BACKGROUND:Multiple grafts have been described for glenoid resurfacing in the setting of anterior shoulder instability with glenoid bone loss. The medial tibial plateau has been shown to have a similar radius of curvature to the glenoid and may be an appropriate anatomic match for glenoid resurfacing. PURPOSE:To evaluate restoration of glenoid concavity and anterior glenohumeral stability among the distal tibial allograft (DTA), distal clavicle autograft (DCA), and medial tibial plateau allograft (MTPA). STUDY DESIGN:Controlled laboratory study. METHODS:Nine sets of fresh-frozen unpaired shoulder, knee, and ankle cadaveric specimens were obtained (mean specimen age, 58.7 years; range, 51-63). Specimens underwent preoperative computed tomography to assess glenoid depth and radius to define the bony shoulder stability ratio (BSSR; glenoid depth over radius). A Kuka robot was used to assess shoulder stability with forces loaded through the rotator cuff and the shoulder in 90° of abduction and neutral rotation. Glenoid bone loss was created via a 10-mm cut, with each graft restoring 100% of the native glenoid width. The following conditions were tested: intact state followed by reconstructions with the DTA, MTPA, and DCA. Posttest computed tomography scans were obtained to calculate the reconstructed BSSR, and motion detectors were used to calculate maximum anterior humeral translation. RESULTS:The BSSR was similar between the intact state (mean ± SD, 0.39 ± 0.11) and 3 reconstructed glenoid grafts (DCA, 0.46 ± 0.11 [P = .10]; MTPA, 0.43 ± 0.07 [P = .45]; DTA, 0.39 ± 0.11 [P = .21]). Maximum anterior translation did not differ between the 3 grafts (DCA, 6.4 ± 3.0 mm [P = .29]; MTPA, 8.4 ± 5.3 mm [P = .11]; DTA, 6.7 ± 3.6 mm [P = .21]) and the intact state (6.0 ± 2.8). CONCLUSION:By way of a cadaveric analysis, the DCA, MTPA, and DTA restored glenoid concavity to a point similar to the intact state. Future investigations with larger sample sizes are warranted to confirm these biomechanical trends and determine clinical significance. CLINICAL RELEVANCE:Restoration of glenoid concavity is essential for achieving stability in patients with anterior shoulder instability and critical glenoid bone loss. This biomechanical study demonstrates that distal clavicle autograft, distal tibia allograft, and medial tibial plateau allograft each restore native glenoid concavity comparable to the intact state, supporting their use as reliable free bone block options for anatomic glenoid reconstruction. Future clinical studies are warranted to determine whether these biomechanical findings translate to improved clinical outcomes.

Background Walch B-type glenoids have been associated with decreased implant survival in anatomic total shoulder arthroplasty (aTSA) and reverse shoulder arthroplasty (rTSA). The literature suggests that posteriorly-based eccentric glenoid wear driven by posterior humeral head subluxation may occur in conjunction with rotator cuff muscular imbalances around the shoulder. This study aims to identify existing rotator cuff and deltoid muscular imbalances in patients undergoing aTSA and rTSA and their association with different Walch-types of glenoid wear. Methods Patients with primary glenohumeral osteoarthritis (OA) or rotator cuff arthropathy who underwent preoperative computed tomography (CT) scans of the affected shoulder from 8/1/2020 to 12/31/2021 were included. Patients were included if they were over 18 years old with Walch-type A or B glenoids as identified on CT within a year of surgery and had at least two years of follow-up. Fatty infiltration was assessed using Goutallier grading, and muscle volumes were quantified using previously established methodologies. Ratios of anterior to posterior muscle volumes were established for the rotator cuff (‘RCR’), deltoid (‘DMR’), and the rotator cuff and deltoid combined (‘CMR’). Glenoid retroversion, inclination, and humeral head subluxation were recorded. Muscle volume ratios were compared between glenoid types using univariate and multivariable regression and Welch’s t-test. Results The included final cohort of 146 patients had a mean age of 64.3 (±10.6) years and mean BMI of 27.7 (±5.7) kg/m2. Glenoid retroversion was greatest in type B2 glenoids (p<0.0001). DMR (p=0.0176) and CMR (p=0.0066) were lower in B2 compared to A1 glenoids, suggesting greater posterior muscle volume in B2 glenoids. RCR was lower in B2 compared to A2 glenoids (p=0.0003); however, DMR (p=0.3809) and CMR (p=0.0569) were not significantly different between these two groups. CMR (p=0.0086), and RCR (p=0.0097) were significantly lower in B2 compared to A1 and A2 glenoids combined, further suggesting greater posterior muscle volume in B2 glenoids. Goutallier scores were not significantly different across the various glenoid types. Conclusion Patients with type B2 glenoids exhibited a higher ratio of posterior to anterior shoulder muscle volumes when accounting for both the rotator cuff and deltoid. Fatty infiltration of the rotator cuff, however, was not associated with a specific wear pattern. This study substantiates existing evidence to suggest that increased posterior muscle volume may play a role in the pathogenesis of posteriorly-based eccentric glenoid wear, warranting further longitudinal studies to confirm these findings.

