Management of the failed Latarjet procedure.

BACKGROUND: To analyze the causes of failure after a Latarjet procedure and to evaluate the results of revision surgery. METHODS: Single-cohort, retrospective, observational study. Fifteen patients (13 males, mean age at revision failed Latarjet 38.9 years [range, 20-57]) with anterior glenohumeral instability who underwent a revision surgery for a failed Latarjet procedure were reviewed. Failure was defined as subluxation or dislocation. Demographic features, the reason for failure, type of lesions observed, and postoperative clinical and functional status were recorded. Functional status was assessed with the Rowe score. Subjective clinical evaluation was performed using the Western Ontario Shoulder Instability Index (WOSI) and Subjective Shoulder Value (SSV). RESULTS: Recurrence occurred in the first year following the Latarjet procedure in 11 patients (73.3%). The causes of failure were graft avulsion in 3 cases, fracture in 1, coracoid misposition in 2 cases, graft nonunion in 1, advanced osteolysis in 4 cases, and persistence of an off-track Hill-Sachs lesion in 1. In 3 cases, no identifiable cause of failure but generalized severe hyperlaxity was found. Regarding revision surgery after the Latarjet procedure, 8 patients underwent an arthroscopic Eden-Hybinette procedure and in 3 patients the graft was repositioned. In the remaining 4 patients, an extra-articular capsular reinforcement was performed. Regarding the latter, 1 patient suffered new dislocations and required an additional revision surgery consisting of an Eden-Hybinette procedure. All patients remained stable after the revision surgery at the latest follow-up, except 2 who reported subluxations after an arthroscopic Eden-Hybinette and an extra-articular capsular reinforcement, but no additional surgical procedure was required. Functional status after revision surgery was satisfactory, with a mean Rowe score of 78 (10-100), WOSI score of 829 (225-1425), and an SSV score of 67 points (40-90). CONCLUSION: The causes of failure after a Latarjet procedure were poor bone graft due to mispositioning, avulsion, fracture or resorption, generalized hyperlaxity, and incomplete restoration of the glenoid track. Our study demonstrates that when the cause of failure is identified and addressed, stability is restored, and clinical and functional scores improved.

How does dynamic arthroscopic tracking compare with radiologic glenoid track for identification of on- and off-track lesions in anterior shoulder instability?

BACKGROUND: Current treatment paradigms for anterior shoulder instability are based on radiologic measurements of glenohumeral bone defects, and mathematical calculation of the glenoid track (GT) is used to classify lesions into on-track and off-track morphology. However, radiologic measurements have shown high variability, and GT widths under dynamic conditions have been reported to be significantly smaller than those under static radiologic conditions. The purpose of this study was to assess the reliability, reproducibility, and diagnostic validity of dynamic arthroscopic standardized tracking (DAST) in comparison to the gold-standard radiologic track measurement method for the identification of on- and off-track bony lesions in patients with anteroinferior shoulder instability. METHODS: Between January 2018 and August 2022, 114 patients with traumatic anterior shoulder instability were evaluated using 3-T magnetic resonance imaging or computed tomography scans; glenoid bone loss, Hill-Sachs interval, GT, and Hill-Sachs occupancy ratio (HSO) were measured, and defects were classified as on-track or off-track defects and peripheral-track defects (based on HSO percentage) by 2 independent researchers. During arthroscopy, a standardized method (DAST method) was used by 2 independent observers to classify defects into on-track defects (central and peripheral) and off-track defects. Interobserver reliability of the DAST and radiologic methods was calculated using the κ statistic and reported as percentage agreement. Diagnostic validity (sensitivity, specificity, positive predictive value, and negative predictive value) of the DAST method was calculated using the radiologic track (HSO percentage) as the gold standard. RESULTS: The radiologically measured mean glenoid bone loss percentage, Hill-Sachs interval, and HSO in off-track lesions were lower with the arthroscopic method (DAST) as compared with the radiologic method. The DAST method showed nearly perfect agreement between the 2 observers for the on-track/off-track classification (κ = 0.96, P < .001) and the on-track central or peripheral /off-track classification (κ = 0.88, P < .001). The radiologic method showed greater interobserver variability (κ = 0.31 and κ = 0.24, respectively) with only fair agreement for both classifications. Inter-method agreement varied between 71% and 79% (95% confidence interval, 62%-86%) between the 2 observers, and reliability was assessed as slight (κ = 0.16) to fair (κ = 0.38). Overall, for identification of an off-track lesion, the DAST method showed maximum specificity (81% and 78%) when radiologic peripheral-track lesions (HSO percentage of 75%-100%) were considered off-track and showed maximum sensitivity when arthroscopic peripheral-track lesions were classified as off-track. CONCLUSION: Although inter-method agreement was low, a standardized arthroscopic tracking method (DAST method) showed superior interobserver agreement and reliability for lesion classification in comparison to the radiologic track method. Incorporating DAST into current algorithms may help reduce variability in surgical decision making.

