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Purpose: To evaluate the effect of an irreparable posterosuperior rotator cuff tear (PSRCT) on glenohumeral joint loads and to quantify improvement after superior capsular reconstruction (SCR) using an acellular dermal allograft., Methods: Ten fresh-frozen cadaveric shoulders were tested using a validated dynamic shoulder simulator. A pressure mapping sensor was placed between the humeral head and glenoid surface. Each specimen underwent the following conditions: (1) native, (2) irreparable PSRCT, and (3) SCR using a 3-mm-thick acellular dermal allograft. Glenohumeral abduction angle (gAA) and superior humeral head migration (SM) were measured using 3-dimensional motion-tracking software. Cumulative deltoid force (cDF) and glenohumeral contact mechanics, including glenohumeral contact area and glenohumeral contact pressure (gCP), were assessed at rest, 15°, 30°, 45°, and maximum angle of glenohumeral abduction., Results: The PSRCT resulted in a significant decrease of gAA along with an increase in SM, cDF, and gCP (P < .001, respectively). SCR did not restore native gAA (P < .001); however, SM was significantly reduced (P < .001). Further, SCR significantly reduced deltoid forces at 30° (P = .007) and 45° of abduction (P = .007) when compared with the PSRCT. SCR did not restore native cDF at 30° (P = .015), 45° (P < .001), and maximum angle (P < .001) of glenohumeral abduction. Compared with the PSRCT, SCR resulted in a significant decrease of gCP at 15° (P = .008), 30° (P = .002), and 45° (P = .006). However, SCR did not completely restore native gCP at 45° (P = .038) and maximum abduction angle (P = .014)., Conclusions: In this dynamic shoulder model, SCR only partially restored native glenohumeral joint loads. However, SCR significantly decreased glenohumeral contact pressure, cumulative deltoid forces, and superior migration, while increasing abduction motion, when compared with the posterosuperior rotator cuff tear., Clinical Relevance: These observations raise concerns regarding the true joint-preserving potential of SCR for an irreparable posterosuperior rotator cuff tear, along with its ability to delay progression of cuff tear arthropathy and eventual conversion to reverse shoulder arthroplasty., (Copyright © 2023 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.)

Purpose: To investigate the influence of intertubercular groove (IG) morphology on the development of different types of biceps reflection pulley (BRP) injuries., Methods: A consecutive cohort of 221 patients with ventral shoulder pain and a preoperative diagnosis suspecting BRP injury, who underwent arthroscopy, was retrospectively reviewed. The presence or absence as well as type of pulley injury (medial, lateral or bilateral) was confirmed arthroscopically. The intertubercular groove was evaluated on MRIs after triplanar reconstruction of the axial plane. IG depth, width, medial wall angle (MWA), lateral wall angle (LWA) and total opening angle (TOA) were measured. IG depth and width were expressed in relation to the humeral head diameter. Measurements were performed by two clinicians independently and averaged., Results: Of 166 included patients 43 had bilateral, 65 medial and 38 lateral BRP lesions. 20 patients had intact BRPs and represented the control group. The intra-class correlation coefficient of measurements was 0.843-0.955. Patients with a medial or bilateral BRP injury had a flatter MWA (38.8° or 40.0° vs. 47.9°, p < 0.001), wider TOA (96.1° or 96.6° vs. 82.6°, p < 0.001), greater width (12.5 or 12.3 vs. 10.8 mm, p = 0.013) and shallower depth (5.5 or 5.4 vs. 6.2 mm, p < 0.001) than the control group. Conversely, the IG morphology of those with lateral BRP injuries did not differ significantly from the control group. The odds ratio for a medial or bilateral BRP injury when the TOA exceeded 95° was 6.8 (95% confidence interval 3.04-15.2)., Conclusion: A dysplastic type of IG morphology with a wide TOA, flat MWA, decreased depth and increased width is associated with the presence of medial and bilateral BRP injuries. A TOA of > 95° increases the likelihood of a medial or bilateral BRP injury 6.8-fold. Lateral BRP injuries are not associated with dysplastic IG morphology. Concomitant LHBT surgery may, therefore, not always be necessary during isolated supraspinatus tendon repair., Level of Evidence: Level III., (© 2023. The Author(s).)

