John J. Christoforetti, MD

Take-Home Points

• Surface landmarks are routinely used for physical examination and surgical technique.
• Common surface landmarks used in establishing arthroscopic portals may be more difficult to accurately identify than previously thought.
• The greater trochanter was the surface landmark most precisely identified by expert examiners.
• Ultrasound examination identified landmarks varied from landmarks identified by palpation alone.

Anatomical surface landmarks about the hip and lower abdomen are often referenced when placing arthroscopic portals and office-based injections.^1-3 However, the degree to which these landmarks can be reproducibly identified using only visual inspection and palpation is unknown.

Safe access to the hip joint and surrounding structures during hip arthroscopy has been a focus in the orthopedic literature. Authors have described anatomical relationships of recommended portals to neurovascular and other anatomical structures.^4-6 This information has been reported in millimeters to centimeters of safety based on cadaver dissection studies.^4-7We conducted a study to assess expert hip arthroscopists’ ability to identify, using only physical examination techniques, the anatomical structures used for reference when creating safe starting points for arthroscopic access. We hypothesized that variance in examiner-identified points would exceed safe distances from neurovascular structures for the most commonly used hip arthroscopic portals. The volunteer in this study provided written informed consent for print and electronic publication of this article.

Methods

In this study, we prospectively assessed 30 expert hip arthroscopic surgeons’ ability to identify commonly referenced surface landmarks on the adult male hip, using only inspection and manual palpation. Surgeons were defined as experts on the basis of their status as hip arthroscopy instructors at the Orthopaedic Learning Center (Rosemont, IL) for the Arthroscopy Association of North America and industry-sponsored hip arthroscopy education faculty (Arthrex). Five surface landmarks were selected for their relevance to publications on safe portal placement^2-5: anterior superior iliac spine (ASIS), tip of greater trochanter (GT), rectus origin (RO), superficial inguinal ring (SIR), and psoas tendon (PT).

A healthy adult male volunteer was placed supine on an examination table and exposed distally from the mid abdomen, with the perineum and the genital area covered bikini-style. An expert musculoskeletal ultrasonographer used a handheld musculoskeletal ultrasound transducer (Sonosite) to identify the 5 landmarks. Short- and long-axis images of each structure were obtained. The examiner applied a round (1 cm in diameter), uniquely colored adhesive label to the skin over each location. A professional photographer using a Canon digital camera and fixed mounts made precise overhead and lateral images. The positional integrity and scale of these images were confirmed with referral to constant anatomical skin features. Images were archived for analysis (Figure 1A).

After the ultrasonographer’s labels were removed, each of the 30 expert hip arthroscopic surgeons identified the structures by static physical examination (inspection and palpation only) and applied the same colored labels to the skin.

The volunteer was not allowed to communicate about label placement with examiners but was encouraged to report any safety-related concerns. The photographer made the same digital photographs of the labels for each examiner as for the ultrasonographer (Figure 1B).

Imaging software (Adobe Photoshop Creative Suite 5.1) was used to superimpose the digital images of the examiner labels on those of the ultrasound-verified anatomical labels (Figure 1C). Measurements were then taken with digital calipers to determine average distance from ultrasound label; accuracy within 10 mm of verified ultrasound label; true average location (TAL) determined by 95% confidence interval (CI); and interobserver variability calculated by 95% prediction interval, which determined the probability of where an additional examiner data point would lie.

In the second arm of the study, examiner data were compared with previously published data on arthroscopic portal safety.

Distances from surface landmarks have been used to create common arthroscopy portals.^2-4 The risk of neurovascular injury resulting from errors in identifying surface landmarks for creating portals was calculated using the direction and distance of the examiner TAL and the nearest published direction and distance of the nearest neurovascular structure. Increased risk of injury resulting from inaccurate identification of surface landmarks was surmised if the TAL of the anatomical structure fell outside the safe distance and direction to the nearest neurovascular structure for each of 4 common portals: anterolateral portal (ALP), anterior portal (AP), posterolateral portal (PLP), and mid-anterior portal (MAP).

Results

Average absolute distance from examiner labels to ultrasonographer labels was 31 mm for ASIS, 24 mm for GT, 26 mm for RO, 19 mm for SIR, and 35 mm for PT (Figure 2).

 

Of the 30 surgeons, 1 (3%) came within 10 mm of the ultrasound for ASIS, 1 (3%) for GT, 4 (13%) for RO, 5 (17%) for SIR, and 1 (3%) for PT (Table 1).

TAL as determined by CI was 16 mm medial and 29 mm inferior for ASIS; 8 mm anterior and 22 mm superior for GT; 10 mm medial and 25 mm inferior for RO; 5 mm lateral and 5 mm inferior for SIR; and 28 mm medial and 16 mm inferior for PT (Figure 3, Table 2). Interobserver variability determined by prediction interval had a range of 18 mm medial to lateral × 36 mm proximal to distal for ASIS; 33 mm anterior to posterior × 48 mm superior to inferior for GT; 41 mm medial to distal × 54 mm proximal to distal for RO; 51 mm medial to lateral × 74 mm proximal to distal for SIR; and 49 mm medial to distal × 61 mm proximal to distal for PT.

Given the difference between examiner data (direction and distance from ultrasound labels) and published data (distance to significant neurovascular structures), inaccurate identification of surface landmarks has the potential to lead to AP and MAP damage (Table 3). The examiner GT and ASIS surface landmarks used for AP overlapped directly with the safe distances for the lateral femoral cutaneous nerve and the terminal branch of the lateral circumflex femoral artery.

Discussion

Others have investigated examiners’ use of palpation, compared with ultrasound, to identify common shoulder and knee structures.^8-10 In a 2011 systematic review, Gilliland and colleagues¹¹ confirmed that accuracy was improved with use of ultrasound (vs palpation) for injections in the shoulder, hip, knee, wrist, and ankle. Given the scarcity of data in this setting, we conducted the present study to assess the precision and accuracy of expert arthroscopists in identifying common surface landmarks. We hypothesized that physical examination and ultrasound examination would differ significantly in precisely and accurately identifying these landmarks.

Working with a standard awake volunteer, our test group of examiners was consistently inaccurate when they accepted ultrasonographer-placed labels as the ideal. Precision within the group, however, trended toward close agreement; examiners consistently placed labels in the same direction and approximate magnitude away from ultrasonographer labels. This suggests that a discrepancy between the ultrasonographic surface structure definitions taught to ultrasonographers and the manually identified definitions taught to surgeons for arthroscopy (training bias) can generate differences in landmark identification.

Given reported low rates of complications in the creation of standard surface anatomy portals, more data is needed to correlate whether safe distance guidelines best apply to the points identified by hip experts or the points identified by ultrasonographers. In a 2013 systematic review, Harris and colleagues⁸ found a 7.5% overall complication rate, with temporary neuropraxia 1 of the 2 most common complications. Whether adding ultrasound to physical examination for the creation of some or all portals will reduce the incidence of these problems is unknown. Regardless of the anatomical area referenced by experts for portal creation, the tight grouping of examiner marks in our study supports a consensus regarding the location of the landmarks studied.

In our study of the use of surface anatomical landmarks for the creation of portals, we analyzed 4 previously described locations: ALP, AP, PLP, and MAP. ALP, AP, and PLP directly reference at least 1 surface anatomical structure; AP references 2 anatomical structures (ASIS, GT); and MAP indirectly references ASIS and GT and directly references ALP and AP. In cadaveric and radiographic studies, 7 neurovascular structures have been described in proximity to ALP, AP, MAP, and PLP: superior gluteal nerve, sciatic nerve, femoral nerve, lateral femoral cutaneous nerve, lateral circumflex femoral artery, and medial circumflex femoral artery.^5,6 Our results showed that use of surface anatomy in AP and MAP creation most likely places structures at risk, given the overlap of examiner CIs and the previously published cadaveric^5,6 and radiographic⁷ data.

Hua and colleagues¹² confirmed the feasibility of using ultrasound for the creation of hip arthroscopy portals. More data is needed to assess how the standard palpation-and-fluoroscopy method described by Byrd³ compares with an ultrasound-guided technique in safety and cost. However, data from our study should not be used to justify a demand for ultrasound during arthroscopy portal establishment, as limitations do not permit such a recommendation.