Similar outcomes in collision athletes with subcritical glenoid bone loss and on-Track Hill Sachs lesion versus off-track Hill Sachs lesion managed with open Bankart repair plus inferior capsular shift.

INTRODUCTION: Open Bankart repair plus inferior capsular shift has not yet been tested under the concept of glenoid track as a predictor of failure. The aim of this study was to compare the subjective and objective outcomes in collision athletes with subcritical glenoid bone loss and on-track Hill Sachs lesions versus those with off-track Hill Sachs lesions, all treated with open Bankart repair. METHODS: Two study groups were created: 50 patients had on-track Hill Sachs lesions, while 38 had off-track lesions. The subcritical glenoid bone loss was ≤ 10%. A minimum follow-up period of 3 years was established. Preoperative and postoperative evaluation of each group and between them was performed. The Western Ontario Shoulder Instability Index score and the American Shoulder and Elbow Surgeons scale were used to assess subjective outcomes. Recurrence rate, range of motion and return to sport were evaluated as objective outcomes. RESULTS: Significant differences were reported in the WOSI and ASES scores between preoperative and postoperative values in each group. There were no significant differences between the two groups (p-value = 0.36 and 0.71). Three dislocations (6%) in the on-track group and 3 (7.8%) in the off-track group were recorded, showing no differences between the two groups (p-value = 0.83). There were no differences in ROM between pre- and post-operatively in each group or when comparing the two groups. CONCLUSIONS: We found no differences between the outcomes of the two groups. According to the surgeon's preference, we recommend performing open Bankart repair plus inferior capsular shift as a treatment alternative in collision athletes with SGBL ≤ 10% independently of the type of Hill Sachs lesion.

Long-term recurrence rate in anterior shoulder instability after Bankart repair based on the on- and off-track concept.

BACKGROUND: Since its first proposal, the concept of on- and off-track lesions in anterior shoulder instability has gained clinical relevance as a tool to predict the failure rate of arthroscopic Bankart repair. Current literature only reports either short-term follow-up or long-term results of small sample sizes. The aim of this study was to provide a long-term evaluation of recurrent instability following arthroscopic Bankart repair in a large cohort using the on-track vs. off-track concept as a predictor for failure. METHODS: We retrospectively analyzed 271 patients who underwent primary arthroscopic Bankart repair for anterior shoulder instability between 1998 and 2007. All patients with a minimum follow-up of 78 months and a preoperative computed tomographic (CT) or magnetic resonance imaging (MRI) scan were included into the study. Preoperative CT and/or MRI scans were used to determine the glenoid track and width of Hill-Sachs lesion. Recurrence of instability was defined as presence of instability symptoms (dislocation, subluxation, and/or apprehension) or revision surgery (stabilization procedure) and was assessed as the primary outcome parameter. RESULTS: The glenoid track of 163 shoulders was assessed (female n = 51, male n = 112) with a mean follow-up of 124 months (99.4-145.6, standard deviation = 2.5) and a mean age of 24 years (20-34.). An off-track Hill-Sachs lesion was found in 77 cases (47%), and in 86 cases (53 %) it was on-track. The rate of recurrent instability in the off-track group was 74% (n = 57) compared with 27% (n = 23) in the on-track group (P < .001). The overall rate of revision surgery due to instability was 29% (n = 48) after a mean time of 50.9 months (±42.8) following Bankart repair. The rate of revision surgery in the off-track group was 48% (n = 37) after a mean of 53.5 months (±42.0) vs. 13% (n = 11) after 42.3 months (±46.3) in the on-track group (P < .001). CONCLUSION: This study shows that the on- and off-track concept helps to distinguish patients for whom an isolated arthroscopic Bankart repair yields long-term benefits. Because of the high rate of recurrent instability in the off-track group, an off-track lesion should be treated surgically in such a way that the off-track lesion is converted into an on-track lesion.

Open anatomical glenoid reconstruction with an iliac crest bone autograft effectively resolves off-track Hill-Sachs lesions to on-track lesions.