BACKGROUND:Distal tibial allograft (DTA) reconstruction has emerged as an effective option for the treatment of recurrent shoulder instability with glenoid bone loss (GBL). However, the ideal location for capsular repair during the procedure remains undetermined. PURPOSE:To evaluate the effect of capsular repair location on humeral head positioning and anterior translation after DTA. STUDY DESIGN:Controlled laboratory study. METHODS:Nine human cadaveric specimens (mean age, 62.2 years [range, 52-69 years]) underwent biomechanical testing in a simulated bone loss model. The rotator cuff tendons were loaded, and anterior stability testing was performed using a Kuka robot with the shoulder in 90° of abduction and neutral external rotation. A motion capture system recorded humeral head position and anterior translation. GBL (mean, 32%) was created, and a DTA graft was prepared to restore 100% of the native glenoid width. The following conditions were tested: intact, soft tissue Bankart lesion, DTA without capsular repair (DTA), DTA with capsule repaired to the graft (intra-articular), and DTA with capsule repaired to the glenoid (extra-articular). A repeated measures analysis of variance was performed to compare the translation and humeral head resting position between the five capsulolabral conditions. RESULTS:There was no difference in anterior translation when comparing DTA without capsular repair and the DTA with the capsule repaired to the graft (5.1 vs 5.3 mm; P > .999), and there was no difference in anterior translation between either of these conditions and the intact state (P > .999 for both). However, capsular repair to the glenoid demonstrated a significantly decreased anterior translation (0.7 vs 7 mm; P < .001) as well as a statistically significant posterior shift in the resting position (-2.5 vs 1.8 mm; P = .004) when compared with the intact state. CONCLUSION:When performing a DTA reconstruction for large GBL, capsular repair to the native glenoid results in a more posterior resting humeral head position and less maximum anterior translation of the humeral head during time-zero biomechanical testing in cadaveric specimens. DTA without capsular repair and DTA with capsular repair to the graft restore glenohumeral position and motion closer to the native state. CLINICAL RELEVANCE:Capsular repair to the native glenoid may overconstrain the glenohumeral joint when performing distal tibial allograft reconstruction in the setting of large glenoid bone loss, but further study is required to determine the impact on patient-reported outcomes or long-term arthritis risk.

Comprehensive evaluation of the shoulder function relies on accurate tracking of humerothoracic and scapulothoracic motion. This study presents a posterior marker configuration comprising three custom 3D-printed clusters (trunk, scapula, upper arm) for use with infrared optoelectronic motion capture systems. The protocol includes a static, unilateral estimation of the glenohumeral joint center (GH). Eight healthy adults performed cycles of abduction/adduction, flexion/extension, horizontal abduction, internal/external rotation, and scapular retraction/protraction. Kinematic trajectories obtained with the proposed marker set were compared to those from ISB-recommended frames using RMSE, linear regression (R2, slope, intercept), and one-way ANOVA on the range of motion (ROM) of the principal angle across subjects. Humerothoracic kinematics showed mean RMSE values of 3.47° (abduction), 12.53° (flexion), 5.39° (horizontal abduction), and 10.61° (internal/external rotation), with R2 > 0.996 and slopes between 0.93 and 1.05. Scapulothoracic retraction/protraction resulted in an RMSE of 4.64°, R2 = 0.95, and slope of 0.82. Scapular medial/lateral rotation during flexion yielded an RMSE of 6.64°, R2 = 0.97, and slope of 1.21. No significant ROM differences were observed between protocols (p > 0.05). To evaluate suitability for constrained environments, cluster visibility was analyzed using ArUco markers. Under the assumption of comparable visibility between monocular video and low-baseline infrared setups, the mean ArUco fill rate was 99.10 %. The mean Euclidean distance between the new static and functional GH center estimates was 14.33 mm. The spinal configuration demonstrated accuracy comparable to sternal tracking while reducing setup complexity, supporting its use in semi-structured environments such as clinical or field-based assessments.

BACKGROUND:Compared with the traditional Grammont design, modern reverse total shoulder arthroplasty (rTSA) implant designs often introduce lateralization of the glenoid and/or humeral components. This study aimed to evaluate the impact of different strategies for achieving lateralization (ie, humeral or glenoid lateralization) in rTSA implant design on rotator cuff biomechanics. METHODS:Computed tomography scans from 16 nonosteoarthritic subjects were used to build customized computational 3-dimensional shoulder models based on the Newcastle Shoulder Model. Four rTSA implant constructs were created: (1) medialized glenoid-medialized humerus (MG-MH); (2) medialized glenoid-lateralized humerus (MG-LH); (3) lateralized glenoid-medialized humerus (LG-MH); and (4) lateralized glenoid-lateralized humerus (LG-LH). All constructs used a humeral stem with 135° neck-shaft angle where the diameter of the glenosphere was 36mm. Simulated rTSA constructs included a subscapularis tendon repaired to its native attachment on the lesser tuberosity. For each design construct, moment arms for both the subscapularis and infraspinatus were calculated for 4 motions: humeral elevation in frontal and scapular plane, internal/external rotation at 20° and 90° of abduction. Moment arms for each construct were also compared to those in a native shoulder. RESULTS:All rTSA constructs influenced the moment arms of the rotator cuff muscles. During humeral elevation, both the subscapularis and infraspinatus exhibited increased adductive moment arms compared to the native shoulder, particularly at lower angles of elevation (0-80° in abduction and 0-50° in the scapular plane). Glenoid lateralization did not significantly affect these changes; however, humeral lateralization enhanced the adductive moment arms of both muscles. Additionally, all rTSA constructs altered the internal and external rotation moment arms of the RC muscles relative to the native shoulder. The subscapularis showed increased internal rotation moment arms that got larger than the native shoulder only after 40° of internal rotation, while the infraspinatus demonstrated increased external rotation moment arms during all external rotation range of motion. Again, glenoid lateralization did not significantly impact these rotational moment arms, whereas humeral lateralization led to an increase in both internal (subscapularis) and external (infraspinatus) rotation moment arms. CONCLUSIONS:While glenoid lateralization of an rTSA implant construct does not substantially alter rotator cuff moment arms, humeral lateralization may have a dual effect: potentially introducing an antagonistic adductive moment relative to the deltoid during early abduction, while also augmenting beneficial rotational moment arms-namely, increased internal rotation from the subscapularis and increased external rotation from the infraspinatus.

