups could also walk up and down stairs (P = .77). No statistical difference in the medical conditions limiting the patients in the 2 groups was found: joint replacement (2% PS; 6% CR; P = .71), arthritis in another joint (43% PS; 45% CR; P = .84), back or spine arthritis (31% PS; 33% CR; P = 1.00), weakness or fatigue (24% PS; 25% CR; P = 1.00), breathing or heart ailments (11% PS; 20% CR; P = .40), and other reasons (27% PS; 25% CR; P = 1.00). In addition, median self-reported knee scores were 95 and 93 points for the PS and CR groups, respectively (P = .55).
Continue to: Patients reported 2 complications...
Patients reported 2 complications since the previous 5- to 8-year follow-up, 1 in each group. The first case underwent a PS TKA that required open reduction internal fixation for a bilateral supracondylar peri-prosthesis femur fracture following a fall, which was subsequently complicated with infection and ultimately led to above-the-knee amputation. In the second case, a CR TKA patient experienced persistent swelling and knee instability. The patient followed up with a local orthopaedist, but to date, no reoperations on the knee have been reported.
Spearman correlations between the patients’ self-reported knee scores (as a percentage of normal) and physician-based knee scores were moderately correlated with physician-based knee scores (rs = 0.42; P < .001).
Reoperation rates were 2% for PS and 0% for CR (P = .38). Kaplan-Meier analysis was performed to evaluate time-related freedom from reoperation and no significance difference between the PS and CR groups was revealed (log-rank test = 1.40, P = .24, Figure 2).
DISCUSSION
The success of TKA in pain relief and restoration of function has led to increased demands for this surgery.1 Such demand has enabled the introduction of a new joint replacement prosthesis to the market.18 Considering the increased incidence of osteoarthritis in the younger population (<55 years of age), critically reviewing the longevity and durability of TKA implant designs is of great importance. Compared with other TKA implant designs, the NexGen Zimmer Biomet Knee system has shown excellent longevity at the 15-year follow-up.5,6,9,11-15 Our study began with 136 patients, and, after eliminating the deceased, those lost to follow-up, and non-responders, a total of 99 patients were available for the 15-year follow-up. At this time-point, 80% of the PS implants and 89% of the CR implants were associated with no or mild pain. Survivorship at the 15-year follow-up was similar in both groups: 98% for PS TKAs and 100% for CR TKAs. The reoperation rate was low in both groups, and no evidence of aseptic loosening was found. Based on our results, the NexGen Zimmer Biomet Knee system can be concluded to show excellent longevity and functional outcomes at the 15-year follow-up.
Our study includes several limiting factors that were taken into consideration during the analysis of the results. One of the main limitations of this work is that it required a 15-year follow-up of predominantly elderly patients; many of the participants may be expected to be deceased at this time-point. In our study, a total of 7 patients were confirmed to be deceased by a first-degree relative or the Social Security Death Index. In addition, unlike Bozic and colleagues’10 previous 5-year follow-up study, radiographic imaging data were not collected at the 15-year follow-up. However, given that this study aimed to assess the functional knee scores and reoperation rates of the PS and CR NexGen Zimmer Biomet Knee system, radiographic information did not appear to be necessary.
CONCLUSION
This study found no significant differences in functional outcomes between the PS and CR NexGen knee implants. Patients who received these implants showed excellent longevity and survivorship at their 15-year follow-up.
1. Lützner J, Hübel U, Kirschner S, Günther KP, Krummenauer F. Langzeitergebnisse in der Knieendoprothetik. Chirurg. 2011;82(7):618-624. doi:10.1007/s00104-010-2001-8.
2. Font-Rodriguez DE, Scuderi GR, Insall J. Survivorship of cemented total knee arthroplasty. Clin Orthop Relat Res. 1997;345:79-86.
3. Rodriguez JA, Bhende H, Ranawat CS. Total condylar knee replacement: a 20-year followup study. Clin Orthop Relat Res. 2001;388:10-17.
4. Van Loon CJM, Wisse MA, de Waal Malefijt MC, Jansen RH, Veth RPH. The kinematic total knee arthroplasty. Arch Orth Traum Surg. 2000;120(1-2):48-52. doi:10.1007/PL00021215.
5. Buechel FFS. Long-term followup after mobile-bearing total knee replacement. Clin Orthop Relat Res. 2002;404:40-50.
6. Ito J, Koshino T, Okamoto R, Saito T. 15-year follow-up study of total knee arthroplasty in patients with rheumatoid arthritis. J Arthroplasty. 2003;18(8):984-992. doi:10.1016/S0883-5403(03)00262-6.
7. Dixon MC, Brown RR, Parsch D, Scott RD. Modular fixed-bearing total knee arthroplasty with retention of the posterior cruciate ligament. J Bone Joint Surg. 2005;87(3):598-603. doi:10.2106/JBJS.C.00591.
8. Duffy GP, Crowder AR, Trousdale RR, Berry DJ. Cemented total knee arthroplasty using a modern prosthesis in young patients with osteoarthritis. J Arthroplasty. 2007;22(6 Suppl 2):67-70. doi:10.1016/j.arth.2007.05.001.
9. Baker PN, Khaw FM, Kirk LMG, Esler CNA, Gregg PJ. A randomised controlled trial of cemented versus cementless press-fit condylar total knee replacement: 15-year survival analysis. J Bone Joint Surg. 2007;89-B(12):1608-1614. doi:10.1302/0301-620x.89b12.19363.
10. Bozic KJ, Kinder J, Menegini M, Zurakowski D, Rosenberg AG, Galante JO. Implant survivorship and complication rates after total knee arthroplasty with a third-generation cemented system: 5 to 8 years followup. Clin Orthop Relat Res. 2005;430:117-124. doi:10.1097/01.blo.0000146539.23869.14.
11. Effenberger H, Berka J, Hilzensauer G, Ramsauer T, Dorn U, Kißlinger E. Miller-Galante total knee arthroplasty: the importance of material and design on the revision rate. Int Orthop. 2001;25(6):378-381. doi:10.1007/s002640100294.
12. Kirk PG, Rorabeck CH, Bourne RB. Clinical comparison of the Miller Galante I and AMK total knee systems. J Arthroplasty. 1994;9(2):131-136. doi:10.1016/0883-5403(94)90061-2.
13. Kobori M, Kamisato S, Yoshida M, Kobori K. Revision of failed metal-backed patellar component of Miller/Galante-I total knee prosthesis. J Orthop Sci. 2000;5(5):436-438. doi:10.1007/s007760070020.
14. Larson CM, Lachiewicz PF. Patellofemoral complications with the insall-burstein II posterior-stabilized total knee arthroplasty. J Arthroplasty. 1999;14(3):288-292. doi:http://dx.doi.org/10.1016/S0883-5403(99)90053-0.
15. Matsuda S, Miura H, Nagamine R, Urabe K, Hirata G, Iwamoto Y. Effect of femoral and tibial component position on patellar tracking following total knee arthroplasty: 10-year follow-up of Miller-Galante I knees. Am J Knee Surg. 2001;14(3):152-156.
16. Miyagi T, Matsuda S, Miura H, Nagamine R, Urabe K. Changes in patellar tracking after total knee arthroplasty: 10-year follow-up of Miller-Balante I knees. Orthopedics. 2002;25(8):811-813. doi:10.3928/0147-7447-20020801-10.
17. Rao AR, Engh GA, Collier MB, Lounici S. Tibial interface wear in retrieved total knee components and correlations with modular insert motion. J Bone Joint Surg. 2002;84(10):1849-1855.
18. Anand R, Graves SE, de Steiger RN, et al. What is the benefit of introducing new hip and knee prostheses? J Bone Joint Surg. 2011;93(3):51-54. doi:10.2106/JBJS.K.00867.
1. Lützner J, Hübel U, Kirschner S, Günther KP, Krummenauer F. Langzeitergebnisse in der Knieendoprothetik. Chirurg. 2011;82(7):618-624. doi:10.1007/s00104-010-2001-8.
2. Font-Rodriguez DE, Scuderi GR, Insall J. Survivorship of cemented total knee arthroplasty. Clin Orthop Relat Res. 1997;345:79-86.
3. Rodriguez JA, Bhende H, Ranawat CS. Total condylar knee replacement: a 20-year followup study. Clin Orthop Relat Res. 2001;388:10-17.
4. Van Loon CJM, Wisse MA, de Waal Malefijt MC, Jansen RH, Veth RPH. The kinematic total knee arthroplasty. Arch Orth Traum Surg. 2000;120(1-2):48-52. doi:10.1007/PL00021215.