INTRODUCTION: The purpose of this study was to determine if "off-track" Hill-Sachs lesions in patients with dynamic anteroinferior instability were transformed into "on-track" lesions using iliac bone autografts with screw fixation. The secondary purpose was to observe if postoperative bony remodeling would occur over time, resulting in recurrent "off-track" Hill-Sachs lesions with corresponding instability. MATERIALS AND METHODS: We retrospectively reviewed clinical and CT records of 8 patients with an "off-track" Hill-Sachs lesion who underwent open anatomical glenoid reconstruction with an iliac crest bone autograft. Hill-Sachs lesions, glenoid track widths, and glenoid surface areas were measured on a preoperative and two postoperative (6 weeks, ≥ 2 years) 3D-CT models to determine graft resorption over time. All patients were available for postoperative clinical and CT final follow-up 3 years (2-4 years) postoperatively. RESULTS: In all patients, the Hill-Sachs lesions were "on-track" 6 weeks postoperatively and remained "on-track" at final-follow-up. Compared to preoperative values, the glenoid track width and glenoid surface area both were higher 6 weeks postoperatively (p < 0.001 and p = 0.023, respectively) and at final follow-up (p < 0.001 and p = 0.023, respectively). Whereas the glenoid track width between 6 weeks and final follow-up showed no decrease (p = 0.234), glenoid surface area tended to decrease (p = 0.055). The median SSV was 93 points (85-95 points), the Rowe score 90 points (80-100 points) and the WOSI 1980 points (1783-2067 points) at final follow-up. No recurrent dislocations or subluxations were observed. CONCLUSIONS: An open anatomical glenoid reconstruction with an iliac crest bone autograft technique using screw fixation effectively transformed "off-track" Hill-Sachs lesions to "on-track" lesions, resulting in good short-term clinical outcomes. Whereas glenoid surface area tended to be reduced by bony remodeling processes over time, the glenoid track width did not decrease at final follow-up and consequently no recurrence of "off-track" lesions occurred. LEVEL OF EVIDENCE: Case series; Level of evidence, IV.

Off-track Hill-Sachs lesions predispose to recurrence after nonoperative management of first-time anterior shoulder dislocations.

PURPOSE: The purpose of this study was to evaluate whether the presence of an off-track Hill-Sachs lesion has an impact on the recurrence rate after nonoperative management of first-time anterior shoulder dislocations. METHODS: A retrospective cohort study was planned with a follow-up via questionnaire after a minimum of 24 months. Fifty four patients were included in the study (mean age: 29.5 years; 16 female, 38 male). All of these patients opted for primary nonoperative management after first-time traumatic anterior shoulder dislocation, in some cases even against the clinician's advice. The glenoid track and the Hill-Sachs interval were evaluated in the MRI scans. The clinical outcome was evaluated via a shoulder-specific questionnaire, ASES-Score and Constant Score. Further, patients were asked to report on recurrent dislocation (yes/no), time to recurrent dislocation, pain, feeling of instability and satisfaction with nonoperative management. RESULTS: In 7 (13%) patients, an off-track Hill-Sachs lesion was present, while in 36 (67%) the lesion was on-track and 11 (20%) did not have a structural Hill-Sachs lesion at all. In total, 31 (57%) patients suffered recurrent dislocations. In the off-track group, all shoulders dislocated again (100%), while 21 (58%) in the on-track group and 3 (27%) in the no structural Hill--Sachs lesion group had a recurrent dislocation, p = 0.008. The mean age in the group with a recurrence was 23.7 ± 10.1 years, while those patients without recurrent dislocation were 37.4 ± 13.1 years old, p < 0.01. The risk for recurrence in patients under 30 years of age was higher than in those older than 30 years (OR = 12.66, p < 0.001). There were no significant differences between patients with on- and off-track lesions regarding patients' sex, height, weight and time to reduction and glenoid diameter. Off-track patients were younger than on-track patients (24.9 ± 7.3 years vs. 29.6 ± 13.6 years). However, this difference was not statistically significant. CONCLUSION: The presence of an off-track Hill-Sachs lesion leads to significantly higher recurrence rates compared to on-track or no structural Hill--Sachs lesions in patients with nonoperative management and should be considered when choosing the right treatment option. Therefore, surgical intervention should be considered in patients with off-track Hill-Sachs lesions. LEVEL OF EVIDENCE: IV.

A retrospective cohort analysis of arthroscopic Bankart repair with or without remplissage in patients with off-track Hill-Sachs lesion evaluated for functional outcomes, recurrent instability, and range of motion.

BACKGROUND: Lone Bankart repair is associated with high rates of recurrence, especially in off-track Hill-Sachs (HS) lesion. The objective of the study was to assess the impact of remplissage in off-track HS lesion influencing the rate of redislocation and range of motion (ROM) of the shoulder. MATERIAL AND METHOD: We retrospectively reviewed 136 patients for arthroscopic Bankart repair without remplissage (group 1, n = 77) or with remplissage (group 2, n =59) for recurrent anterior dislocation of the shoulder with glenoid bone loss of <25%. Further subgroups of on- and off-track HS lesion were based on computed tomographic assessment. At a minimum follow-up of 2 years; patients were evaluated for functional scores (Rowe, Constant-Murley, Western Ontario Shoulder Instability Index), redislocations, and ROM. RESULTS: At a mean follow-up of 54 and 44 months in group 1 and 2, respectively, there was no difference in postoperative functional scores. There were significantly more dislocations in patients with Bankart repair with off-track lesion than in patients with Bankart repair with on-track lesion (P = .02). There were significantly fewer redislocations in patients with off-track lesion who underwent Bankart repair and remplissage than in those who did not undergo remplissage (P = .0007). Compared with group 1 patients, those in group 2 revealed a statistically significant loss of ROM. CONCLUSIONS: Although a nonremplissaged off-track HS lesion remains an important risk factor for recurrent instability, remplissage also results in significant loss of shoulder ROM compared with those who do not undergo remplissage.