Background: Lower trapezius transfer (LTT) has been proposed for restoring the anteroposterior muscular force couple in the setting of an irreparable posterosuperior rotator cuff tear (PSRCT). Adequate graft tensioning during surgery may be a factor critical for sufficient restoration of shoulder kinematics and functional improvement., Purpose/hypothesis: The purpose was to evaluate the effect of tensioning during LTT on glenohumeral kinematics using a dynamic shoulder model. It was hypothesized that LTT, while maintaining physiological tension on the lower trapezius muscle, would improve glenohumeral kinematics more effectively than undertensioned or overtensioned LTT., Study Design: Controlled laboratory study., Methods: A total of 10 fresh-frozen cadaveric shoulders were tested using a validated shoulder simulator. Glenohumeral abduction angle, superior migration of the humeral head, and cumulative deltoid force were compared across 5 conditions: (1) native, (2) irreparable PSRCT, (3) LTT with a 12-N load (undertensioned), (4) LTT with a 24-N load (physiologically tensioned according to the cross-sectional area ratio of the lower trapezius muscle), and (5) LTT with a 36-N load (overtensioned). Glenohumeral abduction angle and superior migration of the humeral head were measured using 3-dimensional motion tracking. Cumulative deltoid force was recorded in real time throughout dynamic abduction motion by load cells connected to actuators., Results: Physiologically tensioned (Δ13.1°), undertensioned (Δ7.3°), and overtensioned (Δ9.9°) LTT each significantly increased the glenohumeral abduction angle compared with the irreparable PSRCT ( P < .001 for all). Physiologically tensioned LTT achieved a significantly greater glenohumeral abduction angle than undertensioned LTT (Δ5.9°; P < .001) or overtensioned LTT (Δ3.2°; P = .038). Superior migration of the humeral head was significantly decreased with LTT compared with the PSRCT, regardless of tensioning. Physiologically tensioned LTT resulted in significantly less superior migration of the humeral head compared with undertensioned LTT (Δ5.3 mm; P = .004). A significant decrease in cumulative deltoid force was only observed with physiologically tensioned LTT compared with the PSRCT (Δ-19.2 N; P = .044). However, compared with the native state, LTT did not completely restore glenohumeral kinematics, regardless of tensioning., Conclusion: LTT was most effective in improving glenohumeral kinematics after an irreparable PSRCT when maintaining physiological tension on the lower trapezius muscle at time zero. However, LTT did not completely restore native glenohumeral kinematics, regardless of tensioning., Clinical Relevance: Tensioning during LTT for an irreparable PSRCT may be important to sufficiently improve glenohumeral kinematics and may be an intraoperatively modifiable key variable to ensure postoperative functional success.

Background: The purpose of the present study was to compare the functional and radiographic outcomes following reverse total shoulder arthroplasty (RTSA) in a senior athletic and non-athletic population., Material and Methods: In this retrospective cohort study, patients who underwent RTSA between 06/2013 and 04/2018 at a single institution were included. Minimum follow-up was 2 years. A standardized questionnaire was utilized for assessment of patients' pre- and postoperative physical fitness and sportive activity. Patients who resumed at least one sport were assigned to the athletic group, while patients who ceased participating in sports were assigned to the non-athletic group. Postoperative clinical outcome measures included the Constant score (CS), American Shoulder and Elbow Surgeons (ASES) score, Simple Shoulder Test (SST), and visual analog scale (VAS) for pain. Active shoulder range of motion (ROM) and abduction strength were assessed. Radiographic evaluation was based on a standardized core set of parameters for radiographic monitoring of patients following shoulder arthroplasty., Results: Sixty-one of 71 patients (85.9%; mean age: 72.1 ± 6.6 years) were available for clinical and radiographic follow-up at a mean of 47.1 ± 18.1 months. Thirty-four patients (55.7%) were assigned to the athletic group and 27 patients (44.3%) to the non-athletic group. The athletic group demonstrated significantly better results for CS (P = 0.002), ASES score (P = 0.001), SST (P = 0.001), VAS (P = 0.022), active external rotation (P = 0.045) and abduction strength (P = 0.016) compared to the non-athletic group. The overall rate of return to sport was 78.0% at an average of 5.3 ± 3.6 months postoperatively. Incomplete radiolucent lines (RLL) around the humeral component were found significantly more frequently in the athletic group compared to the non-athletic group (P = 0.019), whereas the occurrence of complete RLLs around the implant components was similar (P = 0.382). Scapular notching was observed in 18 patients (52.9%) of the athletic group and 12 patients (44.9%) of the non-athletic group (P = 0.51). The overall rate for revision surgery was 8.2%, while postoperative complications were encountered in 3.3% of cases., Conclusion: At mid-term follow-up, the athletic population demonstrated significantly better clinical results following RTSA without a higher rate of implant loosening and scapular notching when compared to non-athletic patients. However, incomplete radiolucency around the humeral component was observed significantly more often in the athletic group., Level of Evidence: III., (© 2022. The Author(s).)