5. Buechel FFS. Long-term followup after mobile-bearing total knee replacement. Clin Orthop Relat Res. 2002;404:40-50.
6. Ito J, Koshino T, Okamoto R, Saito T. 15-year follow-up study of total knee arthroplasty in patients with rheumatoid arthritis. J Arthroplasty. 2003;18(8):984-992. doi:10.1016/S0883-5403(03)00262-6.
7. Dixon MC, Brown RR, Parsch D, Scott RD. Modular fixed-bearing total knee arthroplasty with retention of the posterior cruciate ligament. J Bone Joint Surg. 2005;87(3):598-603. doi:10.2106/JBJS.C.00591.
8. Duffy GP, Crowder AR, Trousdale RR, Berry DJ. Cemented total knee arthroplasty using a modern prosthesis in young patients with osteoarthritis. J Arthroplasty. 2007;22(6 Suppl 2):67-70. doi:10.1016/j.arth.2007.05.001.
9. Baker PN, Khaw FM, Kirk LMG, Esler CNA, Gregg PJ. A randomised controlled trial of cemented versus cementless press-fit condylar total knee replacement: 15-year survival analysis. J Bone Joint Surg. 2007;89-B(12):1608-1614. doi:10.1302/0301-620x.89b12.19363.
10. Bozic KJ, Kinder J, Menegini M, Zurakowski D, Rosenberg AG, Galante JO. Implant survivorship and complication rates after total knee arthroplasty with a third-generation cemented system: 5 to 8 years followup. Clin Orthop Relat Res. 2005;430:117-124. doi:10.1097/01.blo.0000146539.23869.14.
11. Effenberger H, Berka J, Hilzensauer G, Ramsauer T, Dorn U, Kißlinger E. Miller-Galante total knee arthroplasty: the importance of material and design on the revision rate. Int Orthop. 2001;25(6):378-381. doi:10.1007/s002640100294.
12. Kirk PG, Rorabeck CH, Bourne RB. Clinical comparison of the Miller Galante I and AMK total knee systems. J Arthroplasty. 1994;9(2):131-136. doi:10.1016/0883-5403(94)90061-2.
13. Kobori M, Kamisato S, Yoshida M, Kobori K. Revision of failed metal-backed patellar component of Miller/Galante-I total knee prosthesis. J Orthop Sci. 2000;5(5):436-438. doi:10.1007/s007760070020.
14. Larson CM, Lachiewicz PF. Patellofemoral complications with the insall-burstein II posterior-stabilized total knee arthroplasty. J Arthroplasty. 1999;14(3):288-292. doi:http://dx.doi.org/10.1016/S0883-5403(99)90053-0.
15. Matsuda S, Miura H, Nagamine R, Urabe K, Hirata G, Iwamoto Y. Effect of femoral and tibial component position on patellar tracking following total knee arthroplasty: 10-year follow-up of Miller-Galante I knees. Am J Knee Surg. 2001;14(3):152-156.
16. Miyagi T, Matsuda S, Miura H, Nagamine R, Urabe K. Changes in patellar tracking after total knee arthroplasty: 10-year follow-up of Miller-Balante I knees. Orthopedics. 2002;25(8):811-813. doi:10.3928/0147-7447-20020801-10.
17. Rao AR, Engh GA, Collier MB, Lounici S. Tibial interface wear in retrieved total knee components and correlations with modular insert motion. J Bone Joint Surg. 2002;84(10):1849-1855.
18. Anand R, Graves SE, de Steiger RN, et al. What is the benefit of introducing new hip and knee prostheses? J Bone Joint Surg. 2011;93(3):51-54. doi:10.2106/JBJS.K.00867.
TAKE-HOME POINTS
- TKA has a high success rate in pain relief and restoration of function in patients with severe osteoarthritis.
- NexGen (Zimmer Biomet) knee implants showed excellent functional outcomes at 15 years.
- There are no significant differences in functional outcomes between the PS and CR knee systems.
- NexGen knee implants showed excellent longevity and survivorship at 15-year follow-up with no evidence of aseptic loosening.
- There is an increased incidence of knee osteoarthritis in the younger population (<55 years of age).
Comparison of Anterior and Posterior Corticosteroid Injections for Pain Relief and Functional Improvement in Shoulder Impingement Syndrome
Take-Home Points
When conservative treatments for SIS do not resolve symptoms, inflammation and pain can be reduced with use of subacromial CSI.
Both anterior CSI and posterior CSI significantly improved pain and function for up to 6 months
CSI combined with structured PT produced significant improvement in pain and function in patients with SIS, regardless of injection route used.
Clinical response to CSI may not depend on injection accuracy.
Clinicians should rely on their clinical acumen when selecting injection routes, as anterior and posterior are both beneficial.
Shoulder pain, a common clinical problem, occurs in 7% to 34% of the general population and in 21% of people older than 70 years.1Subacromial impingement refers to shoulder pain resulting from mechanical impingement of the rotator cuff underneath the coracoacromial arch between the acromion and the humeral head.2,3 Subacromial impingement syndrome (SIS) is the most common cause of shoulder pain, resulting in significant functional deficits and disability.3
Treatment options for SIS include conservative modalities such as use of nonsteroidal anti-inflammatory drugs, physical therapy (PT), and subacromial corticosteroid injections (CSIs). Studies have found short- and long-term improvement in pain, function, and range of motion after CSI.4-8 Subacromial CSI can be administered through an anterior or a posterior route.4,9 There have been several studies of the accuracy of anterior and posterior CSIs,10-12 with 2 studies finding similar accuracy for these routes.10,11 However, there may be a sex difference: In women, a posterior route may be less accurate than an anterior or a lateral route.12
Although the accuracy of anterior and posterior routes has been studied, their effect on clinical outcomes has not. We conducted a study to understand the effects of anterior and posterior CSIs on SIS. As one of the accuracy studies suggested anterior CSI is more accurate—the anterior route was theorized to provide easier access to the subacromial space12—we hypothesized patients treated with anterior CSI would have superior clinical outcomes 6 months after injection.12,13
Materials and Methods
Study Participants and Randomization
After this study received Institutional Review Board approval, patients with shoulder pain of more than 3 months’ duration and consistent with SIS were screened for inclusion. Eligible patients had pain in the anterior biceps and over the top of the shoulder with overhead activities as well as one or more clinical findings on physical examination: Hawkins-Kennedy sign, Neer sign, painful arc, and infraspinatus pain (pain with external rotation).
Patients were excluded if their history included prior subacromial CSI, adhesive capsulitis (inability to passively abduct shoulder to 90° with scapular stabilization), calcific tendonitis, radiographic evidence of os acromiale, cervical radiculopathy, Spurling sign, neck pain, radiating arm pain or numbness, sensory deficits, or neck and upper extremity motor dysfunction. Also excluded were patients with full-thickness rotator cuff tear, weakness on arm elevation, positive "drop arm sign," or high-riding humerus on standing shoulder radiograph. Patients who had work-related injuries or who were involved in worker compensation were excluded as well.
Enrolled patients were randomly assigned (with use of a computer-based random number generator) to receive either anterior CSI or posterior CSI.
Injection Procedures
All patients were administered 5 mL of lidocaine 1% (without epinephrine) and 2 mL (80 mg) of triamcinolone by 2 board-certified orthopedic surgeons using a 22-gauge 1½-inch needle. For patients who received their subacromial CSI by the anterior route, the arm was held in 0° of abduction and 20° of external rotation. The needle was inserted medial to the humeral head, lateral to the coracoid process, beginning 1 cm inferior to the clavicle with the needle directed posteriorly and laterally toward the acromion.10 For patients who received their CSI by the posterior route, the arm was held in 0° of abduction, the posterolateral corner of the acromion was identified by palpation, and the needle was inserted 1 cm inferior and medial to this point with the needle directed anteriorly and laterally toward the acromion.10,12 In both groups, the subacromial space was identified when a drop in pressure was felt during needle insertion. Accuracy was assessed post hoc by asking patients to grade their response to the injection on a visual analog scale (VAS); VAS score was used as a surrogate for improvement. All patients had a positive Neer test: Pain decreased with impingement maneuvers immediately after injection.
All patients were referred for PT provided according to an evidence-based rehabilitation protocol.14 This program emphasized range of motion with shoulder shrugs, scapular retraction, and pendulum exercises; flexibility with stretching exercises targeting the anterior and posterior aspects of the shoulder and cane stretching for forward elevation and external rotation; and strength with strengthening exercises involving the rotator cuff and scapular stabilizers.