Modern reverse total shoulder arthroplasty (rTSA) designs allow for lateralization of glenoid and humeral components. Prior studies have assessed lateralization biomechanics by evaluating moment arms and muscle forces. However, torque, the product of muscle force and moment arm, is the most direct measure of a muscle's ability to generate joint rotation and a more comprehensive metric to assess rTSA lateralization. Our aim was to evaluate how different lateralization strategies affect the glenohumeral joint torque generated by the rotator cuff and deltoid muscles. To achieve this, we created 16 subject-specific biomechanical shoulder models using computed tomography scans. Four implant configurations were virtually implanted into each subject: medialized glenoid - medialized humerus (MG/MH), medialized glenoid - lateralized humerus (MG/LH), lateralized glenoid - medialized humerus (LG/MH), lateralized glenoid - lateralized humerus (LG/LH). For each design, we evaluated the maximum torque generated by the middle deltoid during scapular plane elevation, alongside the maximum torque generated by the infraspinatus and subscapularis during external and internal rotation at 90° of abduction. The MG/LH configuration generated the greatest middle deltoid torque during early arm elevation, despite having an equivalent moment arm to the MG/MH. Infraspinatus and subscapularis torque were enhanced by progressive lateralization resulting in the MG/MH demonstrating the least torque generating capacity and the LG/LH configuration the greatest, but at the expense of excessive middle deltoid strain, which may increase acromial stress fracture risk. Our findings suggest that joint torque provides a more comprehensive assessment of rTSA lateralization than moment arms or muscle force production alone.

Background: Patients undergoing reverse total shoulder arthroplasty (rTSA) for rotator cuff arthropathy may present with an external rotation (ER) lag due to posterior rotator cuff insufficiency. As a result, the addition of a latissimus dorsi (LD) tendon transfer in combination with rTSA has become increasingly utilized. Initial descriptions of LD tendon transfer involved rerouting of the LD tendon posterior to the long head of the triceps tendon. However, more recent techniques involve rerouting the LD tendon anterior to the long head of the triceps tendon via the deltopectoral approach utilized for rTSA. The purpose of this cadaveric study was to assess the biomechanical effect on ER force of LD tendon transfer anterior vs. posterior to the long head of the triceps tendon in combination with rTSA. Methods: Eight fresh frozen cadaveric shoulders were utilized. A shoulder fellowship trained orthopedic surgeon performed rTSA in each specimen. The rotator cuff tendon attachments were cut to simulate a massive rotator cuff tear. The LD tendon was transferred to the greater tuberosity first anterior to the long head of the triceps, and then posterior to the long head of the triceps. The specimens underwent biomechanical testing for each condition using an established cadaveric shoulder simulator with 6 degrees of freedom for glenohumeral joint motion. Results: Both anterior and posterior LD tendon transfers successfully achieved ER of the humerus when force was applied to the LD tendon. Posterior LD tendon transfer resulted in less required force to achieve ER of the arm throughout range of motion compared to anterior LD tendon transfer (33.4 N vs. 48.6 N, P <.001), which was maintained irrespective of glenohumeral abduction angle. Loading of the long head of the triceps tendon was associated with significantly increased force required for generation of ER only in the anterior LD tendon transfer condition (48.6 N loaded vs. 39.4 N unloaded; P < .001). Conclusion: LD tendon transfer posterior to the long head of the triceps resulted in more efficient humeral ER movements in the setting of rTSA, irrespective of degree of shoulder abduction. Our results also demonstrate that long head of the triceps tension results in decreased efficiency of the LD tendon transfer when performed anterior to the long head of the triceps. While technically more difficult, transfer of the LD tendon posterior to the long head of the triceps provides a mechanical advantage that may improve clinical outcomes in patients with rTSA lacking ER. Level of evidence: Basic Science Study; Biomechanics (c) 2024 Journal of Shoulder and Elbow Surgery Board of Trustees. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

