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The Effect of the Remplissage Procedure on Shoulder Range of Motion: A Cadaveric Study
The Effect of the Remplissage Procedure on Shoulder Range of Motion: A Cadaveric Study Rei Omi, M.D., Ph.D., Alexander W. Hooke, M.A., Kristin D. Zhao, Ph.D., Tomoya Matsuhashi, M.D., Ph.D., Akira Goto, M.D., Ph.D., Nobuyuki Yamamoto, M.D., Ph.D., John W. Sperling, M.D., Scott P. Steinmann, M.D., Eiji Itoi, M.D., Ph.D., and Kai-Nan An, Ph.D.
Purpose: The purpose of this in vitro biomechanical study was to assess the effects of the remplissage procedure for smalland large-sized Hill-Sachs lesions (HSLs) on shoulder range of motion (ROM) with a special interest in the apprehension position. Methods: HSLs of 50% and 100% of the glenoid width were simulated in 7 cadaveric shoulders as small and large lesions, respectively, and the postoperative condition was reproduced by placing suture anchors on the articular surface and tying down the infraspinatus at the medial edge of the would-be lesion site. ROMs were measured in abduction, internal rotation, and external rotation with the humerus in the adducted and abducted position. In addition, the ROM was measured in the anterior apprehension position, in which 2 torques of external rotation and extension were applied simultaneously, and external rotation and horizontal extension ROMs were measured with the humerus in different abduction angles (20 , 40 , and 60 ). Results: For standard ROMs, the procedure for the 50% HSL maintained complete ROMs, whereas the procedure for the 100% HSL significantly decreased external rotation ROM with the humerus in both the adducted and abducted positions, as well as abduction ROM. In the apprehension position, remplissage for the 50% HSL decreased extension ROM with the humerus abducted to 40 and 60 . Remplissage for the 100% HSL significantly decreased both external and extension ROMs regardless of the humeral abduction angle. Conclusions: In the cadaveric model with an intact humeral head and the simulated postoperative condition, the remplissage procedure for a large HSL caused significant restrictions in ROM of abduction in the scapular plane and external rotation with the humerus in both adduction and abduction. It also caused significant restrictions in both external rotation and extension ROMs in the apprehension position. Clinical Relevance: The indication for the remplissage procedure for the larger HSL should be considered carefully, especially for the competitive throwing athlete who needs exceptional external rotation ROM for optimal overhead throwing performance.
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osterolateral defects of the humeral head (HillSachs lesions [HSLs]) are one of the most common findings in patients with recurrent anterior dislocations of the shoulder. It has been reported that the HSL is present in over 80% of recurrent instability cases.1-4 Many studies have investigated the effect of the HSL on From the Biomechanics Laboratory, Department of Orthopedic Surgery, Mayo Clinic (R.O., A.W.H., K.D.Z., T.M., A.G., J.W.S., S.P.S., K-N.A.), Rochester, Minnesota, U.S.A.; and Department of Orthopaedic Surgery, Tohoku University School of Medicine (N.Y., E.I.), Sendai, Japan. The study was funded by Mayo Foundation. The authors report the following potential conflict of interest or source of funding: S.P.S. receives support from Arthrex, Wright Medical, DePuy. Received June 20, 2013; accepted November 4, 2013. Address correspondence to Kai-Nan An, Ph.D., Biomechanics Laboratory, Division of Orthopedic Research, Department of Orthopedic Surgery, Mayo Clinic, 200 First St SW, Rochester, MN 55905, U.S.A. E-mail: [email protected] Ó 2014 by the Arthroscopy Association of North America 0749-8063/13414/$36.00 http://dx.doi.org/10.1016/j.arthro.2013.11.003
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recurrent glenohumeral instability and identified it as a contributor to anterior soft-tissue destabilization.1,4,5 The increased recognition of the HSL in recurrent instability highlights the need to better address the bone deficiency of the humeral head in addition to the arthroscopic Bankart repair (repair of the torn anterior glenoid labrum and capsule). Some procedures directly address the humeral head defect, whereas others manipulate the articular arc length, primarily by augmenting anterior and inferior glenoid bone to prevent engagement of the HSL. Engagement occurs when the arm is brought into a position of athletic function (defined as 90 of abduction combined with external rotation [ER] in the range between 0 and 135 ).1 These solutions vary, including the Latarjet procedure,6,7 rotational humeral osteotomy,8 osteoarticular allograft transplantation,9 and transhumeral impaction bone grafting.10 In 2008 Wolf and colleagues11 described an arthroscopic method of filling the HSL by infraspinatus tenodesis
Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 30, No 2 (February), 2014: pp 178-187
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and posterior capsulodesis, currently known as “remplissage.” This technique has rapidly gained popularity as an arthroscopic technique to manage large HSLs, and although most clinical studies on the procedure have found it to be successful,11-18 Deutsch and Kroll19 reported 1 case of significant ER restriction after the remplissage procedure. This report led us to pay attention to the possible restriction of shoulder range of motion (ROM) after this procedure. In addition, there had been no report on ROM in the shoulder anterior apprehension test position. In this apprehension position, the humerus tracks along a zone of contact known as the glenoid track.20 We believe that the primary stabilization feature of the remplissage procedure is that the infraspinatus and joint capsule form a mechanical block that contacts the glenoid rim at the glenoid track, limiting the humeral head’s lateral translation. This impediment to translation, however, may also lead to a restriction of ROM. The purpose of this in vitro biomechanical study was to assess the effects of the remplissage procedure for small- and large-sized HSLs on shoulder ROM with a special interest in the apprehension position. We hypothesized that the remplissage procedure would decrease the ER ROM and the ROM in the apprehension position in a cadaveric model.
Methods Preparation of Specimens Seven fresh-frozen right cadaveric shoulders (4 male and 3 female shoulders) from donors with a mean age of 72 years (range, 58 to 83 years) at the time of death were secured from our institution’s anatomic bequest
Fig 1. (A) Custom-designed shoulder experimental device. (B) The specimen was secured to a Plexiglas plate on a center column. Forces were applied to each rotator cuff tendon using a pulley system. One electromagnetic sensor (2 arrowheads) was attached to the humeral shaft, and the other sensor (1 arrowhead) was attached to the scapula. The source was attached to the experimental device. The disk (arrow) was attached to the intramedullary rod and used to apply the rotational torques.