Outcome Measures
Pain was measured with VAS scores and function with Single Assessment Numeric Evaluation (SANE) scores. The VAS is a validated outcome measure of pain intensity. A numeric version of the VAS was used: Patients selected the whole number, from 0 (no pain) to 10 (worst possible pain), that best reflected their pain intensity. On SANE, another validated outcome measure, patients rated their shoulder function as a percentage of normal, from 0% (no function possible) to 100% (perfect).15 Before injection, all patients were administered the VAS and SANE questionnaires to establish their baseline pain level and opinion of shoulder function. These measures were repeated 1, 3, and 6 months after injection. Telephone interviews were conducted at 1 month and 6 months. Patients were asked to return to clinic 3 months after injection as part of the standard of care. At 3 months, 47 (86%) of the 55 patients returned for follow-up and were administered the VAS and SANE questionnaires; the other 8 completed the questionnaires by telephone. At each time point, patients were asked to report on their participation in PT and/or adherence to their home exercise program.
Statistical Analysis
Power analysis performed with Student t test and a 2-sided level of P = .05 compared VAS pain scores between the anterior and posterior injection routes and found a mean (SD) difference of 1.4 (1.7).16 Power calculations made with nQuery Advisor Version 7.0 (Statistical Solutions) indicated a total sample size of 60 patients (30/group) would provide 80% power for detecting a significant difference assuming a 20% dropout rate.
Two-way mixed-model analysis of variance (ANOVA) was used to compare the anterior and posterior routes for statistical differences in both VAS pain scores and SANE function scores at baseline and 1, 3, and 6 months after injection. Likewise, time at baseline (just before injection)was compared with follow-up (1, 3, 6 months) with 2-way mixed-model ANOVA adjusting for anterior or posterior route. Multivariate analysis was performed to evaluate differences between baseline and 6-month follow-up with respect to anterior and posterior injection routes, controlling for age, sex, and body mass index (BMI) for VAS and SANE scores. Parametric testing methods were used for statistical analysis, which was performed with IBM SPSS Statistics Version 21.0 (IBM Corp). Significance was set at P < .05.
Results
Patient Characteristics
Of the 55 patients enrolled, 25 (46%) received anterior subacromial CSI and 30 (54%) received posterior CSI. All enrolled patients had a positive Neer impingement test immediately after injection. Mean (SD) age was 48 (9.3) years for anterior group patients and 48 (9.0) years for posterior group patients. There was no significant difference in age or BMI between the 2 groups (Table). 
Five patients (9%) were excluded from the study after randomization and CSI: 2 for a full-thickness rotator cuff tear, 1 for a Bankart lesion, 1 for adhesive capsulitis, and 1 for a worker compensation claim.
One month after injection, 41 patients (75%) reported having engaged in PT as prescribed. Of the 47 patients (86%) who returned for the 3-month follow-up, 25 (46%) reported having engaged in PT between 1 month and 3 months after injection. Fourteen patients (26%) reported attending PT between 3 and 6 months post-injection.
Outcome Measures
Two-way repeated-measures ANOVA with age, sex, and BMI included as covariates revealed no significant differences in VAS scores between the anterior and posterior groups at any time point (P = .45). Both groups had highly significant pain reductions (anterior, F = 9.71, P < .001; posterior, F = 13.46, P < .001). Figure 1 shows mean VAS scores and significant reductions in pain 1, 3, and 6 months after injection (see asterisks for anterior and posterior groups; P < .001 for all). The groups had parallel rates of pain reduction over time, as indicated by a nonsignificant (P = .50) difference in slopes. These pain score reductions were significant for both injection routes and were independent of age, sex, and BMI (P > .05 for all).
Two-way repeated-measures ANOVA with age, sex, and BMI included as covariates revealed no significant differences in SANE scores between the anterior and posterior groups, except for a higher mean score in the anterior group at 3 months
(P = .02). There were no other group differences (P > .10 for all). Both groups had highly significant improvements in function (anterior, F = 17.34,
P < .001; posterior, F = 13.57, P < .001). Figure 2 shows mean SANE scores and significant improvement at 1, 3, and 6 months (see asterisks for anterior and posterior groups; P < .001 for all). The groups had parallel rates of improved function over time, as indicated by a nonsignificant (P = .51) difference in slopes. These function score improvements were significant for both injection routes and were independent of age, sex, and BMI (P > .05 for all).
From the results of this prospective randomized study, we concluded subacromial CSI significantly reduces pain and improves function regardless of route used. In addition, age, sex, and BMI do not significantly affect the efficacy of either anterior CSI or posterior CSI.
Discussion
In patients with SIS, anterior CSI and posterior CSI provided significant improvements in pain and function 1, 3, and 6 months after injection. These effects were independent of age, sex, BMI, and PT participation. There were no significant differences in outcomes between injection routes.
When conservative treatments for SIS do not resolve symptoms, inflammation and pain can be reduced with use of subacromial CSI.4-8 Although clinical outcomes are inconsistent, CSI can be used to address SIS symptoms in appropriate patients. Specifically, Blair and colleagues6 found that, CSI consisting of 4 mL of lidocaine 1% (without epinephrine) and 2 mL (80 mg) of triamcinolone was effective in alleviating shoulder pain and improving shoulder range of motion. Other authors have similarly reported improved outcomes after subacromial injection and short-term follow-up with PT.4,7,8 Our findings are consistent with these reports: CSI coupled with a structured rehabilitation program is effective in alleviating symptoms associated with acute or subacute SIS.
Numerous studies have found improved clinical outcomes after anterior CSI and after posterior CSI,6-8 but no study has directly compared the clinical impact of anterior CSI with that of posterior CSI—which suggests injection route may not affect ultimate clinical outcomes.
CSI accuracy has been studied extensively.10-12,17-20 Although 2 studies found similar accuracy for anterior and posterior routes,10,11 there may be a sex difference: In women, a posterior route may be less accurate than an anterior or a lateral route.12 Collectively, these studies expose the inherent difficulty in treating shoulder pain with localized subacromial injection. Therapy may fail because of errant needle positioning. Two prospective studies found improved clinical outcomes with successful delivery of medication into the subacromial space.17,18 Poor clinical outcomes may result from inaccurate CSI.
In contrast to other clinical studies, our study found that injection route was not associated with differences in clinical response. In a prospective randomized clinical trial in which 75 patients received a subacromial injection, Marder and colleagues12 found anterior routes 84% accurate and posterior routes 56% accurate; they concluded acromion anatomy and subacromial bursa anatomy make posterior injections more difficult. As theorized by Gruson and colleagues,13 with use of an anterior route, the needle enters inferior to the concavity of the acromion and provides easier access to the subacromial space. This idea is in line with Marder and colleagues’12 conclusion that subacromial bursa anatomy provides a favorable environment for accurate CSI.
If accuracy is positively correlated with clinical improvement and anterior routes are more accurate, there should be a difference in response to posterior injections. Our results provide evidence that clinical response to CSI may not depend on injection accuracy. Perhaps merely placing the corticosteroid near the bursa is adequate for improving symptoms or perhaps some of the clinical improvement is due to the systemic effect of corticosteroids. These possibilities require further analysis.
Establishing the efficacy of CSI in SIS is difficult. The literature includes various study designs, different CSI indications and medication formulations, and varying emphasis on the role of organized PT. Rehabilitation has been found to alleviate joint pain by reducing inflammation,14 but data do not universally support this finding.21,22 Nevertheless, use of PT might explain the divergence in clinical outcomes reported by Marder and colleagues,12 who found anterior CSI more accurate than posterior CSI. In our practice, PT is recommended for all SIS patients, not only those who have CSI. Thus, our findings are framed within the context of successful CSI but may include patients who improved with PT alone. This issue raises the question of whether subacromial CSI should be guided by ultrasound. Ultrasound guidance can improve CSI accuracy and clinical outcomes,23-25 though the value of this benefit is debated.26
This study had several limitations. First, pain relief was patient reported. Second, the treatment plan involved CSI with PT but did not control for CSI used alone. PT, which is part of the standard of care for patients with SIS, added another degree of complexity to the study. Third, there may have been some variability in SIS severity (stage 1, 2, or 3). Fourth, although the study design controlled for various shoulder pathologies, advanced imaging, which could have provided diagnosis confirmation, was not available for all patients. Therefore, concurrent conditions may have confounded results. However, randomization was used to try to minimize this effect. Fifth, although injection routes were randomly assigned, the trial was not blinded. Sixth, the study was underpowered by 1 patient, as there was an estimated 20% dropout rate over 3 and 6 months of follow-up. However, we do not think our results were significantly affected.
Although more research is needed to fully describe the role of subacromial CSI in SIS, our study findings suggested that CSI using either an anterior or a posterior route creates a window of symptomatic relief in which patients may be able to engage in PT.
Conclusion
Both anterior CSI and posterior CSI significantly improved pain and function for up to 6 months. No differences were found between anterior and posterior CSIs. In the context of this study, CSI combined with structured PT produced significant improvement in pain and function in patients with SIS, regardless of injection route used. Clinicians should rely on their clinical acumen when selecting injection routes, as anterior and posterior are both beneficial.