Background: Baseball is one of the most popular sports among youth athletes in the United States, and among these players, pitchers are at a particularly high risk of sustaining an injury. Overuse of the arm from repetitive pitching is a common mechanism for injury. Despite the attention that overuse injury has received, little is known regarding the mechanism that leads to elbow injury. This study aims to determine the effect of increasing pitch count on elbow flexion at ball release in a youth pitching cohort. The authors hypothesize that elbow flexion would increase as pitch count increases. Methods: Study subjects included volunteers from youth baseball players from local teams and public advertisements. Retroreflective markers attached to bony landmarks were placed on the players according to International Shoulder Group recommendations. Pitchers threw an indoor simulated game. Three-dimensional marker trajectories were collected using a 12-camera optical motion capture system, and ball velocity was captured using a radar gun. Voluntary maximal isometric strength of the internal and external rotators was evaluated before and after pitching. Paired 2-tailed t tests were performed to determine if a significant change occurred between the fresh and fatigued sets. Results: Twelve adolescent male pitchers were recruited. Eleven of 12 pitchers completed the prescribed 6 sets of 15 pitches, culminating in a 90-pitch simulated game. The ball speed in the second set was found to be the highest in all pitchers and was considered the "peak set"(P = .021), whereas ball speed was the slowest in the sixth set of pitches and was therefore considered the "fatigue set"(P = .001). There was a moderate but statistically significant inverse correlation between elbow flexion at ball release and maximum internal rotation velocity (P = .005). Elbow flexion at ball release was also significantly positively correlated with shoulder abduction at ball release (P = .004). Elbow flexion at ball release was not significantly correlated with ball velocity (P = .108). Conclusions: In a simulated game laboratory setting, increasing pitch count was associated with increasing elbow flexion angle at ball release in youth baseball pitchers. These findings demonstrate that pitching with fatigue may cause biomechanical changes that have been associated with increased rates of elbow injury in the adult throwing population. Further investigation on the association between elbow flexion angle and elbow injury in the youth baseball population is needed. Level of evidence: Basic Science Study; Kinesiology (c) 2024 Journal of Shoulder and Elbow Surgery Board of Trustees. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

BACKGROUND:Distal tibial allograft (DTA) reconstruction for glenoid bone loss (GBL) has gained popularity. While recent studies have demonstrated that glenoid concavity is an important factor in native glenohumeral stability, there remains a paucity of data regarding concavity restoration during reconstructive procedures for GBL and its biomechanical effect. PURPOSE:To compare the restoration of anterior glenohumeral stability and glenoid concavity after DTA and classic Latarjet procedures. STUDY DESIGN:Controlled laboratory study. METHODS:Nine human cadaveric specimens (mean age, 62.2 years; range, 52-69 years) underwent pretesting computed tomography (CT) to assess native glenoid concavity as determined by the glenoid depth and bony shoulder stability ratio (BSSR). GBL was created so the DTA and Latarjet graft could restore 100% of the native glenoid width. The rotator cuff tendons were loaded, and anterior stability testing was performed using a KUKA robot to apply a controlled anterior force with the shoulder in 90° of abduction and neutral external rotation. A motion capture system recorded humeral head translation. The following conditions were tested: intact, soft tissue Bankart lesion; bone loss model with DTA reconstruction; classic Latarjet procedure without conjoint tendon loaded; and classic Latarjet procedure with conjoint tendon loaded (sling effect). All specimens underwent posttesting CT to measure the BSSR of the DTA and Latarjet reconstructions. A repeated-measures analysis of variance was performed to compare the BSSR and anterior translations between the DTA and Latarjet reconstructions. RESULTS:DTA produced greater concavity than the Latarjet procedure (BSSR: 0.45 vs 0.35; P < .001). There was no difference in anterior translation between the DTA and Latarjet procedures with the sling effect (5.1 mm vs 4.7 mm; P > .999). However, maximum anterior translation was decreased after the DTA procedure when compared with the Latarjet technique without the sling effect (5.1 mm vs 10.3 mm; P = .045). CONCLUSION:DTA produces a more concave reconstruction and decreased anterior translation compared with the flatter reconstruction produced by the classic Latarjet procedure without the sling effect. DTA and the classic Latarjet procedure with conjoint tendon loading, however, yielded equivalent reductions in anterior translation. CLINICAL RELEVANCE:Distal tibial allograft reconstruction is a biomechanically equivalent alternative to the classic Latarjet due to the restoration of glenoid concavity in addition to glenoid width. Surgeons should consider the role of concavity when addressing glenohumeral instability with bone loss.

Accurate measurement of internal/external rotation joint angle is critical in assessing the shoulder function, especially in the clinical practice as it plays a key role in evaluating activities of daily living and monitoring the rehabilitation progress. This study analyzed the effectiveness of using a marker cluster placed over the proximal epiphysis of the ulna to measure humeral axial rotation with respect to the thorax, comparing it with the traditional method that uses a cluster placed on the upper arm. Data were collected simultaneously using the proposed indirect approach and a conventional marker cluster to analyze three internal/external rotations performed in the Ski-Pose, frontal, and sagittal plane. Linear regressions for time series comparison reported a coefficient of determination R2 > 0.9919 in all tasks.The linear coefficients (a1) were as follows: Ski-Pose (a1 = 0.64 ± 0.10), frontal plane (a1 = 0.74 ± 0.05), and sagittal plane (a1 = 0.73 ± 0.04). Three additional planar tasks were recorded for concurrent validity and RMSE was reported for the main joint angle, obtaining a maximum of 3.87° for the pure flexion/extension task and 1.94° for the abduction/adduction task. A forearm pronation/supination task without axial rotation yielded a maximum error standard deviation of 2.64°. Proximal ulna tracking showed a statistically higher maximum range of motion than humeral tracking in pure axial rotation tasks. This indirect tracking approach is a promising alternative to the traditional cluster technique due to its reduced sensitivity to soft tissue artifacts.