With diagnostic injection remaining a mainstay of differential diagnosis and treatment about the hip,¹ the data presented here suggest a potential for ultrasound in enhancing outcomes. There is evidence supporting the role of image guidance in improving palpation accuracy in the area of the biceps tendon in the forearm.¹⁰ Potentially, identification and treatment of specific extra-articular structures surrounding the hip could be made safer with more routine use of ultrasound.

 

Limitations

This study had several limitations. The surgeons were limited to palpation and static examination of a body in its natural state. Hip arthroscopic portals typically are created under traction and after a standard perineal post is placed for hip arthroscopy. In addition, in an awake injection setting, the clinician may receive patient feedback in the form of limb movement or speech. To what degree palpation or ultrasound will be affected in these scenarios is unknown.

Another limitation is the lack of serial examination by each examiner—intrarater variability could not be gauged. In addition, with only 1 ultrasonographic examination performed, there is the potential that adding ultrasonographic examinations, or having an examiner perform serial physical examinations, could better define the precision of each component. Given the practical limitations of our volunteer’s time and the schedules of 30 expert arthroscopists, we kept the chosen study design for its single setting.

Conclusion

Visual inspection and manual palpation are standard means of identifying common surface anatomical landmarks for the creation of arthroscopy portals and the placement of injections. Our study results showed variance in landmark identification between expert examiners and an ultrasonographer. The degree of variance exceeded established neurovascular safe zones, particularly for AP and MAP. This new evidence calls for further investigation into the best, safest means of performing hip arthroscopic techniques and injection-based interventions.

Am J Orthop. 2017;46(1):E65-E70. Copyright Frontline Medical Communications Inc. 2017. All rights reserved.

Take-Home Points

• Surface landmarks are routinely used for physical examination and surgical technique.
• Common surface landmarks used in establishing arthroscopic portals may be more difficult to accurately identify than previously thought.
• The greater trochanter was the surface landmark most precisely identified by expert examiners.
• Ultrasound examination identified landmarks varied from landmarks identified by palpation alone.

Anatomical surface landmarks about the hip and lower abdomen are often referenced when placing arthroscopic portals and office-based injections.^1-3 However, the degree to which these landmarks can be reproducibly identified using only visual inspection and palpation is unknown.

Safe access to the hip joint and surrounding structures during hip arthroscopy has been a focus in the orthopedic literature. Authors have described anatomical relationships of recommended portals to neurovascular and other anatomical structures.^4-6 This information has been reported in millimeters to centimeters of safety based on cadaver dissection studies.^4-7We conducted a study to assess expert hip arthroscopists’ ability to identify, using only physical examination techniques, the anatomical structures used for reference when creating safe starting points for arthroscopic access. We hypothesized that variance in examiner-identified points would exceed safe distances from neurovascular structures for the most commonly used hip arthroscopic portals. The volunteer in this study provided written informed consent for print and electronic publication of this article.

Methods

In this study, we prospectively assessed 30 expert hip arthroscopic surgeons’ ability to identify commonly referenced surface landmarks on the adult male hip, using only inspection and manual palpation. Surgeons were defined as experts on the basis of their status as hip arthroscopy instructors at the Orthopaedic Learning Center (Rosemont, IL) for the Arthroscopy Association of North America and industry-sponsored hip arthroscopy education faculty (Arthrex). Five surface landmarks were selected for their relevance to publications on safe portal placement^2-5: anterior superior iliac spine (ASIS), tip of greater trochanter (GT), rectus origin (RO), superficial inguinal ring (SIR), and psoas tendon (PT).

A healthy adult male volunteer was placed supine on an examination table and exposed distally from the mid abdomen, with the perineum and the genital area covered bikini-style. An expert musculoskeletal ultrasonographer used a handheld musculoskeletal ultrasound transducer (Sonosite) to identify the 5 landmarks. Short- and long-axis images of each structure were obtained. The examiner applied a round (1 cm in diameter), uniquely colored adhesive label to the skin over each location. A professional photographer using a Canon digital camera and fixed mounts made precise overhead and lateral images. The positional integrity and scale of these images were confirmed with referral to constant anatomical skin features. Images were archived for analysis (Figure 1A).

After the ultrasonographer’s labels were removed, each of the 30 expert hip arthroscopic surgeons identified the structures by static physical examination (inspection and palpation only) and applied the same colored labels to the skin.

The volunteer was not allowed to communicate about label placement with examiners but was encouraged to report any safety-related concerns. The photographer made the same digital photographs of the labels for each examiner as for the ultrasonographer (Figure 1B).

Imaging software (Adobe Photoshop Creative Suite 5.1) was used to superimpose the digital images of the examiner labels on those of the ultrasound-verified anatomical labels (Figure 1C). Measurements were then taken with digital calipers to determine average distance from ultrasound label; accuracy within 10 mm of verified ultrasound label; true average location (TAL) determined by 95% confidence interval (CI); and interobserver variability calculated by 95% prediction interval, which determined the probability of where an additional examiner data point would lie.

In the second arm of the study, examiner data were compared with previously published data on arthroscopic portal safety.

Distances from surface landmarks have been used to create common arthroscopy portals.^2-4 The risk of neurovascular injury resulting from errors in identifying surface landmarks for creating portals was calculated using the direction and distance of the examiner TAL and the nearest published direction and distance of the nearest neurovascular structure. Increased risk of injury resulting from inaccurate identification of surface landmarks was surmised if the TAL of the anatomical structure fell outside the safe distance and direction to the nearest neurovascular structure for each of 4 common portals: anterolateral portal (ALP), anterior portal (AP), posterolateral portal (PLP), and mid-anterior portal (MAP).

Results

Average absolute distance from examiner labels to ultrasonographer labels was 31 mm for ASIS, 24 mm for GT, 26 mm for RO, 19 mm for SIR, and 35 mm for PT (Figure 2).

 

Of the 30 surgeons, 1 (3%) came within 10 mm of the ultrasound for ASIS, 1 (3%) for GT, 4 (13%) for RO, 5 (17%) for SIR, and 1 (3%) for PT (Table 1).

TAL as determined by CI was 16 mm medial and 29 mm inferior for ASIS; 8 mm anterior and 22 mm superior for GT; 10 mm medial and 25 mm inferior for RO; 5 mm lateral and 5 mm inferior for SIR; and 28 mm medial and 16 mm inferior for PT (Figure 3, Table 2). Interobserver variability determined by prediction interval had a range of 18 mm medial to lateral × 36 mm proximal to distal for ASIS; 33 mm anterior to posterior × 48 mm superior to inferior for GT; 41 mm medial to distal × 54 mm proximal to distal for RO; 51 mm medial to lateral × 74 mm proximal to distal for SIR; and 49 mm medial to distal × 61 mm proximal to distal for PT.

Given the difference between examiner data (direction and distance from ultrasound labels) and published data (distance to significant neurovascular structures), inaccurate identification of surface landmarks has the potential to lead to AP and MAP damage (Table 3). The examiner GT and ASIS surface landmarks used for AP overlapped directly with the safe distances for the lateral femoral cutaneous nerve and the terminal branch of the lateral circumflex femoral artery.

Discussion

Others have investigated examiners’ use of palpation, compared with ultrasound, to identify common shoulder and knee structures.^8-10 In a 2011 systematic review, Gilliland and colleagues¹¹ confirmed that accuracy was improved with use of ultrasound (vs palpation) for injections in the shoulder, hip, knee, wrist, and ankle. Given the scarcity of data in this setting, we conducted the present study to assess the precision and accuracy of expert arthroscopists in identifying common surface landmarks. We hypothesized that physical examination and ultrasound examination would differ significantly in precisely and accurately identifying these landmarks.

Working with a standard awake volunteer, our test group of examiners was consistently inaccurate when they accepted ultrasonographer-placed labels as the ideal. Precision within the group, however, trended toward close agreement; examiners consistently placed labels in the same direction and approximate magnitude away from ultrasonographer labels. This suggests that a discrepancy between the ultrasonographic surface structure definitions taught to ultrasonographers and the manually identified definitions taught to surgeons for arthroscopy (training bias) can generate differences in landmark identification.

Given reported low rates of complications in the creation of standard surface anatomy portals, more data is needed to correlate whether safe distance guidelines best apply to the points identified by hip experts or the points identified by ultrasonographers. In a 2013 systematic review, Harris and colleagues⁸ found a 7.5% overall complication rate, with temporary neuropraxia 1 of the 2 most common complications. Whether adding ultrasound to physical examination for the creation of some or all portals will reduce the incidence of these problems is unknown. Regardless of the anatomical area referenced by experts for portal creation, the tight grouping of examiner marks in our study supports a consensus regarding the location of the landmarks studied.