1. Buchbinder R, Green S, Youd JM. Corticosteroid injections for shoulder pain. Cochrane Database Syst Rev. 2003;(1):CD004016.
2. Bell AD, Conaway D. Corticosteroid injections for painful shoulders. Int J Clin Pract. 2005;59(10):1178-1186.
3. Michener LA, McClure PW, Karduna AR. Anatomical and biomechanical mechanisms of subacromial impingement syndrome. Clin Biomech. 2003;18(5):369-379.
4. Akgün K, Birtane M, Akarirmak U. Is local subacromial corticosteroid injection beneficial in subacromial impingement syndrome? Clin Rheumatol. 2004;23(6):496-500.
5. Bhagra A, Syed H, Reed DA, et al. Efficacy of musculoskeletal injections by primary care providers in the office: a retrospective cohort study. Int J Gen Med. 2013;6:237-243.
6. Blair B, Rokito AS, Cuomo F, Jarolem K, Zuckerman JD. Efficacy of injections of corticosteroids for subacromial impingement syndrome. J Bone Joint Surg Am. 1996;78(11):1685-1689.
7. Cummins CA, Sasso LM, Nicholson D. Impingement syndrome: temporal outcomes of nonoperative treatment.
J Shoulder Elbow Surg. 2009;18(2):172-177.
8. Yu C, Chen CH, Liu HT, Dai MH, Wang IC, Wang KC. Subacromial injections of corticosteroids and Xylocaine for painful subacromial impingement syndrome. Chang Gung Med J. 2006;29(5):474-478.
9. Codsi MJ. The painful shoulder: when to inject and when to refer. Cleve Clin J Med. 2007;74(7):473-474, 477-478, 480-482 passim.
10. Henkus HE, Cobben LP, Coerkamp EG, Nelissen RG, van Arkel ER. The accuracy of subacromial injections: a prospective randomized magnetic resonance imaging study. Arthroscopy. 2006;22(3):277-282.
11. Kang MN, Rizio L, Prybicien M, Middlemas DA, Blacksin MF. The accuracy of subacromial corticosteroid injections: a comparison of multiple methods. J Shoulder Elbow Surg. 2008;17(15):61S-66S.
12. Marder RA, Kim SH, Labson JD, Hunter JC. Injection of the subacromial bursa in patients with rotator cuff syndrome: a prospective, randomized study comparing the effectiveness of different routes. J Bone Joint Surg Am. 2012;94(16):
1442-1447.
13. Gruson, KI, Ruchelsman DE, Zuckerman JD. Subacromial corticosteroid injections. J Shoulder Elbow Surg. 2008;17(1 suppl):118S-130S.
14. Kuhn JE. Exercise in the treatment of rotator cuff impingement: a systematic review and a synthesized evidence-based rehabilitation protocol. J Shoulder Elbow Surg. 2009;18(1):138-160.
15. Williams GN, Gangel TJ, Arciero RA, Uhorchak JM, Taylor DC. Comparison of the Single Assessment Numeric Evaluation method and two shoulder rating scales. Outcomes measures after shoulder surgery. Am J Sports Med. 1999;27(2):214-221.
16. Tashjian RZ, Deloach J, Porucznik CA, Powell AP. Minimal clinically important differences (MCID) and patient acceptable symptomatic state (PASS) for visual analog scales (VAS) measuring pain in patients treated for rotator cuff disease.
J Shoulder Elbow Surg. 2009;88(6):927-932.
17. Eustace JA, Brophy DP, Gibney RP, Bresnihan B, FitzGerald O. Comparison of the accuracy of steroid placement with clinical outcome in patients with shoulder symptoms. Ann Rheum Dis. 1997;56(1):59-63.
18. Esenyel CZ, Esenyel M, Yeiltepe R, et al. The correlation between the accuracy of steroid injections and subsequent shoulder pain and function in subacromial impingement
syndrome [in Turkish]. Acta Orthop Traumatol Turc. 2003;37(1):
41-45.
19. Powell SE, Davis SM, Lee EH, et al. Accuracy of palpation-directed intra-articular glenohumeral injection confirmed by magnetic resonance arthrography. Arthroscopy. 2015;31(2):205-208.
20. Rutten MJ, Maresch BJ, Jager GJ, de Waal Malefijt MC. Injection of the subacromial-subdeltoid bursa: blind or ultrasound-guided? Acta Orthop. 2007;78(2):254-257.
21. Desmeules F, Côté CH, Frémont P. Therapeutic exercise and orthopedic manual therapy for impingement syndrome: a systematic review. Clin J Sport Med. 2003;13(3):176-182.
22. Winters JC, Sobel JS, Groenier KH, Arendzen HJ, Meyboom-de Jong B. Comparison of physiotherapy, manipulation, and corticosteroid injection for treating shoulder complaints in general practice: randomised, single blind study. BMJ. 1997;314(7090):1320-1325.
23. Chen MJ, Lew HL, Hsu TC, et al. Ultrasound-guided shoulder injections in the treatment of subacromial bursitis. Am J Phys Med Rehabil. 2006;85(1):31-35.
24. Hsieh LF, Hsu WC, Lin YJ, Wu SH, Chang KC, Chang HL. Is ultrasound-guided injection more effective in chronic subacromial bursitis? Med Sci Sports Exerc. 2013;45(12):
2205-2213.
25. Naredo E, Cabero F, Beneyto P, et al. A randomized comparative study of short term response to blind injection versus sonographic-guided injection of local corticosteroids in patients with painful shoulder. J Rheumatol. 2004;31(2):308-314.
26. Hall S, Buchbinder R. Do imaging methods that guide needle placement improve outcome? Ann Rheum Dis. 2004;63(9):1007-1008.
Take-Home Points
When conservative treatments for SIS do not resolve symptoms, inflammation and pain can be reduced with use of subacromial CSI.
Both anterior CSI and posterior CSI significantly improved pain and function for up to 6 months
CSI combined with structured PT produced significant improvement in pain and function in patients with SIS, regardless of injection route used.
Clinical response to CSI may not depend on injection accuracy.
Clinicians should rely on their clinical acumen when selecting injection routes, as anterior and posterior are both beneficial.
Shoulder pain, a common clinical problem, occurs in 7% to 34% of the general population and in 21% of people older than 70 years.1Subacromial impingement refers to shoulder pain resulting from mechanical impingement of the rotator cuff underneath the coracoacromial arch between the acromion and the humeral head.2,3 Subacromial impingement syndrome (SIS) is the most common cause of shoulder pain, resulting in significant functional deficits and disability.3
Treatment options for SIS include conservative modalities such as use of nonsteroidal anti-inflammatory drugs, physical therapy (PT), and subacromial corticosteroid injections (CSIs). Studies have found short- and long-term improvement in pain, function, and range of motion after CSI.4-8 Subacromial CSI can be administered through an anterior or a posterior route.4,9 There have been several studies of the accuracy of anterior and posterior CSIs,10-12 with 2 studies finding similar accuracy for these routes.10,11 However, there may be a sex difference: In women, a posterior route may be less accurate than an anterior or a lateral route.12
Although the accuracy of anterior and posterior routes has been studied, their effect on clinical outcomes has not. We conducted a study to understand the effects of anterior and posterior CSIs on SIS. As one of the accuracy studies suggested anterior CSI is more accurate—the anterior route was theorized to provide easier access to the subacromial space12—we hypothesized patients treated with anterior CSI would have superior clinical outcomes 6 months after injection.12,13
Materials and Methods
Study Participants and Randomization
After this study received Institutional Review Board approval, patients with shoulder pain of more than 3 months’ duration and consistent with SIS were screened for inclusion. Eligible patients had pain in the anterior biceps and over the top of the shoulder with overhead activities as well as one or more clinical findings on physical examination: Hawkins-Kennedy sign, Neer sign, painful arc, and infraspinatus pain (pain with external rotation).
Patients were excluded if their history included prior subacromial CSI, adhesive capsulitis (inability to passively abduct shoulder to 90° with scapular stabilization), calcific tendonitis, radiographic evidence of os acromiale, cervical radiculopathy, Spurling sign, neck pain, radiating arm pain or numbness, sensory deficits, or neck and upper extremity motor dysfunction. Also excluded were patients with full-thickness rotator cuff tear, weakness on arm elevation, positive "drop arm sign," or high-riding humerus on standing shoulder radiograph. Patients who had work-related injuries or who were involved in worker compensation were excluded as well.
Enrolled patients were randomly assigned (with use of a computer-based random number generator) to receive either anterior CSI or posterior CSI.