Background:The role of forearm rotation at the time of ulnar collateral ligament (UCL) reconstruction (UCLR) graft tensioning is poorly understood. Purpose:To compare postoperative medial elbow joint gapping in cadaveric elbows after UCLR graft tensioning with the forearm in supination versus pronation. Study Design:Descriptive laboratory study. Methods:A total of 18 full-arm human specimens were stripped of soft tissue except elbow ligamentous and capsular structures. Elbows with an intact, native ligament were tested for medial elbow gapping during valgus stress at 30°, 60°, and 90° with the forearm in neutral, maximal supination, and maximal pronation. Joint gapping was determined with a 3-dimensional motion capture system and calibrated digitized points on the ulna and humerus. The UCL was transected, and reconstruction was performed using a standard docking technique. Elbows were randomized to full supination or pronation at the time of final graft tensioning, and medial elbow joint gapping was again measured for the same positions and same technique. Analysis of variance test was used to compare differences in native and postoperative medial elbow joint gapping (P < .05). Results:The position of forearm rotation did not affect the amount of medial elbow joint gapping during valgus stress at all tested elbow flexion angles with an intact, native UCL. The position of forearm rotation during UCL graft tensioning also did not affect postoperative medial elbow joint gapping during valgus stress at all tested elbow flexion angles. Conclusion:Forearm rotation with an intact UCL and at the time of UCL graft tensioning did not affect the amount of medial elbow joint gapping during valgus torque.

BACKGROUND:Scapulohumeral rhythm (SHR) describes the relative contributions of the humerus and scapula to total shoulder motion and is defined as the ratio of glenohumeral (GH) elevation to scapulothoracic (ST) upward rotation. The impact of reverse total shoulder arthroplasty (rTSA) on scapular kinematics and SHR has not been fully elucidated. The purpose of the present study was to perform a systematic review and meta-analysis of the literature to compare SHR among patients following rTSA and asymptomatic controls. METHODS:A literature search was performed by querying PubMed, EMBASE, and the Cochrane computerized databases to identify studies that assess SHR, or the relationship of GH elevation to ST upward rotation, in patients after rTSA. Study quality was assessed using the Methodological Index for Non-Randomized Studies criteria. Quantitative review was performed for studies that reported either SHR directly, or reported GH and ST rotation. Differences in SHR were compared between different ranges of humeral elevation including rest-30°, 30-60°, 60-90°, and the total arc of elevation. RESULTS:Twenty-seven studies comprised of 464 patients who underwent rTSA were included in the final analysis for review. Among the studies included, 19 (70%) directly assessed SHR. The average SHR across all elevation ranges in the scapular plane was 1.6 (range: 0.8-2.7). The average SHR in the rest-30°, 30-60°, and 60-90° elevation arc ranges were 4.3 (range: 0.8-34), 2.0 (range: 0.7-4), and 1.8 (range: 0.8-3), respectively. Compared to controls, patients who underwent rTSA had greater ST upward rotation, quantified as a significantly lower SHR (1.9 vs. 3.2, P = .0238). CONCLUSION:There is an increased contribution of ST rotation relative to GH motion throughout arm elevation following rTSA compared to asymptomatic shoulders. The average SHR was lowest between 60° and 90° of arm elevation compared to the other measured ranges of arm elevation, indicating a greater contribution of ST rotation required at higher angles of arm elevation. Further investigations are needed to determine the clinical implications of greater ST motion in patients following rTSA, as well as the biomechanical causes and consequences of this alteration in scapular kinematics.

Background:Patients undergoing anatomic total shoulder arthroplasty (aTSA) routinely achieve significant improvements in common patient-reported outcome measures (PROMs). While these structured PROMs produce reliable and standardized data for surgeons, individual patient desires and expectations related to postoperative activities may not be completely captured in standard PROMs. The purpose of the present study was to identify specific activities, sports, and/or hobbies that patients wish they could perform but are unable to following aTSA at a minimum of 2 years postoperatively. Methods:Patients who underwent primary aTSA, with a primary diagnosis of glenohumeral osteoarthritis between February 1, 2016 and January 1, 2021, were identified using an institutional clinical registry. A survey was sent to patients at a minimum of 2 years postoperatively, which included a free-text-response section in addition to 8 selection-based questions assessing patients' ability to perform various activities. Results:The survey was sent to 601 patients and 395 responded (65.7% response rate). The mean age at the time of the surgery for responders was 65.75 ± 8.8 years. There was no significant difference in age (P = .095), sex (P = .691), race (P = .090), or ethnicity (P = .054) between responders and nonresponders. The majority of patients had no difficulty managing toileting (93.7%), driving a car (92.4%), washing their hair (91.9%), and putting on a seatbelt (90.7%). Of the 395 total responders, 131 (33.2%) patients reported at least one desired activity that they could not perform. Of these 131 patients, weightlifting (14.5%), throwing a ball (12.9%), playing tennis (11.4%), carrying/holding groceries (11.4%), and performing pushups/planks (11.4%) were most commonly reported. Conclusion:Following aTSA, patients are able to perform the majority of activities of daily living without difficulty. A subset of patients desire but are unable to participate in several sports and hobbies following aTSA-most commonly, weightlifting, tennis, throwing a ball, and swimming. These limitations present opportunities for further improvements in postoperative outcomes.