In our study of the use of surface anatomical landmarks for the creation of portals, we analyzed 4 previously described locations: ALP, AP, PLP, and MAP. ALP, AP, and PLP directly reference at least 1 surface anatomical structure; AP references 2 anatomical structures (ASIS, GT); and MAP indirectly references ASIS and GT and directly references ALP and AP. In cadaveric and radiographic studies, 7 neurovascular structures have been described in proximity to ALP, AP, MAP, and PLP: superior gluteal nerve, sciatic nerve, femoral nerve, lateral femoral cutaneous nerve, lateral circumflex femoral artery, and medial circumflex femoral artery.^5,6 Our results showed that use of surface anatomy in AP and MAP creation most likely places structures at risk, given the overlap of examiner CIs and the previously published cadaveric^5,6 and radiographic⁷ data.

Hua and colleagues¹² confirmed the feasibility of using ultrasound for the creation of hip arthroscopy portals. More data is needed to assess how the standard palpation-and-fluoroscopy method described by Byrd³ compares with an ultrasound-guided technique in safety and cost. However, data from our study should not be used to justify a demand for ultrasound during arthroscopy portal establishment, as limitations do not permit such a recommendation.

With diagnostic injection remaining a mainstay of differential diagnosis and treatment about the hip,¹ the data presented here suggest a potential for ultrasound in enhancing outcomes. There is evidence supporting the role of image guidance in improving palpation accuracy in the area of the biceps tendon in the forearm.¹⁰ Potentially, identification and treatment of specific extra-articular structures surrounding the hip could be made safer with more routine use of ultrasound.

 

Limitations

This study had several limitations. The surgeons were limited to palpation and static examination of a body in its natural state. Hip arthroscopic portals typically are created under traction and after a standard perineal post is placed for hip arthroscopy. In addition, in an awake injection setting, the clinician may receive patient feedback in the form of limb movement or speech. To what degree palpation or ultrasound will be affected in these scenarios is unknown.

Another limitation is the lack of serial examination by each examiner—intrarater variability could not be gauged. In addition, with only 1 ultrasonographic examination performed, there is the potential that adding ultrasonographic examinations, or having an examiner perform serial physical examinations, could better define the precision of each component. Given the practical limitations of our volunteer’s time and the schedules of 30 expert arthroscopists, we kept the chosen study design for its single setting.

Conclusion

Visual inspection and manual palpation are standard means of identifying common surface anatomical landmarks for the creation of arthroscopy portals and the placement of injections. Our study results showed variance in landmark identification between expert examiners and an ultrasonographer. The degree of variance exceeded established neurovascular safe zones, particularly for AP and MAP. This new evidence calls for further investigation into the best, safest means of performing hip arthroscopic techniques and injection-based interventions.

Am J Orthop. 2017;46(1):E65-E70. Copyright Frontline Medical Communications Inc. 2017. All rights reserved.

Take-Home Points

• Surface landmarks are routinely used for physical examination and surgical technique.
• Common surface landmarks used in establishing arthroscopic portals may be more difficult to accurately identify than previously thought.
• The greater trochanter was the surface landmark most precisely identified by expert examiners.
• Ultrasound examination identified landmarks varied from landmarks identified by palpation alone.

Anatomical surface landmarks about the hip and lower abdomen are often referenced when placing arthroscopic portals and office-based injections.^1-3 However, the degree to which these landmarks can be reproducibly identified using only visual inspection and palpation is unknown.

Safe access to the hip joint and surrounding structures during hip arthroscopy has been a focus in the orthopedic literature. Authors have described anatomical relationships of recommended portals to neurovascular and other anatomical structures.^4-6 This information has been reported in millimeters to centimeters of safety based on cadaver dissection studies.^4-7We conducted a study to assess expert hip arthroscopists’ ability to identify, using only physical examination techniques, the anatomical structures used for reference when creating safe starting points for arthroscopic access. We hypothesized that variance in examiner-identified points would exceed safe distances from neurovascular structures for the most commonly used hip arthroscopic portals. The volunteer in this study provided written informed consent for print and electronic publication of this article.

Methods

In this study, we prospectively assessed 30 expert hip arthroscopic surgeons’ ability to identify commonly referenced surface landmarks on the adult male hip, using only inspection and manual palpation. Surgeons were defined as experts on the basis of their status as hip arthroscopy instructors at the Orthopaedic Learning Center (Rosemont, IL) for the Arthroscopy Association of North America and industry-sponsored hip arthroscopy education faculty (Arthrex). Five surface landmarks were selected for their relevance to publications on safe portal placement^2-5: anterior superior iliac spine (ASIS), tip of greater trochanter (GT), rectus origin (RO), superficial inguinal ring (SIR), and psoas tendon (PT).

A healthy adult male volunteer was placed supine on an examination table and exposed distally from the mid abdomen, with the perineum and the genital area covered bikini-style. An expert musculoskeletal ultrasonographer used a handheld musculoskeletal ultrasound transducer (Sonosite) to identify the 5 landmarks. Short- and long-axis images of each structure were obtained. The examiner applied a round (1 cm in diameter), uniquely colored adhesive label to the skin over each location. A professional photographer using a Canon digital camera and fixed mounts made precise overhead and lateral images. The positional integrity and scale of these images were confirmed with referral to constant anatomical skin features. Images were archived for analysis (Figure 1A).

After the ultrasonographer’s labels were removed, each of the 30 expert hip arthroscopic surgeons identified the structures by static physical examination (inspection and palpation only) and applied the same colored labels to the skin.

The volunteer was not allowed to communicate about label placement with examiners but was encouraged to report any safety-related concerns. The photographer made the same digital photographs of the labels for each examiner as for the ultrasonographer (Figure 1B).

Imaging software (Adobe Photoshop Creative Suite 5.1) was used to superimpose the digital images of the examiner labels on those of the ultrasound-verified anatomical labels (Figure 1C). Measurements were then taken with digital calipers to determine average distance from ultrasound label; accuracy within 10 mm of verified ultrasound label; true average location (TAL) determined by 95% confidence interval (CI); and interobserver variability calculated by 95% prediction interval, which determined the probability of where an additional examiner data point would lie.

In the second arm of the study, examiner data were compared with previously published data on arthroscopic portal safety.

Distances from surface landmarks have been used to create common arthroscopy portals.^2-4 The risk of neurovascular injury resulting from errors in identifying surface landmarks for creating portals was calculated using the direction and distance of the examiner TAL and the nearest published direction and distance of the nearest neurovascular structure. Increased risk of injury resulting from inaccurate identification of surface landmarks was surmised if the TAL of the anatomical structure fell outside the safe distance and direction to the nearest neurovascular structure for each of 4 common portals: anterolateral portal (ALP), anterior portal (AP), posterolateral portal (PLP), and mid-anterior portal (MAP).

Results

Average absolute distance from examiner labels to ultrasonographer labels was 31 mm for ASIS, 24 mm for GT, 26 mm for RO, 19 mm for SIR, and 35 mm for PT (Figure 2).

 

Of the 30 surgeons, 1 (3%) came within 10 mm of the ultrasound for ASIS, 1 (3%) for GT, 4 (13%) for RO, 5 (17%) for SIR, and 1 (3%) for PT (Table 1).

TAL as determined by CI was 16 mm medial and 29 mm inferior for ASIS; 8 mm anterior and 22 mm superior for GT; 10 mm medial and 25 mm inferior for RO; 5 mm lateral and 5 mm inferior for SIR; and 28 mm medial and 16 mm inferior for PT (Figure 3, Table 2). Interobserver variability determined by prediction interval had a range of 18 mm medial to lateral × 36 mm proximal to distal for ASIS; 33 mm anterior to posterior × 48 mm superior to inferior for GT; 41 mm medial to distal × 54 mm proximal to distal for RO; 51 mm medial to lateral × 74 mm proximal to distal for SIR; and 49 mm medial to distal × 61 mm proximal to distal for PT.

Given the difference between examiner data (direction and distance from ultrasound labels) and published data (distance to significant neurovascular structures), inaccurate identification of surface landmarks has the potential to lead to AP and MAP damage (Table 3). The examiner GT and ASIS surface landmarks used for AP overlapped directly with the safe distances for the lateral femoral cutaneous nerve and the terminal branch of the lateral circumflex femoral artery.

