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Lateral Ulnar Collateral Ligament Reconstruction: An Analysis of Ulnar Tunnel Locations
Posterolateral rotatory instability (PLRI) of the elbow is well recognized1 and is the most common type of chronic elbow instability. PLRI is often an end result of traumatic elbow dislocation.2 The “essential lesion” in patients with PLRI of the elbow is injury to the lateral ulnar collateral ligament (LUCL).1 However, more recent research has emphasized the importance of other ligaments in the lateral ligament complex (radial collateral and annular ligaments) in preventing PLRI.3-5 Nevertheless, when conservative treatment fails, the most commonly used surgical treatment involves LUCL reconstruction.1,6-11
Numerous techniques for LUCL reconstruction have been described.1,7-9,11-13 The chosen technique ideally restores normal anatomy. Therefore, the isometric point of origin at the lateral epicondyle and insertion at the supinator tubercle are important landmarks for creating tunnels that reproduce isometry, function, and normal anatomy. Most often, 2 tunnels are created in the ulna to secure the graft. It has been our experience that ulnar tunnel creation can affect the length of the bony bridge and the orientation of the graft.
We conducted a study to identify the precise proximal ulna tunnel location—anterior to posterior, with the distal tunnel at the supinator tubercle on the crest—that allows for the largest bony bridge and most geometrically favorable construct. We hypothesized that a most posteriorly placed proximal tunnel would increase bony bridge size and allow for a more isosceles graft configuration. An isosceles configuration with the humerus tunnel at the isometric location would allow for anterior and posterior bands of the same length with theoretically equal force distribution.
Methods
After obtaining institutional review board approval, we retrospectively reviewed the cases of 17 adults with elbow computed tomography (CT) scans for inclusion in this study. The scans were previously performed for diagnostic workup of several pathologies, including valgus instability, olecranon stress fracture, and valgus extension overload. The scan protocol involved 0.5-mm axial cuts with inclusion of the distal humerus through the proximal radius and ulna in the DICOM (Digital Imaging and Communications in Medicine) format. Exclusion criteria included poor CT quality, inadequate visualization of the entire supinator crest, and age under 18 years. Fifteen patients with adequate CT scans met the inclusion criteria. MIMICS (Materialise’s Interactive Medical Image Control System) software was used to convert scans into patient-specific 3-dimensional (3-D) computer models. (Use of this software to produce anatomically accurate models has been verified in shoulder14 and elbow15 models.) These models were uploaded into Magics rapid prototyping software (Materialise) and manipulated for simulated tunnel drilling by precise bone subtraction methods. This software was used to define an ulnar Cartesian coordinate system with anatomical landmarks as reference points in order to standardize the position of each model (Figure 1).16 The y-axis was defined by the longitudinal axis of the ulna, and the x-axis was the transepicondylar axis, defined as the perpendicular line connecting the y-axis with the supinator crest. The z-axis was then established as the line perpendicular to the x- and y-axes—yielding a 3-D coordinate system that allowed us to manipulate the models in standardized fashion, maintaining the exact positions of the ulna while making measurements.
Surgical simulations were performed in the rapid prototyping software by creating a cylinder and placing it at the desired location of each tunnel. Cylinder diameter was 4 mm, matching the diameter of the drill we use to create each tunnel in our practice. The cylinder was inserted into the bone, perpendicular to the surface of the ulna at the point of insertion, so the cylinder’s deepest point entered the medullary canal of the ulna. Using a Boolean operation in the rapid prototyping software, we subtracted cylinder from bone to create a tunnel (Figure 2).15
In a previous study,17 we determined that the radial head junction is reproducibly about 15 mm proximal to the distinct supinator tubercle, which may be absent or not readily appreciated in up to 50% of cases. Therefore, proximal ulnar tunnels were placed 0, 5, and 10 mm posterior to the supinator crest at the radial head junction. Distal tunnels were placed 15 mm anterior to the radial head junction on the supinator crest (Figure 2). The bony bridges created by these tunnels were measured, as was the distance between the distal tunnel and the supinator tubercle.
Ideal graft configuration was described as an isosceles triangle with ulna tunnels perpendicular to the humeral tunnel (Figure 3).11 Location of the humeral origin in the sagittal plane was determined by finding the isometric point of the lateral humerus using only bony landmarks. Similar techniques have been used to find the isometric point on the medial epicondyle for medial ulnar collateral ligament reconstruction.15,18 With a circle fit into the trochlear notch of the ulna, the isometric point can be determined by the center of the circle. This point was then superimposed on the humerus to identify the starting point (Figure 4). In our simulation, we measured the isosceles configuration by drawing a line between the proximal and distal tunnels, and then another line connecting the bisecting point of the first line with the isometric point on the humerus from which the graft would originate. The angle between the 2 lines was measured; if isosceles, the angle was 90° (Figure 5). Length of the more proximal limb of the graft and the more distal limb of the graft was determined by measuring the distance from the isometric point to the proximal and distal tunnels, respectively (Figure 6).
One-way analysis of variance was used to compare all the tunnels’ bony bridge sizes, graft lengths, and angles to the isometric point. For all comparisons, statistical significance was set at P < .05. As no other studies have compared bony bridges by varying tunnel creation parameters, and as the present study is observational and not comparative, no power analysis was performed.
Results
Bony bridges were significantly longer, and angles more perpendicular, with increasing distance from the proximal tunnel to the supinator crest (Table 1, Figure 5, Figure 7). The bony bridge 0 mm posterior to the supinator crest yielded a mean (SE) bony bridge length of 11.0 (0.2) mm. This proximal tunnel also yielded the smallest mean (SE) perpendicular angle to the isometric point, 131.2° (1.9°). The tunnel most posterior to the supinator crest yielded the longest mean (SE) bony bridge, 13.7 (0.2) mm, and the largest mean (SE) degree of perpendicularity, 95.8° (1.4°). The differences between all tunnels’ bony bridges and isometric angles were statistically significant (P < .00001). The difference between the more distal limb and the more proximal limb of the graft was smallest in the more posteriorly placed proximal tunnel (Table 2, Figure 8). In fact, there was no statistical difference between the proximal and distal limbs of the graft when the proximal tunnel was placed 10 mm posterior to the supinator crest: Mean (SE) was 9.4 (0.5) mm at 0 mm (P < .00001) and 1.1 (0.6) mm at 10 mm (P = .24).
Discussion
PLRI of the elbow is best initially managed nonoperatively. However, when nonoperative management fails, the LUCL is often surgically reconstructed. Reconstruction methods vary by fixation method, graft choice, and bone tunnels.1,7-9,11-13 In 1991, O’Driscoll and colleagues1 described a “yoke” technique for LUCL reconstruction. Since then, the docking technique7 and other techniques have been developed. All these techniques emphasize maximizing anatomical precision and isometry with careful placement of tunnels or fixation devices. The humeral fixation site, at the anterior inferior aspect of the lateral epicondyle at the point of isometry, can be accessed relatively reproducibly. By contrast, the ulnar points of fixation are more variable, because of increased bone stock and overlying soft-tissue and bony anatomy.
Among the challenges in determining the points of ulnar fixation is the bony anatomy that is often used for landmarks. In the literature, the supinator crest or the supintor tubercle is the landmark for placing the distal tunnel.1,7-9,11-13 This is a problem for 2 reasons. First, the supintor crest, a longitudinal structure on the lateral aspect of the ulna, originates from the radial head junction and extends tens of millimeters distally; further specification is needed to guide these ulnar tunnels. The second reason is that use of the supinator tubercle, a prominence on the supinator crest, adds specificity to the location of the ulnar tunnels. During surgery, however, the supinator tubercle may not be a reliable, independently prominent structure; instead, it may be indistinguishable from the supinator crest, on which it rests. One study determined that only about 50% of computer models of patient ulnas had a distinct prominence that could be classified as the supinator tubercle.17 The percentage presumably is lower during surgery, with limited exposure and overlying soft tissues.
In a study of patients with a prominent tubercle, mean (SE) distance from radial head junction to tubercle was 15 (2) mm.17 This finding led us to use the radial head junction as the primary bony landmark in determining the location of the proximal tunnel and placing the distal tunnel 15 mm distally—achieving the same fixation described in the literature but using more distinct landmarks. Our study thus provided a reliable, verified approach to locating the ulnar tunnels in the proximal-distal axis.
We also explored the anterior-posterior orientation of the proximal ulnar tunnel. The 2 primary considerations surrounding the varied proximal tunnel placements were the bony bridge formed between the proximal and distal tunnels and the perpendicularity of the triangle formed by the fixation points. Maximizing the bony bridge is obviously ideal in securing and preventing fixation blowout. Achieving an isoceles reconstruction has been reported in the literature on the various fixation techniques for LUCL reconstruction.11 Although the biomechanical advantage of this fixation type is not fully clear, we assume the construct produces graft stands of equal length, tension, and stability. In addition, the larger footprint created by an isoceles reconstructed ligament increases the stability of the radial head.
Results of the present study showed that the more posterior the proximal ulnar tunnel, the longer the bony bridge and the more isoceles the reconstruction. The difference in bony bridge distance from the most anterior to the most posterior tunnel was about 2 mm, or 18%. For every 1 mm of posteriorization, the bony bridge was 0.2 mm longer. The line from the isometric point of humeral fixation bisecting the proximal and distal tunnels was also more perpendicular with the most posterior tunnel, by about 40°. The resulting proximal and distal limbs of the reconstruction were equal in length, as demonstrated by the smaller difference between the limbs. We assume this isoceles reconstruction more likely applies uniform restraint on the radial head. Thus, an effort should be made to posteriorize the proximal ulnar tunnel during reconstruction.
The study was limited by the number of patient-specific elbow models used. However, given the statistical consistency of measurements, sample size was sufficient. Another limitation, inherent to the model, was that only bony anatomy was incorporated. However, the overlying muscles, tendons, and ligaments can significantly alter tunnel placement, and this study provided other means and cues using more reliable landmarks to adequately place the tunnels. As this was a simulation study, we cannot confirm whether these results would make a difference clinically. The strengths of this study include development and verification of reliable landmarks that can be used to guide ulnar tunnel locations during LUCL reconstruction; these landmarks have been used for medial ulnar collateral ligament reconstruction.15 Other strengths include precise and accurate placement of tunnels and measurement of resulting bony bridges—accomplished independently and without compromising specimen quality.
Conclusion
We recommend drilling the proximal ulnar tunnel posterior to the supinator crest at the level of the radial head junction. A reasonable goal is 10 mm posterior to the crest, though the overlying soft tissue must be considered, and care should be taken to aim the drill anteriorly, toward the ulna’s intramedullary canal, to avoid posterior cortical breach. The distal ulnar tunnel should be drilled just posterior to the supinator crest, 15 mm distal to the radial head junction.
1. O’Driscoll SW, Bell DF, Morrey BF. Posterolateral rotatory instability of the elbow. J Bone Joint Surg Am. 1991;73(3):440-446.
2. O’Driscoll SW. Classification and evaluation of recurrent instability of the elbow. Clin Orthop Relat Res. 2000;370:34-43.
3. Takigawa N, Ryu J, Kish VL, Kinoshita M, Abe M. Functional anatomy of the lateral collateral ligament complex of the elbow: morphology and strain. J Hand Surg Br. 2005;30(2):143-147.
4. McAdams TR, Masters GW, Srivastava S. The effect of arthroscopic sectioning of the lateral ligament complex of the elbow on posterolateral rotatory stability. J Shoulder Elbow Surg. 2005;14(3):298-301.
5. Dunning CE, Zarzour ZD, Patterson SD, Johnson JA, King GJ. Ligamentous stabilizers against posterolateral rotatory instability of the elbow. J Bone Joint Surg Am. 2001;83(12):1823-1828.