Background: In the setting of irreparable posterosuperior rotator cuff tears (PSRCTs), lower trapezius transfer (LTT) may be anatomically better positioned for restoring the muscular force couple compared with latissimus dorsi transfer (LDT). The purpose of the study was to evaluate the effect of LTT and LDT on glenohumeral kinematics using a dynamic shoulder model., Methods: Ten fresh-frozen cadaveric shoulders (mean age: 56.5 ± 17.2 years) were tested using a dynamic shoulder simulator. The maximum abduction angle (MAA), superior humeral head migration (SHM), and cumulative deltoid forces (CDFs) were compared across 4 conditions: (1) native; (2) irreparable PSRCT; (3) LTT using an Achilles tendon allograft; and (4) LDT. MAA and SHM were measured using 3-dimensional motion tracking. CDF was recorded in real time throughout the dynamic abduction motion by load cells connected to actuators., Results: Compared to the native state, the PSRCT resulted in a significant decrease (Δ-24.1°; P < .001) in MAA, with a subsequent significant increase after LTT (Δ13.1°; P < .001) and LDT (Δ8.9°; P < .001). LTT achieved a significantly greater MAA than LDT (Δ4.2°; P = .004). Regarding SHM, both LTT (Δ-9.4 mm; P < .001) and LDT (Δ-5.0 mm; P = .008) demonstrated a significant decrease compared with the PSRCT state. LTT also achieved significantly less SHM compared with the LDT (Δ-4.4 mm; P = .011). Further, only the LTT resulted in a significant decrease in CDF compared with the PSRCT state (Δ-21.3 N; P = .048), whereas LTT and LDT showed similar CDF (Δ-11.3 N; P = .346). However, no technique was able to restore the MAA, SHM, and CDF of the native shoulder (P < .001, respectively)., Conclusion: LTT and LDT both achieved a significant increase in MAA along with significantly less SHM compared with the PSRCT state. Although LTT required significantly less compensatory deltoid forces compared with the PSRCT state, this was not observed for the LDT. Further, the LTT prevented loss of abduction motion and SHM more sufficiently. In the challenging treatment of irreparable PSRCTs, LTT may restore native glenohumeral kinematics more sufficiently, potentially leading to improved postoperative functional outcomes., (Copyright © 2022 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Objective: Implantation of an acellular dermal allograft between glenoid and humerus to restore a stable glenohumeral center of rotation in cases of irreparable posterosuperior rotator cuff tears., Indications: Irreparable posterosuperior rotator cuff tears with low-grade cuff tear arthropathy (Hamada grade 1 and 2) and isolated pseudoparesis for flexion., Contraindications: Absolute: Infection, nerve lesions (brachial plexus, axillary nerve), concomitant irreparable subscapularis tendon tear, anterosuperior subluxation of the humeral head ("anterosuperior escape"). Relative: Cuff tear arthropathy ≥ Hamada grade 3, fatty infiltration of the infraspinatus muscle ≥ Goutallier grade 2, deficiency of the deltoid muscle, inability to adhere to the rehabilitation program, poor compliance., Surgical Technique: Arthroscopic fixation of a 6 mm thick acellular dermal allograft with three suture anchors at the superior glenoid rim and a double-row construct at the greater tuberosity. Dorsal and ventral interval closure with side-to-side sutures., Postoperative Management: Abduction brace for 6 weeks with passive mobilization. Active motion exercises are commenced at 6 weeks with progression to strengthening exercises after 12 weeks., Results: Between April 2019 and September 2020, 15 patients (5 women and 10 men) underwent arthroscopic superior capsule reconstruction using a 6 mm thick acellular dermal allograft for treatment of irreparable posterosuperior rotator cuff tears. After a mean follow-up of 15.4 ± 5.5 months, there was a significant improvement in active flexion (102° ± 37° preop vs. 143° ± 24° postop ; P = 0.001; 95% CI 19.6-63.7), ASES score (45.5 ± 16.1 preop vs. 68.2 ± 17.4 postop ; P < 0.001; 95% CI; 12.9-33.7) and DASH score (57.2 ± 18.6 preop vs. 22.0 ± 17.4 postop ; P < 0.001; 95% CI; -46.0 to 24.7), along with significant pain reduction (4.5 ± 2.0 preop vs. 2.5 ± 2.1 postop ; P = 0.001; 95% CI; -3.2 to 1.1). There were no complications requiring revision surgery., (© 2022. The Author(s), under exclusive licence to Springer Medizin Verlag GmbH, ein Teil von Springer Nature.)