Discussion

Others have investigated examiners’ use of palpation, compared with ultrasound, to identify common shoulder and knee structures.^8-10 In a 2011 systematic review, Gilliland and colleagues¹¹ confirmed that accuracy was improved with use of ultrasound (vs palpation) for injections in the shoulder, hip, knee, wrist, and ankle. Given the scarcity of data in this setting, we conducted the present study to assess the precision and accuracy of expert arthroscopists in identifying common surface landmarks. We hypothesized that physical examination and ultrasound examination would differ significantly in precisely and accurately identifying these landmarks.

Working with a standard awake volunteer, our test group of examiners was consistently inaccurate when they accepted ultrasonographer-placed labels as the ideal. Precision within the group, however, trended toward close agreement; examiners consistently placed labels in the same direction and approximate magnitude away from ultrasonographer labels. This suggests that a discrepancy between the ultrasonographic surface structure definitions taught to ultrasonographers and the manually identified definitions taught to surgeons for arthroscopy (training bias) can generate differences in landmark identification.

Given reported low rates of complications in the creation of standard surface anatomy portals, more data is needed to correlate whether safe distance guidelines best apply to the points identified by hip experts or the points identified by ultrasonographers. In a 2013 systematic review, Harris and colleagues⁸ found a 7.5% overall complication rate, with temporary neuropraxia 1 of the 2 most common complications. Whether adding ultrasound to physical examination for the creation of some or all portals will reduce the incidence of these problems is unknown. Regardless of the anatomical area referenced by experts for portal creation, the tight grouping of examiner marks in our study supports a consensus regarding the location of the landmarks studied.

In our study of the use of surface anatomical landmarks for the creation of portals, we analyzed 4 previously described locations: ALP, AP, PLP, and MAP. ALP, AP, and PLP directly reference at least 1 surface anatomical structure; AP references 2 anatomical structures (ASIS, GT); and MAP indirectly references ASIS and GT and directly references ALP and AP. In cadaveric and radiographic studies, 7 neurovascular structures have been described in proximity to ALP, AP, MAP, and PLP: superior gluteal nerve, sciatic nerve, femoral nerve, lateral femoral cutaneous nerve, lateral circumflex femoral artery, and medial circumflex femoral artery.^5,6 Our results showed that use of surface anatomy in AP and MAP creation most likely places structures at risk, given the overlap of examiner CIs and the previously published cadaveric^5,6 and radiographic⁷ data.

Hua and colleagues¹² confirmed the feasibility of using ultrasound for the creation of hip arthroscopy portals. More data is needed to assess how the standard palpation-and-fluoroscopy method described by Byrd³ compares with an ultrasound-guided technique in safety and cost. However, data from our study should not be used to justify a demand for ultrasound during arthroscopy portal establishment, as limitations do not permit such a recommendation.

With diagnostic injection remaining a mainstay of differential diagnosis and treatment about the hip,¹ the data presented here suggest a potential for ultrasound in enhancing outcomes. There is evidence supporting the role of image guidance in improving palpation accuracy in the area of the biceps tendon in the forearm.¹⁰ Potentially, identification and treatment of specific extra-articular structures surrounding the hip could be made safer with more routine use of ultrasound.

 

Limitations

This study had several limitations. The surgeons were limited to palpation and static examination of a body in its natural state. Hip arthroscopic portals typically are created under traction and after a standard perineal post is placed for hip arthroscopy. In addition, in an awake injection setting, the clinician may receive patient feedback in the form of limb movement or speech. To what degree palpation or ultrasound will be affected in these scenarios is unknown.

Another limitation is the lack of serial examination by each examiner—intrarater variability could not be gauged. In addition, with only 1 ultrasonographic examination performed, there is the potential that adding ultrasonographic examinations, or having an examiner perform serial physical examinations, could better define the precision of each component. Given the practical limitations of our volunteer’s time and the schedules of 30 expert arthroscopists, we kept the chosen study design for its single setting.

Conclusion

Visual inspection and manual palpation are standard means of identifying common surface anatomical landmarks for the creation of arthroscopy portals and the placement of injections. Our study results showed variance in landmark identification between expert examiners and an ultrasonographer. The degree of variance exceeded established neurovascular safe zones, particularly for AP and MAP. This new evidence calls for further investigation into the best, safest means of performing hip arthroscopic techniques and injection-based interventions.

Am J Orthop. 2017;46(1):E65-E70. Copyright Frontline Medical Communications Inc. 2017. All rights reserved.

Take-Home Points

• MASH is a multicenter arthroscopic study of the hip that features a large prospective database of 10 separate institutions in the United States.
• The mean patient demographic was age 34.6 years, BMI 25.9 kg/m², 62.8% females, and 97% white.
• Most patients had anterior or groin pain, but 17.6% had lateral hip pain, 13.8% had posterior hip pain, and 2.9% had low back or sacral pain.
• Patients typically had pain for about 1 year that was worsened with athletic activity as well as sitting.
• The most common surgical procedures that were performed included labral surgery in 64.7%, femoroplasty in 49.9%, acetabuloplasty in 33.3%, and chondroplasty in 31.1%

Arthroscopic surgery of the hip has been growing over the past decade, with drastically increasing rates of arthroscopic hip procedures and increased education and interest in orthopedic trainees.^1-3 The rise of this minimally invasive surgical technique may be attributed to expanding knowledge of surgical management of morphologic hip disorders as a means of hip preservation. Many arthroscopic techniques have been developed to treat intra-articular hip joint pathologies, including femoroacetabular impingement (FAI), labral tears, and cartilage damage.^4-11 These hip pathologies are widely recognized as painful limitations to activities of daily living and sports as well as early indicators of hip osteoarthritis.^12,13 Limited evidence suggests that arthroscopic treatment of these intra-articular hip joint pathologies preserves the hip from osteoarthritis and progression to total hip arthroplasty.^13-15

FAI is the most common etiology of pathologies related to arthroscopic surgery of the hip, including both labral tears and cartilage damage.^4,7,14 FAI is a morphologic bone disorder characterized by impingement of the femur and the acetabulum on flexion or rotation. The etiology of FAI is not completely understood, but evidence suggests that stress to the proximal femoral physis during skeletal growth increases the risk of developing femoral head and neck deformations leading to cam-type FAI.^15-17 Understanding the characteristics of the patient population in which FAI occurs may shed light on the processes of intra-articular damage, such as labral tears and cartilage damage.

In the present study, we collected epidemiologic data, including demographics, pathologic entities treated, patient-reported measures of disease, and surgical treatment preferences, on a hip pathology population that elected to undergo arthroscopic surgery. These data are important in gaining a better understanding of the population and environment in which hip arthroscopy is performed across multiple centers throughout the United States and may help guide clinical practice and research to advance hip arthroscopy.

Methods

The Multicenter Arthroscopic Study of the Hip (MASH) Study Group conducts multicenter clinical studies in arthroscopic hip preservation surgery. Patients are enrolled in this large prospective longitudinal study at 10 sites nationwide by 10 fellowship-trained hip arthroscopists. Institutional Review Board approval was obtained from all institutions before patient enrollment. After enrollment, we collected comprehensive patient data, including demographics, common symptoms and their duration, provocative activities, patient-reported outcome measures (modified Harris Hip Score, International Hip Outcome Tool, 12-item Short Form Health Survey, visual analog scale pain rating, Hip Outcome Score), physical examination findings, imaging findings, diagnoses, surgical findings, and surgical procedures.

All study participants were patients undergoing arthroscopic hip surgery by one of the members of the MASH Study Group. Patients with incomplete preoperative information (needed for data analysis) were excluded. Data analysis was performed with SPSS Statistics Version 21.0 (SPSS Inc.) to obtain descriptive statistics of the quantitative data and frequencies of the nominal data.

Results

Between January 2014 and November 2016, we enrolled 1738 patients (647 male, 1091 female) in the study. Table 1 lists the demographics of the population.

Mean age was 34.6 years (range, 11-77 years); mean height, 67.1 inches (range, 54-180 inches); mean weight, 163.4 pounds (range, 62-325 pounds); and mean body mass index, 25.9 kg/m² (range, 7-57.1 kg/m²). Ninety-seven percent of the patients were white, 1.7% African-American, 1% Hispanic, and 0.30% Asian. In 55% of the cases, the right side was involved; in 43%, the left side; and in 2%, both sides. Only 1.2% of patients reported being a smoker, and 1.1% had services paid through worker’s compensation claims.

