Does an "Off-Track" Hill-Sachs Lesion That Is Misclassified as "Non-Engaging" Affect Outcomes From Bankart Repair Alone Compared With Bankart Repair Combined With Remplissage?

PURPOSE: To determine how intraoperative assessment (engagement test) may affect recurrent dislocation rate and to compare the clinical outcomes, recurrence rates, and presence of on-/off-track conditions between cases that received arthroscopic Bankart repair alone (nonengaged Hill-Sachs lesion) and Bankart repair with remplissage (engaged Hill-Sachs lesion). METHODS: We retrospectively reviewed 213 patients who underwent arthroscopic Bankart repair alone (186 patients with nonengaging lesions, group A) or with remplissage (27 patients with engaging lesion, group B) for recurrent anterior shoulder instability with <25% glenoid bone defect. The presence of an engaging Hill-Sachs lesion was determined during arthroscopic evaluation. On-track or off-track lesions were assessed retrospectively from preoperative 3-dimensional (3D) computed tomography (CT). RESULTS: Mean glenoid bone defect was 13.7% in group A and 20.7% in group B (P < .001). Off-track lesions were identified in 8.1% (15/186) and 100% (27/27) in group B. At the final follow-up (minimum 2 years; mean follow-up periods after surgery of 50.1 months in group A and 47.7 months in group B), there were no significant differences in shoulder functional scores and recurrence rates between groups, despite improvement after surgery. In the off-track lesion (group A-1: nonengaging but off-track lesion), recurrence instability occurred in 9 patients (60%, 9/15). Also, comparing group A-1 and group B, we noted significant differences in shoulder functional scores and recurrence rates (P < .001). CONCLUSION: Of 186 patients, 8.1% with nonengaging Hill-Sachs lesions during direct arthroscopic examination under anesthesia actually demonstrated off-track lesions on preoperative 3D CT scans retrospectively, with 60% experiencing recurrent instability. Intraoperative manual assessment for Hill-Sachs engagement was inferior to 3D CT scan in establishing the presence of off-track defects. LEVEL OF EVIDENCE: III, retrospective comparative study.

Effects of Glenoid and Humeral Bone Defects on Recurrent Anterior Instability of the Shoulder.

For proper treatment of recurrent anterior instability of the shoulder with a bone defect, the defect size should be assessed preoperatively with three-dimensional computed tomography or magnetic resonance imaging. In general, the risk of postoperative recurrence of instability is estimated on the basis of preoperative imaging of bipolar bone defects: more than 20%-25% glenoid bone loss and off-track Hill-Sachs lesions have been considered risk factors for recurrence. In patients with a glenoid bone defect more than 20%-25%, a bone graft procedure, such as the Latarjet procedure, is preferred regardless of the glenoid track concept, because compared with arthroscopic stabilization procedure, it provides greater postoperative stability. For patients with a borderline glenoid bone defect (around 20%), surgeons should discuss surgical options with the patients, considering their demand and physical activity level. In addition, the surgeon should take care to prevent postoperative instability and long-term complications. Arthroscopic soft-tissue reconstruction including labral repair and capsular plication combined with the additional remplissage procedure is an anatomical procedure and could be considered as one of the primary treatment methods for patients with glenoid bone defects around 20%. Therefore, treatment strategies for recurrent anterior shoulder instability combined with bone defects should be determined more flexibly on the basis of the patient's individual condition.

Comparison of the clinical results of isolated Bankart and SLAP 5 lesions after arthroscopic repair.