Background: Current literature reports highly satisfactory short- and midterm clinical outcomes in patients with arthroscopic 270° labral tear repairs. However, data remain limited on long-term clinical outcomes and complication and redislocation rates in patients with traumatic shoulder instability involving anterior, inferior, and posterior labral injury., Purpose: To investigate, at a minimum follow-up of 10 years, the clinical outcomes, complications, and recurrent instability in patients with 270° labral tears involving the anterior, inferior, and posterior labrum treated with arthroscopic stabilization using suture anchors., Study Design: Case series; Level of evidence, 4., Methods: A retrospective outcomes study was completed for all patients with a minimum 10-year follow-up who underwent arthroscopic 270° labral tear repairs with suture anchors by a single surgeon. Outcome measures included pre- and postoperative Rowe score, American Shoulder and Elbow Surgeons (ASES) score, Simple Shoulder Test, visual analog scale for pain, and Single Assessment Numeric Evaluation (SANE). Western Ontario Shoulder Instability Index (WOSI) scores were collected postoperatively. Complication data were collected, including continued instability, subluxation or dislocation events, and revision surgery. Failure was defined as any cause of revision surgery., Results: In total, 21 patients (mean ± SD age, 27.1 ± 9.6 years) with 270° labral repairs were contacted at a minimum 10-year follow-up. All outcome measures showed statistically significant improvements as compared with those preoperatively: Rowe (53.9 ± 11.4 to 88.7 ± 8.9; P = .005), ASES (72.9 ± 18.4 to 91.8 ± 10.8; P = .004), Simple Shoulder Test (8.7 ± 2.4 to 11.2 ± 1.0; P = .013), visual analog scale (2.5 ± 2.6 to 0.5 ± 1.1; P = .037), and SANE (24.0 ± 15.2 to 91.5 ± 8.3; P = .043). The mean postoperative WOSI score at minimum follow-up was 256.3 ± 220.6. Three patients had postoperative complications, including a traumatic subluxation, continued instability, and a traumatic dislocation, 2 of which required revision surgery (14.2% failure rate)., Conclusion: Arthroscopic repairs of 270° labral tears involving the anterior, inferior, and posterior labrum have highly satisfactory clinical outcomes at 10 years, with complication and redislocation rates similar to those reported at 2 years. This suggests that repairs of extensile labral tears are effective in restoring and maintaining mechanical stability of the glenohumeral joint in the long term.