New concepts of radiologic preoperative evaluation of anterior shoulder instability: on-track and off-track lesions.

The shoulder is the most frequently dislocated joint in the body due to a larger range of motion and a small area of articulation between the humeral and glenoid surfaces. Traumatic shoulder dislocations, especially those associated with injury to the labroligamentous or bony stabilizers of the joint, lead to further reduction of articular surface contact with resultant glenohumeral instability and recurrent shoulder dislocations. Imaging plays an increasingly important role in the preoperative evaluation of patients with traumatic shoulder instability by evaluating glenohumeral bone loss (uni- or bipolar), assessing soft tissue injuries and identifying patients at risk of postoperative recurrence. Quantification of bone loss is key to differentiate engaging vs. non-engaging Hill-Sachs lesions, while newer concepts of "on-track" vs. "off-track" lesions are being discussed that can determine the required surgical approaches. In this article, we review the preoperative imaging approaches, traditional treatments, outline the bone loss measurement strategies and review these new tracking concepts with relevant case examples.

The glenoid track: a review of the clinical relevance, method of calculation and current evidence behind this method.

In the setting of bipolar bone injury, orthopedic surgeons are currently making use of the glenoid track method to guide surgical management. Using preoperative CT or MR imaging, this method allows the identification of patients who are more likely to fail a primary capsuloligamentous Bankart repair. As the glenoid track method becomes increasingly used in preoperative planning, it is important for the radiologist to become familiar with its concept and method of calculation. This review article aims to concisely summarize the current literature and the clinical implications of the glenoid track method.

Bipolar bone defect in the shoulder anterior dislocation.

In the anterior shoulder instability with glenoid bone loss among 25 % or more of the inferior glenoid diameter (inverted-pear glenoid), the consensus of recent authors is that glenoid bone grafting (Latarjet procedure) should be performed. The engaging Hill-Sachs lesion has been recognized as a risk factor for recurrent anterior shoulder instability. We have developed a method using radiographic and arthroscopic studies and the concept of the glenoid track to determine whether a Hill-Sachs lesion will engage the anterior glenoid rim, whether or not there is concomitant anterior glenoid bone loss. If the Hill-Sachs lesion engages, it is called an "off-track" Hill-Sachs lesion; if it does not engage, it is an "on-track" lesion. On the basis of our quantitative method, we have developed a treatment paradigm with specific surgical criteria for all patients with anterior shoulder instability (first dislocation or recurrent dislocation), both with and without bipolar bone loss.

MRI Evaluation of Bipolar Bone Loss Using the On-Track Off-Track Method: A Feasibility Study.

OBJECTIVE: The purpose of this study was to determine whether the simultaneous MRI evaluation of Hill-Sachs lesions and glenoid bone loss by use of the on-track off-track method can be used to predict engagement during arthroscopy. MATERIALS AND METHODS: The records of 75 consecutively registered patients (60 male patients, 15 female patients) with a history of previous anterior shoulder instability who underwent preoperative MRI of the shoulder and arthroscopy at our institution were reviewed. A total of 76 MRI examinations were included. Two readers reviewed the MR images of each patient blindly and independently and used the on-track off-track method to predict engagement. These results were compared with the findings related to engagement seen during arthroscopy, which was performed by one of seven orthopedic surgeons. Statistical analyses included Fisher exact test, logistic regression, ROC analysis, and calculation of intraclass correlation coefficients. RESULTS: Using the on-track off-track technique of reading MR images, the reviewers correctly predicted 13 of the 18 engaging (off-track) lesions (sensitivity, 72.2%). Among the 58 shoulders that did not engage (on-track), they correctly predicted 51 (specificity, 87.9%). Overall, the accuracy of the on-track off-track method was 84.2% with a positive predictive value of 65.0% and negative predictive value of 91.1%. CONCLUSION: Our study showed that the on-track off-track method can be used in MRI to accurately assess the bipolar bone loss seen in patients with anterior shoulder instability for predicting the presence of engaging, or off-track, lesions. This information can be used preoperatively to help guide the type of stabilization procedure performed on patients with anterior shoulder instability.

Glenoid track and subcritical Hill-Sachs lesion.