Injection Procedures
All patients were administered 5 mL of lidocaine 1% (without epinephrine) and 2 mL (80 mg) of triamcinolone by 2 board-certified orthopedic surgeons using a 22-gauge 1½-inch needle. For patients who received their subacromial CSI by the anterior route, the arm was held in 0° of abduction and 20° of external rotation. The needle was inserted medial to the humeral head, lateral to the coracoid process, beginning 1 cm inferior to the clavicle with the needle directed posteriorly and laterally toward the acromion.10 For patients who received their CSI by the posterior route, the arm was held in 0° of abduction, the posterolateral corner of the acromion was identified by palpation, and the needle was inserted 1 cm inferior and medial to this point with the needle directed anteriorly and laterally toward the acromion.10,12 In both groups, the subacromial space was identified when a drop in pressure was felt during needle insertion. Accuracy was assessed post hoc by asking patients to grade their response to the injection on a visual analog scale (VAS); VAS score was used as a surrogate for improvement. All patients had a positive Neer test: Pain decreased with impingement maneuvers immediately after injection.
All patients were referred for PT provided according to an evidence-based rehabilitation protocol.14 This program emphasized range of motion with shoulder shrugs, scapular retraction, and pendulum exercises; flexibility with stretching exercises targeting the anterior and posterior aspects of the shoulder and cane stretching for forward elevation and external rotation; and strength with strengthening exercises involving the rotator cuff and scapular stabilizers.
Outcome Measures
Pain was measured with VAS scores and function with Single Assessment Numeric Evaluation (SANE) scores. The VAS is a validated outcome measure of pain intensity. A numeric version of the VAS was used: Patients selected the whole number, from 0 (no pain) to 10 (worst possible pain), that best reflected their pain intensity. On SANE, another validated outcome measure, patients rated their shoulder function as a percentage of normal, from 0% (no function possible) to 100% (perfect).15 Before injection, all patients were administered the VAS and SANE questionnaires to establish their baseline pain level and opinion of shoulder function. These measures were repeated 1, 3, and 6 months after injection. Telephone interviews were conducted at 1 month and 6 months. Patients were asked to return to clinic 3 months after injection as part of the standard of care. At 3 months, 47 (86%) of the 55 patients returned for follow-up and were administered the VAS and SANE questionnaires; the other 8 completed the questionnaires by telephone. At each time point, patients were asked to report on their participation in PT and/or adherence to their home exercise program.
Statistical Analysis
Power analysis performed with Student t test and a 2-sided level of P = .05 compared VAS pain scores between the anterior and posterior injection routes and found a mean (SD) difference of 1.4 (1.7).16 Power calculations made with nQuery Advisor Version 7.0 (Statistical Solutions) indicated a total sample size of 60 patients (30/group) would provide 80% power for detecting a significant difference assuming a 20% dropout rate.
Two-way mixed-model analysis of variance (ANOVA) was used to compare the anterior and posterior routes for statistical differences in both VAS pain scores and SANE function scores at baseline and 1, 3, and 6 months after injection. Likewise, time at baseline (just before injection)was compared with follow-up (1, 3, 6 months) with 2-way mixed-model ANOVA adjusting for anterior or posterior route. Multivariate analysis was performed to evaluate differences between baseline and 6-month follow-up with respect to anterior and posterior injection routes, controlling for age, sex, and body mass index (BMI) for VAS and SANE scores. Parametric testing methods were used for statistical analysis, which was performed with IBM SPSS Statistics Version 21.0 (IBM Corp). Significance was set at P < .05.
Results
Patient Characteristics
Of the 55 patients enrolled, 25 (46%) received anterior subacromial CSI and 30 (54%) received posterior CSI. All enrolled patients had a positive Neer impingement test immediately after injection. Mean (SD) age was 48 (9.3) years for anterior group patients and 48 (9.0) years for posterior group patients. There was no significant difference in age or BMI between the 2 groups (Table).
Five patients (9%) were excluded from the study after randomization and CSI: 2 for a full-thickness rotator cuff tear, 1 for a Bankart lesion, 1 for adhesive capsulitis, and 1 for a worker compensation claim.
One month after injection, 41 patients (75%) reported having engaged in PT as prescribed. Of the 47 patients (86%) who returned for the 3-month follow-up, 25 (46%) reported having engaged in PT between 1 month and 3 months after injection. Fourteen patients (26%) reported attending PT between 3 and 6 months post-injection.
Outcome Measures
Two-way repeated-measures ANOVA with age, sex, and BMI included as covariates revealed no significant differences in VAS scores between the anterior and posterior groups at any time point (P = .45). Both groups had highly significant pain reductions (anterior, F = 9.71, P < .001; posterior, F = 13.46, P < .001). Figure 1 shows mean VAS scores and significant reductions in pain 1, 3, and 6 months after injection (see asterisks for anterior and posterior groups; P < .001 for all). The groups had parallel rates of pain reduction over time, as indicated by a nonsignificant (P = .50) difference in slopes. These pain score reductions were significant for both injection routes and were independent of age, sex, and BMI (P > .05 for all).
Two-way repeated-measures ANOVA with age, sex, and BMI included as covariates revealed no significant differences in SANE scores between the anterior and posterior groups, except for a higher mean score in the anterior group at 3 months
(P = .02). There were no other group differences (P > .10 for all). Both groups had highly significant improvements in function (anterior, F = 17.34,
P < .001; posterior, F = 13.57, P < .001). Figure 2 shows mean SANE scores and significant improvement at 1, 3, and 6 months (see asterisks for anterior and posterior groups; P < .001 for all). The groups had parallel rates of improved function over time, as indicated by a nonsignificant (P = .51) difference in slopes. These function score improvements were significant for both injection routes and were independent of age, sex, and BMI (P > .05 for all).
From the results of this prospective randomized study, we concluded subacromial CSI significantly reduces pain and improves function regardless of route used. In addition, age, sex, and BMI do not significantly affect the efficacy of either anterior CSI or posterior CSI.
Discussion
In patients with SIS, anterior CSI and posterior CSI provided significant improvements in pain and function 1, 3, and 6 months after injection. These effects were independent of age, sex, BMI, and PT participation. There were no significant differences in outcomes between injection routes.
When conservative treatments for SIS do not resolve symptoms, inflammation and pain can be reduced with use of subacromial CSI.4-8 Although clinical outcomes are inconsistent, CSI can be used to address SIS symptoms in appropriate patients. Specifically, Blair and colleagues6 found that, CSI consisting of 4 mL of lidocaine 1% (without epinephrine) and 2 mL (80 mg) of triamcinolone was effective in alleviating shoulder pain and improving shoulder range of motion. Other authors have similarly reported improved outcomes after subacromial injection and short-term follow-up with PT.4,7,8 Our findings are consistent with these reports: CSI coupled with a structured rehabilitation program is effective in alleviating symptoms associated with acute or subacute SIS.
Numerous studies have found improved clinical outcomes after anterior CSI and after posterior CSI,6-8 but no study has directly compared the clinical impact of anterior CSI with that of posterior CSI—which suggests injection route may not affect ultimate clinical outcomes.
CSI accuracy has been studied extensively.10-12,17-20 Although 2 studies found similar accuracy for anterior and posterior routes,10,11 there may be a sex difference: In women, a posterior route may be less accurate than an anterior or a lateral route.12 Collectively, these studies expose the inherent difficulty in treating shoulder pain with localized subacromial injection. Therapy may fail because of errant needle positioning. Two prospective studies found improved clinical outcomes with successful delivery of medication into the subacromial space.17,18 Poor clinical outcomes may result from inaccurate CSI.
In contrast to other clinical studies, our study found that injection route was not associated with differences in clinical response. In a prospective randomized clinical trial in which 75 patients received a subacromial injection, Marder and colleagues12 found anterior routes 84% accurate and posterior routes 56% accurate; they concluded acromion anatomy and subacromial bursa anatomy make posterior injections more difficult. As theorized by Gruson and colleagues,13 with use of an anterior route, the needle enters inferior to the concavity of the acromion and provides easier access to the subacromial space. This idea is in line with Marder and colleagues’12 conclusion that subacromial bursa anatomy provides a favorable environment for accurate CSI.
If accuracy is positively correlated with clinical improvement and anterior routes are more accurate, there should be a difference in response to posterior injections. Our results provide evidence that clinical response to CSI may not depend on injection accuracy. Perhaps merely placing the corticosteroid near the bursa is adequate for improving symptoms or perhaps some of the clinical improvement is due to the systemic effect of corticosteroids. These possibilities require further analysis.