Background: Posterior glenoid wear remains a challenge in anatomic and reverse total shoulder arthroplasty (rTSA) because of an asymmetric erosion with altered retroversion. The purpose of this study was to assess glenoid morphology and evaluate the influence of acromial orientation in posterior glenoid erosion patterns by using 3-dimensional (3D) models., Material and Methods: Computed tomographic (CT) shoulder scans from 3 study centers of patients awaiting rTSA between 2017 and 2018 were converted into 3D models and analyzed by 2 observers. Morphology, orientation and greatest depth of erosion, inclination, current retroversion and premorbid retroversion, surface areas of the glenoid, and external acromial orientation and posterior acromial slope were assessed. Measurements were compared between wear patterns, glenoid erosion entities, and genders., Results: In the complete cohort of 68 patients (63.8 ± 10.0 years; 19 female, 49 male), a mean of 85.9° (±22.2°) was observed for the glenoid erosion orientation. Additionally, a further distinct classification of the glenoid erosion as posterior-central (PC, n = 39), posterior-inferior (PI, n = 12), and posterior-superior (PS, n = 17) wear patterns was possible. These wear patterns significantly (P < .001) distinguished by erosion orientation (PC = 86.9° ± 12.0°, PI = 116.3° ± 10.3°, PS = 62.3° ± 18.9°). The greatest depth of erosion found was 7.3 ± 2.7 mm in PC wear patterns (PC vs. PI: P = .03; PC vs. PS: n.s.; PI vs. PS: n.s.). Overall, the observed erosion divided the glenoid surface into a paleoglenoid proportion of 48% (±11%) and a neoglenoid proportion of 52% (±12%). For the complete cohort, glenoid inclination was 85.4° (±6.6°), premorbid glenoid retroversion was 80.7° (±8.1°), and current glenoid retroversion was 73.4° (±7.4°), with an estimated increase of 6.9° (±6.0°). The mean external acromial orientation was 118.2° (±8.9°), and the mean posterior acromial slope was 107.2° (±9.6°). There were no further significant differences if parameters were compared by wear patterns, entities, and gender., Conclusion: Three significantly differently oriented wear patterns (posterior-superior, posterior-central, and posterior-inferior) were distinguished in shoulders demonstrating posterior wear on axillary imaging. No significant differences between the observed erosion patterns or any relevant correlations were found regarding the orientation of the acromion., (Copyright © 2021 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: In the past decade, superior capsular reconstruction has emerged as a potential surgical approach in young patients with irreparable posterosuperior rotator cuff tears (RCT) and absence of severe degenerative changes. Recently, the use of locally available and biological viable autografts, such as the long head of the biceps tendon (LHBT) for SCR has emerged, with promising early results., Purpose/hypothesis: The purpose of this study was to investigate the effect of using the LHBT for reconstruction of the superior capsule on shoulder kinematics, along with different fixation constructs in a dynamic biomechanical model. The authors hypothesized that each of the 3 proposed fixation techniques would restore native joint kinematics, including glenohumeral superior translation (ghST), maximum abduction angle (MAA), maximum cumulative deltoid force (cDF), and subacromial peak contact pressure (sCP)., Study Design: Controlled laboratory study., Methods: Eight fresh-frozen cadaveric shoulders (mean age, 53.4 ± 14.2 years) were tested using a dynamic shoulder simulator. Each specimen underwent the following 5 conditions: (1) intact, (2) irreparable posterosuperior rotator cuff tear (psRCT), (3) V-shaped LHBT reconstruction, (4) box-shaped LHBT reconstruction, and (5) single-stranded LHBT reconstruction. MAA, ghST, cDF and sCP were assessed in each tested condition., Results: Each of the 3 LHBT techniques for reconstruction of the superior capsule significantly increased MAA while significantly decreasing ghST and cDF compared with the psRCT ( P < .001 and P < .001, respectively). Additionally, the V-shaped and box-shaped techniques significantly decreased sCP ( P = .009 and P = .016, respectively) compared with the psRCT. The V-shaped technique further showed a significantly increased MAA ( P < .001, respectively) and decreased cDF ( P = .042 and P = .039, respectively) when compared with the box-shaped and single-stranded techniques, as well as a significantly decreased ghST ( P = .027) when compared with the box-shaped technique., Conclusion: In a dynamic biomechanical cadaveric model, using the LHBT for reconstruction of the superior capsule improved shoulder function by preventing superior humeral migration, decreasing deltoid forces and sCP. As such, the development of rotator cuff tear arthropathy in patients with irreparable psRCTs could potentially be delayed., Clinical Relevance: Using a biologically viable and locally available LHBT autograft is a cost-effective, potentially time-saving, and technically feasible alternative for reconstruction of the superior capsule, which may result in favorable outcomes in irreparable psRCTs. Moreover, each of the 3 techniques restored native shoulder biomechanics, which may help improve shoulder function by preventing superior humeral head migration and the development of rotator cuff tear arthropathy in young patients with irreparable rotator cuff tears.

Irreparable rotator cuff tears represent a significant everyday clinical challenge. A high degree of tendon retraction and muscle degeneration means that a direct reconstruction is impossible. Patients often suffer from pain and pseudoparalysis. In older patients this can reliably be resolved by the implantation of a semiconstrained inverse shoulder prosthesis; however, for younger patients joint-preserving techniques should be employed. Furthermore, for frail older patients who may not be suitable for a joint replacement operation, alternative treatment strategies are required. Management options include physiotherapy and pain relieving or reconstructive operations. Minimally invasive arthroscopic treatment approaches can lead to pain relief and slight functional improvements in selected patients; however, to restore the active movement of the joint a partial cuff repair, augmentation with a graft or replacement with muscle transfer is necessary. This article presents the various treatment options and the results reported in the literature. Through this a treatment algorithm is suggested in order to facilitate management decisions.