Regarding symptom location, 40.9% of patients described pain in the groin region, 24.2% in the anterior hip region, and 11.3% in a C-sign distribution (Table 2).

Lateral pain was reported by 17.6% of patients, and 13.8% of patients complained of pain in the posterior hip and buttock region.

Figure 1 shows that, before surgery, symptoms lasted more than 2 years in 38.4% of cases, between 1 and 2 years in 22%, between 4 and 12 months in 28.7%, and less than 4 months in 10.9%. Figure 2 shows that symptoms were provoked during sports in 47.1% of cases, while sitting in 46.8%, while walking in 39.5%, while standing in 26.4%, and while climbing stairs in 19%.

In addition, 22.3% of patients had a detectable limp, and catching, clicking, or locking occurred in 23.4% of patients.

Table 3 lists the results of the patient-reported outcome measures.

Mean visual analog scale pain rating was 51.8 (range, 0-100), mean modified Harris Hip Score was 53.8 (range, 0-91), mean Hip Outcome Score for activities of daily living was 62.3 (range, 5.9-100), mean Hip Outcome Score for sports was 39.4 (range, 0-100), and mean International Hip Outcome Tool was 33.9 (range, 0-99.3).

Of the 1738 patients enrolled, 424 (24.4%) had prior surgery related to current symptoms, 252 (14.5%) had 1 previous surgery, 120 (6.9%) had 2 previous surgeries, and 52 (3%) had 3 previous surgeries. Twenty-six patients (1.5%) had a previous revision hip arthroscopy on the ipsilateral side, and 14 (0.8%) had a previous hip arthroscopy on the contralateral side. Before surgery, 80% of patients received an intra-articular injection of corticosteroid and lidocaine. The peritrochanteric region was injected in 11.5% of patients and the psoas bursa in 2.2% (Table 4).

Eighty percent of patients attended physical therapy for their hip before electing to have surgery.

Of the 1011 patients who had magnetic resonance imaging (MRI) performed, 943 (93.3%) had abnormal acetabular labrum findings, and 163 (17.1%) had acetabular articular damage. According to radiographic evaluation, 953 patients had abnormal hip joint morphology consistent with FAI. Figure 3 shows the FAI classification percentages.

The combination of cam-type and pincer-type impingement was noted in 42.6% of cases, isolated cam-type impingement in 47%, and isolated pincer-type impingement in 29.5% (61 of the 107 isolated pincer cases had positive radiographic signs of focal acetabular overcoverage). Conversely, 84 patients (4.8%) had signs of hip dysplasia (lateral center edge angle, <25°). Of all 1738 patients, 1602 (92.5%) had Tönnis grade 0 osteoarthritis on radiographic evaluation, 6.3% had Tönnis grade 1, and 1.5% had Tönnis grade 2. The lateral joint space was the most common location for arthrosis (2.1%), followed by the medial joint space (1.3%) and the central joint space (1.1%).

On clinical examination, 1079 patients (62.1%) had a positive anterior impingement sign. The subspine impingement sign was positive in 447 patients (25.7%), and the trochanteric pain sign was positive in 400 (23%). Table 5 lists range-of-motion values for flexion and hip rotation from 90° of flexion.

Loss of motion for hip flexion (<110°) occurred in 57.3% of patients, hip internal rotation of <15° in 42%, external rotation of <45° in 47.3%, and total hip rotation of <60° in 41.7%.

As seen in Table 6, labral pathology was the most common diagnosis (1426/1738 patients, 82%).

Of the entire population, 354 (20.4%) had mild complexity labral tears, 288 (16.6%) had moderate complexity labral tears, and 130 (7.5%) had severe complexity labral tears. Of the 1738 cases total, 487 (28%) had labral bruising, and 167 (9.6%) had degenerative tears. Other diagnoses were 4 cases of septic arthritis (0.2%), 2 cases of avascular necrosis (0.1%), 36 cases of gluteus minimus/medius tears (2.1%), and 198 ligamentum teres tears (11.4%).

As seen in Table 7, the most common procedure was femoroplasty (867/1738, 49.9%).

Other common procedures were synovectomy (833, 47.9%), acetabuloplasty (579, 33.3%), and acetabular chondroplasty (541, 31.1%). Of the 1124 labral tears, 847 (75.3%) were repaired, 154 (13.7%) were reconstructed, and 81 (7.2%) were débrided.

 

Discussion

In this study, we collected epidemiologic data (demographics, pathologic entities treated, patient-reported measures of disease, surgical treatment preferences) from a large multicenter population of hip pathology patients who elected to undergo arthroscopic surgery. Our results showed these patients were most commonly younger to middle-aged white females with pain primarily in the groin region. Most had pain for at least 1 year, and it was commonly exacerbated by sitting and athletics. Patients reported clinically significant pain and functional limitation, which showed evidence of affecting general physical and mental health. It was not uncommon for patients to have undergone another, related surgery and nonoperative treatments, including intra-articular injection and/or physical therapy, before surgery. There was a high incidence of abnormal hip morphology suggestive of a cam lesion, but the incidence of arthritic changes on radiographs was relatively low. Labral tear was the most common diagnosis, and most often it was addressed with repair. Many patients underwent femoroplasty, acetabuloplasty, and chondroplasty in addition to labral repair.

According to patient-reported outcome measures administered before surgery, 40% to 65% of patients seeking hip preservation surgery reported functional deficits and pain—which falls within the range of results from other multicenter studies on the epidemiology of FAI.^18,19 There was, however, a high amount of variability in individual scores on the functional and pain measures; some patients rated their functional ability very high. These findings were supported by the general health forms measuring global physical and mental health. Mean Physical Health and Mental Health scores on the 12-item Short Form Health Survey indicated that patients seeking hip preservation surgery thought their hip condition affected their general well-being. This finding is consistent with research on FAI,¹⁸ hip arthritis,²⁰ and total hip arthroplasty.¹⁹Our results further showed that hip arthroscopists commonly prescribed alternative treatment measures ahead of surgery. Before elective surgery, 80% of patients received an intra-articular injection, underwent physical therapy, or both. This could suggest a high failure rate for patients who chose conservative treatment approaches for hip-related pathology. However, our study was limited in that it may have included patients who had improved significantly with conservative measures and decided to forgo arthroscopic hip surgery. Although conservative treatment often is recommended in an effort to potentially avoid surgery, there is a lack of research evaluating the efficacy of nonoperative care.^21,22Analysis of diagnostic imaging and clinical examination findings revealed some unique characteristics of patients undergoing elective hip preservation surgery. MRI showed labral pathology in an overwhelming majority of these patients, but few had evidence of articular damage. Previous research has found a 67% rate of arthritic changes on diagnostic imaging, but our rate was much lower (17%).²³ Radiograph evaluation confirmed the pattern: More than 90% of our patients had Tönnis grade 0 osteoarthritis. Tönnis grade 1 or 2 osteoarthritis is a predictor of acetabular cartilage degeneration,²³ and long-term studies have related these osteoarthritic changes to poorer hip arthroscopy outcomes.²⁴ Thus, the lower incidence of osteoarthritis in our study population may reflect current evidence-based practice and a contemporary approach to patient selection.

Most of our patients had isolated cam-type FAI as opposed to pincer-type FAI or a combination of cam and pincer—contrary to research findings that combination cam–pincer FAI is most prevalent.^25,26 Our results are more consistent with more recent research findings of a higher incidence of isolated cam lesion, particularly in female patients, and combination cam–pincer in male patients.^18,27,28 Similar distributions of surgical procedures and diagnoses exist between the present study and other multicenter evaluations of the epidemiologic characteristics of patients with hip pathology.¹⁸Our study had several limitations. First, the population consisted entirely of patients who sought evaluation by a hip arthroscopy specialist and underwent elective surgery. Therefore, the data cannot be applied to a more general orthopedic population or to patients who consult other medical specialists. Second, the population, which was 97% white and had small percentages of African-American, Latino, and Asian patients, lacked ethnic diversity. This finding is consistent with recent epidemiologic research in which ethnicity was identified as a factor in patterns of hip disease.^13,29,30 Access to specialists, however, was likely affected by multiple other factors. Fourth, the validity and the reliability of the imaging modalities used have been questioned.^31-33 There is controversy regarding ideal imaging modalities for assessment of articular cartilage damage^31,32 and FAI. However, the modalities that we used to determine diagnoses in this study are well supported²⁶ and represent common practice patterns.