Establishing the efficacy of CSI in SIS is difficult. The literature includes various study designs, different CSI indications and medication formulations, and varying emphasis on the role of organized PT. Rehabilitation has been found to alleviate joint pain by reducing inflammation,14 but data do not universally support this finding.21,22 Nevertheless, use of PT might explain the divergence in clinical outcomes reported by Marder and colleagues,12 who found anterior CSI more accurate than posterior CSI. In our practice, PT is recommended for all SIS patients, not only those who have CSI. Thus, our findings are framed within the context of successful CSI but may include patients who improved with PT alone. This issue raises the question of whether subacromial CSI should be guided by ultrasound. Ultrasound guidance can improve CSI accuracy and clinical outcomes,23-25 though the value of this benefit is debated.26
This study had several limitations. First, pain relief was patient reported. Second, the treatment plan involved CSI with PT but did not control for CSI used alone. PT, which is part of the standard of care for patients with SIS, added another degree of complexity to the study. Third, there may have been some variability in SIS severity (stage 1, 2, or 3). Fourth, although the study design controlled for various shoulder pathologies, advanced imaging, which could have provided diagnosis confirmation, was not available for all patients. Therefore, concurrent conditions may have confounded results. However, randomization was used to try to minimize this effect. Fifth, although injection routes were randomly assigned, the trial was not blinded. Sixth, the study was underpowered by 1 patient, as there was an estimated 20% dropout rate over 3 and 6 months of follow-up. However, we do not think our results were significantly affected.
Although more research is needed to fully describe the role of subacromial CSI in SIS, our study findings suggested that CSI using either an anterior or a posterior route creates a window of symptomatic relief in which patients may be able to engage in PT.
Conclusion
Both anterior CSI and posterior CSI significantly improved pain and function for up to 6 months. No differences were found between anterior and posterior CSIs. In the context of this study, CSI combined with structured PT produced significant improvement in pain and function in patients with SIS, regardless of injection route used. Clinicians should rely on their clinical acumen when selecting injection routes, as anterior and posterior are both beneficial.
Take-Home Points
When conservative treatments for SIS do not resolve symptoms, inflammation and pain can be reduced with use of subacromial CSI.
Both anterior CSI and posterior CSI significantly improved pain and function for up to 6 months
CSI combined with structured PT produced significant improvement in pain and function in patients with SIS, regardless of injection route used.
Clinical response to CSI may not depend on injection accuracy.
Clinicians should rely on their clinical acumen when selecting injection routes, as anterior and posterior are both beneficial.
Shoulder pain, a common clinical problem, occurs in 7% to 34% of the general population and in 21% of people older than 70 years.1Subacromial impingement refers to shoulder pain resulting from mechanical impingement of the rotator cuff underneath the coracoacromial arch between the acromion and the humeral head.2,3 Subacromial impingement syndrome (SIS) is the most common cause of shoulder pain, resulting in significant functional deficits and disability.3
Treatment options for SIS include conservative modalities such as use of nonsteroidal anti-inflammatory drugs, physical therapy (PT), and subacromial corticosteroid injections (CSIs). Studies have found short- and long-term improvement in pain, function, and range of motion after CSI.4-8 Subacromial CSI can be administered through an anterior or a posterior route.4,9 There have been several studies of the accuracy of anterior and posterior CSIs,10-12 with 2 studies finding similar accuracy for these routes.10,11 However, there may be a sex difference: In women, a posterior route may be less accurate than an anterior or a lateral route.12
Although the accuracy of anterior and posterior routes has been studied, their effect on clinical outcomes has not. We conducted a study to understand the effects of anterior and posterior CSIs on SIS. As one of the accuracy studies suggested anterior CSI is more accurate—the anterior route was theorized to provide easier access to the subacromial space12—we hypothesized patients treated with anterior CSI would have superior clinical outcomes 6 months after injection.12,13
Materials and Methods
Study Participants and Randomization
After this study received Institutional Review Board approval, patients with shoulder pain of more than 3 months’ duration and consistent with SIS were screened for inclusion. Eligible patients had pain in the anterior biceps and over the top of the shoulder with overhead activities as well as one or more clinical findings on physical examination: Hawkins-Kennedy sign, Neer sign, painful arc, and infraspinatus pain (pain with external rotation).
Patients were excluded if their history included prior subacromial CSI, adhesive capsulitis (inability to passively abduct shoulder to 90° with scapular stabilization), calcific tendonitis, radiographic evidence of os acromiale, cervical radiculopathy, Spurling sign, neck pain, radiating arm pain or numbness, sensory deficits, or neck and upper extremity motor dysfunction. Also excluded were patients with full-thickness rotator cuff tear, weakness on arm elevation, positive "drop arm sign," or high-riding humerus on standing shoulder radiograph. Patients who had work-related injuries or who were involved in worker compensation were excluded as well.
Enrolled patients were randomly assigned (with use of a computer-based random number generator) to receive either anterior CSI or posterior CSI.
Injection Procedures
All patients were administered 5 mL of lidocaine 1% (without epinephrine) and 2 mL (80 mg) of triamcinolone by 2 board-certified orthopedic surgeons using a 22-gauge 1½-inch needle. For patients who received their subacromial CSI by the anterior route, the arm was held in 0° of abduction and 20° of external rotation. The needle was inserted medial to the humeral head, lateral to the coracoid process, beginning 1 cm inferior to the clavicle with the needle directed posteriorly and laterally toward the acromion.10 For patients who received their CSI by the posterior route, the arm was held in 0° of abduction, the posterolateral corner of the acromion was identified by palpation, and the needle was inserted 1 cm inferior and medial to this point with the needle directed anteriorly and laterally toward the acromion.10,12 In both groups, the subacromial space was identified when a drop in pressure was felt during needle insertion. Accuracy was assessed post hoc by asking patients to grade their response to the injection on a visual analog scale (VAS); VAS score was used as a surrogate for improvement. All patients had a positive Neer test: Pain decreased with impingement maneuvers immediately after injection.
All patients were referred for PT provided according to an evidence-based rehabilitation protocol.14 This program emphasized range of motion with shoulder shrugs, scapular retraction, and pendulum exercises; flexibility with stretching exercises targeting the anterior and posterior aspects of the shoulder and cane stretching for forward elevation and external rotation; and strength with strengthening exercises involving the rotator cuff and scapular stabilizers.
Outcome Measures
Pain was measured with VAS scores and function with Single Assessment Numeric Evaluation (SANE) scores. The VAS is a validated outcome measure of pain intensity. A numeric version of the VAS was used: Patients selected the whole number, from 0 (no pain) to 10 (worst possible pain), that best reflected their pain intensity. On SANE, another validated outcome measure, patients rated their shoulder function as a percentage of normal, from 0% (no function possible) to 100% (perfect).15 Before injection, all patients were administered the VAS and SANE questionnaires to establish their baseline pain level and opinion of shoulder function. These measures were repeated 1, 3, and 6 months after injection. Telephone interviews were conducted at 1 month and 6 months. Patients were asked to return to clinic 3 months after injection as part of the standard of care. At 3 months, 47 (86%) of the 55 patients returned for follow-up and were administered the VAS and SANE questionnaires; the other 8 completed the questionnaires by telephone. At each time point, patients were asked to report on their participation in PT and/or adherence to their home exercise program.
Statistical Analysis
Power analysis performed with Student t test and a 2-sided level of P = .05 compared VAS pain scores between the anterior and posterior injection routes and found a mean (SD) difference of 1.4 (1.7).16 Power calculations made with nQuery Advisor Version 7.0 (Statistical Solutions) indicated a total sample size of 60 patients (30/group) would provide 80% power for detecting a significant difference assuming a 20% dropout rate.
Two-way mixed-model analysis of variance (ANOVA) was used to compare the anterior and posterior routes for statistical differences in both VAS pain scores and SANE function scores at baseline and 1, 3, and 6 months after injection. Likewise, time at baseline (just before injection)was compared with follow-up (1, 3, 6 months) with 2-way mixed-model ANOVA adjusting for anterior or posterior route. Multivariate analysis was performed to evaluate differences between baseline and 6-month follow-up with respect to anterior and posterior injection routes, controlling for age, sex, and body mass index (BMI) for VAS and SANE scores. Parametric testing methods were used for statistical analysis, which was performed with IBM SPSS Statistics Version 21.0 (IBM Corp). Significance was set at P < .05.
Results
Patient Characteristics
Of the 55 patients enrolled, 25 (46%) received anterior subacromial CSI and 30 (54%) received posterior CSI. All enrolled patients had a positive Neer impingement test immediately after injection. Mean (SD) age was 48 (9.3) years for anterior group patients and 48 (9.0) years for posterior group patients. There was no significant difference in age or BMI between the 2 groups (Table).
Five patients (9%) were excluded from the study after randomization and CSI: 2 for a full-thickness rotator cuff tear, 1 for a Bankart lesion, 1 for adhesive capsulitis, and 1 for a worker compensation claim.
One month after injection, 41 patients (75%) reported having engaged in PT as prescribed. Of the 47 patients (86%) who returned for the 3-month follow-up, 25 (46%) reported having engaged in PT between 1 month and 3 months after injection. Fourteen patients (26%) reported attending PT between 3 and 6 months post-injection.