Purpose: To evaluate the effect of dermal allograft fixation at different angles of glenohumeral abduction on deltoid forces during superior capsule reconstruction (SCR)., Methods: Fifteen cadaveric specimens were tested using a dynamic shoulder simulator. Following testing in the native state, shoulders underwent SCR in 2 of 5 possible fixation angles; 0°, 15°, 30°, 45°, or 60° of glenohumeral abduction, allowing for 6 specimens per group. Angles were measured radiographically with the glenoid fixed perpendicular to the floor. Maximum mean deltoid abduction force was compared among 5 separate conditions within each angle group: (1) native shoulder, (2) complete supraspinatus (SSP) and superior capsule tear, (3) SCR alone, (4) SCR with posterior margin sutured, and (5) SCR with anterior and posterior margins sutured., Results: SSP tears significantly increased the maximum deltoid forces for all 5 fixation angles compared with the native state (P < .05). Specimens repaired at 0°, 30°, and 45° were unable to restore deltoid forces compared with the native state in any condition (P < .05). SCR at 15° with anterior and posterior margin convergence showed similar abduction forces compared with the native state (P = .19). When fixed at 60° abduction, SCR alone significantly reduced deltoid forces compared to SSP (Δ143N, P < .001) and native (Δ48N, P < .001). No significant differences were found between the 3 repair subtypes (SCR ± anterior/posterior margin repair) in the 60° group., Conclusions: SCR with anterior and posterior margin convergence tensioned at 15° of glenohumeral abduction showed similar deltoid abduction force requirements compared with the native state, whereas graft fixation in 60° significantly reduced deltoid force in all SCR conditions., Clinical Relevance: Increased graft tension with a greater abduction angle may provide greater functional outcome by placing less load on the deltoid. In contrast, graft fixation in lower abduction angles may require additional margin convergence to reproduce native forces., (Copyright © 2019 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.)

Purpose: To evaluate the effect of critical shoulder angle (CSA), acromion index (AI), and glenoid inclination (GI) on the postoperative healing rate after arthroscopic supraspinatus tendon repair., Methods: Patients after arthroscopic repair of a symptomatic, unilateral, single-tendon, full-thickness supraspinatus tear in whom nonoperative management had failed were retrospectively reviewed. Magnetic resonance imaging (MRI) studies were obtained 6 months postoperatively and were evaluated by 2 independent observers. Repair integrity was classified as either intact or torn. Preoperative true anteroposterior radiographs were used to measure CSA, AI, and GI., Results: Fifty-seven patients were evaluated 6 months postoperatively. The mean patient age at surgery was 54.7 ± 7.7 years. On MRI studies, 41 patients (71.9%) had an intact repair and 16 patients (28.1%) had a full-thickness retear. There were no significant differences between the intact and retear group in regard to patient age (P = .648), initial tear size (P = .205), or fatty degeneration (P = .508). The mean CSA for the retear group (37° ± 4°) was significantly higher than that in the intact group (35° ± 3°; P = .014). If the CSA was >38°, the odds ratio of having a retear was 3.78 (95% confidence interval 1.05 to 13.58; P = .042). Average AI for the retear group (0.73 ± 0.09) was significantly higher than that in the intact group (0.69 ± 0.06; P = .049). The mean GI was 17° ± 6° for the intact group and 16° ± 6° for the retear group (P = .739)., Conclusions: At short-term follow-up, higher CSA and AI significantly increased the retear risk after arthroscopic supraspinatus tendon repair. CSA >38° increased the retear risk almost 4-fold. Overall GI was elevated but did not correlate with failure rate., Level of Evidence: III, case control study., (Copyright © 2018 Arthroscopy Association of North America. All rights reserved.)