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program. Specimens with a rotator cuff tear, joint contracture, or radiographic evidence of glenohumeral osteoarthritis were excluded. The shoulders were thawed overnight at room temperature. Each specimen was disarticulated at the scapulothoracic joint proximally and transected at the middle part of the humerus, distal to the deltoid muscle attachment. To create precise anatomic coordinate systems on the humerus, 2 reference points for the medial and lateral epicondyles of the humerus were obtained by drilling small (1 mm in diameter) holes at the distal end of the humeral stump before each humerus was cut. The skin, the subcutaneous tissues, and all muscles except for the rotator cuff muscles were removed. The joint was vented to atmospheric pressure during the specimen preparation. A fiberglass rod was inserted into the medullary canal of the humeral shaft and cemented. The intramedullary rod and scapula were secured on a custom-designed shoulder experimental device (Fig 1).21,22 The shoulder experimental device allows the humerus to be placed in a specified plane of abduction (e.g., the scapular or coronal plane), angle of abduction, and angle of humeral rotation (external or internal). Four sutures were attached to the tendons of the subscapularis, supraspinatus, infraspinatus, and teres minor muscles to load the muscles with a weight-and-pulley system. A 22N total compressive force23 was applied across the glenohumeral joint, divided between the subscapularis (10 N), supraspinatus (3.5 N), and infraspinatus/teres minor (8.5 N) tendons. This force kept the humeral head centered in the glenoid fossa. The magnitude and distribution of the 22-N compressive force was determined by the physiological cross-sectional area of each
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muscle.20,24,25 The specimen was kept moist with a spray of saline solution applied every 10 to 15 minutes during the test. Testing was performed at room temperature (24 C). Definition of Shoulder Joint Coordinate System The 6 degree of freedom electromagnetic tracking system (Polhemus, Colchester, VT) with accompanying MotionMonitor software (Innovative Sports Training, Chicago, IL) was used to measure the joint motion. Sensors were rigidly fixed to the scapula and humerus (Fig 1B), and anatomic coordinate systems were defined using a calibrated digitizing stylus attached to a sensor, as reported in a previous study.21,22 For the setup used in this study, the electromagnetic Polhemus system has a static accuracy of 0.8 mm and an angular accuracy of 0.15 . Anatomic coordinate systems were defined according to International Society of Biomechanics standards,26 with the humeral head center defined using a functional rotation approach.27 Simulation of Remplissage Procedure The initial approach to the glenohumeral joint consisted of a lesser tuberosity osteotomy (Fig 2A) that was used to access the posterior superolateral part of the humeral head. The osteotomy was fixed afterward on completion of the remplissage procedure simulation with 1 double-loaded 5.5-mm Corkscrew FT titanium suture anchor (Arthrex, Naples, FL) (Fig 2B). The effect of the osteotomy on shoulder motion was tested as a separate condition in the experimental protocol. After extensive pilot testing, we found that it was not possible to create a Hill-Sachs bone defect without significantly damaging the surrounding soft tissue. The goal of this study was not to investigate the effectiveness of the remplissage procedure in preventing HSL engagement; rather, the goal was to investigate the postoperative condition of the remplissage procedure, as it specifically relates to ROM limitations due to the
shortening of the infraspinatus tenodesis and posterior capsulodesis. Therefore we determined that the best replication of the remplissage postoperative condition was to create a medially relocated infraspinatus footprint using 2 suture anchors on the articular surface of the humeral head and tying down the capsulotendinous structure on a line representing the medial edge of the HSL rather than making an actual bone defect (Fig 3). According to previous reports,28,29 the angular orientation of the lesion was defined with the position of the lesion centered at 209 from the anterior border of the humeral head articular cartilage with the humeral head modeled as a circle viewed superiorly (Fig 3A). Two sizes of lesions were simulated with widths equal to 50% of the glenoid width (50% HSL) and 100% of the glenoid width (100% HSL). As shown in Figs 3A and 3B, once the center point of the lesion (point F) was marked using the method by Kaar et al.28 at the medial margin of the infraspinatus footprint in the posterior superolateral humeral head, the first line was drawn to connect the humeral head articular center (point C) to point F. The glenoid width was then measured using a caliper, and 2 marks (points S and L) were made on the humeral head articular surface at lengths of 50% and 100% of the glenoid width, respectively, from point F. Finally, 2 lines, passing through reference points S and L, were drawn parallel to the longitudinal line on the humeral head surface through point C. These 2 lines were considered the medial edges of the imaginary HSLs of 2 different sizes (50% HSL and 100% HSL). Two 5.5-mm Corkscrew FT titanium suture anchors were used to reproduce the medially relocated infraspinatus footprint. The number of anchors used was determined by referring to the method in the original remplissage article,11 although actual Hill-Sachs defects were not created in our cadaveric model. They were placed on the articular surface of the humeral head
Fig 2. (A) The lesser tuberosity osteotomy was performed (arrowheads), and 1 double-loaded titanium suture anchor was inserted in the middle of the osteotomy plane (arrow). (B) The osteotomy was fixed with 1 double-loaded suture anchor on completion of the remplissage procedure simulation (arrows).
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Fig 3. (A) The angular orientation of the lesion was defined and marked with the position of the lesion (point F [white dot]) centered at 209 from the anterior border of the humeral head articular cartilage with the humeral head modeled as a circle viewed superiorly. (B) Once the angle orientation was defined by means of the previous method (line CF), 2 lines were drawn longitudinally, parallel to the humeral axis on the surface of the humeral head, to represent 100% of the glenoid width (line LF) and 50% of the glenoid width (line SF). The solid black line represents the medial edge of the 100% HSL, and the dotted black line represents the medial edge of the 50% HSL. Two holes for anchor placement were created on each black line 1 cm from line CF. The dotted white oval depicts the glenoid rim. (C, articular center of humeral head; F, footprint.) (C) Two anchors were used to simulate the postoperative condition of the remplissage procedure for each defect size.
1 cm away from line CF and on the longitudinal lines of the 50% HSL and 100% HSL (Fig 3C). On the basis of pilot testing, the distance of 1 cm away from line CF was determined as the appropriate distance for both the 50% HSL and 100% HSL to create a secure bumper of infraspinatus at the critical engaging point on line CF where the defect reaches its greatest width. The accompanying sutures were passed through the posterior joint capsule and infraspinatus tendon by a horizontal mattress technique and then tied on the subdeltoid side of the rotator cuff. Test Conditions The testing protocol was designed to study the effects of the remplissage procedure on glenohumeral ROM. The following shoulder conditions were tested: (1) intact, (2) repaired osteotomy of the lesser tuberosity, (3) remplissage procedure for the 50% HSL, and (4) remplissage procedure for the 100% HSL. Motion Measurements Standard ROMs were measured in abduction in the scapular plane (Fig 4A), internal rotation (IR) and ER with the humerus in the adducted position (0 of abduction), and IR and ER with the humerus in 60 of glenohumeral abduction (simulating 90 of humerothoracic abduction30) (Fig 4B). In addition, a series of ROMs was also measured in the directions of ER and horizontal extension with the humerus placed in 20 , 40 , and 60 of glenohumeral abduction (Fig 4C), simulating 30 , 60 , and 90 of humerothoracic abduction, respectively, in the apprehension position.20 This series of ROMs is different from the former
standard ROMs in that 2 torques of both ER and horizontal extension were applied simultaneously while the ROMs were measured in ER and horizontal extension. This apprehension condition was selected because it is a provocative position for engagement of the HSL and subsequent redislocation of the shoulder. ROM was measured with the electromagnetic tracking system while a set torque was applied to the humerus through either the distal end of the intramedullary rod (for abduction and horizontal extension) or a disc (Fig 1B) attached to the rod (for IR and ER). The torque was determined by use of a force transducer and momentarm measures from the axes of rotation to the point of force application. The end-ROM torques were 250 Nmm for IR and ER, 600 N-mm for horizontal extension, and 800 N-mm for abduction, as described in previous studies.20,25 Conversion of Size of HSL to Its Equivalent in Other Methods This study quantified the size of the HSL relative to the glenoid, whereas previous studies used different measurements to describe its size.31-33 Sekiya et al.33 described the defect size as a percentage of the humeral head diameter. Cho et al.31 described the defect size as the linear distance of the width between 2 edges of the lesion measured along line CF (Fig 3C) and expressed as a percentage of the humeral head diameter. Our study took the necessary anatomic measurements so that the lesion sizes were described both relative to the glenoid and relative to the humeral head so that comparisons with the methods described earlier could be made.
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Fig 4. (A) ROM in the abduction direction was measured in the scapular plane. (B) IR and ER ROMs are measured with the humerus in the adducted position (0 of abduction) and in the abducted position (60 of abduction in scapular plane). (C) ER and horizontal extension ROMs were measured in the apprehension position, in which the 2 different torques in the ER and horizontal extension directions were applied at the same time. The humerus abduction angle in each condition (20 , 40 , and 60 ) was kept stable during the ROM measurement.
Data Analyses Statistical analysis was performed with JMP 10.0 software (SAS Institute, Cary, NC). A repeatedmeasures analysis of variance was run individually on the ROM data for each arm position. The sphericity assumption was tested by use of the Mauchly sphericity test, and in the cases in which the Mauchly test was significant, a Huynh-Feldt correction was used. For the arm positions showing a significant difference in ROM between surgical conditions, a pair-wise repeatedmeasures analysis was run with proper corrections made to the a level. For all analyses, the significance level was set at a ¼ .05. Sample size calculation was performed based on ROM in degrees as the primary outcome. With 7 cadaveric shoulders, there was 80% power to detect a difference of 14 in mean ROMs between the conditions.