OBJECTIVES: This study aims to compare the clinical results of patients with traumatic isolated Bankart lesions and type V superior labrum anterior to posterior (SLAP) lesions after arthroscopic repair. PATIENTS AND METHODS: Patients who underwent arthroscopic repair for traumatic anterior glenohumeral instability were evaluated retrospectively between December 2014 and January 2019. Fifty-one patients (49 males, 2 females; mean age 25 years; range, 18 to 36 years) without bone defects affecting >20% of the glenoid fossa, off-track engaging Hills-Sachs lesions, multidirectional instability, or ligamentous laxity were included in the study. Group 1 had 31 patients with isolated Bankart lesions and group 2 had 20 patients with type V SLAP lesions. There were only two female patients in group 1 and all patients were male in group 2. The mean age was 25 years (range, 18 to 36 years) in group 1 and 25 years (range, 19 to 35 years) in group 2. Rowe, Constant, and Western Ontario Shoulder Instability (WOSI) scoring systems were used to evaluate the clinical outcomes of the patients preoperatively and at the last follow-up. RESULTS: The mean follow-up time was 32 months (range, 12 to 48 months) in group 1 and 28.5 months (range, 12 to 42 months) in group 2. There were no statistically significant differences between the two groups in terms of the number of shoulder dislocations before the surgery, mean age at the time of surgery, and the mean time from the first dislocation to surgical treatment. When the Rowe, Constant, and WOSI scores were evaluated preoperatively and at the last follow-up, there were statistically significant changes within, but not between, the two groups. CONCLUSION: In type V SLAP lesions, the affected and repaired labrum surface area is larger than isolated Bankart lesions. However, as a result of appropriate surgical treatment, the affected surface area does not have a negative effect on clinical outcomes, and similar clinical results can be obtained in patients with type V SLAP lesions compared to patients with isolated Bankart lesions.

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.

Altered shoulder kinematics using a new model for multiple dislocations-induced Bankart lesions.

BACKGROUND: Many active individuals undergo multiple dislocations during the course of a season before surgical treatment without considering the implications of each successive injury. Therefore, the purpose of this study was to develop a multiple dislocation model for the glenohumeral joint and evaluate the resulting changes in joint function. METHODS: Eight cadaveric shoulders were evaluated using a robotic testing system. A simulated clinical exam was performed by applying a 50 N anterior load to the humerus at 60° of glenohumeral abduction and external rotation. Each joint was then dislocated. The same loads were applied again and the resulting kinematics were recorded following each of 10 dislocations. The force required to achieve dislocation was recorded and capsulolabral status was assessed. FINDINGS: A reproducible Bankart lesion was repeatedly created following the dislocation protocol. The force required for all dislocations significantly decreased following the 1st dislocation. In addition, even lower forces were required to achieve the 5th and subsequent dislocations (p < 0.05). Anterior translation in response to an anterior load during the simulated clinical exam increased between the intact and injured joints (p < 0.05). However, anterior translation reached a plateau following the 3rd to 10th dislocations and was increased compared with the 1st dislocation (p < 0.05). INTERPRETATION: A repeatable Bankart lesion was not surgically made, but created by our new dislocation model. Joint function appeared to reach a constant level after the 3rd to 5th dislocations. Thus, multiple dislocations result in a deleterious dose dependent effect suggesting additional damage is not sustained after the fifth dislocation. LEVEL OF EVIDENCE: Controlled laboratory study.

Glenoid retroversion is an important factor for humeral head centration and the biomechanics of posterior shoulder stability.

PURPOSE: Glenoid retroversion is a known independent risk factor for recurrent posterior instability. The purpose was to investigate progressive angles of glenoid retroversion and their influence on humeral head centration and posterior translation with intact, detached, and repaired posterior labrum in a cadaveric human shoulder model. METHODS: A total of 10 fresh-frozen human cadaveric shoulders were investigated for this study. After CT- canning, the glenoids were aligned parallel to the floor, with the capsule intact, and the humerus was fixed in 60° of abduction and neutral rotation. Version of the glenoid was created after wedge resection from posterior and fixed with an external fixator throughout the testing. Specimens underwent three conditions: intact, detached, and repaired posterior labrum, while version of the glenoid was set from + 5° anteversion to - 25° retroversion by 5° increments. Within the biomechanical setup, the glenohumeral joint was axially loaded (22 N) to center the joint. At 0° of glenoid version and intact labrum, the initial position was used as baseline and served as point zero of centerization. After cyclic preloading, posterior translation force (20 N) was then applied by a material testing machine, while start and endpoints of the scapula placed on an X-Y table were measured. RESULTS: The decentralization of the humeral head at glenoid version angles of 5°, 10°, 15°, and 20° of retroversion and 5° of anteversion was significantly different (P < 0.001). Every increment of 5° of retroversion led to an additional decentralization of the humeral head overall by (average ± SD) 2.0 mm ± 0.3 in the intact and 2.0 mm ± 0.7 in the detached labrum condition. The repaired showed significantly lower posterior translation compared to the intact condition at 10° (P = 0.012) and 15° (P < 0.01) of retroversion. In addition, CT measured parameters (depth, diameter, and native version) of the glenoid showed no correlation with angle of dislocation of each specimen. CONCLUSION: Bony alignment in terms of glenoid retroversion angle plays an important role in joint centration and posterior translation, especially in retroversion angles greater than 10°. Isolated posterior labrum repair has a significant effect on posterior translation in glenoid retroversion angles of 5° and 10°. Bony correction of glenoid version may be considered to address posterior shoulder instability with retroversion > 15°.