6. Eygendaal D. Ligamentous reconstruction around the elbow using triceps tendon. Acta Orthop Scand. 2004;75(5):516-523.
7. Jones KJ, Dodson CC, Osbahr DC, et al. The docking technique for lateral ulnar collateral ligament reconstruction: surgical technique and clinical outcomes. J Shoulder Elbow Surg. 2012;21(3):389-395.
8. Lee BP, Teo LH. Surgical reconstruction for posterolateral rotatory instability of the elbow. J Shoulder Elbow Surg. 2003;12(5):476-479.
9. Lin KY, Shen PH, Lee CH, Pan RY, Lin LC, Shen HC. Functional outcomes of surgical reconstruction for posterolateral rotatory instability of the elbow. Injury. 2012;43(10):1657-1661.
10. Olsen BS, Søjbjerg JO. The treatment of recurrent posterolateral instability of the elbow. J Bone Joint Surg Br. 2003;85(3):342-346.
11. Sanchez-Sotelo J, Morrey BF, O’Driscoll SW. Ligamentous repair and reconstruction for posterolateral rotatory instability of the elbow. J Bone Joint Surg Br. 2005;87(1):54-61.
12. Savoie FH 3rd, Field LD, Gurley DJ. Arthroscopic and open radial ulnohumeral ligament reconstruction for posterolateral rotatory instability of the elbow. Hand Clin. 2009;25(3):323-329.
13. Savoie FH 3rd, O’Brien MJ, Field LD, Gurley DJ. Arthroscopic and open radial ulnohumeral ligament reconstruction for posterolateral rotatory instability of the elbow. Clin Sports Med. 2010;29(4):611-618.
14. Bryce CD, Pennypacker JL, Kulkarni N, et al. Validation of three-dimensional models of in situ scapulae. J Shoulder Elbow Surg. 2008;17(5):825-832.
15. Byram IR, Khanna K, Gardner TR, Ahmad CS. Characterizing bone tunnel placement in medial ulnar collateral ligament reconstruction using patient-specific 3-dimensional computed tomography modeling. Am J Sports Med. 2013;41(4):894-902.
16. Shiba R, Sorbie C, Siu DW, Bryant JT, Cooke TD, Wevers HW. Geometry of the humeroulnar joint. J Orthop Res. 1988;6(6):897-906.
17. Anakwenze OA, Khanna K, Levine WN, Ahmad CS. Characterization of the supinator tubercle for lateral ulnar collateral ligament reconstruction. Orthop J Sports Med. 2014;2(4):2325967114530969. doi:10.1177/2325967114530969.
18. Sasashige Y, Ochi M, Ikuta Y. Optimal attachment site for reconstruction of the ulnar collateral ligament. A cadaver study. Arch Orthop Trauma Surg. 1994;113(5):265-270.
Posterolateral rotatory instability (PLRI) of the elbow is well recognized1 and is the most common type of chronic elbow instability. PLRI is often an end result of traumatic elbow dislocation.2 The “essential lesion” in patients with PLRI of the elbow is injury to the lateral ulnar collateral ligament (LUCL).1 However, more recent research has emphasized the importance of other ligaments in the lateral ligament complex (radial collateral and annular ligaments) in preventing PLRI.3-5 Nevertheless, when conservative treatment fails, the most commonly used surgical treatment involves LUCL reconstruction.1,6-11
Numerous techniques for LUCL reconstruction have been described.1,7-9,11-13 The chosen technique ideally restores normal anatomy. Therefore, the isometric point of origin at the lateral epicondyle and insertion at the supinator tubercle are important landmarks for creating tunnels that reproduce isometry, function, and normal anatomy. Most often, 2 tunnels are created in the ulna to secure the graft. It has been our experience that ulnar tunnel creation can affect the length of the bony bridge and the orientation of the graft.
We conducted a study to identify the precise proximal ulna tunnel location—anterior to posterior, with the distal tunnel at the supinator tubercle on the crest—that allows for the largest bony bridge and most geometrically favorable construct. We hypothesized that a most posteriorly placed proximal tunnel would increase bony bridge size and allow for a more isosceles graft configuration. An isosceles configuration with the humerus tunnel at the isometric location would allow for anterior and posterior bands of the same length with theoretically equal force distribution.
Methods
After obtaining institutional review board approval, we retrospectively reviewed the cases of 17 adults with elbow computed tomography (CT) scans for inclusion in this study. The scans were previously performed for diagnostic workup of several pathologies, including valgus instability, olecranon stress fracture, and valgus extension overload. The scan protocol involved 0.5-mm axial cuts with inclusion of the distal humerus through the proximal radius and ulna in the DICOM (Digital Imaging and Communications in Medicine) format. Exclusion criteria included poor CT quality, inadequate visualization of the entire supinator crest, and age under 18 years. Fifteen patients with adequate CT scans met the inclusion criteria. MIMICS (Materialise’s Interactive Medical Image Control System) software was used to convert scans into patient-specific 3-dimensional (3-D) computer models. (Use of this software to produce anatomically accurate models has been verified in shoulder14 and elbow15 models.) These models were uploaded into Magics rapid prototyping software (Materialise) and manipulated for simulated tunnel drilling by precise bone subtraction methods. This software was used to define an ulnar Cartesian coordinate system with anatomical landmarks as reference points in order to standardize the position of each model (Figure 1).16 The y-axis was defined by the longitudinal axis of the ulna, and the x-axis was the transepicondylar axis, defined as the perpendicular line connecting the y-axis with the supinator crest. The z-axis was then established as the line perpendicular to the x- and y-axes—yielding a 3-D coordinate system that allowed us to manipulate the models in standardized fashion, maintaining the exact positions of the ulna while making measurements.
Surgical simulations were performed in the rapid prototyping software by creating a cylinder and placing it at the desired location of each tunnel. Cylinder diameter was 4 mm, matching the diameter of the drill we use to create each tunnel in our practice. The cylinder was inserted into the bone, perpendicular to the surface of the ulna at the point of insertion, so the cylinder’s deepest point entered the medullary canal of the ulna. Using a Boolean operation in the rapid prototyping software, we subtracted cylinder from bone to create a tunnel (Figure 2).15
In a previous study,17 we determined that the radial head junction is reproducibly about 15 mm proximal to the distinct supinator tubercle, which may be absent or not readily appreciated in up to 50% of cases. Therefore, proximal ulnar tunnels were placed 0, 5, and 10 mm posterior to the supinator crest at the radial head junction. Distal tunnels were placed 15 mm anterior to the radial head junction on the supinator crest (Figure 2). The bony bridges created by these tunnels were measured, as was the distance between the distal tunnel and the supinator tubercle.
Ideal graft configuration was described as an isosceles triangle with ulna tunnels perpendicular to the humeral tunnel (Figure 3).11 Location of the humeral origin in the sagittal plane was determined by finding the isometric point of the lateral humerus using only bony landmarks. Similar techniques have been used to find the isometric point on the medial epicondyle for medial ulnar collateral ligament reconstruction.15,18 With a circle fit into the trochlear notch of the ulna, the isometric point can be determined by the center of the circle. This point was then superimposed on the humerus to identify the starting point (Figure 4). In our simulation, we measured the isosceles configuration by drawing a line between the proximal and distal tunnels, and then another line connecting the bisecting point of the first line with the isometric point on the humerus from which the graft would originate. The angle between the 2 lines was measured; if isosceles, the angle was 90° (Figure 5). Length of the more proximal limb of the graft and the more distal limb of the graft was determined by measuring the distance from the isometric point to the proximal and distal tunnels, respectively (Figure 6).
One-way analysis of variance was used to compare all the tunnels’ bony bridge sizes, graft lengths, and angles to the isometric point. For all comparisons, statistical significance was set at P < .05. As no other studies have compared bony bridges by varying tunnel creation parameters, and as the present study is observational and not comparative, no power analysis was performed.
Results
Bony bridges were significantly longer, and angles more perpendicular, with increasing distance from the proximal tunnel to the supinator crest (Table 1, Figure 5, Figure 7). The bony bridge 0 mm posterior to the supinator crest yielded a mean (SE) bony bridge length of 11.0 (0.2) mm. This proximal tunnel also yielded the smallest mean (SE) perpendicular angle to the isometric point, 131.2° (1.9°). The tunnel most posterior to the supinator crest yielded the longest mean (SE) bony bridge, 13.7 (0.2) mm, and the largest mean (SE) degree of perpendicularity, 95.8° (1.4°). The differences between all tunnels’ bony bridges and isometric angles were statistically significant (P < .00001). The difference between the more distal limb and the more proximal limb of the graft was smallest in the more posteriorly placed proximal tunnel (Table 2, Figure 8). In fact, there was no statistical difference between the proximal and distal limbs of the graft when the proximal tunnel was placed 10 mm posterior to the supinator crest: Mean (SE) was 9.4 (0.5) mm at 0 mm (P < .00001) and 1.1 (0.6) mm at 10 mm (P = .24).
Discussion
PLRI of the elbow is best initially managed nonoperatively. However, when nonoperative management fails, the LUCL is often surgically reconstructed. Reconstruction methods vary by fixation method, graft choice, and bone tunnels.1,7-9,11-13 In 1991, O’Driscoll and colleagues1 described a “yoke” technique for LUCL reconstruction. Since then, the docking technique7 and other techniques have been developed. All these techniques emphasize maximizing anatomical precision and isometry with careful placement of tunnels or fixation devices. The humeral fixation site, at the anterior inferior aspect of the lateral epicondyle at the point of isometry, can be accessed relatively reproducibly. By contrast, the ulnar points of fixation are more variable, because of increased bone stock and overlying soft-tissue and bony anatomy.
Among the challenges in determining the points of ulnar fixation is the bony anatomy that is often used for landmarks. In the literature, the supinator crest or the supintor tubercle is the landmark for placing the distal tunnel.1,7-9,11-13 This is a problem for 2 reasons. First, the supintor crest, a longitudinal structure on the lateral aspect of the ulna, originates from the radial head junction and extends tens of millimeters distally; further specification is needed to guide these ulnar tunnels. The second reason is that use of the supinator tubercle, a prominence on the supinator crest, adds specificity to the location of the ulnar tunnels. During surgery, however, the supinator tubercle may not be a reliable, independently prominent structure; instead, it may be indistinguishable from the supinator crest, on which it rests. One study determined that only about 50% of computer models of patient ulnas had a distinct prominence that could be classified as the supinator tubercle.17 The percentage presumably is lower during surgery, with limited exposure and overlying soft tissues.
In a study of patients with a prominent tubercle, mean (SE) distance from radial head junction to tubercle was 15 (2) mm.17 This finding led us to use the radial head junction as the primary bony landmark in determining the location of the proximal tunnel and placing the distal tunnel 15 mm distally—achieving the same fixation described in the literature but using more distinct landmarks. Our study thus provided a reliable, verified approach to locating the ulnar tunnels in the proximal-distal axis.
We also explored the anterior-posterior orientation of the proximal ulnar tunnel. The 2 primary considerations surrounding the varied proximal tunnel placements were the bony bridge formed between the proximal and distal tunnels and the perpendicularity of the triangle formed by the fixation points. Maximizing the bony bridge is obviously ideal in securing and preventing fixation blowout. Achieving an isoceles reconstruction has been reported in the literature on the various fixation techniques for LUCL reconstruction.11 Although the biomechanical advantage of this fixation type is not fully clear, we assume the construct produces graft stands of equal length, tension, and stability. In addition, the larger footprint created by an isoceles reconstructed ligament increases the stability of the radial head.