Background: We have proposed the concept of glenoid track ("on-track/off-track" lesion) to evaluate the risk of engagement of the Hill-Sachs lesion with the glenoid after arthroscopic Bankart repair. This concept has been widely used and many clinical validation studies have been reported. To measure the glenoid track width, we have recommended to use 3-dimensional computed tomography (CT) images. However, the CT method has the issue of radiation exposure and involves time and effort to make 3-dimensional CT images from 2-dimensional images. For these reasons, there are several reports describing the measurement method using magnetic resonance imaging. Recently, the threshold of the critical glenoid bone loss becomes lower. A zone of bone loss below the critical size is called "subcritical bone loss", which might be related to deterioration of quality of life and bone grafting is recommended. We applied the concept of "subcritical bone loss" to the glenoid track. Patients with "on-track" lesions can be divided into 2 subgroups: those with a "peripheral-track" lesion (most medial 1/4) and those with a "central-track" lesion (the rest 3/4). More recently, similar evaluation methods to evaluate the risk of "off-track" lesions have been reported: ''distance to dislocation'' and "Hill-Sachs interval/glenoid track ratio". Also, similar concept to "peripheral-track" lesion, "near-track" lesion was reported. The concept of "peripheral-track" lesion is a concept of assessing an "on-track" lesion which is very close to the medial margin of the glenoid track (subcritical bone loss). Methods: Similar evaluation methods to evaluate the risk of "off-track" or "peripheral-track" lesions were proposed in the literature. A review was performed by searching PubMed. Journal articles published between January 2014 and January 2023 were taken into account. They were compared and their differences were explained. Results: The "near-track" lesion concept is similar to "peripheral-track" lesion. However, the cutoff value is different: Hill-Sachs occupancy ≥ 75% is the "peripheral-track" lesion, whereas "distance to dislocation" < 8 mm is the "near-track" lesion. Conclusion: We introduced update of the glenoid track concept including the evaluation method, peripheral-track lesion, and its clinical application.

Association of Instability History and Off-Track Hill-Sachs Lesions in Anterior Shoulder Instability.

Background: The glenoid track concept is now widely accepted, and its evaluation is considered essential for making decisions about surgery. Purpose: To define preoperative descriptive data and clinical and functional features in patients with anterior glenohumeral instability according to glenoid track status and to analyze the influence of off-track Hill-Sachs (HS) lesions on preoperative shoulder function. Study Design: Case-control study; Level of evidence, 3. Methods: Preoperative magnetic resonance imaging or computed tomography scans were used to measure the glenoid track. Descriptive data and preoperative objective and subjective clinical and functional features were compared between patients with on-track HS lesions versus off-track HS lesions. Multivariate regression analysis was conducted to identify potential risk factors for off-track HS lesion development. Results: A total of 235 patients (201 men, 34 women; mean age, 29.6 ± 8.6 years) were included- 134 shoulders (57%) with on-track HS lesions and 101 shoulders (43%) with off-track HS lesions. Age <20 years at first dislocation, number of dislocations, and ≥2 years between first dislocation and surgery were significantly different between the study groups (P = .005, P = .0001, and P = .01, respectively). Regarding these characteristics, the odds ratios for the risk of developing an off-track lesion were 2.67 (95% CI, 1.2-5.99)-1.2 times higher for each additional instability episode (95% CI, 1.025-1.14) and 2.42 times higher (95% CI, 1.176-4.608) for patients whose first dislocation was ≥2 years before surgery, respectively. Patients with off-track HS lesions had a significantly greater degree of instability (P = .04), worse Rowe scores (48.8 ± 15.3 vs 54.8 ± 28.3 for on-track HS lesions; P = .04), and lower Western Ontario Shoulder Instability scores (975 ± 454 vs 1179 ± 428 for on-track HS lesions; P = .01). Conclusion: Characteristics related to a history of instability (age <20 years at first instability episode, larger number of dislocations, ≥2 years between first dislocation and surgery) were found to be risk factors for the development of an off-track HS lesion in this study. Off-track lesions led to a higher degree of instability and worse objective and subjective preoperative shoulder function versus on-track HS lesions.

Management of off-track Hill-Sachs lesions in anterior glenohumeral instability.