Biomechanical effects of position and angle of insertion for all-suture anchors in arthroscopic Bankart repair.

BACKGROUND: The biomechanical properties of all-suture anchor for labral repair depending on the insertion angle and location are lacking. The purpose of this study was to quantify the biomechanical fixation characteristics of the anchor position and insertion angle of all-suture anchors for arthroscopic Bankart repair. METHODS: Twenty-four fresh frozen cadaveric glenoid were used. All-suture anchors with 1.5-mm diameter were randomly inserted at 2:30, 4:00, and 5:30 o'clock positions on the glenoid edge, with either 30°, 45° or 60° insertion angles to the mediolateral axis of the glenoid. Anchors were preloaded to 5 N and cyclically loaded from 5 N to 20 N for 10 cycles, followed by a load to failure test at 60 mm/min. Permanent, non-recoverable displacement was quantified at the end of the cyclic loading test to yield load. FINDINGS: All-suture anchors implanted at the 2:30 o'clock position of the glenoid provided greater stiffness, yield load, and ultimate load than those inserted at the 4:00 and 5:30 o'clock positions, regardless of the insertion angle. Displacement at yield and ultimate load were similar among the positions and insertion angles (yield load, vs. 4:00, p = 0.01; vs. 5:30, p = 0.045; ultimate load, vs. 4:00, p < 0.01; vs. 5:30, p < 0.01). The insertion angles of 30°, 45° and 60° did not influence mechanical stability between the 4:00 and 5:30 o'clock positions. INTERPRETATION: The insertion angle of all-suture anchors does not significantly affect the stability at antero-inferior quadrant of the glenoid.

Does Anchor Placement on the Glenoid Affect Functional Outcome After Arthroscopic Bankart Repair?

BACKGROUND: In arthroscopic Bankart repair, anchor positions can affect glenoid labral height and functional outcomes. PURPOSE: To evaluate anchor placement on the glenoid during Bankart lesion repair and determine which placement would lead to better functional outcomes. STUDY DESIGN: Cohort study; Level of evidence, 3. METHOD: This study included 90 patients (74 males, 16 females; average age, 23.7 years; range, 18-47 years) who underwent surgery for Bankart lesions between December 2009 and March 2014. The mean follow-up duration was 32.7 months (range, 26-48 months). We divided anchor positions into 2 groups: on the glenoid face and at the glenoid edge. The anchor position on the glenoid and the labral height were examined with computed tomography (CT) arthrography at 4.5-month follow-up, and Rowe scores were calculated at 2-year follow-up. RESULTS: The group with the anchor placed on the glenoid face contained 63 patients, and the group with the anchor placed at the glenoid edge or rim contained 27 patients. Mean labral heights at 4.5 months postoperatively in the 2 groups were 5.4 ± 0.22 mm and 3.2 ± 0.16 mm, respectively ( P < .01), and mean Rowe scores at 2 years were 94.7 and 79.5, respectively ( P < .01). Rowe scores calculated at 2-year follow-up were significantly related to anchor position ( P < .01). CONCLUSION: Anchors positioned on the glenoid face resulted in the greatest restored labral height and better functional outcome (Rowe score). Thus, anchor placement on the glenoid face should be considered, as it may yield better functional outcome in arthroscopic Bankart repair.

Chronic anterior shoulder instability with significant Hill-Sachs lesion: Arthroscopic Bankart with remplissage versus open Latarjet procedure.