Objectives: Glenoid bone loss occurs in more than 80% of patients with recurrent glenohumeral instability. The Latarjet procedure has become the gold standard for restoration of bone loss despite a high (15-30%) complication rate.1–3 Distal tibial allograft (DTA) reconstruction has recently gained interest due to its ability to restore width and concavity to the glenoid while providing a cartilage surface.4 The purpose of this study is to evaluate the restoration of glenohumeral anterior stability and glenoid concavity after DTA reconstruction when compared to the Latarjet procedure in a glenoid bone loss model. Methods: Five human cadaveric specimens (mean age: 62.2, range 57-69; 80% male) underwent preoperative computed tomography (CT) scans to assess native glenoid concavity as determined by the glenoid depth and bony shoulder stability ratio (BSSR). Stability testing was performed using a cadaveric shoulder simulator that allows 6 DoF at the glenohumeral joint. The specimens were placed with the scapula at 30° upward rotation and humerus at 60° glenohumeral abduction with a constant compressive force created by loading the supraspinatus, infraspinatus, teres minor, and subscapularis muscles (2lbs, 3lbs, 1lb and 4lbs respectively). A Kuka robot applied a 40N anterior force through the pectoralis tendon with the humerus in neutral as well as 60 degrees of external rotation. A motion capture system recorded humeral head translations for each condition. To create the Latarjet and DTA conditions, the coracoid was first harvested and the thickness was measured. A distal tibial allograft was then contoured to an identical size. A glenoid defect was created to match the thickness of the graft since both Latarjet and DTA aimed for a 100% glenoid restoration.. The following conditions were tested: 1. intact, 2. Bankart lesion, 3. bone loss model with DTA reconstruction, 4. Latarjet procedure without the conjoint tendon loaded, and 5. Latarjet with conjoint tendon loading (‘sling effect’). All specimens underwent post-testing CT scan to measure the BSSR of the DTA and Latarjet reconstructions. A repeated measures ANOVA was performed to determine if there was a significant difference in maximum anterior translation or BSSR between the distal tibial allograft reconstruction and Latarjet procedure (with or without the sling effect). Results: The mean preoperative glenoid depth measured 2.61±1.03mm with a BSSR of 0.40±0.16. However, postoperative measurements showed that BSSR for the DTA was greater than the Latarjet (0.46±0.11 vs 0.35±0.5). The maximum anterior translation was significantly lower after the DTA reconstruction than the Latarjet procedure without the sling effect (5.5mm vs 9.6mm, p = 0.044). However, there was no difference in anterior translation between the DTA reconstruction and Latarjet procedure with the sling effect applied (5.5mm vs 4.7mm, p = 0.36). The DTA reconstructed the glenoid with a significantly greater concavity than the Latarjet procedure (BSSR: 0.46 vs 0.35, p = 0.036). Conclusions: When addressing bone loss in glenohumeral instability, additional factors besides the restoration of glenoid width contribute to stability. The concave reconstruction produced by the distal tibial allograft decreases anterior translation compared to the flat reconstruction produced by the Latarjet, but there is no difference in translation between the DTA and Latarjet procedure when the sling effect is applied. The DTA reconstruction provides an alternative to the Latarjet procedure with equivalent biomechanical properties and less morbidity or change to the native shoulder structure.

BackgroundReturning patients to their desired activities following anatomic total shoulder arthroplasty (aTSA) is an important criterion to achieve high patient satisfaction. While patients who undergo aTSA return to sports at relatively high rates, individuals’ specific desired and achieved activities following aTSA remain poorly defined.MethodsA shoulder arthroplasty registry at a tertiary care orthopedic hospital was reviewed retrospectively between February 1, 2016 and January 1, 2021 to identify specific patient activity and functional capabilities following aTSA at a minimum of two years postoperatively. Individual items and responses of the American Shoulder and Elbow Surgeons (ASES) and Shoulder Activity Scale (SAS) relating to activity levels, as well as free text responses pertaining to usual work and sport, were tabulated.ResultsAmong 597 patients who underwent 632 primary anatomic TSAs (mean age 65.9 ± 8.3 years, 41.5% female), the median ASES score per affected limb improved from 40.0 (IQR 27.4-54.7) preoperatively to 94.9 (IQR 83.8-98.3) at 2 years (p<0.001), while median SAS improved from 8.0 (IQR 5.0-12.0) preoperatively to 10.0 (6.0-14.0) at 2 years (p<0.001). Two years after surgery, 78.5%, 88.6%, and 83.5% of patients were able to comb their hair, manage toileting, and put on a coat without any difficulty, respectively. A relatively small proportion of patients were able to reach a high shelf (64.7%) and lift 10 pounds above the shoulder (57.4%) without difficulty. Of the 524 (82.9%) patients who returned to recreational activities 2 years after surgery, golf (25.6%), walking (22.7%), weight training (16.8%), and swimming (15.8%) were the most commonly reported activities. Cooking and cleaning (29.9%, n = 189), desk-related work (27.2%, n = 172), yard-work or gardening (14.2%, n = 90), heavy lifting activities (6.5%, n = 41), and grocery shopping (2.5%, n = 16) were the most common forms of usual work.ConclusionPatients undergoing aTSA report a wide spectrum of desired recreational activities. A range of functional capabilities exists within this patient population with regards to usual sporting activity, work activity, and activities of daily living. Preoperative patient counseling may attempt to identify patients’ desired postoperative activities for more individualized education regarding their prognosis for returning to desired activities.