Results Comparison of Different Definitions for Size of HSL The defect sizes of the 50% HSL and 100% HSL in our study were 9.9% 1.4% and 39.6% 5.6% of the humeral head diameter as described by Sekiya et al.33
With the method of Cho et al.,31 the defect sizes were 31.4% 2.2% and 62.8% 4.5%, respectively. Validation of Lesser Tuberosity Osteotomy There were no statistically significant differences in the ROM between the intact and osteotomy conditions for any arm position with the exception of the ER ROM with the humerus abducted. This position showed a 4 increase in the ER ROM (Figs 5 and 6). Given that 10 of the 11 arm positions tested showed no ROM differences between the intact and osteotomy conditions, and that the single condition showing a statistically significant difference was arguably clinically significant at 4 , the assumption that the osteotomy did affect the ROM is considered validated. Standard ROM The remplissage procedure for the 50% HSL and 100% HSL decreased the abduction ROM from 84.3 9.0 (mean standard deviation) in the intact condition to 73.4 15.3 and 66.0 12.0 , respectively. The 100% HSL condition decreased relative to both the intact and osteotomy conditions at a statistically
Fig 5. Standard ROMs of 5 different directions: abduction in scapular plane, IR and ER with humerus adducted, and IR and ER with humerus abducted at 60 . Statistically significant differences are indicated with brackets.
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Fig 6. (A) ROM of ER and (B) horizontal extension at the 3 different apprehension positions (with humerus abducted at 20 , 40 , and 60 ). Statistically significant differences are indicated with brackets.
significant level (P < .05). The procedure for the 50% HSL decreased the mean ER ROM in both the adducted and abducted positions to 68.6 16.6 and 83.3 15.8 , respectively, which were not statistically different from the intact condition (73.5 19.8 and 93.1 7.0 , respectively). However, the procedure for the 100% HSL decreased ER ROM in the adducted and abducted positions to 47.2 18.9 and 56.9 22.2 , respectively, which were statistically different from the intact, osteotomy, and 50% HSL conditions in their respective arm positions (except for the intact adducted position). No statistically significant differences were found in IR ROM (Fig 5). ROM in Apprehension Position For ER, the ROM of the intact condition was 80.0 12.1 (20 of abduction), 79.2 12.0 (40 of abduction), and 73.8 10.3 (60 of abduction). There was no statistically significant difference between the intact and 50% HSL conditions in any abduction angle. However, the 100% HSL condition decreased ER ROM to 32.8 15.2 (20 of abduction), 32.3 15.7 (40 of abduction), and 34.8 11.9 (60 of abduction). Compared with the intact condition, these changes were statistically significantly different at P < .05 in 20 and 60 of abduction and at P ¼ .058 in 40 of abduction (Fig 6A). For extension, the ROM of the intact condition was 26.4 10.0 (20 of abduction), 30.7 6.6 (40 of abduction), and 31.1 5.6 (60 of abduction). Compared with the intact condition, the 100% HSL condition decreased the ROM to 4.0 3.6 (20 of abduction), 2.2 3.9 (40 of abduction), and 6.3 5.6 (60 of abduction). These changes were statistically significantly different at P < .05 in 40 and 60 of abduction and at P ¼ .10 in 20 of abduction. The negative values, in this case, indicate that the angle was
anterior to the scapular plane. In addition, the 50% HSL condition showed a statistically significant decrease in horizontal extension with the humerus in 40 and 60 of abduction (11.7 10.2 and 8.2 5.9 , respectively) (Fig 6B).
Discussion When one reviews the results of our study, it is evident that in the cadaveric model with an intact humeral head and the simulated postoperative condition, the remplissage procedure restricts the ROM of the glenohumeral joint in several planes of motion, with procedures on large HSLs having the most adverse effects. The ROM after the repair of the 100% HSL was decreased in abduction, all conditions of ER, and all conditions of horizontal extension. The IR ROM appears to be unaffected by the remplissage procedure, with little to no difference between the intact and postoperative procedures. As we expected, the ROM in the apprehension position decreased dramatically after the remplissage procedure for the 100% HSL in both ER and extension regardless of the humeral abduction angle. In addition, the procedure for the 50% HSL, the smaller lesion, showed notable restrictive effects on the horizontal extension ROM with the humerus in the apprehension position. The decrease in abduction ROM was unexpected because it has never been previously reported clinically or through in vitro study. Had this result been expected, the study protocol would have been slightly different to include abduction ROM testing in a variety of planes. Although the largest abduction difference identified was less than 20 , this new finding should be noted as a topic needing further study. There have been several methods reported to describe the size of the HSL,20,31,33 with no clear consensus
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about the best method to use. Our study used the glenoid track concept introduced by Yamamoto et al.20 This method enables the simultaneous evaluation of the relation between the HSL and the glenoid in the search for the engagement of the HSL onto the anterior glenoid rim. It also enables the evaluation of the defect size during arthroscopic surgery. The 2 lesion sizes in our study differ by a factor of 2, whereas the same lesions expressed in the method of Sekiya et al.33 would differ by a factor of 4. The reason for this discrepancy is that in the method of Sekiya et al., the lesion is measured by looking directly at the humeral head articular surface in a single view, regardless of the size and location of the lesion. A future study could be performed to determine the most effective method to describe the size of engaging HSLs. In this study, as we explained in the summary presented earlier, we found that the remplissage procedure for the large HSL, the 100% HSL, significantly decreased the ER ROM with the humerus in both the adducted and abducted positions. The first in vitro study about the remplissage procedure was recently reported by Giles et al.32 Our results for ROM differed from theirs, although their main concern was the difference in stability and ROM restriction between the remplissage procedure and other procedures for the engaging HSL (i.e., humeral head allograft and partial resurfacing arthroplasty). The motions tested in their study included internal-external ROM with the humerus in either the adducted or abducted position, as well as horizontal extension. Among these motions, the only significant loss in ROM relative to the intact condition was found in internal-external ROM with the humerus in the adducted position after the remplissage procedure on a 30% HSL (sized relative to the humeral head diameter) rather than the larger 45% lesion, for unknown reasons. Moreover, the difference in ROM between them was about 15 . There are 2 important factors to consider when comparing our results with those of Giles et al. First, Giles et al. defined the size of the HSL relative to the humeral head diameter, whereas we defined it relative to the glenoid width. Hence an HSL of 100% of the glenoid width used in our study is equivalent to an HSL of 40% of the humeral head diameter as described in the beginning of the “Results” section, which falls between the 30% and 45% Hill-Sachs defects used by Giles et al., making it difficult to compare our results with theirs directly. Second, because Giles et al. did not report the IR and ER separately, it cannot be determined whether the reduction in ROM seen in their study was due to the ER restriction, as was found in our study. If an assumption of restricted ER ROM is made in the study of Giles et al., their finding of a decrease in IR/ER only in the adducted position after remplissage on the smaller defect still appears to be different from our results, in
which the ER decreased significantly between the intact and 100% HSL conditions in both the adduction and abduction positions and the procedure for the larger lesion had an even more significant negative effect on ER ROM. In addition, the same can be said for the other report from the same group, in which the IR/ER ROMs were significantly restricted only in the adducted position relative to the intact condition after the procedure for both 15% HSL and 30% HSL.34 One reason for the difference in the abducted position is that we performed the procedure differently. We placed anchors on the articular surface at the anticipated location of the medial edge of the lesion to create the soft-tissue bumper, as it was called in the articles mentioned previously.32,34 As was shown by magnetic resonance imaging in a previous article reported by Nourissat et al.,15 the Hill-Sachs defect is supposed to be filled with the ingrowth of the inset infraspinatus and posterosuperior capsule after a biological healing process. The expected postoperative state of the procedure is depicted in Fig 7A. In our cadaveric model, if we followed the original description of this procedure and placed the anchors into the valley of the defect, we may have encountered the condition depicted in Fig 7B, in which the glenoid traveled beyond the medial edge of the defect because of the lack of a mechanical block, the essential stabilizing mechanism of this procedure, which is supposed to exist after the completion of this procedure with biological healing. Fearing such a situation, we fixed the anchors on the articular surface at the medial edge of each imaginary HSL without creating the actual defect (Fig 7C) to obtain the mechanical block. We believe that our model simulated a more realistic postoperative condition of the remplissage procedure and the ROM restriction in ER with the humerus in abduction would be an accurate consequence. The remplissage procedure is a minimally invasive approach to convert an intra-articular HSL, which would engage and cause a failed stabilization surgery, into an extra-articular lesion, without the morbidity associated with open procedures and additional graft material, making the procedure quick and easy to perform. With interest in the remplissage procedure increasing, several reports on the clinical results of the procedure have recently been published,12-19 after the original report of Purchase et al.11 In these reports, except for a case reported by Deutsch and Kroll,19 no problems with decreased ROM, including ER, were reported. However, we noticed that the ROM with the shoulder in the apprehension position, considered the position of athletic function by Burkhart and De Beer,1 in which the engaging HSL was first found and diagnosed, had not been specifically addressed. This position was of concern because after the completion of the remplissage procedure, the path of the glenoid with the
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Fig 7. (A) The original remplissage procedure with biological healing between the freshened surfaces of the HSL and inset infraspinatus; (B) the simulated remplissage procedure in a cadaveric study without biological healing; and (C) the simulated postoperative condition of the remplissage procedure in this study, creating a mechanical block at the medial border of each size of HSL that is essential for this procedure.