BACKGROUND: The objective of this study was to compare short-term shoulder stability after arthroscopic Bankart repair with remplissage versus the open Latarjet procedure in patients who had chronic anterior shoulder instability with a significant Hill-Sachs lesion. HYPOTHESIS: The dislocation recurrence rate is higher after Bankart repair with remplissage than after open Latarjet. PATIENTS AND METHODS: An observational non-randomised retrospective cohort study was conducted at two surgical centres in patients treated for chronic anterior shoulder instability with a significant Hill-Sachs defect between January 2009 and July 2014. The study compared 43 patients managed by arthroscopic Bankart repair and remplissage and 43 patients managed with open Latarjet. The two groups were matched on age at surgery and on follow-up duration. All patients were evaluated by independent observers based on a questionnaire including recurrences, range of motion, and functional outcomes (Shoulder Subjective Value [SSV], Walch-Duplay score, and Rowe score). RESULTS: Mean follow-up was 47.3 months (range, 24-67 months). The recurrence rate at last follow-up was not significantly different between the two groups (9.3% versus 11.2%; P=0.67). The Bankart group had significantly greater loss of external rotation and a significantly higher proportion of patients with residual pain (21% versus 9%, P=0.023). The SSV, Walch-Duplay score, and Rowe score values were similar between groups. DISCUSSION: In patients who had chronic anterior shoulder instability with a significant Hill-Sachs lesion, arthroscopic Bankart repair with remplissage and open Latarjet were reliable and safe procedures associated with low and similar recurrence rates. However, loss of external rotation and residual pain were significantly more common with the combined Bankart-remplissage procedure. LEVEL OF EVIDENCE: III; comparative retrospective study.

Results of Arthroscopic Bankart Repair for Anterior-Inferior Shoulder Instability at 13-Year Follow-up.

BACKGROUND: Anterior-inferior shoulder instability is a common injury in young patients, particularly those practicing overhead-throwing sports. Long-term results after open procedures are well studied and evaluated. However, the long-term results after arthroscopic repair and risk factors of recurrence require further assessment. HYPOTHESIS: Arthroscopic Bankart repair results are comparable with those of open repair as described in the literature. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: A total of 180 shoulders with anterior-inferior shoulder instability were stabilized arthroscopically, met the inclusion criteria and the patients were able to be contacted at a minimum of 10-year follow-up. Of these patients, 143 agreed to participate in the study. Assessment was performed clinically in 104 patients using the American Shoulder and Elbow Surgeons score, Constant score, American Academy of Orthopaedic Surgeons score, Rowe score, and the Dawson 12-item questionnaire. The Samilson-Prieto score was used to assess degenerative arthropathy in radiographs available for 100 shoulders. Additionally, 15 patients participated through a specific questionnaire and 24 patients through a telephone survey. RESULTS: The overall redislocation rate was 18.18%. Redislocation rates for the different types of fixation devices were as follows: FASTak/Bio-FASTak, 15.1% (17/112); SureTac, 26.3% (5/19); and Panalok, 33.3% (4/12). Concomitant superior labral anterior-posterior repair had no effect on clinical outcome. Redislocation rate was significantly affected by the patient's age and duration of postoperative rehabilitation. Redislocation rate tended to be higher if there had been more than 1 dislocation preoperatively ( P = .098). Severe dislocation arthropathy was observed in 12% of patients, and degenerative changes were significantly correlated with the number of preoperative dislocations, patient age, and number of anchors. The patient satisfaction rate was 92.3%, and return to the preinjury sport level was possible in 49.5%. CONCLUSION: Clinical outcome at a mean follow-up of 13 years after arthroscopic repair of anterior-inferior shoulder instability is comparable with the reported results of open Bankart repair in the literature and allows management of concomitant lesions arthroscopically. Modifiable risk factors of postoperative redislocation and arthropathy must be considered. Stabilization after the first-time dislocation achieves better clinical and radiological outcomes than after multiple dislocations.

Modified technique for reconstructing reverse Hill-Sachs lesion in locked chronic posterior shoulder dislocation.