Bone loss has been identified as a risk factor for recurrent shoulder dislocations or failure after soft tissue repair. Although the range for "critical" bone loss is yet to be determined, glenoid and humeral bone defects should not be regarded as independent problems, but the interaction between them during shoulder motion should be evaluated as suggested by the glenoid track concept. The glenoid track concept is now widely accepted and considered essential for making decisions about surgery. Soft-tissue procedures usually work well in patients with on-track Hill-Sachs lesions but in off-track lesions do not. In this situation additional procedures should be performed.Different surgical options have been described to address off-track Hill-Sachs lesions, most commonly remplissage, Latarjet or free bone block procedures. Coracoid graft and free bone grafts convert the off-track Hill-Sachs lesion into on-track by lengthening the glenoid-track, whereas remplissage fill-in the humeral lesion so that it does not engage. In the setting of a Hill-Sachs lesion with little or no glenoid bone loss, remplissage has demonstrated satisfactory outcomes with a low complications and recurrence rate. Favorable results have been reported with glenoid bone grafting when managing isolated Hill-Sachs or bipolar lesions. Studies analyzing Latarjet and Eden-Hybinette procedures show that both procedures are safe and effective in the management of anterior glenohumeral instability. Attention should be paid to those patients with large bone defects not amenable to be restored with an isolated Latarjet that may be better addressed with an Eden-Hybinnete or adding a remplissage to the Latarjet procedure.

Utility of Talus Osteochondral Allograft Augmentation for Varying Hill-Sachs Lesion Sizes: A Cadaveric Study.

Background: Humeral head reconstruction with fresh osteochondral allografts (OCA) serves as a potential treatment option for anatomic reconstruction. More specifically, talus OCA is a promising graft source because of its high congruency with a dense cartilaginous surface. Purpose: To analyze the surface geometry of the talus OCA plug augmentation for the management of shoulder instability with varying sizes of Hill-Sachs lesions (HSLs). Study Design: Controlled laboratory study. Methods: Seven fresh-frozen cadaveric shoulders were tested in this study. The humeral heads were analyzed using actual patients' computed tomography scans. Surface laser scan analysis was performed on 7 testing states: (1) native state; (2) small HSL; (3) talus OCA augmentation for small HSL; (4) medium HSL; (5) talus OCA augmentation for medium HSL; (6) large HSL; and (7) talus OCA augmentation for large HSL. OCA plugs were harvested from the talus allograft and placed in the most medial and superior aspect of each HSL lesion. Surface congruency was calculated as the mean absolute error and the root mean squared error in the distance. A 1-way repeated-measures analysis of variance was performed to evaluate the effects of the difference in the HSL size and associated talus OCA plugs on surface congruency and the HSL surface area. Results: The surface area analysis of the humeral head with the large (1469 ± 75 mm2), medium (1391 ± 81 mm2), and small (1230 ± 54 mm2) HSLs exhibited significantly higher surface areas than the native state (1007 ± 88 mm2; P < .001 for all sizes). The native state exhibited significantly lower surface areas as compared with after talus OCA augmentation for large HSLs (1235 ± 63 mm2; P < .001) but not for small or medium HSLs. Talus OCA augmentation yielded improved surface areas and congruency after treatment in small, medium, and large HSLs (P < .001). Conclusion: Talus OCA plug augmentation restored surface area and congruency across all tested HSLs, and the surface area was best improved with the most common HSLs-small and medium. Clinical Relevance: Talus OCA plugs may provide a viable option for restoring congruity of the shoulder in patients with recurrent anterior glenohumeral instability and an HSL.

Humeral Head Reconstruction With Osteochondral Allograft: Bone Plug Optimization for Hill-Sachs Lesions Using CT-Based Computer Modeling Analysis.

Background: Engaging Hill-Sachs lesions (HSLs) pose a significant risk for failure of surgical repair of recurrent anterior shoulder instability. Reconstruction with fresh osteochondral allograft (OCA) has been proposed as a treatment for large HSLs. Purpose: To determine the optimal characteristics of talus OCA bone plugs in a computer-simulated HSL model. Study Design: Descriptive laboratory study; Level of evidence, 6. Methods: Included were 132 patients with recurrent anterior instability with visible HSLs; patients who had multidirectional instability or previous shoulder surgery were excluded. Three-dimensional computed tomography models were constructed, and a custom computer optimization algorithm was generated to maximize bone plug surface area at the most superior apex (superiorization) and minimize its position relative to the most medial margin of the HSL defect (medialization). The optimal number, diameter, medialization, and superiorization of the bone plug(s) were reported. Percentages of restored glenoid track width and conversion from off- to on-track HSLs after bone plug optimization were calculated. Results: A total of 86 patients were included in the final analysis. Off-track lesions made up 19.7% of HSLs and, of these, the mean bone plug size was 9.9 ± 1.4 mm, with 2.2 mm ± 1.7 mm of medialization and 3.3 mm ± 2.9 mm of superiorization. The optimization identified 21% of HSLs requiring 1 bone plug, 65% requiring 2 plugs, and 14% requiring 3 plugs, with a mean overall coverage of 60%. The mean width of the restored HSLs was 68%, and all off-track HSLs (n = 17) were restored to on-track. A Jenks natural-breaks analysis calculated 3 ideal bone plug diameters of 8 mm (small), 10.4 mm (medium), and 12 mm (large) in order to convert this group of HSLs to on-track. Conclusion: Using a custom computer algorithm, we have demonstrated the optimal talus OCA bone plug diameters for reconstructing HSLs to successfully restore the HSL track and, on average, 60% of the HSL surface area and 68% of the HSL width. Clinical Relevance: Reconstructing HSLs with talus OCA is a promising treatment option with excellent fit and restoration of HSLs. This study will help guide surgeons to optimize OCA bone plugs from the humeral head, femoral head, and talus for varying sizes of HSLs.