arm in the apprehension position, which was termed the glenoid track by Yamamoto et al.,20 is filled with and closed by the inset infraspinatus tendon and joint capsule, causing the glenoid to travel around the lesion medially and possibly leading to ROM restriction of the glenohumeral joint. As described in the “Results” section, in the shoulder apprehension position, the procedure for smaller lesions (50% HSL) decreased extension with the humerus in 40 and 60 of abduction. Furthermore, the procedure for the larger lesion (100% HSL) caused even more significant restriction in both ER and extension compared with the intact condition. According to Burkhart,35 pitchers participating in high-level sports activities maximize their shoulder rotational arc by hyper-external rotation in the late cocking phase of throwing to throw a fastball. Therefore it is of particular concern to us that the reduction in ER in this position may have a negative effect on the performance of those throwing athletes. This new finding will bring renewed attention to the possible ROM restriction of the shoulder in the apprehension position after this procedure. Limitations There are some limitations in this study. First, there was a lack of information regarding the medical history or any symptoms of the shoulder joint of the cadavers. We may not be able to say that the cadaveric shoulders were completely normal; however, the shoulders were screened using macroscopic and radiologic examinations before testing. Second, the specimens used in this study were from elderly donors, whereas the remplissage procedure is typically performed in young patients.
Third, we performed a lesser tuberosity osteotomy to expose the posterosuperior part of the humeral head and reproduce the identical HSL accurately across the different specimens, whereas the actual procedure is performed solely with arthroscopy. We did our best to repair the lesser tuberosity osteotomy and the soft tissue around it. As described in the “Results” section, there was only 1 arm position (ER with the humerus in the abducted position) in which a statistically significant difference was observed between the intact condition and the condition after the osteotomy repair. However the difference on average between them was 4 , and we believe that the osteotomy had minimal effect on the subsequent results of the remplissage procedure. Fourth, although the remplissage procedure is generally performed in addition to Bankart repair (repair of the torn anterior glenoid labrum and capsule), we intentionally did not create a Bankart lesion. This is because the primary objective was to investigate the effect on shoulder ROM that is inherent to the remplissage procedure and including a Bankart lesion may have had confounding effects. Fifth, we did not create a HillSachs defect. Instead, we created the infraspinatus footprint using suture anchors on the articular surface at the medial edge of the imaginary lesion because this best replicates the medial shift of the infraspinatus attachment after remplissage. However, by using intact humeral heads, we could have missed the other effects of the procedure on ROM. For example, had the infraspinatus been pulled into the defect, its tension would have been increased and the posterior joint capsule would have become tighter, which seems to be related to other ROM restrictions to IR. Sixth, the
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results obtained represent the condition immediately after the completion of the remplissage procedure. Therefore the long-term effects of this procedure in vivo might be different.
Conclusions In the cadaveric model with an intact humeral head and the simulated postoperative condition, the remplissage procedure for a large HSL caused significant restrictions in ROM of abduction in the scapular plane and ER with the humerus in both adduction and abduction. It also caused significant restrictions in both ER and extension ROMs in the apprehension position.
Acknowledgment The authors thank Arthrex for providing the Corkscrew FT anchors.
References 1. Burkhart SS, De Beer JF. Traumatic glenohumeral bone defects and their relationship to failure of arthroscopic Bankart repairs: Significance of the inverted-pear glenoid and the humeral engaging Hill-Sachs lesion. Arthroscopy 2000;16:677-694. 2. Calandra JJ, Baker CL, Uribe J. The incidence of HillSachs lesions in initial anterior shoulder dislocations. Arthroscopy 1989;5:254-257. 3. Chen AL, Hunt SA, Hawkins RJ, Zuckerman JD. Management of bone loss associated with recurrent anterior glenohumeral instability. Am J Sports Med 2005;33: 912-925. 4. Rowe CR, Zarins B, Ciullo JV. Recurrent anterior dislocation of the shoulder after surgical repair. Apparent causes of failure and treatment. J Bone Joint Surg Am 1984;66:159-168. 5. Boileau P, Villalba M, Hery JY, Balg F, Ahrens P, Neyton L. Risk factors for recurrence of shoulder instability after arthroscopic Bankart repair. J Bone Joint Surg Am 2006;88:1755-1763. 6. Allain J, Goutallier D, Glorion C. Long-term results of the Latarjet procedure for the treatment of anterior instability of the shoulder. J Bone Joint Surg Am 1998;80:841-852. 7. Latarjet M. Treatment of recurrent dislocation of the shoulder. Lyon Chir 1954;49:994-997 (in French). 8. Weber BG, Simpson LA, Hardegger F. Rotational humeral osteotomy for recurrent anterior dislocation of the shoulder associated with a large Hill-Sachs lesion. J Bone Joint Surg Am 1984;66:1443-1450. 9. Kropf EJ, Sekiya JK. Osteoarticular allograft transplantation for large humeral head defects in glenohumeral instability. Arthroscopy 2007;23:322.e1-322.e5. 10. Re P, Gallo RA, Richmond JC. Transhumeral head plasty for large Hill-Sachs lesions. Arthroscopy 2006;22:798.e1-798.e4. 11. Purchase RJ, Wolf EM, Hobgood ER, Pollock ME, Smalley CC. Hill-Sachs “remplissage”: An arthroscopic solution for the engaging Hill-Sachs lesion. Arthroscopy 2008;24:723-726.