Am J Orthop. 2017;46(1):35-41. Copyright Frontline Medical Communications Inc. 2017. All rights reserved.

Take-Home Points

• MASH is a multicenter arthroscopic study of the hip that features a large prospective database of 10 separate institutions in the United States.
• The mean patient demographic was age 34.6 years, BMI 25.9 kg/m², 62.8% females, and 97% white.
• Most patients had anterior or groin pain, but 17.6% had lateral hip pain, 13.8% had posterior hip pain, and 2.9% had low back or sacral pain.
• Patients typically had pain for about 1 year that was worsened with athletic activity as well as sitting.
• The most common surgical procedures that were performed included labral surgery in 64.7%, femoroplasty in 49.9%, acetabuloplasty in 33.3%, and chondroplasty in 31.1%

Arthroscopic surgery of the hip has been growing over the past decade, with drastically increasing rates of arthroscopic hip procedures and increased education and interest in orthopedic trainees.^1-3 The rise of this minimally invasive surgical technique may be attributed to expanding knowledge of surgical management of morphologic hip disorders as a means of hip preservation. Many arthroscopic techniques have been developed to treat intra-articular hip joint pathologies, including femoroacetabular impingement (FAI), labral tears, and cartilage damage.^4-11 These hip pathologies are widely recognized as painful limitations to activities of daily living and sports as well as early indicators of hip osteoarthritis.^12,13 Limited evidence suggests that arthroscopic treatment of these intra-articular hip joint pathologies preserves the hip from osteoarthritis and progression to total hip arthroplasty.^13-15

FAI is the most common etiology of pathologies related to arthroscopic surgery of the hip, including both labral tears and cartilage damage.^4,7,14 FAI is a morphologic bone disorder characterized by impingement of the femur and the acetabulum on flexion or rotation. The etiology of FAI is not completely understood, but evidence suggests that stress to the proximal femoral physis during skeletal growth increases the risk of developing femoral head and neck deformations leading to cam-type FAI.^15-17 Understanding the characteristics of the patient population in which FAI occurs may shed light on the processes of intra-articular damage, such as labral tears and cartilage damage.

In the present study, we collected epidemiologic data, including demographics, pathologic entities treated, patient-reported measures of disease, and surgical treatment preferences, on a hip pathology population that elected to undergo arthroscopic surgery. These data are important in gaining a better understanding of the population and environment in which hip arthroscopy is performed across multiple centers throughout the United States and may help guide clinical practice and research to advance hip arthroscopy.

Methods

The Multicenter Arthroscopic Study of the Hip (MASH) Study Group conducts multicenter clinical studies in arthroscopic hip preservation surgery. Patients are enrolled in this large prospective longitudinal study at 10 sites nationwide by 10 fellowship-trained hip arthroscopists. Institutional Review Board approval was obtained from all institutions before patient enrollment. After enrollment, we collected comprehensive patient data, including demographics, common symptoms and their duration, provocative activities, patient-reported outcome measures (modified Harris Hip Score, International Hip Outcome Tool, 12-item Short Form Health Survey, visual analog scale pain rating, Hip Outcome Score), physical examination findings, imaging findings, diagnoses, surgical findings, and surgical procedures.

All study participants were patients undergoing arthroscopic hip surgery by one of the members of the MASH Study Group. Patients with incomplete preoperative information (needed for data analysis) were excluded. Data analysis was performed with SPSS Statistics Version 21.0 (SPSS Inc.) to obtain descriptive statistics of the quantitative data and frequencies of the nominal data.

Results

Between January 2014 and November 2016, we enrolled 1738 patients (647 male, 1091 female) in the study. Table 1 lists the demographics of the population.

Mean age was 34.6 years (range, 11-77 years); mean height, 67.1 inches (range, 54-180 inches); mean weight, 163.4 pounds (range, 62-325 pounds); and mean body mass index, 25.9 kg/m² (range, 7-57.1 kg/m²). Ninety-seven percent of the patients were white, 1.7% African-American, 1% Hispanic, and 0.30% Asian. In 55% of the cases, the right side was involved; in 43%, the left side; and in 2%, both sides. Only 1.2% of patients reported being a smoker, and 1.1% had services paid through worker’s compensation claims.

Regarding symptom location, 40.9% of patients described pain in the groin region, 24.2% in the anterior hip region, and 11.3% in a C-sign distribution (Table 2).

Lateral pain was reported by 17.6% of patients, and 13.8% of patients complained of pain in the posterior hip and buttock region.

Figure 1 shows that, before surgery, symptoms lasted more than 2 years in 38.4% of cases, between 1 and 2 years in 22%, between 4 and 12 months in 28.7%, and less than 4 months in 10.9%. Figure 2 shows that symptoms were provoked during sports in 47.1% of cases, while sitting in 46.8%, while walking in 39.5%, while standing in 26.4%, and while climbing stairs in 19%.

In addition, 22.3% of patients had a detectable limp, and catching, clicking, or locking occurred in 23.4% of patients.

Table 3 lists the results of the patient-reported outcome measures.

Mean visual analog scale pain rating was 51.8 (range, 0-100), mean modified Harris Hip Score was 53.8 (range, 0-91), mean Hip Outcome Score for activities of daily living was 62.3 (range, 5.9-100), mean Hip Outcome Score for sports was 39.4 (range, 0-100), and mean International Hip Outcome Tool was 33.9 (range, 0-99.3).

Of the 1738 patients enrolled, 424 (24.4%) had prior surgery related to current symptoms, 252 (14.5%) had 1 previous surgery, 120 (6.9%) had 2 previous surgeries, and 52 (3%) had 3 previous surgeries. Twenty-six patients (1.5%) had a previous revision hip arthroscopy on the ipsilateral side, and 14 (0.8%) had a previous hip arthroscopy on the contralateral side. Before surgery, 80% of patients received an intra-articular injection of corticosteroid and lidocaine. The peritrochanteric region was injected in 11.5% of patients and the psoas bursa in 2.2% (Table 4).

Eighty percent of patients attended physical therapy for their hip before electing to have surgery.

Of the 1011 patients who had magnetic resonance imaging (MRI) performed, 943 (93.3%) had abnormal acetabular labrum findings, and 163 (17.1%) had acetabular articular damage. According to radiographic evaluation, 953 patients had abnormal hip joint morphology consistent with FAI. Figure 3 shows the FAI classification percentages.

The combination of cam-type and pincer-type impingement was noted in 42.6% of cases, isolated cam-type impingement in 47%, and isolated pincer-type impingement in 29.5% (61 of the 107 isolated pincer cases had positive radiographic signs of focal acetabular overcoverage). Conversely, 84 patients (4.8%) had signs of hip dysplasia (lateral center edge angle, <25°). Of all 1738 patients, 1602 (92.5%) had Tönnis grade 0 osteoarthritis on radiographic evaluation, 6.3% had Tönnis grade 1, and 1.5% had Tönnis grade 2. The lateral joint space was the most common location for arthrosis (2.1%), followed by the medial joint space (1.3%) and the central joint space (1.1%).

On clinical examination, 1079 patients (62.1%) had a positive anterior impingement sign. The subspine impingement sign was positive in 447 patients (25.7%), and the trochanteric pain sign was positive in 400 (23%). Table 5 lists range-of-motion values for flexion and hip rotation from 90° of flexion.

Loss of motion for hip flexion (<110°) occurred in 57.3% of patients, hip internal rotation of <15° in 42%, external rotation of <45° in 47.3%, and total hip rotation of <60° in 41.7%.

As seen in Table 6, labral pathology was the most common diagnosis (1426/1738 patients, 82%).

Of the entire population, 354 (20.4%) had mild complexity labral tears, 288 (16.6%) had moderate complexity labral tears, and 130 (7.5%) had severe complexity labral tears. Of the 1738 cases total, 487 (28%) had labral bruising, and 167 (9.6%) had degenerative tears. Other diagnoses were 4 cases of septic arthritis (0.2%), 2 cases of avascular necrosis (0.1%), 36 cases of gluteus minimus/medius tears (2.1%), and 198 ligamentum teres tears (11.4%).

As seen in Table 7, the most common procedure was femoroplasty (867/1738, 49.9%).

Other common procedures were synovectomy (833, 47.9%), acetabuloplasty (579, 33.3%), and acetabular chondroplasty (541, 31.1%). Of the 1124 labral tears, 847 (75.3%) were repaired, 154 (13.7%) were reconstructed, and 81 (7.2%) were débrided.