Outcome Measures
Two-way repeated-measures ANOVA with age, sex, and BMI included as covariates revealed no significant differences in VAS scores between the anterior and posterior groups at any time point (P = .45). Both groups had highly significant pain reductions (anterior, F = 9.71, P < .001; posterior, F = 13.46, P < .001). Figure 1 shows mean VAS scores and significant reductions in pain 1, 3, and 6 months after injection (see asterisks for anterior and posterior groups; P < .001 for all). The groups had parallel rates of pain reduction over time, as indicated by a nonsignificant (P = .50) difference in slopes. These pain score reductions were significant for both injection routes and were independent of age, sex, and BMI (P > .05 for all).
Two-way repeated-measures ANOVA with age, sex, and BMI included as covariates revealed no significant differences in SANE scores between the anterior and posterior groups, except for a higher mean score in the anterior group at 3 months
(P = .02). There were no other group differences (P > .10 for all). Both groups had highly significant improvements in function (anterior, F = 17.34,
P < .001; posterior, F = 13.57, P < .001). Figure 2 shows mean SANE scores and significant improvement at 1, 3, and 6 months (see asterisks for anterior and posterior groups; P < .001 for all). The groups had parallel rates of improved function over time, as indicated by a nonsignificant (P = .51) difference in slopes. These function score improvements were significant for both injection routes and were independent of age, sex, and BMI (P > .05 for all).
From the results of this prospective randomized study, we concluded subacromial CSI significantly reduces pain and improves function regardless of route used. In addition, age, sex, and BMI do not significantly affect the efficacy of either anterior CSI or posterior CSI.
Discussion
In patients with SIS, anterior CSI and posterior CSI provided significant improvements in pain and function 1, 3, and 6 months after injection. These effects were independent of age, sex, BMI, and PT participation. There were no significant differences in outcomes between injection routes.
When conservative treatments for SIS do not resolve symptoms, inflammation and pain can be reduced with use of subacromial CSI.4-8 Although clinical outcomes are inconsistent, CSI can be used to address SIS symptoms in appropriate patients. Specifically, Blair and colleagues6 found that, CSI consisting of 4 mL of lidocaine 1% (without epinephrine) and 2 mL (80 mg) of triamcinolone was effective in alleviating shoulder pain and improving shoulder range of motion. Other authors have similarly reported improved outcomes after subacromial injection and short-term follow-up with PT.4,7,8 Our findings are consistent with these reports: CSI coupled with a structured rehabilitation program is effective in alleviating symptoms associated with acute or subacute SIS.
Numerous studies have found improved clinical outcomes after anterior CSI and after posterior CSI,6-8 but no study has directly compared the clinical impact of anterior CSI with that of posterior CSI—which suggests injection route may not affect ultimate clinical outcomes.
CSI accuracy has been studied extensively.10-12,17-20 Although 2 studies found similar accuracy for anterior and posterior routes,10,11 there may be a sex difference: In women, a posterior route may be less accurate than an anterior or a lateral route.12 Collectively, these studies expose the inherent difficulty in treating shoulder pain with localized subacromial injection. Therapy may fail because of errant needle positioning. Two prospective studies found improved clinical outcomes with successful delivery of medication into the subacromial space.17,18 Poor clinical outcomes may result from inaccurate CSI.
In contrast to other clinical studies, our study found that injection route was not associated with differences in clinical response. In a prospective randomized clinical trial in which 75 patients received a subacromial injection, Marder and colleagues12 found anterior routes 84% accurate and posterior routes 56% accurate; they concluded acromion anatomy and subacromial bursa anatomy make posterior injections more difficult. As theorized by Gruson and colleagues,13 with use of an anterior route, the needle enters inferior to the concavity of the acromion and provides easier access to the subacromial space. This idea is in line with Marder and colleagues’12 conclusion that subacromial bursa anatomy provides a favorable environment for accurate CSI.
If accuracy is positively correlated with clinical improvement and anterior routes are more accurate, there should be a difference in response to posterior injections. Our results provide evidence that clinical response to CSI may not depend on injection accuracy. Perhaps merely placing the corticosteroid near the bursa is adequate for improving symptoms or perhaps some of the clinical improvement is due to the systemic effect of corticosteroids. These possibilities require further analysis.
Establishing the efficacy of CSI in SIS is difficult. The literature includes various study designs, different CSI indications and medication formulations, and varying emphasis on the role of organized PT. Rehabilitation has been found to alleviate joint pain by reducing inflammation,14 but data do not universally support this finding.21,22 Nevertheless, use of PT might explain the divergence in clinical outcomes reported by Marder and colleagues,12 who found anterior CSI more accurate than posterior CSI. In our practice, PT is recommended for all SIS patients, not only those who have CSI. Thus, our findings are framed within the context of successful CSI but may include patients who improved with PT alone. This issue raises the question of whether subacromial CSI should be guided by ultrasound. Ultrasound guidance can improve CSI accuracy and clinical outcomes,23-25 though the value of this benefit is debated.26
This study had several limitations. First, pain relief was patient reported. Second, the treatment plan involved CSI with PT but did not control for CSI used alone. PT, which is part of the standard of care for patients with SIS, added another degree of complexity to the study. Third, there may have been some variability in SIS severity (stage 1, 2, or 3). Fourth, although the study design controlled for various shoulder pathologies, advanced imaging, which could have provided diagnosis confirmation, was not available for all patients. Therefore, concurrent conditions may have confounded results. However, randomization was used to try to minimize this effect. Fifth, although injection routes were randomly assigned, the trial was not blinded. Sixth, the study was underpowered by 1 patient, as there was an estimated 20% dropout rate over 3 and 6 months of follow-up. However, we do not think our results were significantly affected.
Although more research is needed to fully describe the role of subacromial CSI in SIS, our study findings suggested that CSI using either an anterior or a posterior route creates a window of symptomatic relief in which patients may be able to engage in PT.
Conclusion
Both anterior CSI and posterior CSI significantly improved pain and function for up to 6 months. No differences were found between anterior and posterior CSIs. In the context of this study, CSI combined with structured PT produced significant improvement in pain and function in patients with SIS, regardless of injection route used. Clinicians should rely on their clinical acumen when selecting injection routes, as anterior and posterior are both beneficial.
1. Buchbinder R, Green S, Youd JM. Corticosteroid injections for shoulder pain. Cochrane Database Syst Rev. 2003;(1):CD004016.
2. Bell AD, Conaway D. Corticosteroid injections for painful shoulders. Int J Clin Pract. 2005;59(10):1178-1186.
3. Michener LA, McClure PW, Karduna AR. Anatomical and biomechanical mechanisms of subacromial impingement syndrome. Clin Biomech. 2003;18(5):369-379.
4. Akgün K, Birtane M, Akarirmak U. Is local subacromial corticosteroid injection beneficial in subacromial impingement syndrome? Clin Rheumatol. 2004;23(6):496-500.
5. Bhagra A, Syed H, Reed DA, et al. Efficacy of musculoskeletal injections by primary care providers in the office: a retrospective cohort study. Int J Gen Med. 2013;6:237-243.
6. Blair B, Rokito AS, Cuomo F, Jarolem K, Zuckerman JD. Efficacy of injections of corticosteroids for subacromial impingement syndrome. J Bone Joint Surg Am. 1996;78(11):1685-1689.
7. Cummins CA, Sasso LM, Nicholson D. Impingement syndrome: temporal outcomes of nonoperative treatment.
J Shoulder Elbow Surg. 2009;18(2):172-177.
8. Yu C, Chen CH, Liu HT, Dai MH, Wang IC, Wang KC. Subacromial injections of corticosteroids and Xylocaine for painful subacromial impingement syndrome. Chang Gung Med J. 2006;29(5):474-478.
9. Codsi MJ. The painful shoulder: when to inject and when to refer. Cleve Clin J Med. 2007;74(7):473-474, 477-478, 480-482 passim.
10. Henkus HE, Cobben LP, Coerkamp EG, Nelissen RG, van Arkel ER. The accuracy of subacromial injections: a prospective randomized magnetic resonance imaging study. Arthroscopy. 2006;22(3):277-282.
11. Kang MN, Rizio L, Prybicien M, Middlemas DA, Blacksin MF. The accuracy of subacromial corticosteroid injections: a comparison of multiple methods. J Shoulder Elbow Surg. 2008;17(15):61S-66S.
12. Marder RA, Kim SH, Labson JD, Hunter JC. Injection of the subacromial bursa in patients with rotator cuff syndrome: a prospective, randomized study comparing the effectiveness of different routes. J Bone Joint Surg Am. 2012;94(16):
1442-1447.
13. Gruson, KI, Ruchelsman DE, Zuckerman JD. Subacromial corticosteroid injections. J Shoulder Elbow Surg. 2008;17(1 suppl):118S-130S.