12. Boileau P, O’Shea K, Vargas P, Pinedo M, Old J, Zumstein M. Anatomical and functional results after arthroscopic HillSachs remplissage. J Bone Joint Surg Am 2012;94:618-626. 13. Haviv B, Mayo L, Biggs D. Outcomes of arthroscopic “remplissage”: Capsulotenodesis of the engaging large Hill-Sachs lesion. J Orthop Surg Res 2011;6:29. 14. Koo SS, Burkhart SS, Ochoa E. Arthroscopic doublepulley remplissage technique for engaging Hill-Sachs lesions in anterior shoulder instability repairs. Arthroscopy 2009;25:1343-1348. 15. Nourissat G, Kilinc AS, Werther JR, Doursounian L. A prospective, comparative, radiological, and clinical study of the influence of the “remplissage” procedure on shoulder range of motion after stabilization by arthroscopic Bankart repair. Am J Sports Med 2011;39:2147-2152. 16. Park MJ, Garcia G, Malhotra A, Major N, Tjoumakaris FP, Kelly JDIV. The evaluation of arthroscopic remplissage by high-resolution magnetic resonance imaging. Am J Sports Med 2012;40:2331-2336. 17. Park MJ, Tjoumakaris FP, Garcia G, Patel A, Kelly JD IV. Arthroscopic remplissage with Bankart repair for the treatment of glenohumeral instability with Hill-Sachs defects. Arthroscopy 2011;27:1187-1194. 18. Zhu YM, Lu Y, Zhang J, Shen JW, Jiang CY. Arthroscopic Bankart repair combined with remplissage technique for the treatment of anterior shoulder instability with engaging Hill-Sachs lesion: A report of 49 cases with a minimum 2-year follow-up. Am J Sports Med 2011;39: 1640-1647. 19. Deutsch AA, Kroll DG. Decreased range of motion following arthroscopic remplissage. Orthopedics 2008;31:492. 20. Yamamoto N, Itoi E, Abe H, et al. Contact between the glenoid and the humeral head in abduction, external rotation, and horizontal extension: A new concept of glenoid track. J Shoulder Elbow Surg 2007;16:649-656. 21. Muraki T, Yamamoto N, Zhao KD, et al. Effect of posteroinferior capsule tightness on contact pressure and area beneath the coracoacromial arch during pitching motion. Am J Sports Med 2010;38:600-607. 22. Muraki T, Yamamoto N, Zhao KD, et al. Effects of posterior capsule tightness on subacromial contact behavior during shoulder motions. J Shoulder Elbow Surg 2012;21:1160-1167. 23. Warner JJ, Deng XH, Warren RF, Torzilli PA. Static capsuloligamentous restraints to superior-inferior translation of the glenohumeral joint. Am J Sports Med 1992;20:675-685. 24. Bassett RW, Browne AO, Morrey BF, An KN. Glenohumeral muscle force and moment mechanics in a position of shoulder instability. J Biomech 1990;23:405-415. 25. Yamamoto N, Itoi E, Tuoheti Y, et al. Glenohumeral joint motion after medial shift of the attachment site of the supraspinatus tendon: A cadaveric study. J Shoulder Elbow Surg 2007;16:373-378. 26. Wu G, van der Helm FC, Veeger HE, et al. ISB recommendation on definitions of joint coordinate systems of various joints for the reporting of human joint motiondPart II: Shoulder, elbow, wrist and hand. J Biomech 2005;38:981-992. 27. Veeger HE. The position of the rotation center of the glenohumeral joint. J Biomech 2000;33:1711-1715. 28. Kaar SG, Fening SD, Jones MH, Colbrunn RW, Miniaci A. Effect of humeral head defect size on glenohumeral
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29.
30. 31.
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stability: A cadaveric study of simulated Hill-Sachs defects. Am J Sports Med 2010;38:594-599. Richards RD, Sartoris DJ, Pathria MN, Resnick D. Hill-Sachs lesion and normal humeral groove: MR imaging features allowing their differentiation. Radiology 1994;190:665-668. Poppen NK, Walker PS. Normal and abnormal motion of the shoulder. J Bone Joint Surg Am 1976;58:195-201. Cho SH, Cho NS, Rhee YG. Preoperative analysis of the Hill-Sachs lesion in anterior shoulder instability: How to predict engagement of the lesion. Am J Sports Med 2011;39:2389-2395. Giles JW, Elkinson I, Ferreira LM, et al. Moderate to large engaging Hill-Sachs defects: An in vitro biomechanical
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comparison of the remplissage procedure, allograft humeral head reconstruction, and partial resurfacing arthroplasty. J Shoulder Elbow Surg 2012;21:1142-1151. 33. Sekiya JK, Wickwire AC, Stehle JH, Debski RE. Hill-Sachs defects and repair using osteoarticular allograft transplantation: Biomechanical analysis using a joint compression model. Am J Sports Med 2009;37:2459-2466. 34. Elkinson I, Giles JW, Faber KJ, et al. The effect of the remplissage procedure on shoulder stability and range of motion: An in vitro biomechanical assessment. J Bone Joint Surg Am 2012;94:1003-1012. 35. Burkhart SS. Internal impingement of the shoulder. Instr Course Lect 2006;55:29-34.
Purpose: The purpose of this in vitro biomechanical study was to assess the effects of the remplissage procedure for smalland large-sized Hill-Sachs lesions (HSLs) on shoulder range of motion (ROM) with a special interest in the apprehension position. Methods: HSLs of 50% and 100% of the glenoid width were simulated in 7 cadaveric shoulders as small and large lesions, respectively, and the postoperative condition was reproduced by placing suture anchors on the articular surface and tying down the infraspinatus at the medial edge of the would-be lesion site. ROMs were measured in abduction, internal rotation, and external rotation with the humerus in the adducted and abducted position. In addition, the ROM was measured in the anterior apprehension position, in which 2 torques of external rotation and extension were applied simultaneously, and external rotation and horizontal extension ROMs were measured with the humerus in different abduction angles (20 , 40 , and 60 ). Results: For standard ROMs, the procedure for the 50% HSL maintained complete ROMs, whereas the procedure for the 100% HSL significantly decreased external rotation ROM with the humerus in both the adducted and abducted positions, as well as abduction ROM. In the apprehension position, remplissage for the 50% HSL decreased extension ROM with the humerus abducted to 40 and 60 . Remplissage for the 100% HSL significantly decreased both external and extension ROMs regardless of the humeral abduction angle. Conclusions: In the cadaveric model with an intact humeral head and the simulated postoperative condition, the remplissage procedure for a large HSL caused significant restrictions in ROM of abduction in the scapular plane and external rotation with the humerus in both adduction and abduction. It also caused significant restrictions in both external rotation and extension ROMs in the apprehension position. Clinical Relevance: The indication for the remplissage procedure for the larger HSL should be considered carefully, especially for the competitive throwing athlete who needs exceptional external rotation ROM for optimal overhead throwing performance.
P
osterolateral defects of the humeral head (HillSachs lesions [HSLs]) are one of the most common findings in patients with recurrent anterior dislocations of the shoulder. It has been reported that the HSL is present in over 80% of recurrent instability cases.1-4 Many studies have investigated the effect of the HSL on From the Biomechanics Laboratory, Department of Orthopedic Surgery, Mayo Clinic (R.O., A.W.H., K.D.Z., T.M., A.G., J.W.S., S.P.S., K-N.A.), Rochester, Minnesota, U.S.A.; and Department of Orthopaedic Surgery, Tohoku University School of Medicine (N.Y., E.I.), Sendai, Japan. The study was funded by Mayo Foundation. The authors report the following potential conflict of interest or source of funding: S.P.S. receives support from Arthrex, Wright Medical, DePuy. Received June 20, 2013; accepted November 4, 2013. Address correspondence to Kai-Nan An, Ph.D., Biomechanics Laboratory, Division of Orthopedic Research, Department of Orthopedic Surgery, Mayo Clinic, 200 First St SW, Rochester, MN 55905, U.S.A. E-mail: [email protected] Ó 2014 by the Arthroscopy Association of North America 0749-8063/13414/$36.00 http://dx.doi.org/10.1016/j.arthro.2013.11.003
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recurrent glenohumeral instability and identified it as a contributor to anterior soft-tissue destabilization.1,4,5 The increased recognition of the HSL in recurrent instability highlights the need to better address the bone deficiency of the humeral head in addition to the arthroscopic Bankart repair (repair of the torn anterior glenoid labrum and capsule). Some procedures directly address the humeral head defect, whereas others manipulate the articular arc length, primarily by augmenting anterior and inferior glenoid bone to prevent engagement of the HSL. Engagement occurs when the arm is brought into a position of athletic function (defined as 90 of abduction combined with external rotation [ER] in the range between 0 and 135 ).1 These solutions vary, including the Latarjet procedure,6,7 rotational humeral osteotomy,8 osteoarticular allograft transplantation,9 and transhumeral impaction bone grafting.10 In 2008 Wolf and colleagues11 described an arthroscopic method of filling the HSL by infraspinatus tenodesis
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and posterior capsulodesis, currently known as “remplissage.” This technique has rapidly gained popularity as an arthroscopic technique to manage large HSLs, and although most clinical studies on the procedure have found it to be successful,11-18 Deutsch and Kroll19 reported 1 case of significant ER restriction after the remplissage procedure. This report led us to pay attention to the possible restriction of shoulder range of motion (ROM) after this procedure. In addition, there had been no report on ROM in the shoulder anterior apprehension test position. In this apprehension position, the humerus tracks along a zone of contact known as the glenoid track.20 We believe that the primary stabilization feature of the remplissage procedure is that the infraspinatus and joint capsule form a mechanical block that contacts the glenoid rim at the glenoid track, limiting the humeral head’s lateral translation. This impediment to translation, however, may also lead to a restriction of ROM. The purpose of this in vitro biomechanical study was to assess the effects of the remplissage procedure for small- and large-sized HSLs on shoulder ROM with a special interest in the apprehension position. We hypothesized that the remplissage procedure would decrease the ER ROM and the ROM in the apprehension position in a cadaveric model.