 

Discussion

In this study, we collected epidemiologic data (demographics, pathologic entities treated, patient-reported measures of disease, surgical treatment preferences) from a large multicenter population of hip pathology patients who elected to undergo arthroscopic surgery. Our results showed these patients were most commonly younger to middle-aged white females with pain primarily in the groin region. Most had pain for at least 1 year, and it was commonly exacerbated by sitting and athletics. Patients reported clinically significant pain and functional limitation, which showed evidence of affecting general physical and mental health. It was not uncommon for patients to have undergone another, related surgery and nonoperative treatments, including intra-articular injection and/or physical therapy, before surgery. There was a high incidence of abnormal hip morphology suggestive of a cam lesion, but the incidence of arthritic changes on radiographs was relatively low. Labral tear was the most common diagnosis, and most often it was addressed with repair. Many patients underwent femoroplasty, acetabuloplasty, and chondroplasty in addition to labral repair.

According to patient-reported outcome measures administered before surgery, 40% to 65% of patients seeking hip preservation surgery reported functional deficits and pain—which falls within the range of results from other multicenter studies on the epidemiology of FAI.^18,19 There was, however, a high amount of variability in individual scores on the functional and pain measures; some patients rated their functional ability very high. These findings were supported by the general health forms measuring global physical and mental health. Mean Physical Health and Mental Health scores on the 12-item Short Form Health Survey indicated that patients seeking hip preservation surgery thought their hip condition affected their general well-being. This finding is consistent with research on FAI,¹⁸ hip arthritis,²⁰ and total hip arthroplasty.¹⁹Our results further showed that hip arthroscopists commonly prescribed alternative treatment measures ahead of surgery. Before elective surgery, 80% of patients received an intra-articular injection, underwent physical therapy, or both. This could suggest a high failure rate for patients who chose conservative treatment approaches for hip-related pathology. However, our study was limited in that it may have included patients who had improved significantly with conservative measures and decided to forgo arthroscopic hip surgery. Although conservative treatment often is recommended in an effort to potentially avoid surgery, there is a lack of research evaluating the efficacy of nonoperative care.^21,22Analysis of diagnostic imaging and clinical examination findings revealed some unique characteristics of patients undergoing elective hip preservation surgery. MRI showed labral pathology in an overwhelming majority of these patients, but few had evidence of articular damage. Previous research has found a 67% rate of arthritic changes on diagnostic imaging, but our rate was much lower (17%).²³ Radiograph evaluation confirmed the pattern: More than 90% of our patients had Tönnis grade 0 osteoarthritis. Tönnis grade 1 or 2 osteoarthritis is a predictor of acetabular cartilage degeneration,²³ and long-term studies have related these osteoarthritic changes to poorer hip arthroscopy outcomes.²⁴ Thus, the lower incidence of osteoarthritis in our study population may reflect current evidence-based practice and a contemporary approach to patient selection.

Most of our patients had isolated cam-type FAI as opposed to pincer-type FAI or a combination of cam and pincer—contrary to research findings that combination cam–pincer FAI is most prevalent.^25,26 Our results are more consistent with more recent research findings of a higher incidence of isolated cam lesion, particularly in female patients, and combination cam–pincer in male patients.^18,27,28 Similar distributions of surgical procedures and diagnoses exist between the present study and other multicenter evaluations of the epidemiologic characteristics of patients with hip pathology.¹⁸Our study had several limitations. First, the population consisted entirely of patients who sought evaluation by a hip arthroscopy specialist and underwent elective surgery. Therefore, the data cannot be applied to a more general orthopedic population or to patients who consult other medical specialists. Second, the population, which was 97% white and had small percentages of African-American, Latino, and Asian patients, lacked ethnic diversity. This finding is consistent with recent epidemiologic research in which ethnicity was identified as a factor in patterns of hip disease.^13,29,30 Access to specialists, however, was likely affected by multiple other factors. Fourth, the validity and the reliability of the imaging modalities used have been questioned.^31-33 There is controversy regarding ideal imaging modalities for assessment of articular cartilage damage^31,32 and FAI. However, the modalities that we used to determine diagnoses in this study are well supported²⁶ and represent common practice patterns.

Am J Orthop. 2017;46(1):35-41. Copyright Frontline Medical Communications Inc. 2017. All rights reserved.

Take-Home Points

• MASH is a multicenter arthroscopic study of the hip that features a large prospective database of 10 separate institutions in the United States.
• The mean patient demographic was age 34.6 years, BMI 25.9 kg/m², 62.8% females, and 97% white.
• Most patients had anterior or groin pain, but 17.6% had lateral hip pain, 13.8% had posterior hip pain, and 2.9% had low back or sacral pain.
• Patients typically had pain for about 1 year that was worsened with athletic activity as well as sitting.
• The most common surgical procedures that were performed included labral surgery in 64.7%, femoroplasty in 49.9%, acetabuloplasty in 33.3%, and chondroplasty in 31.1%

Arthroscopic surgery of the hip has been growing over the past decade, with drastically increasing rates of arthroscopic hip procedures and increased education and interest in orthopedic trainees.^1-3 The rise of this minimally invasive surgical technique may be attributed to expanding knowledge of surgical management of morphologic hip disorders as a means of hip preservation. Many arthroscopic techniques have been developed to treat intra-articular hip joint pathologies, including femoroacetabular impingement (FAI), labral tears, and cartilage damage.^4-11 These hip pathologies are widely recognized as painful limitations to activities of daily living and sports as well as early indicators of hip osteoarthritis.^12,13 Limited evidence suggests that arthroscopic treatment of these intra-articular hip joint pathologies preserves the hip from osteoarthritis and progression to total hip arthroplasty.^13-15

FAI is the most common etiology of pathologies related to arthroscopic surgery of the hip, including both labral tears and cartilage damage.^4,7,14 FAI is a morphologic bone disorder characterized by impingement of the femur and the acetabulum on flexion or rotation. The etiology of FAI is not completely understood, but evidence suggests that stress to the proximal femoral physis during skeletal growth increases the risk of developing femoral head and neck deformations leading to cam-type FAI.^15-17 Understanding the characteristics of the patient population in which FAI occurs may shed light on the processes of intra-articular damage, such as labral tears and cartilage damage.

In the present study, we collected epidemiologic data, including demographics, pathologic entities treated, patient-reported measures of disease, and surgical treatment preferences, on a hip pathology population that elected to undergo arthroscopic surgery. These data are important in gaining a better understanding of the population and environment in which hip arthroscopy is performed across multiple centers throughout the United States and may help guide clinical practice and research to advance hip arthroscopy.

Methods

The Multicenter Arthroscopic Study of the Hip (MASH) Study Group conducts multicenter clinical studies in arthroscopic hip preservation surgery. Patients are enrolled in this large prospective longitudinal study at 10 sites nationwide by 10 fellowship-trained hip arthroscopists. Institutional Review Board approval was obtained from all institutions before patient enrollment. After enrollment, we collected comprehensive patient data, including demographics, common symptoms and their duration, provocative activities, patient-reported outcome measures (modified Harris Hip Score, International Hip Outcome Tool, 12-item Short Form Health Survey, visual analog scale pain rating, Hip Outcome Score), physical examination findings, imaging findings, diagnoses, surgical findings, and surgical procedures.

All study participants were patients undergoing arthroscopic hip surgery by one of the members of the MASH Study Group. Patients with incomplete preoperative information (needed for data analysis) were excluded. Data analysis was performed with SPSS Statistics Version 21.0 (SPSS Inc.) to obtain descriptive statistics of the quantitative data and frequencies of the nominal data.

Results

Between January 2014 and November 2016, we enrolled 1738 patients (647 male, 1091 female) in the study. Table 1 lists the demographics of the population.

Mean age was 34.6 years (range, 11-77 years); mean height, 67.1 inches (range, 54-180 inches); mean weight, 163.4 pounds (range, 62-325 pounds); and mean body mass index, 25.9 kg/m² (range, 7-57.1 kg/m²). Ninety-seven percent of the patients were white, 1.7% African-American, 1% Hispanic, and 0.30% Asian. In 55% of the cases, the right side was involved; in 43%, the left side; and in 2%, both sides. Only 1.2% of patients reported being a smoker, and 1.1% had services paid through worker’s compensation claims.

Regarding symptom location, 40.9% of patients described pain in the groin region, 24.2% in the anterior hip region, and 11.3% in a C-sign distribution (Table 2).