Results of the present study showed that the more posterior the proximal ulnar tunnel, the longer the bony bridge and the more isoceles the reconstruction. The difference in bony bridge distance from the most anterior to the most posterior tunnel was about 2 mm, or 18%. For every 1 mm of posteriorization, the bony bridge was 0.2 mm longer. The line from the isometric point of humeral fixation bisecting the proximal and distal tunnels was also more perpendicular with the most posterior tunnel, by about 40°. The resulting proximal and distal limbs of the reconstruction were equal in length, as demonstrated by the smaller difference between the limbs. We assume this isoceles reconstruction more likely applies uniform restraint on the radial head. Thus, an effort should be made to posteriorize the proximal ulnar tunnel during reconstruction.
The study was limited by the number of patient-specific elbow models used. However, given the statistical consistency of measurements, sample size was sufficient. Another limitation, inherent to the model, was that only bony anatomy was incorporated. However, the overlying muscles, tendons, and ligaments can significantly alter tunnel placement, and this study provided other means and cues using more reliable landmarks to adequately place the tunnels. As this was a simulation study, we cannot confirm whether these results would make a difference clinically. The strengths of this study include development and verification of reliable landmarks that can be used to guide ulnar tunnel locations during LUCL reconstruction; these landmarks have been used for medial ulnar collateral ligament reconstruction.15 Other strengths include precise and accurate placement of tunnels and measurement of resulting bony bridges—accomplished independently and without compromising specimen quality.
Conclusion
We recommend drilling the proximal ulnar tunnel posterior to the supinator crest at the level of the radial head junction. A reasonable goal is 10 mm posterior to the crest, though the overlying soft tissue must be considered, and care should be taken to aim the drill anteriorly, toward the ulna’s intramedullary canal, to avoid posterior cortical breach. The distal ulnar tunnel should be drilled just posterior to the supinator crest, 15 mm distal to the radial head junction.
Posterolateral rotatory instability (PLRI) of the elbow is well recognized1 and is the most common type of chronic elbow instability. PLRI is often an end result of traumatic elbow dislocation.2 The “essential lesion” in patients with PLRI of the elbow is injury to the lateral ulnar collateral ligament (LUCL).1 However, more recent research has emphasized the importance of other ligaments in the lateral ligament complex (radial collateral and annular ligaments) in preventing PLRI.3-5 Nevertheless, when conservative treatment fails, the most commonly used surgical treatment involves LUCL reconstruction.1,6-11
Numerous techniques for LUCL reconstruction have been described.1,7-9,11-13 The chosen technique ideally restores normal anatomy. Therefore, the isometric point of origin at the lateral epicondyle and insertion at the supinator tubercle are important landmarks for creating tunnels that reproduce isometry, function, and normal anatomy. Most often, 2 tunnels are created in the ulna to secure the graft. It has been our experience that ulnar tunnel creation can affect the length of the bony bridge and the orientation of the graft.
We conducted a study to identify the precise proximal ulna tunnel location—anterior to posterior, with the distal tunnel at the supinator tubercle on the crest—that allows for the largest bony bridge and most geometrically favorable construct. We hypothesized that a most posteriorly placed proximal tunnel would increase bony bridge size and allow for a more isosceles graft configuration. An isosceles configuration with the humerus tunnel at the isometric location would allow for anterior and posterior bands of the same length with theoretically equal force distribution.
Methods
After obtaining institutional review board approval, we retrospectively reviewed the cases of 17 adults with elbow computed tomography (CT) scans for inclusion in this study. The scans were previously performed for diagnostic workup of several pathologies, including valgus instability, olecranon stress fracture, and valgus extension overload. The scan protocol involved 0.5-mm axial cuts with inclusion of the distal humerus through the proximal radius and ulna in the DICOM (Digital Imaging and Communications in Medicine) format. Exclusion criteria included poor CT quality, inadequate visualization of the entire supinator crest, and age under 18 years. Fifteen patients with adequate CT scans met the inclusion criteria. MIMICS (Materialise’s Interactive Medical Image Control System) software was used to convert scans into patient-specific 3-dimensional (3-D) computer models. (Use of this software to produce anatomically accurate models has been verified in shoulder14 and elbow15 models.) These models were uploaded into Magics rapid prototyping software (Materialise) and manipulated for simulated tunnel drilling by precise bone subtraction methods. This software was used to define an ulnar Cartesian coordinate system with anatomical landmarks as reference points in order to standardize the position of each model (Figure 1).16 The y-axis was defined by the longitudinal axis of the ulna, and the x-axis was the transepicondylar axis, defined as the perpendicular line connecting the y-axis with the supinator crest. The z-axis was then established as the line perpendicular to the x- and y-axes—yielding a 3-D coordinate system that allowed us to manipulate the models in standardized fashion, maintaining the exact positions of the ulna while making measurements.
Surgical simulations were performed in the rapid prototyping software by creating a cylinder and placing it at the desired location of each tunnel. Cylinder diameter was 4 mm, matching the diameter of the drill we use to create each tunnel in our practice. The cylinder was inserted into the bone, perpendicular to the surface of the ulna at the point of insertion, so the cylinder’s deepest point entered the medullary canal of the ulna. Using a Boolean operation in the rapid prototyping software, we subtracted cylinder from bone to create a tunnel (Figure 2).15
In a previous study,17 we determined that the radial head junction is reproducibly about 15 mm proximal to the distinct supinator tubercle, which may be absent or not readily appreciated in up to 50% of cases. Therefore, proximal ulnar tunnels were placed 0, 5, and 10 mm posterior to the supinator crest at the radial head junction. Distal tunnels were placed 15 mm anterior to the radial head junction on the supinator crest (Figure 2). The bony bridges created by these tunnels were measured, as was the distance between the distal tunnel and the supinator tubercle.
Ideal graft configuration was described as an isosceles triangle with ulna tunnels perpendicular to the humeral tunnel (Figure 3).11 Location of the humeral origin in the sagittal plane was determined by finding the isometric point of the lateral humerus using only bony landmarks. Similar techniques have been used to find the isometric point on the medial epicondyle for medial ulnar collateral ligament reconstruction.15,18 With a circle fit into the trochlear notch of the ulna, the isometric point can be determined by the center of the circle. This point was then superimposed on the humerus to identify the starting point (Figure 4). In our simulation, we measured the isosceles configuration by drawing a line between the proximal and distal tunnels, and then another line connecting the bisecting point of the first line with the isometric point on the humerus from which the graft would originate. The angle between the 2 lines was measured; if isosceles, the angle was 90° (Figure 5). Length of the more proximal limb of the graft and the more distal limb of the graft was determined by measuring the distance from the isometric point to the proximal and distal tunnels, respectively (Figure 6).
One-way analysis of variance was used to compare all the tunnels’ bony bridge sizes, graft lengths, and angles to the isometric point. For all comparisons, statistical significance was set at P < .05. As no other studies have compared bony bridges by varying tunnel creation parameters, and as the present study is observational and not comparative, no power analysis was performed.
Results
Bony bridges were significantly longer, and angles more perpendicular, with increasing distance from the proximal tunnel to the supinator crest (Table 1, Figure 5, Figure 7). The bony bridge 0 mm posterior to the supinator crest yielded a mean (SE) bony bridge length of 11.0 (0.2) mm. This proximal tunnel also yielded the smallest mean (SE) perpendicular angle to the isometric point, 131.2° (1.9°). The tunnel most posterior to the supinator crest yielded the longest mean (SE) bony bridge, 13.7 (0.2) mm, and the largest mean (SE) degree of perpendicularity, 95.8° (1.4°). The differences between all tunnels’ bony bridges and isometric angles were statistically significant (P < .00001). The difference between the more distal limb and the more proximal limb of the graft was smallest in the more posteriorly placed proximal tunnel (Table 2, Figure 8). In fact, there was no statistical difference between the proximal and distal limbs of the graft when the proximal tunnel was placed 10 mm posterior to the supinator crest: Mean (SE) was 9.4 (0.5) mm at 0 mm (P < .00001) and 1.1 (0.6) mm at 10 mm (P = .24).
Discussion
PLRI of the elbow is best initially managed nonoperatively. However, when nonoperative management fails, the LUCL is often surgically reconstructed. Reconstruction methods vary by fixation method, graft choice, and bone tunnels.1,7-9,11-13 In 1991, O’Driscoll and colleagues1 described a “yoke” technique for LUCL reconstruction. Since then, the docking technique7 and other techniques have been developed. All these techniques emphasize maximizing anatomical precision and isometry with careful placement of tunnels or fixation devices. The humeral fixation site, at the anterior inferior aspect of the lateral epicondyle at the point of isometry, can be accessed relatively reproducibly. By contrast, the ulnar points of fixation are more variable, because of increased bone stock and overlying soft-tissue and bony anatomy.
Among the challenges in determining the points of ulnar fixation is the bony anatomy that is often used for landmarks. In the literature, the supinator crest or the supintor tubercle is the landmark for placing the distal tunnel.1,7-9,11-13 This is a problem for 2 reasons. First, the supintor crest, a longitudinal structure on the lateral aspect of the ulna, originates from the radial head junction and extends tens of millimeters distally; further specification is needed to guide these ulnar tunnels. The second reason is that use of the supinator tubercle, a prominence on the supinator crest, adds specificity to the location of the ulnar tunnels. During surgery, however, the supinator tubercle may not be a reliable, independently prominent structure; instead, it may be indistinguishable from the supinator crest, on which it rests. One study determined that only about 50% of computer models of patient ulnas had a distinct prominence that could be classified as the supinator tubercle.17 The percentage presumably is lower during surgery, with limited exposure and overlying soft tissues.
In a study of patients with a prominent tubercle, mean (SE) distance from radial head junction to tubercle was 15 (2) mm.17 This finding led us to use the radial head junction as the primary bony landmark in determining the location of the proximal tunnel and placing the distal tunnel 15 mm distally—achieving the same fixation described in the literature but using more distinct landmarks. Our study thus provided a reliable, verified approach to locating the ulnar tunnels in the proximal-distal axis.
We also explored the anterior-posterior orientation of the proximal ulnar tunnel. The 2 primary considerations surrounding the varied proximal tunnel placements were the bony bridge formed between the proximal and distal tunnels and the perpendicularity of the triangle formed by the fixation points. Maximizing the bony bridge is obviously ideal in securing and preventing fixation blowout. Achieving an isoceles reconstruction has been reported in the literature on the various fixation techniques for LUCL reconstruction.11 Although the biomechanical advantage of this fixation type is not fully clear, we assume the construct produces graft stands of equal length, tension, and stability. In addition, the larger footprint created by an isoceles reconstructed ligament increases the stability of the radial head.
Results of the present study showed that the more posterior the proximal ulnar tunnel, the longer the bony bridge and the more isoceles the reconstruction. The difference in bony bridge distance from the most anterior to the most posterior tunnel was about 2 mm, or 18%. For every 1 mm of posteriorization, the bony bridge was 0.2 mm longer. The line from the isometric point of humeral fixation bisecting the proximal and distal tunnels was also more perpendicular with the most posterior tunnel, by about 40°. The resulting proximal and distal limbs of the reconstruction were equal in length, as demonstrated by the smaller difference between the limbs. We assume this isoceles reconstruction more likely applies uniform restraint on the radial head. Thus, an effort should be made to posteriorize the proximal ulnar tunnel during reconstruction.
The study was limited by the number of patient-specific elbow models used. However, given the statistical consistency of measurements, sample size was sufficient. Another limitation, inherent to the model, was that only bony anatomy was incorporated. However, the overlying muscles, tendons, and ligaments can significantly alter tunnel placement, and this study provided other means and cues using more reliable landmarks to adequately place the tunnels. As this was a simulation study, we cannot confirm whether these results would make a difference clinically. The strengths of this study include development and verification of reliable landmarks that can be used to guide ulnar tunnel locations during LUCL reconstruction; these landmarks have been used for medial ulnar collateral ligament reconstruction.15 Other strengths include precise and accurate placement of tunnels and measurement of resulting bony bridges—accomplished independently and without compromising specimen quality.