Methods Preparation of Specimens Seven fresh-frozen right cadaveric shoulders (4 male and 3 female shoulders) from donors with a mean age of 72 years (range, 58 to 83 years) at the time of death were secured from our institution’s anatomic bequest
Fig 1. (A) Custom-designed shoulder experimental device. (B) The specimen was secured to a Plexiglas plate on a center column. Forces were applied to each rotator cuff tendon using a pulley system. One electromagnetic sensor (2 arrowheads) was attached to the humeral shaft, and the other sensor (1 arrowhead) was attached to the scapula. The source was attached to the experimental device. The disk (arrow) was attached to the intramedullary rod and used to apply the rotational torques.
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program. Specimens with a rotator cuff tear, joint contracture, or radiographic evidence of glenohumeral osteoarthritis were excluded. The shoulders were thawed overnight at room temperature. Each specimen was disarticulated at the scapulothoracic joint proximally and transected at the middle part of the humerus, distal to the deltoid muscle attachment. To create precise anatomic coordinate systems on the humerus, 2 reference points for the medial and lateral epicondyles of the humerus were obtained by drilling small (1 mm in diameter) holes at the distal end of the humeral stump before each humerus was cut. The skin, the subcutaneous tissues, and all muscles except for the rotator cuff muscles were removed. The joint was vented to atmospheric pressure during the specimen preparation. A fiberglass rod was inserted into the medullary canal of the humeral shaft and cemented. The intramedullary rod and scapula were secured on a custom-designed shoulder experimental device (Fig 1).21,22 The shoulder experimental device allows the humerus to be placed in a specified plane of abduction (e.g., the scapular or coronal plane), angle of abduction, and angle of humeral rotation (external or internal). Four sutures were attached to the tendons of the subscapularis, supraspinatus, infraspinatus, and teres minor muscles to load the muscles with a weight-and-pulley system. A 22N total compressive force23 was applied across the glenohumeral joint, divided between the subscapularis (10 N), supraspinatus (3.5 N), and infraspinatus/teres minor (8.5 N) tendons. This force kept the humeral head centered in the glenoid fossa. The magnitude and distribution of the 22-N compressive force was determined by the physiological cross-sectional area of each
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muscle.20,24,25 The specimen was kept moist with a spray of saline solution applied every 10 to 15 minutes during the test. Testing was performed at room temperature (24 C). Definition of Shoulder Joint Coordinate System The 6 degree of freedom electromagnetic tracking system (Polhemus, Colchester, VT) with accompanying MotionMonitor software (Innovative Sports Training, Chicago, IL) was used to measure the joint motion. Sensors were rigidly fixed to the scapula and humerus (Fig 1B), and anatomic coordinate systems were defined using a calibrated digitizing stylus attached to a sensor, as reported in a previous study.21,22 For the setup used in this study, the electromagnetic Polhemus system has a static accuracy of 0.8 mm and an angular accuracy of 0.15 . Anatomic coordinate systems were defined according to International Society of Biomechanics standards,26 with the humeral head center defined using a functional rotation approach.27 Simulation of Remplissage Procedure The initial approach to the glenohumeral joint consisted of a lesser tuberosity osteotomy (Fig 2A) that was used to access the posterior superolateral part of the humeral head. The osteotomy was fixed afterward on completion of the remplissage procedure simulation with 1 double-loaded 5.5-mm Corkscrew FT titanium suture anchor (Arthrex, Naples, FL) (Fig 2B). The effect of the osteotomy on shoulder motion was tested as a separate condition in the experimental protocol. After extensive pilot testing, we found that it was not possible to create a Hill-Sachs bone defect without significantly damaging the surrounding soft tissue. The goal of this study was not to investigate the effectiveness of the remplissage procedure in preventing HSL engagement; rather, the goal was to investigate the postoperative condition of the remplissage procedure, as it specifically relates to ROM limitations due to the
shortening of the infraspinatus tenodesis and posterior capsulodesis. Therefore we determined that the best replication of the remplissage postoperative condition was to create a medially relocated infraspinatus footprint using 2 suture anchors on the articular surface of the humeral head and tying down the capsulotendinous structure on a line representing the medial edge of the HSL rather than making an actual bone defect (Fig 3). According to previous reports,28,29 the angular orientation of the lesion was defined with the position of the lesion centered at 209 from the anterior border of the humeral head articular cartilage with the humeral head modeled as a circle viewed superiorly (Fig 3A). Two sizes of lesions were simulated with widths equal to 50% of the glenoid width (50% HSL) and 100% of the glenoid width (100% HSL). As shown in Figs 3A and 3B, once the center point of the lesion (point F) was marked using the method by Kaar et al.28 at the medial margin of the infraspinatus footprint in the posterior superolateral humeral head, the first line was drawn to connect the humeral head articular center (point C) to point F. The glenoid width was then measured using a caliper, and 2 marks (points S and L) were made on the humeral head articular surface at lengths of 50% and 100% of the glenoid width, respectively, from point F. Finally, 2 lines, passing through reference points S and L, were drawn parallel to the longitudinal line on the humeral head surface through point C. These 2 lines were considered the medial edges of the imaginary HSLs of 2 different sizes (50% HSL and 100% HSL). Two 5.5-mm Corkscrew FT titanium suture anchors were used to reproduce the medially relocated infraspinatus footprint. The number of anchors used was determined by referring to the method in the original remplissage article,11 although actual Hill-Sachs defects were not created in our cadaveric model. They were placed on the articular surface of the humeral head
Fig 2. (A) The lesser tuberosity osteotomy was performed (arrowheads), and 1 double-loaded titanium suture anchor was inserted in the middle of the osteotomy plane (arrow). (B) The osteotomy was fixed with 1 double-loaded suture anchor on completion of the remplissage procedure simulation (arrows).
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Fig 3. (A) The angular orientation of the lesion was defined and marked with the position of the lesion (point F [white dot]) centered at 209 from the anterior border of the humeral head articular cartilage with the humeral head modeled as a circle viewed superiorly. (B) Once the angle orientation was defined by means of the previous method (line CF), 2 lines were drawn longitudinally, parallel to the humeral axis on the surface of the humeral head, to represent 100% of the glenoid width (line LF) and 50% of the glenoid width (line SF). The solid black line represents the medial edge of the 100% HSL, and the dotted black line represents the medial edge of the 50% HSL. Two holes for anchor placement were created on each black line 1 cm from line CF. The dotted white oval depicts the glenoid rim. (C, articular center of humeral head; F, footprint.) (C) Two anchors were used to simulate the postoperative condition of the remplissage procedure for each defect size.