Lateral pain was reported by 17.6% of patients, and 13.8% of patients complained of pain in the posterior hip and buttock region.

Figure 1 shows that, before surgery, symptoms lasted more than 2 years in 38.4% of cases, between 1 and 2 years in 22%, between 4 and 12 months in 28.7%, and less than 4 months in 10.9%. Figure 2 shows that symptoms were provoked during sports in 47.1% of cases, while sitting in 46.8%, while walking in 39.5%, while standing in 26.4%, and while climbing stairs in 19%.

In addition, 22.3% of patients had a detectable limp, and catching, clicking, or locking occurred in 23.4% of patients.

Table 3 lists the results of the patient-reported outcome measures.

Mean visual analog scale pain rating was 51.8 (range, 0-100), mean modified Harris Hip Score was 53.8 (range, 0-91), mean Hip Outcome Score for activities of daily living was 62.3 (range, 5.9-100), mean Hip Outcome Score for sports was 39.4 (range, 0-100), and mean International Hip Outcome Tool was 33.9 (range, 0-99.3).

Of the 1738 patients enrolled, 424 (24.4%) had prior surgery related to current symptoms, 252 (14.5%) had 1 previous surgery, 120 (6.9%) had 2 previous surgeries, and 52 (3%) had 3 previous surgeries. Twenty-six patients (1.5%) had a previous revision hip arthroscopy on the ipsilateral side, and 14 (0.8%) had a previous hip arthroscopy on the contralateral side. Before surgery, 80% of patients received an intra-articular injection of corticosteroid and lidocaine. The peritrochanteric region was injected in 11.5% of patients and the psoas bursa in 2.2% (Table 4).

Eighty percent of patients attended physical therapy for their hip before electing to have surgery.

Of the 1011 patients who had magnetic resonance imaging (MRI) performed, 943 (93.3%) had abnormal acetabular labrum findings, and 163 (17.1%) had acetabular articular damage. According to radiographic evaluation, 953 patients had abnormal hip joint morphology consistent with FAI. Figure 3 shows the FAI classification percentages.

The combination of cam-type and pincer-type impingement was noted in 42.6% of cases, isolated cam-type impingement in 47%, and isolated pincer-type impingement in 29.5% (61 of the 107 isolated pincer cases had positive radiographic signs of focal acetabular overcoverage). Conversely, 84 patients (4.8%) had signs of hip dysplasia (lateral center edge angle, <25°). Of all 1738 patients, 1602 (92.5%) had Tönnis grade 0 osteoarthritis on radiographic evaluation, 6.3% had Tönnis grade 1, and 1.5% had Tönnis grade 2. The lateral joint space was the most common location for arthrosis (2.1%), followed by the medial joint space (1.3%) and the central joint space (1.1%).

On clinical examination, 1079 patients (62.1%) had a positive anterior impingement sign. The subspine impingement sign was positive in 447 patients (25.7%), and the trochanteric pain sign was positive in 400 (23%). Table 5 lists range-of-motion values for flexion and hip rotation from 90° of flexion.

Loss of motion for hip flexion (<110°) occurred in 57.3% of patients, hip internal rotation of <15° in 42%, external rotation of <45° in 47.3%, and total hip rotation of <60° in 41.7%.

As seen in Table 6, labral pathology was the most common diagnosis (1426/1738 patients, 82%).

Of the entire population, 354 (20.4%) had mild complexity labral tears, 288 (16.6%) had moderate complexity labral tears, and 130 (7.5%) had severe complexity labral tears. Of the 1738 cases total, 487 (28%) had labral bruising, and 167 (9.6%) had degenerative tears. Other diagnoses were 4 cases of septic arthritis (0.2%), 2 cases of avascular necrosis (0.1%), 36 cases of gluteus minimus/medius tears (2.1%), and 198 ligamentum teres tears (11.4%).

As seen in Table 7, the most common procedure was femoroplasty (867/1738, 49.9%).

Other common procedures were synovectomy (833, 47.9%), acetabuloplasty (579, 33.3%), and acetabular chondroplasty (541, 31.1%). Of the 1124 labral tears, 847 (75.3%) were repaired, 154 (13.7%) were reconstructed, and 81 (7.2%) were débrided.

 

Discussion

In this study, we collected epidemiologic data (demographics, pathologic entities treated, patient-reported measures of disease, surgical treatment preferences) from a large multicenter population of hip pathology patients who elected to undergo arthroscopic surgery. Our results showed these patients were most commonly younger to middle-aged white females with pain primarily in the groin region. Most had pain for at least 1 year, and it was commonly exacerbated by sitting and athletics. Patients reported clinically significant pain and functional limitation, which showed evidence of affecting general physical and mental health. It was not uncommon for patients to have undergone another, related surgery and nonoperative treatments, including intra-articular injection and/or physical therapy, before surgery. There was a high incidence of abnormal hip morphology suggestive of a cam lesion, but the incidence of arthritic changes on radiographs was relatively low. Labral tear was the most common diagnosis, and most often it was addressed with repair. Many patients underwent femoroplasty, acetabuloplasty, and chondroplasty in addition to labral repair.

According to patient-reported outcome measures administered before surgery, 40% to 65% of patients seeking hip preservation surgery reported functional deficits and pain—which falls within the range of results from other multicenter studies on the epidemiology of FAI.^18,19 There was, however, a high amount of variability in individual scores on the functional and pain measures; some patients rated their functional ability very high. These findings were supported by the general health forms measuring global physical and mental health. Mean Physical Health and Mental Health scores on the 12-item Short Form Health Survey indicated that patients seeking hip preservation surgery thought their hip condition affected their general well-being. This finding is consistent with research on FAI,¹⁸ hip arthritis,²⁰ and total hip arthroplasty.¹⁹Our results further showed that hip arthroscopists commonly prescribed alternative treatment measures ahead of surgery. Before elective surgery, 80% of patients received an intra-articular injection, underwent physical therapy, or both. This could suggest a high failure rate for patients who chose conservative treatment approaches for hip-related pathology. However, our study was limited in that it may have included patients who had improved significantly with conservative measures and decided to forgo arthroscopic hip surgery. Although conservative treatment often is recommended in an effort to potentially avoid surgery, there is a lack of research evaluating the efficacy of nonoperative care.^21,22Analysis of diagnostic imaging and clinical examination findings revealed some unique characteristics of patients undergoing elective hip preservation surgery. MRI showed labral pathology in an overwhelming majority of these patients, but few had evidence of articular damage. Previous research has found a 67% rate of arthritic changes on diagnostic imaging, but our rate was much lower (17%).²³ Radiograph evaluation confirmed the pattern: More than 90% of our patients had Tönnis grade 0 osteoarthritis. Tönnis grade 1 or 2 osteoarthritis is a predictor of acetabular cartilage degeneration,²³ and long-term studies have related these osteoarthritic changes to poorer hip arthroscopy outcomes.²⁴ Thus, the lower incidence of osteoarthritis in our study population may reflect current evidence-based practice and a contemporary approach to patient selection.

Most of our patients had isolated cam-type FAI as opposed to pincer-type FAI or a combination of cam and pincer—contrary to research findings that combination cam–pincer FAI is most prevalent.^25,26 Our results are more consistent with more recent research findings of a higher incidence of isolated cam lesion, particularly in female patients, and combination cam–pincer in male patients.^18,27,28 Similar distributions of surgical procedures and diagnoses exist between the present study and other multicenter evaluations of the epidemiologic characteristics of patients with hip pathology.¹⁸Our study had several limitations. First, the population consisted entirely of patients who sought evaluation by a hip arthroscopy specialist and underwent elective surgery. Therefore, the data cannot be applied to a more general orthopedic population or to patients who consult other medical specialists. Second, the population, which was 97% white and had small percentages of African-American, Latino, and Asian patients, lacked ethnic diversity. This finding is consistent with recent epidemiologic research in which ethnicity was identified as a factor in patterns of hip disease.^13,29,30 Access to specialists, however, was likely affected by multiple other factors. Fourth, the validity and the reliability of the imaging modalities used have been questioned.^31-33 There is controversy regarding ideal imaging modalities for assessment of articular cartilage damage^31,32 and FAI. However, the modalities that we used to determine diagnoses in this study are well supported²⁶ and represent common practice patterns.

Am J Orthop. 2017;46(1):35-41. Copyright Frontline Medical Communications Inc. 2017. All rights reserved.