BACKGROUND: Among the uncommon and frequently missed orthopedics injuries is the posterior shoulder dislocation, accounting for about 2-4 % of all shoulder dislocations. Commonly, it is associated with the well-known reverse Hill-Sachs lesion. Several surgical treatment modalities such as transfer of subscapularis tendon or lesser tuberosity, humeral rotational osteotomy, osteochondral grafts were used to repair this defect. Hemiarthroplasty or total shoulder arthroplasty was used as salvage procedure in non-constructable defect or neglected old dislocation. PATIENTS AND METHODS: This study included 11 patients with locked chronic posterior shoulder dislocation and reverse Hill-Sachs defects falling in the target range (25-50 % of the head size). The mean age of the patients was 39 (range 31-49) years. Mean time from injury to surgery was 9 (range 3-18) weeks. Open reduction in the dislocated head with the transfer of subscapularis tendon and the attached lesser tuberosity was done to reconstruct the reverse Hill-Sachs defect. The transferred tuberosity was fixed with size 5 Ethibond sutures. RESULTS: The mean follow-up period was 29 (range 24-39) months. The median of the scores was much improved, reaching 30 (range 20-34) (satisfactory) compared with preoperative median of 24 (range 20-25) (unsatisfactory). This was statistically highly significant (P = 0.002). Postoperatively, 9 patients had no pain or restricted daily living activities. No patient had symptoms of shoulder instability. According to the modified UCLA shoulder rating scale, there were 4 patients rated excellent, 5 patients rated good, one patient rated fair and one patient rated poor. CONCLUSION: Reconstructing the reverse Hill-Sachs defect provides adequate stability, pain relief and function in patients with locked chronic posterior shoulder dislocation and a defect involving 25-50 % of the humeral head. The used technique is simple and cost effective with no need for subsequent hardware removal. LEVEL OF EVIDENCE: II.

What Is the Critical Value of Glenoid Bone Loss at Which Soft Tissue Bankart Repair Does Not Restore Glenohumeral Translation, Restricts Range of Motion, and Leads to Abnormal Humeral Head Position?

BACKGROUND: A general consensus has been formed that glenoid bone loss greater than 20% to 25% is the critical amount at which bony augmentation procedures are needed; however, recent clinical results suggest that the critical levels must be reconsidered to lower values. PURPOSE: This study aimed to find the critical value of anterior glenoid bone loss when a soft tissue repair is not adequate to restore anterior-inferior glenohumeral translation, rotational range of motion, or humeral head position using a biomechanical anterior shoulder instability model. STUDY DESIGN: Controlled laboratory study. METHODS: Eight cadaveric shoulders were tested with a customized shoulder testing system. Range of motion, translation, and humeral head position were measured at 60° of glenohumeral abduction in the scapular plane under a total of 40-N rotator cuff muscle loading in the following 11 conditions: intact; soft tissue Bankart lesion and repair; Bankart lesion with 10%, 15%, 20%, and 25% glenoid bone defects based on the largest anteroposterior width of the glenoid; and soft tissue Bankart repair for each respective glenoid defect. Serial osteotomies for each percentage of bone loss were made parallel to the long axis of the glenoid. RESULTS: There was significantly decreased external rotation (121.2° ± 2.8° to 113.5° ± 3.3°; P = .004), increased anteroinferior translation with an externally applied load (3.0 ± 1.2 mm to 7.5 ± 1.1 mm at 20 N; P = .008), and increased posterior (0.2 ± 0.6 mm to 2.7 ± 0.8 mm; P = .049) and inferior shift (2.9 ± 0.7 mm to 6.6 ± 1.1 mm; P = .018) of the humeral head apex in the position of maximum external rotation after soft tissue Bankart repair of a 15% glenoid defect compared with the repair of a Bankart lesion without a glenoid defect, respectively. CONCLUSION: Glenoid defects of 15% or more of the largest anteroposterior glenoid width should be considered the critical bone loss amount at which soft tissue repair cannot restore glenohumeral translation, restricts rotational range of motion, and leads to abnormal humeral head position. CLINICAL RELEVANCE: The critical level of anterior glenoid bone loss at which bony restorations should be considered is closer to 15% of the largest anteroposterior width of glenoid for defects perpendicular to the superoinferior glenoid axis, which is lower than the commonly accepted threshold of 20% to 25%.

Biomechanical Evaluation of Glenoid Version and Dislocation Direction on the Influence of Anterior Shoulder Instability and Development of Hill-Sachs Lesions.