1 cm away from line CF and on the longitudinal lines of the 50% HSL and 100% HSL (Fig 3C). On the basis of pilot testing, the distance of 1 cm away from line CF was determined as the appropriate distance for both the 50% HSL and 100% HSL to create a secure bumper of infraspinatus at the critical engaging point on line CF where the defect reaches its greatest width. The accompanying sutures were passed through the posterior joint capsule and infraspinatus tendon by a horizontal mattress technique and then tied on the subdeltoid side of the rotator cuff. Test Conditions The testing protocol was designed to study the effects of the remplissage procedure on glenohumeral ROM. The following shoulder conditions were tested: (1) intact, (2) repaired osteotomy of the lesser tuberosity, (3) remplissage procedure for the 50% HSL, and (4) remplissage procedure for the 100% HSL. Motion Measurements Standard ROMs were measured in abduction in the scapular plane (Fig 4A), internal rotation (IR) and ER with the humerus in the adducted position (0 of abduction), and IR and ER with the humerus in 60 of glenohumeral abduction (simulating 90 of humerothoracic abduction30) (Fig 4B). In addition, a series of ROMs was also measured in the directions of ER and horizontal extension with the humerus placed in 20 , 40 , and 60 of glenohumeral abduction (Fig 4C), simulating 30 , 60 , and 90 of humerothoracic abduction, respectively, in the apprehension position.20 This series of ROMs is different from the former
standard ROMs in that 2 torques of both ER and horizontal extension were applied simultaneously while the ROMs were measured in ER and horizontal extension. This apprehension condition was selected because it is a provocative position for engagement of the HSL and subsequent redislocation of the shoulder. ROM was measured with the electromagnetic tracking system while a set torque was applied to the humerus through either the distal end of the intramedullary rod (for abduction and horizontal extension) or a disc (Fig 1B) attached to the rod (for IR and ER). The torque was determined by use of a force transducer and momentarm measures from the axes of rotation to the point of force application. The end-ROM torques were 250 Nmm for IR and ER, 600 N-mm for horizontal extension, and 800 N-mm for abduction, as described in previous studies.20,25 Conversion of Size of HSL to Its Equivalent in Other Methods This study quantified the size of the HSL relative to the glenoid, whereas previous studies used different measurements to describe its size.31-33 Sekiya et al.33 described the defect size as a percentage of the humeral head diameter. Cho et al.31 described the defect size as the linear distance of the width between 2 edges of the lesion measured along line CF (Fig 3C) and expressed as a percentage of the humeral head diameter. Our study took the necessary anatomic measurements so that the lesion sizes were described both relative to the glenoid and relative to the humeral head so that comparisons with the methods described earlier could be made.
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Fig 4. (A) ROM in the abduction direction was measured in the scapular plane. (B) IR and ER ROMs are measured with the humerus in the adducted position (0 of abduction) and in the abducted position (60 of abduction in scapular plane). (C) ER and horizontal extension ROMs were measured in the apprehension position, in which the 2 different torques in the ER and horizontal extension directions were applied at the same time. The humerus abduction angle in each condition (20 , 40 , and 60 ) was kept stable during the ROM measurement.
Data Analyses Statistical analysis was performed with JMP 10.0 software (SAS Institute, Cary, NC). A repeatedmeasures analysis of variance was run individually on the ROM data for each arm position. The sphericity assumption was tested by use of the Mauchly sphericity test, and in the cases in which the Mauchly test was significant, a Huynh-Feldt correction was used. For the arm positions showing a significant difference in ROM between surgical conditions, a pair-wise repeatedmeasures analysis was run with proper corrections made to the a level. For all analyses, the significance level was set at a ¼ .05. Sample size calculation was performed based on ROM in degrees as the primary outcome. With 7 cadaveric shoulders, there was 80% power to detect a difference of 14 in mean ROMs between the conditions.
Results Comparison of Different Definitions for Size of HSL The defect sizes of the 50% HSL and 100% HSL in our study were 9.9% 1.4% and 39.6% 5.6% of the humeral head diameter as described by Sekiya et al.33
With the method of Cho et al.,31 the defect sizes were 31.4% 2.2% and 62.8% 4.5%, respectively. Validation of Lesser Tuberosity Osteotomy There were no statistically significant differences in the ROM between the intact and osteotomy conditions for any arm position with the exception of the ER ROM with the humerus abducted. This position showed a 4 increase in the ER ROM (Figs 5 and 6). Given that 10 of the 11 arm positions tested showed no ROM differences between the intact and osteotomy conditions, and that the single condition showing a statistically significant difference was arguably clinically significant at 4 , the assumption that the osteotomy did affect the ROM is considered validated. Standard ROM The remplissage procedure for the 50% HSL and 100% HSL decreased the abduction ROM from 84.3 9.0 (mean standard deviation) in the intact condition to 73.4 15.3 and 66.0 12.0 , respectively. The 100% HSL condition decreased relative to both the intact and osteotomy conditions at a statistically
Fig 5. Standard ROMs of 5 different directions: abduction in scapular plane, IR and ER with humerus adducted, and IR and ER with humerus abducted at 60 . Statistically significant differences are indicated with brackets.
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Fig 6. (A) ROM of ER and (B) horizontal extension at the 3 different apprehension positions (with humerus abducted at 20 , 40 , and 60 ). Statistically significant differences are indicated with brackets.
significant level (P < .05). The procedure for the 50% HSL decreased the mean ER ROM in both the adducted and abducted positions to 68.6 16.6 and 83.3 15.8 , respectively, which were not statistically different from the intact condition (73.5 19.8 and 93.1 7.0 , respectively). However, the procedure for the 100% HSL decreased ER ROM in the adducted and abducted positions to 47.2 18.9 and 56.9 22.2 , respectively, which were statistically different from the intact, osteotomy, and 50% HSL conditions in their respective arm positions (except for the intact adducted position). No statistically significant differences were found in IR ROM (Fig 5). ROM in Apprehension Position For ER, the ROM of the intact condition was 80.0 12.1 (20 of abduction), 79.2 12.0 (40 of abduction), and 73.8 10.3 (60 of abduction). There was no statistically significant difference between the intact and 50% HSL conditions in any abduction angle. However, the 100% HSL condition decreased ER ROM to 32.8 15.2 (20 of abduction), 32.3 15.7 (40 of abduction), and 34.8 11.9 (60 of abduction). Compared with the intact condition, these changes were statistically significantly different at P < .05 in 20 and 60 of abduction and at P ¼ .058 in 40 of abduction (Fig 6A). For extension, the ROM of the intact condition was 26.4 10.0 (20 of abduction), 30.7 6.6 (40 of abduction), and 31.1 5.6 (60 of abduction). Compared with the intact condition, the 100% HSL condition decreased the ROM to 4.0 3.6 (20 of abduction), 2.2 3.9 (40 of abduction), and 6.3 5.6 (60 of abduction). These changes were statistically significantly different at P < .05 in 40 and 60 of abduction and at P ¼ .10 in 20 of abduction. The negative values, in this case, indicate that the angle was
anterior to the scapular plane. In addition, the 50% HSL condition showed a statistically significant decrease in horizontal extension with the humerus in 40 and 60 of abduction (11.7 10.2 and 8.2 5.9 , respectively) (Fig 6B).