Conclusion
We recommend drilling the proximal ulnar tunnel posterior to the supinator crest at the level of the radial head junction. A reasonable goal is 10 mm posterior to the crest, though the overlying soft tissue must be considered, and care should be taken to aim the drill anteriorly, toward the ulna’s intramedullary canal, to avoid posterior cortical breach. The distal ulnar tunnel should be drilled just posterior to the supinator crest, 15 mm distal to the radial head junction.
1. O’Driscoll SW, Bell DF, Morrey BF. Posterolateral rotatory instability of the elbow. J Bone Joint Surg Am. 1991;73(3):440-446.
2. O’Driscoll SW. Classification and evaluation of recurrent instability of the elbow. Clin Orthop Relat Res. 2000;370:34-43.
3. Takigawa N, Ryu J, Kish VL, Kinoshita M, Abe M. Functional anatomy of the lateral collateral ligament complex of the elbow: morphology and strain. J Hand Surg Br. 2005;30(2):143-147.
4. McAdams TR, Masters GW, Srivastava S. The effect of arthroscopic sectioning of the lateral ligament complex of the elbow on posterolateral rotatory stability. J Shoulder Elbow Surg. 2005;14(3):298-301.
5. Dunning CE, Zarzour ZD, Patterson SD, Johnson JA, King GJ. Ligamentous stabilizers against posterolateral rotatory instability of the elbow. J Bone Joint Surg Am. 2001;83(12):1823-1828.
6. Eygendaal D. Ligamentous reconstruction around the elbow using triceps tendon. Acta Orthop Scand. 2004;75(5):516-523.
7. Jones KJ, Dodson CC, Osbahr DC, et al. The docking technique for lateral ulnar collateral ligament reconstruction: surgical technique and clinical outcomes. J Shoulder Elbow Surg. 2012;21(3):389-395.
8. Lee BP, Teo LH. Surgical reconstruction for posterolateral rotatory instability of the elbow. J Shoulder Elbow Surg. 2003;12(5):476-479.
9. Lin KY, Shen PH, Lee CH, Pan RY, Lin LC, Shen HC. Functional outcomes of surgical reconstruction for posterolateral rotatory instability of the elbow. Injury. 2012;43(10):1657-1661.
10. Olsen BS, Søjbjerg JO. The treatment of recurrent posterolateral instability of the elbow. J Bone Joint Surg Br. 2003;85(3):342-346.
11. Sanchez-Sotelo J, Morrey BF, O’Driscoll SW. Ligamentous repair and reconstruction for posterolateral rotatory instability of the elbow. J Bone Joint Surg Br. 2005;87(1):54-61.
12. Savoie FH 3rd, Field LD, Gurley DJ. Arthroscopic and open radial ulnohumeral ligament reconstruction for posterolateral rotatory instability of the elbow. Hand Clin. 2009;25(3):323-329.
13. Savoie FH 3rd, O’Brien MJ, Field LD, Gurley DJ. Arthroscopic and open radial ulnohumeral ligament reconstruction for posterolateral rotatory instability of the elbow. Clin Sports Med. 2010;29(4):611-618.
14. Bryce CD, Pennypacker JL, Kulkarni N, et al. Validation of three-dimensional models of in situ scapulae. J Shoulder Elbow Surg. 2008;17(5):825-832.
15. Byram IR, Khanna K, Gardner TR, Ahmad CS. Characterizing bone tunnel placement in medial ulnar collateral ligament reconstruction using patient-specific 3-dimensional computed tomography modeling. Am J Sports Med. 2013;41(4):894-902.
16. Shiba R, Sorbie C, Siu DW, Bryant JT, Cooke TD, Wevers HW. Geometry of the humeroulnar joint. J Orthop Res. 1988;6(6):897-906.
17. Anakwenze OA, Khanna K, Levine WN, Ahmad CS. Characterization of the supinator tubercle for lateral ulnar collateral ligament reconstruction. Orthop J Sports Med. 2014;2(4):2325967114530969. doi:10.1177/2325967114530969.
18. Sasashige Y, Ochi M, Ikuta Y. Optimal attachment site for reconstruction of the ulnar collateral ligament. A cadaver study. Arch Orthop Trauma Surg. 1994;113(5):265-270.
1. O’Driscoll SW, Bell DF, Morrey BF. Posterolateral rotatory instability of the elbow. J Bone Joint Surg Am. 1991;73(3):440-446.
2. O’Driscoll SW. Classification and evaluation of recurrent instability of the elbow. Clin Orthop Relat Res. 2000;370:34-43.
3. Takigawa N, Ryu J, Kish VL, Kinoshita M, Abe M. Functional anatomy of the lateral collateral ligament complex of the elbow: morphology and strain. J Hand Surg Br. 2005;30(2):143-147.
4. McAdams TR, Masters GW, Srivastava S. The effect of arthroscopic sectioning of the lateral ligament complex of the elbow on posterolateral rotatory stability. J Shoulder Elbow Surg. 2005;14(3):298-301.
5. Dunning CE, Zarzour ZD, Patterson SD, Johnson JA, King GJ. Ligamentous stabilizers against posterolateral rotatory instability of the elbow. J Bone Joint Surg Am. 2001;83(12):1823-1828.
6. Eygendaal D. Ligamentous reconstruction around the elbow using triceps tendon. Acta Orthop Scand. 2004;75(5):516-523.
7. Jones KJ, Dodson CC, Osbahr DC, et al. The docking technique for lateral ulnar collateral ligament reconstruction: surgical technique and clinical outcomes. J Shoulder Elbow Surg. 2012;21(3):389-395.
8. Lee BP, Teo LH. Surgical reconstruction for posterolateral rotatory instability of the elbow. J Shoulder Elbow Surg. 2003;12(5):476-479.
9. Lin KY, Shen PH, Lee CH, Pan RY, Lin LC, Shen HC. Functional outcomes of surgical reconstruction for posterolateral rotatory instability of the elbow. Injury. 2012;43(10):1657-1661.
10. Olsen BS, Søjbjerg JO. The treatment of recurrent posterolateral instability of the elbow. J Bone Joint Surg Br. 2003;85(3):342-346.
11. Sanchez-Sotelo J, Morrey BF, O’Driscoll SW. Ligamentous repair and reconstruction for posterolateral rotatory instability of the elbow. J Bone Joint Surg Br. 2005;87(1):54-61.
12. Savoie FH 3rd, Field LD, Gurley DJ. Arthroscopic and open radial ulnohumeral ligament reconstruction for posterolateral rotatory instability of the elbow. Hand Clin. 2009;25(3):323-329.
13. Savoie FH 3rd, O’Brien MJ, Field LD, Gurley DJ. Arthroscopic and open radial ulnohumeral ligament reconstruction for posterolateral rotatory instability of the elbow. Clin Sports Med. 2010;29(4):611-618.
14. Bryce CD, Pennypacker JL, Kulkarni N, et al. Validation of three-dimensional models of in situ scapulae. J Shoulder Elbow Surg. 2008;17(5):825-832.
15. Byram IR, Khanna K, Gardner TR, Ahmad CS. Characterizing bone tunnel placement in medial ulnar collateral ligament reconstruction using patient-specific 3-dimensional computed tomography modeling. Am J Sports Med. 2013;41(4):894-902.
16. Shiba R, Sorbie C, Siu DW, Bryant JT, Cooke TD, Wevers HW. Geometry of the humeroulnar joint. J Orthop Res. 1988;6(6):897-906.
17. Anakwenze OA, Khanna K, Levine WN, Ahmad CS. Characterization of the supinator tubercle for lateral ulnar collateral ligament reconstruction. Orthop J Sports Med. 2014;2(4):2325967114530969. doi:10.1177/2325967114530969.
18. Sasashige Y, Ochi M, Ikuta Y. Optimal attachment site for reconstruction of the ulnar collateral ligament. A cadaver study. Arch Orthop Trauma Surg. 1994;113(5):265-270.
Coracoid Fracture After Reverse Total Shoulder Arthroplasty: A Report of 2 Cases
Reverse total shoulder arthroplasty (RTSA) performed in carefully selected patients often leads to satisfactory outcomes.1,2 In recent years, its indications and the number performed per year have expanded. Subsequently, there has been a concomitant rise in reported complications,2,3 with a rate ranging from 19% to 68%.2,3 Some common complications include scapular notching,2-4 fracture,2,3,5-7 dislocation,2,3,7 and infection.2,3,7
In this series, we describe 2 cases of coracoid fracture after RTSA. The patients provided written informed consent for print and electronic publication of these case reports.
Case Series
Case 1
An independently functioning 81-year-old right hand–dominant woman (BMI, 22.1 [height, 160 cm; weight, 56.7 kg]) presented with increasing left shoulder pain and dysfunction after a motor vehicle accident 2 months earlier. She had reported vague chronic left shoulder pain in the past, but after the accident her pain was significantly worse. A subacromial corticosteroid injection by her primary care physician provided temporary symptomatic relief, but her symptoms recurred.
On presentation, there was obvious anterior superior escape of the humeral head, which was accentuated by shoulder shrug. Her deltoid motor function was found to be intact, and her active shoulder range of motion was severely limited (pseudoparesis). There was notable crepitation as well as significant weakness and pain with abduction and external rotation strength testing.
Radiographic imaging showed anterior superior escape of the humeral head with some early degenerative changes (Seebauer type IIB8 [Figure 1A]). Magnetic resonance imaging confirmed a full-thickness retracted massive rotator cuff tear with complete involvement of the supraspinatus, infraspinatus, and most of the subscapularis muscles. Significant glenohumeral degenerative changes consistent with cuff tear arthropathy were also seen without any evidence of fracture.
After thorough discussion of options, risks, and benefits, the decision was made to proceed with RTSA. The patient underwent the procedure without complications. A DePuy Delta Xtend prosthesis was used with a cemented humeral stem, polyethylene, and glenosphere, sizes of 12, +3, and 38, respectively. The glenosphere component, positioned inferiorly to avoid scapular notching, was secured with 3 screws, and the stem was placed in neutral version. The patient’s shoulder was reduced, ranged, and noted to be stable, allowing for supple passive range of motion without evidence of excessive tightness. She was placed in a sling with the shoulder positioned in neutral alignment. Her postoperative radiograph (Figure 1B) showed satisfactory implantation of the reverse total shoulder prosthesis. Her postoperative course was uneventful, and rehabilitation consisted of 6 weeks of sling protection, with advancing passive and active range of motion. Strengthening exercises were initiated 6 weeks after surgery.
At the patient’s 6-week postoperative visit, she demonstrated pain-free passive elevation to 80° and active forward elevation to 70°. At her 3-month postoperative visit, she reported a 1-week onset of anterior shoulder pain accompanied by a strange noise at the anterior aspect of the operative shoulder. She denied any recent trauma. She continued to have minimal shoulder pain with passive forward flexion of 80°; however, her active forward elevation was very limited because of pain in the anterior aspect of her shoulder. Active external rotation was noted to be 20° and internal rotation was to her buttock. She had pain to palpation of the coracoid process. Radiographs were unchanged from immediate postoperative radiographs. Computed tomography (CT), which was ordered to ensure that the implant was stable with no loosening, showed satisfactory alignment of the prosthesis and no loosening. However, CT was notable for a nondisplaced fracture through the base of the coracoid (Figures 2A-2D). The patient stopped formal physical therapy, and sling immobilization was initiated. After 3 weeks, the sling was discontinued and physical therapy was begun again. She responded satisfactorily to this treatment approach, and, at her 6-month postoperative follow-up, she was without pain, instability, or crepitation. Her range of motion had improved with pain-free active forward flexion, external rotation, and abduction of 100°, 15°, and 90°, respectively. At 28-month postoperative follow-up, her visual analog scale, American Shoulder and Elbow Surgeons score, and Simple Shoulder Test score were 3, 73, and 67, respectively.