Background: The amount of glenoid width that must be restored with a Latarjet procedure in order to reestablish glenohumeral stability has not been determined. Purpose/Hypothesis: The purpose of this article was to determine the percentage of glenoid width restoration necessary for glenohumeral stability after Latarjet by measuring anterior humeral head translation and force distribution on the coracoid graft. The hypothesis was that at least 100% of glenoid width restoration with Latarjet would be required to maintain glenohumeral stability. Study Design: Controlled laboratory study. Methods: Nine cadaveric shoulders were prepared and mounted on an established shoulder simulator. A lesser tuberosity osteotomy (LTO) was performed to allow accurate removal of glenoid bone. Coracoid osteotomy was performed, and the coracoid graft was sized to a depth of 10 mm. Glenoid bone was sequentially removed, and Latarjet was performed using 2 screws to reestablish 110%, 100%, 90%, and 80% of native glenoid width. The graft was passed through a subscapularis muscle split, and the LTO was repaired. A motion tracking system recorded glenohumeral translations, and force distribution was recorded using a TekScan pressure sensor secured to the glenoid face and coracoid graft. Testing conditions included native; LTO; Bankart tear; and 110%, 100%, 90%, and 80% of glenoid width restoration with Latarjet. Glenohumeral translations were recorded while applying an anteroinferior load of 44 N at 90° of humerothoracic abduction and 0° or 45° of glenohumeral external rotation. Force distribution was recorded without an anteroinferior load. Results: Anterior humeral head translation progressively increased as the proportion of glenoid width restored decreased. A marked increase in anterior humeral head translation was found with 90% versus 100% glenoid width restoration (10.8 ± 3.0 vs 4.1 ± 2.6 mm, respectively; P < .001). Greater glenoid bone loss also led to increased force on the coracoid graft relative to the native glenoid bone after Latarjet. A pronounced increase in force on the coracoid graft was seen with 90% versus 100% glenoid width restoration ( P < .001). Conclusion: Anterior humeral head translation and force distribution on the coracoid graft dramatically increased when <100% of the native glenoid width was restored with a Latarjet procedure. Clinical Relevance: If a Latarjet is unable to fully restore the native glenoid width, surgeons should consider alternative graft sources to minimize the risk of recurrent instability or coracoid overload.

Background:As the use of all-suture anchors continues to increase, limited biomechanical data on the use of these anchors in various configurations for tenodesis of the long head biceps tendon (LHBT) exists. The aim of this study was to compare the biomechanical properties of a 2-anchor luggage tag suprapectoral biceps tenodesis (Sup-BT) vs. a single-anchor whipstitch subpectoral biceps tenodesis (Sub-BT) using all-suture anchors. The hypothesis was that the Sub-BT will have a higher ultimate load to failure and less creep relative to the Sup-BT construct.Methods:Eighteen fresh frozen cadaveric humeri were used. The specimens were randomly divided into 2 groups of 9; i) The Sup-BT were performed with 2 1.8 mm knotless all-suture anchors using a luggage-tag fixation configuration, ii) The Sub-BT were performed using a single 1.9 mm all-suture anchor and a whipstitch suture configuration with a tied knot. The humeri were tested on a hydraulic MTS machine where the specimens were preloaded at 5 N for 2 minutes and then cyclically loaded from 5 to 50 N for 1000 cycles at 1 Hz while maximum displacement was recorded with a motion system and markers attached to the bone and bicep tendon. The tendon was then tensioned at a rate of 1 mm/s to obtain the ultimate load to failure. CT scans of the specimens were used to calculate the bone mineral density at the site of the anchor/bone interface and video recordings were captured during load to failure to document all modes of failure.Results:There was no significant difference in the average load to failure of the Sup-BT and Sub-BT groups (197 N ± 45 N (SD), 164 N ± 68 N (SD) respectively; P = .122) or creep under fatigue between the Sup-BT vs. Sub-BT specimens (3.1 mm, SD = 1.5 vs. 2.2 mm, SD = 0.9; P = .162). The bone mineral density was statistically different between the 2 groups (P < .001); however, there were no observed failures at the anchor/bone interface and no correlation between failure load and bone mineral density.Conclusion:The ultimate load to failure and creep between a Sup-BT with 2 knotless all-suture anchors using a luggage tag suture configuration was equivalent to a Sub-BT with 1 all-suture anchor using a whipstitched suture configuration and a tied knot. Surgeons can perform either technique confidently knowing that they are biomechanically equivalent in a cadaver model at time zero, and they offer similar strength to other fixation methods cited in the literature.

Background: Irreparable subscapularis (SSc) tears alter the dynamic force coupling of the shoulder, resulting in pain, weakness, and impaired shoulder function. Pectoralis major (Pma), pectoralis minor (Pmi), and latissimus dorsi (LD) transfers are treatment options for irreparable SSc tears, but clinical outcomes vary. The purpose of this study was to compare the biomechanical properties of Pma, Pmi, and LD transfers in an SSc-deficient shoulder using a computational model. Methods: A computer shoulder model was used to investigate the moment arms of Pma, Pmi, and LD tendon transfers compared with an intact SSc. Nine computed tomography scans from subjects without osteoarthritis were used. Virtual Pma, Pmi, and LD transfers were performed to the upper border of the SSc insertion site on the lesser tuberosity of the humerus. Muscle moment arms were computed for functional motions of 0 degrees-80 degrees of internal rotation with the ann in 20 degrees and 90 degrees of shoulder abduction and 0 degrees-150 degrees of shoulder abduction. The results were compared with those of the native SSc moment arms. A repeated-measures analysis of variance was then performed to determine significant differences. Results: Internal rotation moment arms of the transferred Pma and Pmi decreased significantly after 30 degrees and 40 degrees of internal rotation compared with the SSc moment arm of the intact shoulder, whereas the moment arm of LD transfer more closely mimicked that of the native SSc through 0 degrees-80 degrees of internal rotation. All 3 tendon transfer configurations demonstrated weak abductive moment arms (7.6-8.0 mm), comparable to the intact SSc (7.8 mm) but significantly lower than the intact adductive moment arms of the native Pma and LD (26.8 mm and 28.2 mm, respectively). Conclusion: LD transfer most closely approximates the native SS regarding internal rotation moment arms. However, LD transfer also showed a reduction in adductive moment arms. (C) 2021 Journal of Shoulder and Elbow Surgery Board of Trustees. All rights reserved.