Discussion When one reviews the results of our study, it is evident that in the cadaveric model with an intact humeral head and the simulated postoperative condition, the remplissage procedure restricts the ROM of the glenohumeral joint in several planes of motion, with procedures on large HSLs having the most adverse effects. The ROM after the repair of the 100% HSL was decreased in abduction, all conditions of ER, and all conditions of horizontal extension. The IR ROM appears to be unaffected by the remplissage procedure, with little to no difference between the intact and postoperative procedures. As we expected, the ROM in the apprehension position decreased dramatically after the remplissage procedure for the 100% HSL in both ER and extension regardless of the humeral abduction angle. In addition, the procedure for the 50% HSL, the smaller lesion, showed notable restrictive effects on the horizontal extension ROM with the humerus in the apprehension position. The decrease in abduction ROM was unexpected because it has never been previously reported clinically or through in vitro study. Had this result been expected, the study protocol would have been slightly different to include abduction ROM testing in a variety of planes. Although the largest abduction difference identified was less than 20 , this new finding should be noted as a topic needing further study. There have been several methods reported to describe the size of the HSL,20,31,33 with no clear consensus
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about the best method to use. Our study used the glenoid track concept introduced by Yamamoto et al.20 This method enables the simultaneous evaluation of the relation between the HSL and the glenoid in the search for the engagement of the HSL onto the anterior glenoid rim. It also enables the evaluation of the defect size during arthroscopic surgery. The 2 lesion sizes in our study differ by a factor of 2, whereas the same lesions expressed in the method of Sekiya et al.33 would differ by a factor of 4. The reason for this discrepancy is that in the method of Sekiya et al., the lesion is measured by looking directly at the humeral head articular surface in a single view, regardless of the size and location of the lesion. A future study could be performed to determine the most effective method to describe the size of engaging HSLs. In this study, as we explained in the summary presented earlier, we found that the remplissage procedure for the large HSL, the 100% HSL, significantly decreased the ER ROM with the humerus in both the adducted and abducted positions. The first in vitro study about the remplissage procedure was recently reported by Giles et al.32 Our results for ROM differed from theirs, although their main concern was the difference in stability and ROM restriction between the remplissage procedure and other procedures for the engaging HSL (i.e., humeral head allograft and partial resurfacing arthroplasty). The motions tested in their study included internal-external ROM with the humerus in either the adducted or abducted position, as well as horizontal extension. Among these motions, the only significant loss in ROM relative to the intact condition was found in internal-external ROM with the humerus in the adducted position after the remplissage procedure on a 30% HSL (sized relative to the humeral head diameter) rather than the larger 45% lesion, for unknown reasons. Moreover, the difference in ROM between them was about 15 . There are 2 important factors to consider when comparing our results with those of Giles et al. First, Giles et al. defined the size of the HSL relative to the humeral head diameter, whereas we defined it relative to the glenoid width. Hence an HSL of 100% of the glenoid width used in our study is equivalent to an HSL of 40% of the humeral head diameter as described in the beginning of the “Results” section, which falls between the 30% and 45% Hill-Sachs defects used by Giles et al., making it difficult to compare our results with theirs directly. Second, because Giles et al. did not report the IR and ER separately, it cannot be determined whether the reduction in ROM seen in their study was due to the ER restriction, as was found in our study. If an assumption of restricted ER ROM is made in the study of Giles et al., their finding of a decrease in IR/ER only in the adducted position after remplissage on the smaller defect still appears to be different from our results, in
which the ER decreased significantly between the intact and 100% HSL conditions in both the adduction and abduction positions and the procedure for the larger lesion had an even more significant negative effect on ER ROM. In addition, the same can be said for the other report from the same group, in which the IR/ER ROMs were significantly restricted only in the adducted position relative to the intact condition after the procedure for both 15% HSL and 30% HSL.34 One reason for the difference in the abducted position is that we performed the procedure differently. We placed anchors on the articular surface at the anticipated location of the medial edge of the lesion to create the soft-tissue bumper, as it was called in the articles mentioned previously.32,34 As was shown by magnetic resonance imaging in a previous article reported by Nourissat et al.,15 the Hill-Sachs defect is supposed to be filled with the ingrowth of the inset infraspinatus and posterosuperior capsule after a biological healing process. The expected postoperative state of the procedure is depicted in Fig 7A. In our cadaveric model, if we followed the original description of this procedure and placed the anchors into the valley of the defect, we may have encountered the condition depicted in Fig 7B, in which the glenoid traveled beyond the medial edge of the defect because of the lack of a mechanical block, the essential stabilizing mechanism of this procedure, which is supposed to exist after the completion of this procedure with biological healing. Fearing such a situation, we fixed the anchors on the articular surface at the medial edge of each imaginary HSL without creating the actual defect (Fig 7C) to obtain the mechanical block. We believe that our model simulated a more realistic postoperative condition of the remplissage procedure and the ROM restriction in ER with the humerus in abduction would be an accurate consequence. The remplissage procedure is a minimally invasive approach to convert an intra-articular HSL, which would engage and cause a failed stabilization surgery, into an extra-articular lesion, without the morbidity associated with open procedures and additional graft material, making the procedure quick and easy to perform. With interest in the remplissage procedure increasing, several reports on the clinical results of the procedure have recently been published,12-19 after the original report of Purchase et al.11 In these reports, except for a case reported by Deutsch and Kroll,19 no problems with decreased ROM, including ER, were reported. However, we noticed that the ROM with the shoulder in the apprehension position, considered the position of athletic function by Burkhart and De Beer,1 in which the engaging HSL was first found and diagnosed, had not been specifically addressed. This position was of concern because after the completion of the remplissage procedure, the path of the glenoid with the
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Fig 7. (A) The original remplissage procedure with biological healing between the freshened surfaces of the HSL and inset infraspinatus; (B) the simulated remplissage procedure in a cadaveric study without biological healing; and (C) the simulated postoperative condition of the remplissage procedure in this study, creating a mechanical block at the medial border of each size of HSL that is essential for this procedure.
arm in the apprehension position, which was termed the glenoid track by Yamamoto et al.,20 is filled with and closed by the inset infraspinatus tendon and joint capsule, causing the glenoid to travel around the lesion medially and possibly leading to ROM restriction of the glenohumeral joint. As described in the “Results” section, in the shoulder apprehension position, the procedure for smaller lesions (50% HSL) decreased extension with the humerus in 40 and 60 of abduction. Furthermore, the procedure for the larger lesion (100% HSL) caused even more significant restriction in both ER and extension compared with the intact condition. According to Burkhart,35 pitchers participating in high-level sports activities maximize their shoulder rotational arc by hyper-external rotation in the late cocking phase of throwing to throw a fastball. Therefore it is of particular concern to us that the reduction in ER in this position may have a negative effect on the performance of those throwing athletes. This new finding will bring renewed attention to the possible ROM restriction of the shoulder in the apprehension position after this procedure. Limitations There are some limitations in this study. First, there was a lack of information regarding the medical history or any symptoms of the shoulder joint of the cadavers. We may not be able to say that the cadaveric shoulders were completely normal; however, the shoulders were screened using macroscopic and radiologic examinations before testing. Second, the specimens used in this study were from elderly donors, whereas the remplissage procedure is typically performed in young patients.
Third, we performed a lesser tuberosity osteotomy to expose the posterosuperior part of the humeral head and reproduce the identical HSL accurately across the different specimens, whereas the actual procedure is performed solely with arthroscopy. We did our best to repair the lesser tuberosity osteotomy and the soft tissue around it. As described in the “Results” section, there was only 1 arm position (ER with the humerus in the abducted position) in which a statistically significant difference was observed between the intact condition and the condition after the osteotomy repair. However the difference on average between them was 4 , and we believe that the osteotomy had minimal effect on the subsequent results of the remplissage procedure. Fourth, although the remplissage procedure is generally performed in addition to Bankart repair (repair of the torn anterior glenoid labrum and capsule), we intentionally did not create a Bankart lesion. This is because the primary objective was to investigate the effect on shoulder ROM that is inherent to the remplissage procedure and including a Bankart lesion may have had confounding effects. Fifth, we did not create a HillSachs defect. Instead, we created the infraspinatus footprint using suture anchors on the articular surface at the medial edge of the imaginary lesion because this best replicates the medial shift of the infraspinatus attachment after remplissage. However, by using intact humeral heads, we could have missed the other effects of the procedure on ROM. For example, had the infraspinatus been pulled into the defect, its tension would have been increased and the posterior joint capsule would have become tighter, which seems to be related to other ROM restrictions to IR. Sixth, the
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results obtained represent the condition immediately after the completion of the remplissage procedure. Therefore the long-term effects of this procedure in vivo might be different.
Conclusions In the cadaveric model with an intact humeral head and the simulated postoperative condition, the remplissage procedure for a large HSL caused significant restrictions in ROM of abduction in the scapular plane and ER with the humerus in both adduction and abduction. It also caused significant restrictions in both ER and extension ROMs in the apprehension position.
Acknowledgment The authors thank Arthrex for providing the Corkscrew FT anchors.
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