Case 2
A 68-year-old, right-handed woman (BMI, 22.5 [height, 160 cm; weight, 57.6 kg]) presented with right shoulder pain and dysfunction of 3 years’ duration. She had undergone an open rotator cuff repair at an outside facility 4 years ago that was unsuccessful. At the time of her presentation to our institution, she had already undergone a failed course of physical therapy. A trial of corticosteroid subacromial injections did not adequately manage her symptoms.
On presentation, her active forward flexion, abduction, and external rotation were 40°, 30°, and 10°, respectively. She had full passive range of motion and pain with active and passive shoulder motion. Radiographic imaging showed superior migration of the humeral head with evidence of glenohumeral arthropathy suggestive of rotator cuff arthropathy (Seebauer type IIA8). After thorough discussion of options, risks, and benefits, the decision was made to proceed with RTSA. She underwent the procedure without complications. A DePuy Delta Xtend prosthesis was used with a cemented humeral stem, polyethylene, and glenosphere, sizes of 8, +3, and 38, respectively. The glenosphere component, positioned inferiorly to avoid scapular notching, was secured with 4 screws, and the stem was placed in neutral version. Her shoulder was reduced, ranged, and noted to be stable, allowing for supple passive range of motion without evidence of excessive tightness. She was placed in a sling with the shoulder positioned in neutral alignment. Her postoperative radiographs revealed satisfactory implantation of the reverse total shoulder prosthesis. Her postoperative course was uneventful. She was taken out of her shoulder immobilizer 4 weeks after surgery and began home-based physical therapy.
At 1 year after surgery, the patient had minimal shoulder pain with active forward flexion, external rotation, and abduction of 135°, 20°, and 85°, respectively. She presented to our clinic 15 months after RTSA with acute onset of pain about her anterior shoulder. She denied any recent trauma or infectious exposures. On examination, her motion was unchanged from prior examinations. However, she was tender on palpation of the coracoid. Radiographs at that time were unchanged (Figures 3A, 3B). Laboratory tests (erythrocyte sedimentation rate, C-reactive protein, and complete blood count with differential) that were subsequently ordered to rule out an occult infection were within normal limits. Computed tomography, which was ordered for further assessment and to ensure that the implant was stable with no loosening, showed satisfactory alignment of the prosthesis without loosening. However, a lucency was noted in the midportion of the coracoid that was suggestive of a fracture (Figures 4A, 4B). A conservative plan of treatment was advised with sling immobilization for 3 weeks and follow-up visits. The patient responded satisfactorily to this treatment approach, and, at her latest follow-up, 8 months after presenting with a coracoid fracture, she was pain-free. At the 5-year postoperative follow-up, her visual analog scale, American Shoulder and Elbow Surgeons score, and Simple Shoulder Test score were 1-2, 78, and 75, respectively.
Discussion
The reverse prosthesis, a semi-constrained ball-and-socket device, provides satisfactory functional outcomes when used in carefully selected patients with rotator cuff arthropathy and pseudoparalysis, failed shoulder arthroplasty, and fracture sequelae.1,9-11 By the traditional Grammont principles of medializing the center of rotation and lowering the humerus, shear forces about the glenoid are reduced and the deltoid muscle is tensioned, allowing for adequate torque generation, required to facilitate shoulder motion.12,13 While long-term outcomes concerning durability and survivorship are pending, some studies have attempted to improve our understanding of implant and functional longevity. Guery and colleagues14 noted an implant survival of 91% at 120 months. However, increased pain and decreased function were seen at the 6-year mark.14 A more recent study by Cuff and colleagues15 revealed 94% implant survivorship and sustained improvement in range of motion and pain at 5 years.
Despite considerable success, RTSA can be associated with a myriad of complications. The most common complications of RTSA include scapular notching (44%-96%), glenoid side failure (5%-40%), instability (2.4%-31%), and infection (1%-15.3%).2,3 In the setting of inflammatory arthropathy, there is an increased risk for intraoperative and postoperative fractures.16,17 To date, there are only 2 reported cases of coracoid process fractures after RTSA.18,19 In the case by Nolan and colleagues,18 conservative management with a sling for 6 weeks led to successful resolution of symptoms. Although little information is provided on the management of these rare fractures, literature on the slightly more common scapular (0.9%-7.2%) and acromial (0.9%-4.9%) fractures suggest that periscapular fractures are on the rise, may increase the risk for revision surgery, and can lead to inferior outcomes when compared with patients without fractures.5,20,21
Acromial fractures after RTSA have been reported to occur at a rate of 0.9% to 4.9%.5,21 This is a concern because of RTSA reliance on a functional deltoid.5,6 The cause of these fractures remains to be fully elucidated. Wahlquist and colleagues6 in 2011 reported the cases of 5 patients that sustained acromial base fractures after RTSA. All 5 patients were noted to have unsatisfactory functional results despite achieving union (3 were treated with open reduction and internal fixation, and 2 were treated nonoperatively). Acromial fractures tend to present with pain within 6 months of surgery, which may indicate excessive constraint about the scapula, eventually leading to fracture. Furthermore, disruption of this bony structure can lead to devastating results because the acromial base serves as a fulcrum for the deltoid.
Despite a well-placed reverse prosthesis, there is increased reliance on surrounding glenohumeral musculature, resulting from poor rotator cuff function and biomechanical differences compared with a native shoulder. Both our patients were found to have relatively small body habitus. It is possible that, by nature of their smaller statures, they were more susceptible to consequences of excessive joint and soft-tissue tension after RTSA. One explanation for acromial fractures after RTSA is that, by excessively lengthening and/or lateralizing the deltoid, the tension on the acromion in these elderly patients may be sufficient to cause a fracture. A similar mechanism may explain their coracoid fractures. As the arm is lengthened and the prosthesis is tightened, the conjoint tendon is significantly tensioned. We routinely check the tension of these muscles as an extra confirmation of joint stability. However, excessive tension for a significant duration may provide too much stress for bone turnover to match with the inherent repair process, potentially causing a fracture. Recent evidence has also found that bone mineral density of the coracoid diminishes with age, suggesting some predisposition to fracture with lower-energy mechanisms.22
Another possible cause for coracoid fractures may be the orientation of the implants. While we did not have mechanistic evidence, it is possible that, with adduction and internal rotation, prosthetic impingement against the coracoid is feasible, particularly in patients of small stature. Although a glenoid implant placed high can increase the chance for coracoid–implant impingement, the fact that the patients improved without revision makes chronic mechanical impingement less likely. Drill holes, especially multiple ones, placed throughout the base of the coracoid may also predispose to coracoid fractures.
Patients with periscapular fractures (acromion, scapular spine, or coracoid) after RTSA often present with pain and occasional deficits in function. Both patients in this series noted pain out of proportion to examination. The onset of this pain differed, with 1 patient noting pain within the first 3 months and 1 noting discomfort later. Neither patient had any trauma. In the presence of significant symptoms, negative radiographs, and a poor response to conservative treatment, we recommend advanced imaging to rule out fracture. However, prior to obtaining advanced imaging, proper radiographic techniques should be utilized. Eyres and colleagues,23 in a series of 12 fractures of the coracoid process, relied primarily on coracoid views directed 45° in a cephalic direction and thin-slice CT. An isotope bone scan identified 1 case not initially found on radiographs.23
Conservative management with use of a sling until resolution of symptoms was successful in our series. If symptoms persist, a bone stimulator can be used prior to implementing a surgical solution; however, current evidence does not expound on timing and utility of such modalities. Perhaps as important as treatment is education of the patient and the rehabilitation team about the importance of identifying increasing pain as a potential sign of impending fracture in this population. Subsequent activity modification until the pain resolves can help avoid the setback in postoperative recovery that this complication may cause.
Conclusion
We present 2 patients with coracoid fractures encountered at 3 months and 15 months after RTSA. Nonoperative management proved adequate in treating both cases. We suggest a high level of suspicion for possible fracture in the patient who comes in with new-onset pain in a localized region with or without functional deficits.
1. Lawrence TM, Ahmadi S, Sanchez-Sotelo J, Sperling JW, Cofield RH. Patient reported activities after reverse shoulder arthroplasty: part II. J Shoulder Elbow Surg. 2012;21(11):1464-1469.
2. Cheung E, Willis M, Walker M, Clark R, Frankle MA. Complications in reverse total shoulder arthroplasty. J Am Acad Orthop Surg. 2011;19(7):439-449.
3. Affonso J, Nicholson GP, Frankle MA, et al. Complications of the reverse prosthesis: prevention and treatment. Instr Course Lect. 2012;61:157-168.
4. Lévigne C, Garret J, Boileau P, Alami G, Favard L, Walch G. Scapular notching in reverse shoulder arthroplasty: is it important to avoid it and how? Clin Orthop Relat Res. 2011;469(9):2512-2520.
5. Hamid N, Connor PM, Fleischli JF, D’Alessandro DF. Acromial fracture after reverse shoulder arthroplasty. Am J Orthop. 2011;40(7):E125-E129.
6. Wahlquist TC, Hunt AF, Braman JP. Acromial base fractures after reverse total shoulder arthroplasty: report of five cases. J Shoulder Elbow Surg. 2011;20(7):1178-1183.
7. Zumstein MA, Pinedo M, Old J, Boileau P. Problems, complications, reoperations, and revisions in reverse total shoulder arthroplasty: a systematic review. J Shoulder Elbow Surg. 2011;20(1):146-157.
8. Visotsky JL, Basamania C, Seebauer L, Rockwood CA, Jensen KL. Cuff tear arthropathy: pathogenesis, classification, and algorithm for treatment. J Bone Joint Surg Am. 2004;86(suppl 2):35-40.
9. Gamradt SC, Gelber J, Zhang AL. Shoulder function and pain level after revision of failed reverse shoulder replacement to hemiarthroplasty. Int J Shoulder Surg. 2012;6(2):29-35.
10. Garrigues GE, Johnston PS, Pepe MD, Tucker BS, Ramsey ML, Austin LS. Hemiarthroplasty versus reverse total shoulder arthroplasty for acute proximal humerus fractures in elderly patients. Orthopedics. 2012;35(5):e703-e708.
11. Patel DN, Young B, Onyekwelu I, Zuckerman JD, Kwon YW. Reverse total shoulder arthroplasty for failed shoulder arthroplasty. J Shoulder Elbow Surg. 2012;21(11):1473-1483.
12. Grammont PM, Baulot E. The classic: Delta shoulder prosthesis for rotator cuff rupture. 1993. Clin Orthop Relat Res. 2011;469(9):2424.
13. Schwartz DG, Kang SH, Lynch TS, et al. The anterior deltoid’s importance in reverse shoulder arthroplasty: a cadaveric biomechanical study. J Shoulder Elbow Surg. 2013;22(3):357-364.
14. Guery J, Favard L, Sirveaux F, Oudet D, Mole D, Walch G. Reverse total shoulder arthroplasty. Survivorship analysis of eighty replacements followed for five to ten years. J Bone Joint Surg Am. 2006;88(8):1742-1747.
15. Cuff D, Clark R, Pupello D, Frankle M. Reverse shoulder arthroplasty for the treatment of rotator cuff deficiency: a concise follow-up, at a minimum of five years, of a previous report. J Bone Joint Surg Am. 2012;94(21):1996-2000.
16. Young AA, Smith MM, Bacle G, Moraga C, Walch G. Early results of reverse shoulder arthroplasty in patients with rheumatoid arthritis. J Bone Joint Surg. 2011;93(20):1915-1923.