14. Kuhn JE. Exercise in the treatment of rotator cuff impingement: a systematic review and a synthesized evidence-based rehabilitation protocol. J Shoulder Elbow Surg. 2009;18(1):138-160.
15. Williams GN, Gangel TJ, Arciero RA, Uhorchak JM, Taylor DC. Comparison of the Single Assessment Numeric Evaluation method and two shoulder rating scales. Outcomes measures after shoulder surgery. Am J Sports Med. 1999;27(2):214-221.
16. Tashjian RZ, Deloach J, Porucznik CA, Powell AP. Minimal clinically important differences (MCID) and patient acceptable symptomatic state (PASS) for visual analog scales (VAS) measuring pain in patients treated for rotator cuff disease.
J Shoulder Elbow Surg. 2009;88(6):927-932.
17. Eustace JA, Brophy DP, Gibney RP, Bresnihan B, FitzGerald O. Comparison of the accuracy of steroid placement with clinical outcome in patients with shoulder symptoms. Ann Rheum Dis. 1997;56(1):59-63.
18. Esenyel CZ, Esenyel M, Yeiltepe R, et al. The correlation between the accuracy of steroid injections and subsequent shoulder pain and function in subacromial impingement
syndrome [in Turkish]. Acta Orthop Traumatol Turc. 2003;37(1):
41-45.
19. Powell SE, Davis SM, Lee EH, et al. Accuracy of palpation-directed intra-articular glenohumeral injection confirmed by magnetic resonance arthrography. Arthroscopy. 2015;31(2):205-208.
20. Rutten MJ, Maresch BJ, Jager GJ, de Waal Malefijt MC. Injection of the subacromial-subdeltoid bursa: blind or ultrasound-guided? Acta Orthop. 2007;78(2):254-257.
21. Desmeules F, Côté CH, Frémont P. Therapeutic exercise and orthopedic manual therapy for impingement syndrome: a systematic review. Clin J Sport Med. 2003;13(3):176-182.
22. Winters JC, Sobel JS, Groenier KH, Arendzen HJ, Meyboom-de Jong B. Comparison of physiotherapy, manipulation, and corticosteroid injection for treating shoulder complaints in general practice: randomised, single blind study. BMJ. 1997;314(7090):1320-1325.
23. Chen MJ, Lew HL, Hsu TC, et al. Ultrasound-guided shoulder injections in the treatment of subacromial bursitis. Am J Phys Med Rehabil. 2006;85(1):31-35.
24. Hsieh LF, Hsu WC, Lin YJ, Wu SH, Chang KC, Chang HL. Is ultrasound-guided injection more effective in chronic subacromial bursitis? Med Sci Sports Exerc. 2013;45(12):
2205-2213.
25. Naredo E, Cabero F, Beneyto P, et al. A randomized comparative study of short term response to blind injection versus sonographic-guided injection of local corticosteroids in patients with painful shoulder. J Rheumatol. 2004;31(2):308-314.
26. Hall S, Buchbinder R. Do imaging methods that guide needle placement improve outcome? Ann Rheum Dis. 2004;63(9):1007-1008.
1. Buchbinder R, Green S, Youd JM. Corticosteroid injections for shoulder pain. Cochrane Database Syst Rev. 2003;(1):CD004016.
2. Bell AD, Conaway D. Corticosteroid injections for painful shoulders. Int J Clin Pract. 2005;59(10):1178-1186.
3. Michener LA, McClure PW, Karduna AR. Anatomical and biomechanical mechanisms of subacromial impingement syndrome. Clin Biomech. 2003;18(5):369-379.
4. Akgün K, Birtane M, Akarirmak U. Is local subacromial corticosteroid injection beneficial in subacromial impingement syndrome? Clin Rheumatol. 2004;23(6):496-500.
5. Bhagra A, Syed H, Reed DA, et al. Efficacy of musculoskeletal injections by primary care providers in the office: a retrospective cohort study. Int J Gen Med. 2013;6:237-243.
6. Blair B, Rokito AS, Cuomo F, Jarolem K, Zuckerman JD. Efficacy of injections of corticosteroids for subacromial impingement syndrome. J Bone Joint Surg Am. 1996;78(11):1685-1689.
7. Cummins CA, Sasso LM, Nicholson D. Impingement syndrome: temporal outcomes of nonoperative treatment.
J Shoulder Elbow Surg. 2009;18(2):172-177.
8. Yu C, Chen CH, Liu HT, Dai MH, Wang IC, Wang KC. Subacromial injections of corticosteroids and Xylocaine for painful subacromial impingement syndrome. Chang Gung Med J. 2006;29(5):474-478.
9. Codsi MJ. The painful shoulder: when to inject and when to refer. Cleve Clin J Med. 2007;74(7):473-474, 477-478, 480-482 passim.
10. Henkus HE, Cobben LP, Coerkamp EG, Nelissen RG, van Arkel ER. The accuracy of subacromial injections: a prospective randomized magnetic resonance imaging study. Arthroscopy. 2006;22(3):277-282.
11. Kang MN, Rizio L, Prybicien M, Middlemas DA, Blacksin MF. The accuracy of subacromial corticosteroid injections: a comparison of multiple methods. J Shoulder Elbow Surg. 2008;17(15):61S-66S.
12. Marder RA, Kim SH, Labson JD, Hunter JC. Injection of the subacromial bursa in patients with rotator cuff syndrome: a prospective, randomized study comparing the effectiveness of different routes. J Bone Joint Surg Am. 2012;94(16):
1442-1447.
13. Gruson, KI, Ruchelsman DE, Zuckerman JD. Subacromial corticosteroid injections. J Shoulder Elbow Surg. 2008;17(1 suppl):118S-130S.
14. Kuhn JE. Exercise in the treatment of rotator cuff impingement: a systematic review and a synthesized evidence-based rehabilitation protocol. J Shoulder Elbow Surg. 2009;18(1):138-160.
15. Williams GN, Gangel TJ, Arciero RA, Uhorchak JM, Taylor DC. Comparison of the Single Assessment Numeric Evaluation method and two shoulder rating scales. Outcomes measures after shoulder surgery. Am J Sports Med. 1999;27(2):214-221.
16. Tashjian RZ, Deloach J, Porucznik CA, Powell AP. Minimal clinically important differences (MCID) and patient acceptable symptomatic state (PASS) for visual analog scales (VAS) measuring pain in patients treated for rotator cuff disease.
J Shoulder Elbow Surg. 2009;88(6):927-932.
17. Eustace JA, Brophy DP, Gibney RP, Bresnihan B, FitzGerald O. Comparison of the accuracy of steroid placement with clinical outcome in patients with shoulder symptoms. Ann Rheum Dis. 1997;56(1):59-63.
18. Esenyel CZ, Esenyel M, Yeiltepe R, et al. The correlation between the accuracy of steroid injections and subsequent shoulder pain and function in subacromial impingement
syndrome [in Turkish]. Acta Orthop Traumatol Turc. 2003;37(1):
41-45.
19. Powell SE, Davis SM, Lee EH, et al. Accuracy of palpation-directed intra-articular glenohumeral injection confirmed by magnetic resonance arthrography. Arthroscopy. 2015;31(2):205-208.
20. Rutten MJ, Maresch BJ, Jager GJ, de Waal Malefijt MC. Injection of the subacromial-subdeltoid bursa: blind or ultrasound-guided? Acta Orthop. 2007;78(2):254-257.
21. Desmeules F, Côté CH, Frémont P. Therapeutic exercise and orthopedic manual therapy for impingement syndrome: a systematic review. Clin J Sport Med. 2003;13(3):176-182.
22. Winters JC, Sobel JS, Groenier KH, Arendzen HJ, Meyboom-de Jong B. Comparison of physiotherapy, manipulation, and corticosteroid injection for treating shoulder complaints in general practice: randomised, single blind study. BMJ. 1997;314(7090):1320-1325.
23. Chen MJ, Lew HL, Hsu TC, et al. Ultrasound-guided shoulder injections in the treatment of subacromial bursitis. Am J Phys Med Rehabil. 2006;85(1):31-35.
24. Hsieh LF, Hsu WC, Lin YJ, Wu SH, Chang KC, Chang HL. Is ultrasound-guided injection more effective in chronic subacromial bursitis? Med Sci Sports Exerc. 2013;45(12):
2205-2213.
25. Naredo E, Cabero F, Beneyto P, et al. A randomized comparative study of short term response to blind injection versus sonographic-guided injection of local corticosteroids in patients with painful shoulder. J Rheumatol. 2004;31(2):308-314.
26. Hall S, Buchbinder R. Do imaging methods that guide needle placement improve outcome? Ann Rheum Dis. 2004;63(9):1007-1008.