Objectives: Significant anterior glenoid bone loss in the setting of recurrent instability may warrant a coracoid transfer (Latarjet). However, the amount of glenoid width that must be restored with a Latarjet in order to reestablish glenohumeral stability has not been studied. We hypothesize that restoration of greater than 90% of glenoid width with a Latarjet will be necessary to restore glenohumeral stability. We also hypothesize that there will be significant increases in anterior humeral head translation when 90% or less of the native glenoid width is restored and that contact pressures on the coracoid graft will increase. Methods: Seven cadaveric specimens were prepared and mounted on an established shoulder simulator, which loads shoulder tendons through a system of pulleys and weights. A motion tracking system to record glenohumeral translations was placed on the scapula and humerus and registered based on a computed tomography (CT) scan. Contact pressures were mapped and recorded using a TekScan secured to the glenoid face and coracoid graft transfer (Figure 1). The humerus was placed in 90 degrees of humerothoracic abduction. Coracoid osteotomy was performed, and the coracoid graft was sized to a depth of 10mm. A lesser tuberosity osteotomy (LTO) was performed to allow accurate removal of glenoid bone. The amount of bone loss needed to re-establish 110%, 100%, 90% and 80% of native glenoid width after Latarjet was calculated by directly measuring the widest point of the glenoid and confirming accuracy based on the CT scan. Glenoid bone loss was established using a burr and the coracoid graft transfer was secured to the anteroinferior glenoid with two screws. The conjoined tendon was passed through a subscapularis split and the LTO was repaired with multiple Kirshner wires prior to each testing condition (Figure 2). Additionally, the rotator interval was closed and the capsule was repaired prior to each testing condition. The supraspinatus, subscapularis, infraspinatus and conjoined tendons were each loaded with 22N. Testing conditions included native glenohumeral joint, LTO, Bankart tear, and then 110%, 100%, 90% and 80% of glenoid width restoration with Latarjet. Glenohumeral translations and contact pressures were recorded with an anteroinferior load of 0 or 44N at 0 degrees of glenohumeral external rotation. Results: Progressive increases in anterior humeral head translation occurred with an anteroinferior load as the amount of glenoid width restored decreased (Figure 3). An anteroinferior load created an average of 5.5mm, 9.6mm, 3.3mm, 3.6mm, 9.2mm and 10.2mm of anterior translation in the LTO, Bankart, 110%, 100%, 90% and 80% of glenoid restoration cohorts, respectively. Greater glenoid bone loss also led to more contact pressure on the coracoid graft after Latarjet (Figure 4). An anteroinferior load produced 26.4%, 46.9%, 86.2% and 94.4% of the contact pressures on the coracoid graft relative to the native glenoid with glenoid width restored to 110%, 100%, 90% and 80%, respectively. Conclusions: There is an increase in anterior humeral head translation and contact pressure on the coracoid graft when 90% or less of the native glenoid width is restored with Latarjet. By determining the goals for glenoid width restoration after Latarjet, the findings of this study may provide guidance for patient-specific size requirements for the coracoid based on preoperative imaging. When greater than 90% of glenoid width cannot be restored with a Latarjet, surgeons may consider alternative graft sources.

Background: Aseptic loosening from implant-associated osteolysis in reverse shoulder arthroplasty (RSA) may contribute to premature implant failure. Although articular side polyethylene (PE) damage has been well documented in the literature, no studies to date have investigated backside wear in RSA. The aims of this investigation were to (1) document and compare the damage between the backside and articular surface in explanted RSA components, (2) assess whether certain quadrants have a greater propensity for damage, and (3) report the most common mode(s) of backside PE damage. Methods: Twenty-one RSA humeral liners retrieved during revision procedures between 2005 and 2014 were included for analysis. The mean time between implantation and extraction was 16 months (10 days-88 months). Diagnoses at the time of revision included dislocation (10), infection (4), mechanical failure (3), loosening (2), and unknown (2). Liners were examined under light microscopy (-10-30 magnification) and damage on the articular and backside of the liner surface was graded using the modified Hood score. The location and damage modality were compared between the articular side and backside of the implant. Results: Damage was noted on the articular surfaces of all 21 liners and on the backside surface of 20 liners. The total damage in all the quadrants was higher on the articular surface than on the backside of the component, with a mean difference in total quadrant damage scores of 11.74 +/- 3.53 (P<.001). There was no difference in damage among the quadrants on the backside (P=.44) or the articular surface (P=.08). The articular side exhibited greater scratching, abrasion, and surface deformation than the backside (P<.001). Conclusions: This short-term retrieval study demonstrated that backside PE damage occurs on the humeral component of RSA implants. There was greater damage to the articular side of the liner but wear to the backside was present in almost all liners. The clinical importance of backside wear in RSA and its overall contribution to PE particulate disease and osteolysis needs further investigation. (C) 2021 Published by Elsevier Inc. on behalf of Journal of Shoulder and Elbow Surgery Board of Trustees.