17. Hattrup SJ, Sanchez-Sotelo J, Sperling JW, Cofield RH. Reverse shoulder replacement for patients with inflammatory arthritis. J Hand Surg Am. 2012;37(9):1888-1894.
18. Nolan BM, Ankerson E, Wiater JM. Reverse total shoulder arthroplasty improves function in cuff tear arthropathy. Clin Orthop Relat Res. 2011;469(9):2476-2482.
19. Stechel A, Fuhrmann U, Irlenbusch L, Rott O, Irlenbusch U. Reversed shoulder arthroplasty in cuff tear arthritis, fracture sequelae, and revision arthroplasty. Acta Orthop. 2010;81(3):367-372.
20. Teusink MJ, Otto RJ, Cottrell BJ, Frankle MA. What is the effect of postoperative scapular fracture on outcomes of reverse shoulder arthroplasty? J Shoulder Elbow Surg. 2014;23(6):782-790.
21. Walch G, Bacle G, Lädermann A, Nové-Josserand L, Smithers CJ. Do the indications, results, and complications of reverse shoulder arthroplasty change with surgeon’s experience? J Shoulder Elbow Surg. 2012;21(11):1470-1477.
22. Beranger JS, Maqdes A, Pujol N, Desmoineaux P, Beaufils P. Bone mineral density of the coracoid process decreases with age [published online ahead of print December 17, 2014]. Knee Surg Sports Traumatol Arthrosc.
23. Eyres KS, Brooks A, Stanley D. Fractures of the coracoid process. J Bone Joint Surg Br. 1995;77(3):425-428.
Reverse total shoulder arthroplasty (RTSA) performed in carefully selected patients often leads to satisfactory outcomes.1,2 In recent years, its indications and the number performed per year have expanded. Subsequently, there has been a concomitant rise in reported complications,2,3 with a rate ranging from 19% to 68%.2,3 Some common complications include scapular notching,2-4 fracture,2,3,5-7 dislocation,2,3,7 and infection.2,3,7
In this series, we describe 2 cases of coracoid fracture after RTSA. The patients provided written informed consent for print and electronic publication of these case reports.
Case Series
Case 1
An independently functioning 81-year-old right hand–dominant woman (BMI, 22.1 [height, 160 cm; weight, 56.7 kg]) presented with increasing left shoulder pain and dysfunction after a motor vehicle accident 2 months earlier. She had reported vague chronic left shoulder pain in the past, but after the accident her pain was significantly worse. A subacromial corticosteroid injection by her primary care physician provided temporary symptomatic relief, but her symptoms recurred.
On presentation, there was obvious anterior superior escape of the humeral head, which was accentuated by shoulder shrug. Her deltoid motor function was found to be intact, and her active shoulder range of motion was severely limited (pseudoparesis). There was notable crepitation as well as significant weakness and pain with abduction and external rotation strength testing.
Radiographic imaging showed anterior superior escape of the humeral head with some early degenerative changes (Seebauer type IIB8 [Figure 1A]). Magnetic resonance imaging confirmed a full-thickness retracted massive rotator cuff tear with complete involvement of the supraspinatus, infraspinatus, and most of the subscapularis muscles. Significant glenohumeral degenerative changes consistent with cuff tear arthropathy were also seen without any evidence of fracture.
After thorough discussion of options, risks, and benefits, the decision was made to proceed with RTSA. The patient underwent the procedure without complications. A DePuy Delta Xtend prosthesis was used with a cemented humeral stem, polyethylene, and glenosphere, sizes of 12, +3, and 38, respectively. The glenosphere component, positioned inferiorly to avoid scapular notching, was secured with 3 screws, and the stem was placed in neutral version. The patient’s shoulder was reduced, ranged, and noted to be stable, allowing for supple passive range of motion without evidence of excessive tightness. She was placed in a sling with the shoulder positioned in neutral alignment. Her postoperative radiograph (Figure 1B) showed satisfactory implantation of the reverse total shoulder prosthesis. Her postoperative course was uneventful, and rehabilitation consisted of 6 weeks of sling protection, with advancing passive and active range of motion. Strengthening exercises were initiated 6 weeks after surgery.
At the patient’s 6-week postoperative visit, she demonstrated pain-free passive elevation to 80° and active forward elevation to 70°. At her 3-month postoperative visit, she reported a 1-week onset of anterior shoulder pain accompanied by a strange noise at the anterior aspect of the operative shoulder. She denied any recent trauma. She continued to have minimal shoulder pain with passive forward flexion of 80°; however, her active forward elevation was very limited because of pain in the anterior aspect of her shoulder. Active external rotation was noted to be 20° and internal rotation was to her buttock. She had pain to palpation of the coracoid process. Radiographs were unchanged from immediate postoperative radiographs. Computed tomography (CT), which was ordered to ensure that the implant was stable with no loosening, showed satisfactory alignment of the prosthesis and no loosening. However, CT was notable for a nondisplaced fracture through the base of the coracoid (Figures 2A-2D). The patient stopped formal physical therapy, and sling immobilization was initiated. After 3 weeks, the sling was discontinued and physical therapy was begun again. She responded satisfactorily to this treatment approach, and, at her 6-month postoperative follow-up, she was without pain, instability, or crepitation. Her range of motion had improved with pain-free active forward flexion, external rotation, and abduction of 100°, 15°, and 90°, respectively. At 28-month postoperative follow-up, her visual analog scale, American Shoulder and Elbow Surgeons score, and Simple Shoulder Test score were 3, 73, and 67, respectively.
Case 2
A 68-year-old, right-handed woman (BMI, 22.5 [height, 160 cm; weight, 57.6 kg]) presented with right shoulder pain and dysfunction of 3 years’ duration. She had undergone an open rotator cuff repair at an outside facility 4 years ago that was unsuccessful. At the time of her presentation to our institution, she had already undergone a failed course of physical therapy. A trial of corticosteroid subacromial injections did not adequately manage her symptoms.
On presentation, her active forward flexion, abduction, and external rotation were 40°, 30°, and 10°, respectively. She had full passive range of motion and pain with active and passive shoulder motion. Radiographic imaging showed superior migration of the humeral head with evidence of glenohumeral arthropathy suggestive of rotator cuff arthropathy (Seebauer type IIA8). After thorough discussion of options, risks, and benefits, the decision was made to proceed with RTSA. She underwent the procedure without complications. A DePuy Delta Xtend prosthesis was used with a cemented humeral stem, polyethylene, and glenosphere, sizes of 8, +3, and 38, respectively. The glenosphere component, positioned inferiorly to avoid scapular notching, was secured with 4 screws, and the stem was placed in neutral version. Her shoulder was reduced, ranged, and noted to be stable, allowing for supple passive range of motion without evidence of excessive tightness. She was placed in a sling with the shoulder positioned in neutral alignment. Her postoperative radiographs revealed satisfactory implantation of the reverse total shoulder prosthesis. Her postoperative course was uneventful. She was taken out of her shoulder immobilizer 4 weeks after surgery and began home-based physical therapy.
At 1 year after surgery, the patient had minimal shoulder pain with active forward flexion, external rotation, and abduction of 135°, 20°, and 85°, respectively. She presented to our clinic 15 months after RTSA with acute onset of pain about her anterior shoulder. She denied any recent trauma or infectious exposures. On examination, her motion was unchanged from prior examinations. However, she was tender on palpation of the coracoid. Radiographs at that time were unchanged (Figures 3A, 3B). Laboratory tests (erythrocyte sedimentation rate, C-reactive protein, and complete blood count with differential) that were subsequently ordered to rule out an occult infection were within normal limits. Computed tomography, which was ordered for further assessment and to ensure that the implant was stable with no loosening, showed satisfactory alignment of the prosthesis without loosening. However, a lucency was noted in the midportion of the coracoid that was suggestive of a fracture (Figures 4A, 4B). A conservative plan of treatment was advised with sling immobilization for 3 weeks and follow-up visits. The patient responded satisfactorily to this treatment approach, and, at her latest follow-up, 8 months after presenting with a coracoid fracture, she was pain-free. At the 5-year postoperative follow-up, her visual analog scale, American Shoulder and Elbow Surgeons score, and Simple Shoulder Test score were 1-2, 78, and 75, respectively.
Discussion
The reverse prosthesis, a semi-constrained ball-and-socket device, provides satisfactory functional outcomes when used in carefully selected patients with rotator cuff arthropathy and pseudoparalysis, failed shoulder arthroplasty, and fracture sequelae.1,9-11 By the traditional Grammont principles of medializing the center of rotation and lowering the humerus, shear forces about the glenoid are reduced and the deltoid muscle is tensioned, allowing for adequate torque generation, required to facilitate shoulder motion.12,13 While long-term outcomes concerning durability and survivorship are pending, some studies have attempted to improve our understanding of implant and functional longevity. Guery and colleagues14 noted an implant survival of 91% at 120 months. However, increased pain and decreased function were seen at the 6-year mark.14 A more recent study by Cuff and colleagues15 revealed 94% implant survivorship and sustained improvement in range of motion and pain at 5 years.
Despite considerable success, RTSA can be associated with a myriad of complications. The most common complications of RTSA include scapular notching (44%-96%), glenoid side failure (5%-40%), instability (2.4%-31%), and infection (1%-15.3%).2,3 In the setting of inflammatory arthropathy, there is an increased risk for intraoperative and postoperative fractures.16,17 To date, there are only 2 reported cases of coracoid process fractures after RTSA.18,19 In the case by Nolan and colleagues,18 conservative management with a sling for 6 weeks led to successful resolution of symptoms. Although little information is provided on the management of these rare fractures, literature on the slightly more common scapular (0.9%-7.2%) and acromial (0.9%-4.9%) fractures suggest that periscapular fractures are on the rise, may increase the risk for revision surgery, and can lead to inferior outcomes when compared with patients without fractures.5,20,21
Acromial fractures after RTSA have been reported to occur at a rate of 0.9% to 4.9%.5,21 This is a concern because of RTSA reliance on a functional deltoid.5,6 The cause of these fractures remains to be fully elucidated. Wahlquist and colleagues6 in 2011 reported the cases of 5 patients that sustained acromial base fractures after RTSA. All 5 patients were noted to have unsatisfactory functional results despite achieving union (3 were treated with open reduction and internal fixation, and 2 were treated nonoperatively). Acromial fractures tend to present with pain within 6 months of surgery, which may indicate excessive constraint about the scapula, eventually leading to fracture. Furthermore, disruption of this bony structure can lead to devastating results because the acromial base serves as a fulcrum for the deltoid.
Despite a well-placed reverse prosthesis, there is increased reliance on surrounding glenohumeral musculature, resulting from poor rotator cuff function and biomechanical differences compared with a native shoulder. Both our patients were found to have relatively small body habitus. It is possible that, by nature of their smaller statures, they were more susceptible to consequences of excessive joint and soft-tissue tension after RTSA. One explanation for acromial fractures after RTSA is that, by excessively lengthening and/or lateralizing the deltoid, the tension on the acromion in these elderly patients may be sufficient to cause a fracture. A similar mechanism may explain their coracoid fractures. As the arm is lengthened and the prosthesis is tightened, the conjoint tendon is significantly tensioned. We routinely check the tension of these muscles as an extra confirmation of joint stability. However, excessive tension for a significant duration may provide too much stress for bone turnover to match with the inherent repair process, potentially causing a fracture. Recent evidence has also found that bone mineral density of the coracoid diminishes with age, suggesting some predisposition to fracture with lower-energy mechanisms.22
Another possible cause for coracoid fractures may be the orientation of the implants. While we did not have mechanistic evidence, it is possible that, with adduction and internal rotation, prosthetic impingement against the coracoid is feasible, particularly in patients of small stature. Although a glenoid implant placed high can increase the chance for coracoid–implant impingement, the fact that the patients improved without revision makes chronic mechanical impingement less likely. Drill holes, especially multiple ones, placed throughout the base of the coracoid may also predispose to coracoid fractures.