Background: Previous biomechanical studies regarding deltoid function during glenohumeral abduction have primarily used static testing protocols., Hypotheses: (1) Deltoid forces required for scapular plane abduction increase as simulated rotator cuff tears become larger, and (2) maximal abduction decreases despite increased deltoid forces., Study Design: Controlled laboratory study., Methods: Twelve fresh-frozen cadaveric shoulders with a mean age of 67 years (range, 64-74 years) were used. The supraspinatus and anterior, middle, and posterior deltoid tendons were attached to individual shoulder simulator actuators. Deltoid forces and maximum abduction were recorded for the following tear patterns: intact, isolated subscapularis (SSC), isolated supraspinatus (SSP), anterosuperior (SSP + SSC), posterosuperior (infraspinatus [ISP] + SSP), and massive (SSC + SSP + ISP). Optical triads tracked 3-dimensional motion during dynamic testing. Fluoroscopy and computed tomography were used to measure critical shoulder angle, acromial index, and superior humeral head migration with massive tears. Mean values for maximum glenohumeral abduction and deltoid forces were determined. Linear mixed-effects regression examined changes in motion and forces over time. Pearson product-moment correlation coefficients ( r) among deltoid forces, critical shoulder angles, and acromial indices were calculated., Results: Shoulders with an intact cuff required 193.8 N (95% CI, 125.5 to 262.1) total deltoid force to achieve 79.8° (95% CI, 66.4° to 93.2°) of maximum glenohumeral abduction. Compared with native shoulders, abduction decreased after simulated SSP (-27.2%; 95% CI, -43.3% to -11.1%, P = .04), anterosuperior (-51.5%; 95% CI, -70.2% to -32.8%, P < .01), and massive (-48.4%; 95% CI, -65.2% to -31.5%, P < .01) cuff tears. Increased total deltoid forces were required for simulated anterosuperior (+108.1%; 95% CI, 68.7% to 147.5%, P < .01) and massive (+57.2%; 95% CI, 19.6% to 94.7%, P = .05) cuff tears. Anterior deltoid forces were significantly greater in anterosuperior ( P < .01) and massive ( P = .03) tears. Middle deltoid forces were greater with anterosuperior tears ( P = .03). Posterior deltoid forces were greater with anterosuperior ( P = .02) and posterosuperior ( P = .04) tears. Anterior deltoid force was negatively correlated ( r = -0.89, P = .01) with critical shoulder angle (34.3°; 95% CI, 32.0° to 36.6°). Deltoid forces had no statistical correlation with acromial index (0.55; 95% CI, 0.48 to 0.61). Superior migration was 8.3 mm (95% CI, 5.5 to 11.1 mm) during testing of massive rotator cuff tears., Conclusion: Shoulders with rotator cuff tears require considerable compensatory deltoid function to prevent abduction motion loss. Anterosuperior tears resulted in the largest motion loss despite the greatest increase in deltoid force., Clinical Relevance: Rotator cuff tears place more strain on the deltoid to prevent abduction motion loss. Fatigue or injury to the deltoid may result in a precipitous decline in abduction, regardless of tear size.

Background: The aim of this study was to evaluate the midterm results and complications of a total shoulder arthroplasty implanted with a metal-backed, bone-ingrowth glenoid component., Materials and Methods: In total, 62 patients (65 shoulders) diagnosed with primary osteoarthritis were treated with total shoulder arthroplasty with a cementless glenoid component. The mean age was 66 years (range, 54-85 years). Fifty-three patients were evaluated after a mean of 64 months (range, 26-85 months). Functional results were documented by use of the age- and sex-adjusted Constant score. Radiolucent line (RLL) assessment of the glenoid component was performed by use of true anteroposterior and axillary views., Results: The Constant score improved significantly from 49% preoperatively to 89.8% postoperatively (P < .0001). Active range of motion improved significantly for flexion (from 118° to 146°), abduction (from 87° to 133°), and external rotation (from 21° to 44°) (P < .0001). In 3 cases (5.7%), RLLs of 1 mm or less were present, and 1 case (1.8%) had an RLL of 2 mm or less in 1 zone. Glenoid component loosening occurred in 5 cases (9.4%) because of breakage of the cage screw. Four of these patients presented preoperatively with a type B1 glenoid and one patient with type A2. Two of the patients who underwent revision also had a complete tear of the rotator cuff. The revision rate was 11.3% (6 patients) after a mean of 68 months., Conclusion: After midterm follow-up, clinical outcomes of patients operated on with a cementless, metal-backed glenoid implant improved significantly. However, an unacceptable rate of complications and revisions was found. Glenoid loosening predominantly occurred in patients with preoperative eccentric glenoid morphology and was also related to cranial migration of the proximal humerus during the follow-up period., (Copyright © 2013 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Mosby, Inc. All rights reserved.)