BACKGROUND: Abnormal glenoid version is a risk factor for shoulder instability. However, the degree to which the variance in version (both anteversion and retroversion) affects one's predisposition for instability is not well understood. PURPOSE: To determine the influence of glenoid version on anterior shoulder joint stability and to determine if the direction of the humeral head dislocation is a stimulus for the development of Hill-Sachs lesions. STUDY DESIGN: Controlled laboratory study. METHODS: Ten human cadaveric shoulders (mean age, 59.4 ± 4.3 years) were tested using a custom shoulder dislocation device placed in a position of apprehension (90° of abduction with 90° of external rotation). Glenoid version was adjusted in 5° increments for a total of 6 version angles tested: +10°, +5°, 0°, -5°, -10°, and -15° (anteversion angles are positive, and retroversion angles are negative). Two humeral dislocation directions were tested. The first direction was true anterior through the anterior-posterior glenoid axis. The second dislocation direction was 35° inferior from the anterior-posterior glenoid axis based on the deforming force role of the pectoralis major. The force and energy to dislocate were recorded. RESULTS: Changes in glenoid version manifested a linear effect on the dislocation force. The energy to dislocate increased as a second-order polynomial as a function of increasing glenoid retroversion. Glenoid version of +10° anteversion and -15° retroversion was highly unstable, resulting in spontaneous dislocation in one-quarter (10/40) and one-half (25/40) of the specimens anteriorly and posteriorly, respectively, in the absence of an applied dislocation force. The greater tuberosity was observed to engage with the anterior glenoid rim, consistent with Hill-Sachs lesions, 40% more frequently when the dislocation direction was true anterior compared with 35° inferior from the anterior-posterior glenoid axis. The engagement of the greater tuberosity caused an increase in the energy required to dislocate. CONCLUSION: Glenoid version has a direct effect on the force required for a dislocation. An anterior-inferior dislocation direction requires less energy for a dislocation and results in a lower risk of the development of a Hill-Sachs lesion than a direct anterior dislocation direction. CLINICAL RELEVANCE: Consideration should be given to glenoid version when choosing a surgical treatment option for anterior shoulder instability.

Remplissage of an Off-track Hill-Sachs Lesion Is Necessary to Restore Biomechanical Glenohumeral Joint Stability in a Bipolar Bone Loss Model.

PURPOSE: To validate the glenoid track concept in a cadaveric bipolar bone loss model and to test whether "on-track" and "off-track" lesions can be stabilized with Bankart repair (BR) with or without Hill-Sachs remplissage (HSR). METHODS: Eight fresh-frozen cadaveric shoulders were tested in a custom apparatus with passive axial rotation and then progressive translational loading (10 to 40 N) at mid-range (60°) and end-range external rotation (90°). Injury conditions included glenoid bone loss of 15% with on-track (15%) and off-track (30%) Hill-Sachs lesions. Repair conditions included BR with HSR and BR without HSR. RESULTS: For on-track lesions, engagement occurred with translation testing in one shoulder (12.5%) at end-range rotation. After BR, engagement was prevented for this shoulder. For off-track lesions, engagement with translation testing occurred in 8 shoulders (100%) at end-range rotation and in 6 (75%) at mid-range rotation. After BR, engagement was prevented in 4 of 6 engaging shoulders (67%) at mid-range rotation but was prevented in zero of 8 (0%) at end-range rotation. Adding HSR prevented engagement in all 14 engaging shoulders with off-track lesions (100%). BR with HSR resulted in supraphysiological stiffness for off-track lesions at mid- and end-range rotation (13.3 N/m vs 7.0 N/m and 10.0 N/m vs 5.0 N/m, P = .0002) and for on-track lesions at end-range rotation (10.1 N/m vs 5.0 N/m, P = .0002). Stiffness of BR with HSR was not different from the intact shoulder for on-track lesions at mid-range rotation (7.2 N/m vs 7.0 N/m, P > .99). CONCLUSIONS: The patterns of engagement of Hill-Sachs lesions with a 15% glenoid defect in this model give support to the glenoid track concept. BR plus remplissage resulted in supraphysiological shoulder stiffness but was necessary to prevent engagement of off-track bipolar bone lesions. CLINICAL RELEVANCE: This biomechanical study provides evidence to aid in surgical decision making by examining the effects of bipolar bone loss and soft-tissue reconstruction on shoulder stability.