Patients with periscapular fractures (acromion, scapular spine, or coracoid) after RTSA often present with pain and occasional deficits in function. Both patients in this series noted pain out of proportion to examination. The onset of this pain differed, with 1 patient noting pain within the first 3 months and 1 noting discomfort later. Neither patient had any trauma. In the presence of significant symptoms, negative radiographs, and a poor response to conservative treatment, we recommend advanced imaging to rule out fracture. However, prior to obtaining advanced imaging, proper radiographic techniques should be utilized. Eyres and colleagues,23 in a series of 12 fractures of the coracoid process, relied primarily on coracoid views directed 45° in a cephalic direction and thin-slice CT. An isotope bone scan identified 1 case not initially found on radiographs.23
Conservative management with use of a sling until resolution of symptoms was successful in our series. If symptoms persist, a bone stimulator can be used prior to implementing a surgical solution; however, current evidence does not expound on timing and utility of such modalities. Perhaps as important as treatment is education of the patient and the rehabilitation team about the importance of identifying increasing pain as a potential sign of impending fracture in this population. Subsequent activity modification until the pain resolves can help avoid the setback in postoperative recovery that this complication may cause.
Conclusion
We present 2 patients with coracoid fractures encountered at 3 months and 15 months after RTSA. Nonoperative management proved adequate in treating both cases. We suggest a high level of suspicion for possible fracture in the patient who comes in with new-onset pain in a localized region with or without functional deficits.
Reverse total shoulder arthroplasty (RTSA) performed in carefully selected patients often leads to satisfactory outcomes.1,2 In recent years, its indications and the number performed per year have expanded. Subsequently, there has been a concomitant rise in reported complications,2,3 with a rate ranging from 19% to 68%.2,3 Some common complications include scapular notching,2-4 fracture,2,3,5-7 dislocation,2,3,7 and infection.2,3,7
In this series, we describe 2 cases of coracoid fracture after RTSA. The patients provided written informed consent for print and electronic publication of these case reports.
Case Series
Case 1
An independently functioning 81-year-old right hand–dominant woman (BMI, 22.1 [height, 160 cm; weight, 56.7 kg]) presented with increasing left shoulder pain and dysfunction after a motor vehicle accident 2 months earlier. She had reported vague chronic left shoulder pain in the past, but after the accident her pain was significantly worse. A subacromial corticosteroid injection by her primary care physician provided temporary symptomatic relief, but her symptoms recurred.
On presentation, there was obvious anterior superior escape of the humeral head, which was accentuated by shoulder shrug. Her deltoid motor function was found to be intact, and her active shoulder range of motion was severely limited (pseudoparesis). There was notable crepitation as well as significant weakness and pain with abduction and external rotation strength testing.
Radiographic imaging showed anterior superior escape of the humeral head with some early degenerative changes (Seebauer type IIB8 [Figure 1A]). Magnetic resonance imaging confirmed a full-thickness retracted massive rotator cuff tear with complete involvement of the supraspinatus, infraspinatus, and most of the subscapularis muscles. Significant glenohumeral degenerative changes consistent with cuff tear arthropathy were also seen without any evidence of fracture.
After thorough discussion of options, risks, and benefits, the decision was made to proceed with RTSA. The patient underwent the procedure without complications. A DePuy Delta Xtend prosthesis was used with a cemented humeral stem, polyethylene, and glenosphere, sizes of 12, +3, and 38, respectively. The glenosphere component, positioned inferiorly to avoid scapular notching, was secured with 3 screws, and the stem was placed in neutral version. The patient’s shoulder was reduced, ranged, and noted to be stable, allowing for supple passive range of motion without evidence of excessive tightness. She was placed in a sling with the shoulder positioned in neutral alignment. Her postoperative radiograph (Figure 1B) showed satisfactory implantation of the reverse total shoulder prosthesis. Her postoperative course was uneventful, and rehabilitation consisted of 6 weeks of sling protection, with advancing passive and active range of motion. Strengthening exercises were initiated 6 weeks after surgery.
At the patient’s 6-week postoperative visit, she demonstrated pain-free passive elevation to 80° and active forward elevation to 70°. At her 3-month postoperative visit, she reported a 1-week onset of anterior shoulder pain accompanied by a strange noise at the anterior aspect of the operative shoulder. She denied any recent trauma. She continued to have minimal shoulder pain with passive forward flexion of 80°; however, her active forward elevation was very limited because of pain in the anterior aspect of her shoulder. Active external rotation was noted to be 20° and internal rotation was to her buttock. She had pain to palpation of the coracoid process. Radiographs were unchanged from immediate postoperative radiographs. Computed tomography (CT), which was ordered to ensure that the implant was stable with no loosening, showed satisfactory alignment of the prosthesis and no loosening. However, CT was notable for a nondisplaced fracture through the base of the coracoid (Figures 2A-2D). The patient stopped formal physical therapy, and sling immobilization was initiated. After 3 weeks, the sling was discontinued and physical therapy was begun again. She responded satisfactorily to this treatment approach, and, at her 6-month postoperative follow-up, she was without pain, instability, or crepitation. Her range of motion had improved with pain-free active forward flexion, external rotation, and abduction of 100°, 15°, and 90°, respectively. At 28-month postoperative follow-up, her visual analog scale, American Shoulder and Elbow Surgeons score, and Simple Shoulder Test score were 3, 73, and 67, respectively.
Case 2
A 68-year-old, right-handed woman (BMI, 22.5 [height, 160 cm; weight, 57.6 kg]) presented with right shoulder pain and dysfunction of 3 years’ duration. She had undergone an open rotator cuff repair at an outside facility 4 years ago that was unsuccessful. At the time of her presentation to our institution, she had already undergone a failed course of physical therapy. A trial of corticosteroid subacromial injections did not adequately manage her symptoms.
On presentation, her active forward flexion, abduction, and external rotation were 40°, 30°, and 10°, respectively. She had full passive range of motion and pain with active and passive shoulder motion. Radiographic imaging showed superior migration of the humeral head with evidence of glenohumeral arthropathy suggestive of rotator cuff arthropathy (Seebauer type IIA8). After thorough discussion of options, risks, and benefits, the decision was made to proceed with RTSA. She underwent the procedure without complications. A DePuy Delta Xtend prosthesis was used with a cemented humeral stem, polyethylene, and glenosphere, sizes of 8, +3, and 38, respectively. The glenosphere component, positioned inferiorly to avoid scapular notching, was secured with 4 screws, and the stem was placed in neutral version. Her shoulder was reduced, ranged, and noted to be stable, allowing for supple passive range of motion without evidence of excessive tightness. She was placed in a sling with the shoulder positioned in neutral alignment. Her postoperative radiographs revealed satisfactory implantation of the reverse total shoulder prosthesis. Her postoperative course was uneventful. She was taken out of her shoulder immobilizer 4 weeks after surgery and began home-based physical therapy.
At 1 year after surgery, the patient had minimal shoulder pain with active forward flexion, external rotation, and abduction of 135°, 20°, and 85°, respectively. She presented to our clinic 15 months after RTSA with acute onset of pain about her anterior shoulder. She denied any recent trauma or infectious exposures. On examination, her motion was unchanged from prior examinations. However, she was tender on palpation of the coracoid. Radiographs at that time were unchanged (Figures 3A, 3B). Laboratory tests (erythrocyte sedimentation rate, C-reactive protein, and complete blood count with differential) that were subsequently ordered to rule out an occult infection were within normal limits. Computed tomography, which was ordered for further assessment and to ensure that the implant was stable with no loosening, showed satisfactory alignment of the prosthesis without loosening. However, a lucency was noted in the midportion of the coracoid that was suggestive of a fracture (Figures 4A, 4B). A conservative plan of treatment was advised with sling immobilization for 3 weeks and follow-up visits. The patient responded satisfactorily to this treatment approach, and, at her latest follow-up, 8 months after presenting with a coracoid fracture, she was pain-free. At the 5-year postoperative follow-up, her visual analog scale, American Shoulder and Elbow Surgeons score, and Simple Shoulder Test score were 1-2, 78, and 75, respectively.
Discussion
The reverse prosthesis, a semi-constrained ball-and-socket device, provides satisfactory functional outcomes when used in carefully selected patients with rotator cuff arthropathy and pseudoparalysis, failed shoulder arthroplasty, and fracture sequelae.1,9-11 By the traditional Grammont principles of medializing the center of rotation and lowering the humerus, shear forces about the glenoid are reduced and the deltoid muscle is tensioned, allowing for adequate torque generation, required to facilitate shoulder motion.12,13 While long-term outcomes concerning durability and survivorship are pending, some studies have attempted to improve our understanding of implant and functional longevity. Guery and colleagues14 noted an implant survival of 91% at 120 months. However, increased pain and decreased function were seen at the 6-year mark.14 A more recent study by Cuff and colleagues15 revealed 94% implant survivorship and sustained improvement in range of motion and pain at 5 years.
Despite considerable success, RTSA can be associated with a myriad of complications. The most common complications of RTSA include scapular notching (44%-96%), glenoid side failure (5%-40%), instability (2.4%-31%), and infection (1%-15.3%).2,3 In the setting of inflammatory arthropathy, there is an increased risk for intraoperative and postoperative fractures.16,17 To date, there are only 2 reported cases of coracoid process fractures after RTSA.18,19 In the case by Nolan and colleagues,18 conservative management with a sling for 6 weeks led to successful resolution of symptoms. Although little information is provided on the management of these rare fractures, literature on the slightly more common scapular (0.9%-7.2%) and acromial (0.9%-4.9%) fractures suggest that periscapular fractures are on the rise, may increase the risk for revision surgery, and can lead to inferior outcomes when compared with patients without fractures.5,20,21
Acromial fractures after RTSA have been reported to occur at a rate of 0.9% to 4.9%.5,21 This is a concern because of RTSA reliance on a functional deltoid.5,6 The cause of these fractures remains to be fully elucidated. Wahlquist and colleagues6 in 2011 reported the cases of 5 patients that sustained acromial base fractures after RTSA. All 5 patients were noted to have unsatisfactory functional results despite achieving union (3 were treated with open reduction and internal fixation, and 2 were treated nonoperatively). Acromial fractures tend to present with pain within 6 months of surgery, which may indicate excessive constraint about the scapula, eventually leading to fracture. Furthermore, disruption of this bony structure can lead to devastating results because the acromial base serves as a fulcrum for the deltoid.
Despite a well-placed reverse prosthesis, there is increased reliance on surrounding glenohumeral musculature, resulting from poor rotator cuff function and biomechanical differences compared with a native shoulder. Both our patients were found to have relatively small body habitus. It is possible that, by nature of their smaller statures, they were more susceptible to consequences of excessive joint and soft-tissue tension after RTSA. One explanation for acromial fractures after RTSA is that, by excessively lengthening and/or lateralizing the deltoid, the tension on the acromion in these elderly patients may be sufficient to cause a fracture. A similar mechanism may explain their coracoid fractures. As the arm is lengthened and the prosthesis is tightened, the conjoint tendon is significantly tensioned. We routinely check the tension of these muscles as an extra confirmation of joint stability. However, excessive tension for a significant duration may provide too much stress for bone turnover to match with the inherent repair process, potentially causing a fracture. Recent evidence has also found that bone mineral density of the coracoid diminishes with age, suggesting some predisposition to fracture with lower-energy mechanisms.22
Another possible cause for coracoid fractures may be the orientation of the implants. While we did not have mechanistic evidence, it is possible that, with adduction and internal rotation, prosthetic impingement against the coracoid is feasible, particularly in patients of small stature. Although a glenoid implant placed high can increase the chance for coracoid–implant impingement, the fact that the patients improved without revision makes chronic mechanical impingement less likely. Drill holes, especially multiple ones, placed throughout the base of the coracoid may also predispose to coracoid fractures.