Regulation of Off-track bidirectional signaling by Semaphorin-1a and Wnt signaling in the Drosophila motor axon guidance.

Off-track receptor tyrosine kinase (OTK) has been shown to play an important role in the Drosophila motor axon pathfinding. The results of biochemical and genetic interactions previously suggested that OTK acts as a component of Semaphorin-1a/Plexin A (Sema-1a/PlexA) signaling during embryonic motor axon guidance and further showed that OTK binds to Wnt family members Wnt2 and Wnt4 and their common receptor Frizzled (Fz). However, the molecular mechanisms underlying the motor axon guidance function of OTK remain elusive. Here, we conclude that OTK mediates the forward and reverse signaling required for intersegmental nerve b (ISNb) motor axon pathfinding and we also demonstrate that the loss of two copies of Sema-1a synergistically enhances the bypass phenotype observed in otk mutants. Furthermore, the amorphic wnt2 mutation resulted in increased premature branching phenotypes, and the loss of fz function caused a frequent inability of ISNb motor axons to defasciculate at specific choice points. Consistent with a previous study, wnt4 mutant axons were often defective in recognizing target muscles. Interestingly, the bypass phenotype of otk mutants was robustly suppressed by loss of function mutations in wnt2, wnt4, or fz. In contrast, total ISNb defects of otk were increased by the loss-of-function alleles in wnt2 and wnt4, but not fz. These findings indicate that OTK may participate in the crosstalk between the Sema-1a/PlexA and Wnt signaling pathways, thereby contributing to ISNb motor axon pathfinding and target recognition.

Arthroscopic Bankart Repair With Remplissage as an Alternative to Latarjet for Anterior Glenohumeral Instability With More Than 15% Glenoid Bone Loss.

Background: Surgical management of anterior shoulder instability continues to evolve. The clinical effectiveness of arthroscopic Bankart repair with remplissage (REMP) in patients with increasing glenoid bone loss (GBL) has not been thoroughly compared with Latarjet. Purpose/Hypothesis: The purpose of this study was to compare 2-year outcomes of REMP versus open Latarjet in patients with >15% GBL. We hypothesized that there would be no difference. Study Design: Cohort study; Level of evidence, 3. Methods: A multicenter, retrospective study was performed on a consecutive series of patients who underwent primary REMP or Latarjet by 4 shoulder specialists between August 2013 and December 2019 for >15% GBL. Procedure performance was based on shared decision making between the surgeon and patient. Baseline and 2-year postoperative range of motion (ROM) and the following patient-reported outcomes (PROs) were collected: Western Ontario Shoulder Instability Index, Single Assessment Numeric Evaluation, and visual analog scale for pain. Return to sport, satisfaction, complications, recurrence, and revisions were reviewed. Results: A total of 47 patients were available for study, including 22 who underwent REMP and 25 who underwent Latarjet. Baseline demographic characteristics, ROM, and PROs were similar between the groups. Mean preoperative GBL (REMP 25.8% ± 7.8% vs Latarjet 25.1% ± 9.0%; P = .800) and off-track lesions (REMP 59.1% vs Latarjet 44.0%; P = .302) were similar. Postoperative change in external rotation favored Latarjet (10° ± 22° vs -4° ± 13°; P = .017). Postoperative PROs, return to the sports (86.4% vs 87.5%; P = .99), and satisfaction (95.5% vs 95.8%; P = .99) were similar between groups. There were no recurrent dislocations in either group. One infected hematoma was encountered in the Latarjet cohort. Conclusion: At short-term follow-up, the hypothesis was upheld. REMP and Latarjet provided similar outcomes for patients with >15% GBL, although REMP patients experienced slightly decreased external rotation. Although larger series and longer-term follow-ups are required, remplissage may be considered in patients with >15% glenoid bone loss.

Clinical Relevance of Persistent Off-Track Hill-Sachs Lesion After Arthroscopic Latarjet Procedure.