Patients with periscapular fractures (acromion, scapular spine, or coracoid) after RTSA often present with pain and occasional deficits in function. Both patients in this series noted pain out of proportion to examination. The onset of this pain differed, with 1 patient noting pain within the first 3 months and 1 noting discomfort later. Neither patient had any trauma. In the presence of significant symptoms, negative radiographs, and a poor response to conservative treatment, we recommend advanced imaging to rule out fracture. However, prior to obtaining advanced imaging, proper radiographic techniques should be utilized. Eyres and colleagues,23 in a series of 12 fractures of the coracoid process, relied primarily on coracoid views directed 45° in a cephalic direction and thin-slice CT. An isotope bone scan identified 1 case not initially found on radiographs.23
Conservative management with use of a sling until resolution of symptoms was successful in our series. If symptoms persist, a bone stimulator can be used prior to implementing a surgical solution; however, current evidence does not expound on timing and utility of such modalities. Perhaps as important as treatment is education of the patient and the rehabilitation team about the importance of identifying increasing pain as a potential sign of impending fracture in this population. Subsequent activity modification until the pain resolves can help avoid the setback in postoperative recovery that this complication may cause.
Conclusion
We present 2 patients with coracoid fractures encountered at 3 months and 15 months after RTSA. Nonoperative management proved adequate in treating both cases. We suggest a high level of suspicion for possible fracture in the patient who comes in with new-onset pain in a localized region with or without functional deficits.
1. Lawrence TM, Ahmadi S, Sanchez-Sotelo J, Sperling JW, Cofield RH. Patient reported activities after reverse shoulder arthroplasty: part II. J Shoulder Elbow Surg. 2012;21(11):1464-1469.
2. Cheung E, Willis M, Walker M, Clark R, Frankle MA. Complications in reverse total shoulder arthroplasty. J Am Acad Orthop Surg. 2011;19(7):439-449.
3. Affonso J, Nicholson GP, Frankle MA, et al. Complications of the reverse prosthesis: prevention and treatment. Instr Course Lect. 2012;61:157-168.
4. Lévigne C, Garret J, Boileau P, Alami G, Favard L, Walch G. Scapular notching in reverse shoulder arthroplasty: is it important to avoid it and how? Clin Orthop Relat Res. 2011;469(9):2512-2520.
5. Hamid N, Connor PM, Fleischli JF, D’Alessandro DF. Acromial fracture after reverse shoulder arthroplasty. Am J Orthop. 2011;40(7):E125-E129.
6. Wahlquist TC, Hunt AF, Braman JP. Acromial base fractures after reverse total shoulder arthroplasty: report of five cases. J Shoulder Elbow Surg. 2011;20(7):1178-1183.
7. Zumstein MA, Pinedo M, Old J, Boileau P. Problems, complications, reoperations, and revisions in reverse total shoulder arthroplasty: a systematic review. J Shoulder Elbow Surg. 2011;20(1):146-157.
8. Visotsky JL, Basamania C, Seebauer L, Rockwood CA, Jensen KL. Cuff tear arthropathy: pathogenesis, classification, and algorithm for treatment. J Bone Joint Surg Am. 2004;86(suppl 2):35-40.
9. Gamradt SC, Gelber J, Zhang AL. Shoulder function and pain level after revision of failed reverse shoulder replacement to hemiarthroplasty. Int J Shoulder Surg. 2012;6(2):29-35.
10. Garrigues GE, Johnston PS, Pepe MD, Tucker BS, Ramsey ML, Austin LS. Hemiarthroplasty versus reverse total shoulder arthroplasty for acute proximal humerus fractures in elderly patients. Orthopedics. 2012;35(5):e703-e708.
11. Patel DN, Young B, Onyekwelu I, Zuckerman JD, Kwon YW. Reverse total shoulder arthroplasty for failed shoulder arthroplasty. J Shoulder Elbow Surg. 2012;21(11):1473-1483.
12. Grammont PM, Baulot E. The classic: Delta shoulder prosthesis for rotator cuff rupture. 1993. Clin Orthop Relat Res. 2011;469(9):2424.
13. Schwartz DG, Kang SH, Lynch TS, et al. The anterior deltoid’s importance in reverse shoulder arthroplasty: a cadaveric biomechanical study. J Shoulder Elbow Surg. 2013;22(3):357-364.
14. Guery J, Favard L, Sirveaux F, Oudet D, Mole D, Walch G. Reverse total shoulder arthroplasty. Survivorship analysis of eighty replacements followed for five to ten years. J Bone Joint Surg Am. 2006;88(8):1742-1747.
15. Cuff D, Clark R, Pupello D, Frankle M. Reverse shoulder arthroplasty for the treatment of rotator cuff deficiency: a concise follow-up, at a minimum of five years, of a previous report. J Bone Joint Surg Am. 2012;94(21):1996-2000.
16. Young AA, Smith MM, Bacle G, Moraga C, Walch G. Early results of reverse shoulder arthroplasty in patients with rheumatoid arthritis. J Bone Joint Surg. 2011;93(20):1915-1923.
17. Hattrup SJ, Sanchez-Sotelo J, Sperling JW, Cofield RH. Reverse shoulder replacement for patients with inflammatory arthritis. J Hand Surg Am. 2012;37(9):1888-1894.
18. Nolan BM, Ankerson E, Wiater JM. Reverse total shoulder arthroplasty improves function in cuff tear arthropathy. Clin Orthop Relat Res. 2011;469(9):2476-2482.
19. Stechel A, Fuhrmann U, Irlenbusch L, Rott O, Irlenbusch U. Reversed shoulder arthroplasty in cuff tear arthritis, fracture sequelae, and revision arthroplasty. Acta Orthop. 2010;81(3):367-372.
20. Teusink MJ, Otto RJ, Cottrell BJ, Frankle MA. What is the effect of postoperative scapular fracture on outcomes of reverse shoulder arthroplasty? J Shoulder Elbow Surg. 2014;23(6):782-790.
21. Walch G, Bacle G, Lädermann A, Nové-Josserand L, Smithers CJ. Do the indications, results, and complications of reverse shoulder arthroplasty change with surgeon’s experience? J Shoulder Elbow Surg. 2012;21(11):1470-1477.
22. Beranger JS, Maqdes A, Pujol N, Desmoineaux P, Beaufils P. Bone mineral density of the coracoid process decreases with age [published online ahead of print December 17, 2014]. Knee Surg Sports Traumatol Arthrosc.
23. Eyres KS, Brooks A, Stanley D. Fractures of the coracoid process. J Bone Joint Surg Br. 1995;77(3):425-428.
1. Lawrence TM, Ahmadi S, Sanchez-Sotelo J, Sperling JW, Cofield RH. Patient reported activities after reverse shoulder arthroplasty: part II. J Shoulder Elbow Surg. 2012;21(11):1464-1469.
2. Cheung E, Willis M, Walker M, Clark R, Frankle MA. Complications in reverse total shoulder arthroplasty. J Am Acad Orthop Surg. 2011;19(7):439-449.
3. Affonso J, Nicholson GP, Frankle MA, et al. Complications of the reverse prosthesis: prevention and treatment. Instr Course Lect. 2012;61:157-168.
4. Lévigne C, Garret J, Boileau P, Alami G, Favard L, Walch G. Scapular notching in reverse shoulder arthroplasty: is it important to avoid it and how? Clin Orthop Relat Res. 2011;469(9):2512-2520.
5. Hamid N, Connor PM, Fleischli JF, D’Alessandro DF. Acromial fracture after reverse shoulder arthroplasty. Am J Orthop. 2011;40(7):E125-E129.
6. Wahlquist TC, Hunt AF, Braman JP. Acromial base fractures after reverse total shoulder arthroplasty: report of five cases. J Shoulder Elbow Surg. 2011;20(7):1178-1183.
7. Zumstein MA, Pinedo M, Old J, Boileau P. Problems, complications, reoperations, and revisions in reverse total shoulder arthroplasty: a systematic review. J Shoulder Elbow Surg. 2011;20(1):146-157.
8. Visotsky JL, Basamania C, Seebauer L, Rockwood CA, Jensen KL. Cuff tear arthropathy: pathogenesis, classification, and algorithm for treatment. J Bone Joint Surg Am. 2004;86(suppl 2):35-40.
9. Gamradt SC, Gelber J, Zhang AL. Shoulder function and pain level after revision of failed reverse shoulder replacement to hemiarthroplasty. Int J Shoulder Surg. 2012;6(2):29-35.
10. Garrigues GE, Johnston PS, Pepe MD, Tucker BS, Ramsey ML, Austin LS. Hemiarthroplasty versus reverse total shoulder arthroplasty for acute proximal humerus fractures in elderly patients. Orthopedics. 2012;35(5):e703-e708.
11. Patel DN, Young B, Onyekwelu I, Zuckerman JD, Kwon YW. Reverse total shoulder arthroplasty for failed shoulder arthroplasty. J Shoulder Elbow Surg. 2012;21(11):1473-1483.
12. Grammont PM, Baulot E. The classic: Delta shoulder prosthesis for rotator cuff rupture. 1993. Clin Orthop Relat Res. 2011;469(9):2424.
13. Schwartz DG, Kang SH, Lynch TS, et al. The anterior deltoid’s importance in reverse shoulder arthroplasty: a cadaveric biomechanical study. J Shoulder Elbow Surg. 2013;22(3):357-364.
14. Guery J, Favard L, Sirveaux F, Oudet D, Mole D, Walch G. Reverse total shoulder arthroplasty. Survivorship analysis of eighty replacements followed for five to ten years. J Bone Joint Surg Am. 2006;88(8):1742-1747.
15. Cuff D, Clark R, Pupello D, Frankle M. Reverse shoulder arthroplasty for the treatment of rotator cuff deficiency: a concise follow-up, at a minimum of five years, of a previous report. J Bone Joint Surg Am. 2012;94(21):1996-2000.
16. Young AA, Smith MM, Bacle G, Moraga C, Walch G. Early results of reverse shoulder arthroplasty in patients with rheumatoid arthritis. J Bone Joint Surg. 2011;93(20):1915-1923.
17. Hattrup SJ, Sanchez-Sotelo J, Sperling JW, Cofield RH. Reverse shoulder replacement for patients with inflammatory arthritis. J Hand Surg Am. 2012;37(9):1888-1894.
18. Nolan BM, Ankerson E, Wiater JM. Reverse total shoulder arthroplasty improves function in cuff tear arthropathy. Clin Orthop Relat Res. 2011;469(9):2476-2482.
19. Stechel A, Fuhrmann U, Irlenbusch L, Rott O, Irlenbusch U. Reversed shoulder arthroplasty in cuff tear arthritis, fracture sequelae, and revision arthroplasty. Acta Orthop. 2010;81(3):367-372.
20. Teusink MJ, Otto RJ, Cottrell BJ, Frankle MA. What is the effect of postoperative scapular fracture on outcomes of reverse shoulder arthroplasty? J Shoulder Elbow Surg. 2014;23(6):782-790.
21. Walch G, Bacle G, Lädermann A, Nové-Josserand L, Smithers CJ. Do the indications, results, and complications of reverse shoulder arthroplasty change with surgeon’s experience? J Shoulder Elbow Surg. 2012;21(11):1470-1477.
22. Beranger JS, Maqdes A, Pujol N, Desmoineaux P, Beaufils P. Bone mineral density of the coracoid process decreases with age [published online ahead of print December 17, 2014]. Knee Surg Sports Traumatol Arthrosc.
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