BACKGROUND: The Latarjet procedure is often used to address off-track Hill-Sachs lesions (OFF-HS) in shoulders with anterior instability. There are concerns as to whether the Latarjet procedure is able to convert all OFF-HS into on-track Hill-Sachs lesions (ON-HS) and whether this limitation could explain the cases of recurrent postoperative instability. HYPOTHESIS: Latarjet surgery converts many preoperative OFF-HS lesions, but not all of them, and there is a difference in the failure rate between shoulders with converted lesions and those with persistent OFF-HS lesions. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Patients with anterior shoulder instability and an OFF-HS lesion treated with an arthroscopic classic Latarjet procedure between January 2010 and September 2017 were retrospectively evaluated. Patients with moderate or severe shoulder arthrosis, rotator cuff tears, or age older than 50 years were excluded. Glenoid track (GT), HS, HS interval (HSI), and the difference between HSI and GT (ΔHSI-GT) were measured preoperatively. A postoperative computed tomography scan and a clinical evaluation, including the Rowe and Western Ontario Shoulder Instability scores, were performed at a minimum 1- and 2-year follow-up, respectively. Postoperatively, 2 groups of patients were obtained: (1) patients with postoperative persistent OFF-HS; (2) patients with postoperative ON-HS. Clinical and imaging data were compared between the 2 groups. RESULTS: A total of 51 patients (n = 51 shoulders), with a mean age of 29.8 ± 8.4 years (range, 15-50 years), met the inclusion criteria. Six shoulders (11.8%) still showed OFF-HS lesions despite Latarjet surgery. There were no postoperative dislocations, but 3 patients reported subluxations. The subluxation rate was significantly higher in the postoperative persistent OFF-HS group (2 [33%] vs 1 [2.2%]; P = .033). There was a wider preoperative HSI (29.8 ± 2.4 mm vs 22.9 ± 3.5 mm; P < .001) and a larger preoperative ΔHSI-GT (12.2 ± 3.8 mm vs 4.82 ± 3.2 mm; P < .001) in the persistent OFF-HS group. A receiver operating characteristic curve was performed based on preoperative ΔHSI-GT values. A preoperative ΔHSI-GT value ≥7.45 mm predicted a persistent OFF-HS after Latarjet surgery (sensitivity, 100%; specificity, 87%; positive predictive value, 50%; and negative predictive value, 100%). CONCLUSION: Latarjet surgery converted many preoperative OFF-HS lesions into ON-HS lesions, but not all of them. Six patients (11.8%) retained an OFF-HS and had a statistically significantly higher failure rate after Latarjet surgery compared with those with postoperative ON-HS lesions. Because there were few postoperative OFF-HS lesions and few recurrences, findings are statistically fragile and should be confirmed with larger series.

Arthroscopic Versus Open Anterior Shoulder Stabilization: A Prospective Randomized Clinical Trial With 15-Year Follow-up With an Assessment of the Glenoid Being "On-Track" and "Off-Track" as a Predictor of Failure.

BACKGROUND: Recent studies have demonstrated equivalent short-term results when comparing arthroscopic versus open anterior shoulder stabilization. However, none have evaluated the long-term clinical outcomes of patients after arthroscopic or open anterior shoulder stabilization, with inclusion of an assessment of preoperative glenoid tracking. PURPOSE: To compare long-term clinical outcomes of patients with recurrent anterior shoulder instability randomized to open and arthroscopic stabilization groups. Additionally, preoperative magnetic resonance imaging (MRI) studies were used to assess whether the shoulders were "on-track" or "off-track" to ascertain a prediction of increased failure risk. STUDY DESIGN: Randomized controlled trial; Level of evidence, 1. METHODS: A consecutive series of 64 patients with recurrent anterior shoulder instability were randomized to receive either arthroscopic or open stabilization by a single surgeon. Follow-up assessments were performed at minimum 15-year follow-up using established postoperative evaluations. Clinical failure was defined as any recurrent dislocation postoperatively or subjective instability. Preoperative MRI scans were obtained to calculate the glenoid track and designate shoulders as on-track or off-track. These results were then correlated with the patients' clinical results at their latest follow-up. RESULTS: Of 64 patients, 60 (28 arthroscopic and 32 open) were contacted or examined for follow-up (range, 15-17 years). The mean age at the time of surgery was 25 years (range, 19-42 years), while the mean age at the time of this assessment was 40 years (range, 34-57 years). The rates of arthroscopic and open long-term failure were 14.3% (4/28) and 12.5% (4/32), respectively. There were no differences in subjective shoulder outcome scores between the treatment groups. Of the 56 shoulders, with available MRI studies, 8 (14.3%) were determined to be off-track. Of these 8 shoulders, there were 2 surgical failures (25.0%; 1 treated arthroscopically, 1 treated open). In the on-track group, 6 of 48 had failed surgery (12.5%; 3 open, 3 arthroscopic [P = .280]). CONCLUSION: Long-term clinical outcomes were comparable at 15 years postoperatively between the arthroscopic and open stabilization groups. The presence of an off-track lesion may be associated with a higher rate of recurrent instability in both cohorts at long-term follow-up; however, this study was underpowered to verify this situation.