Search

Introduction: Lately, mavacamten emerged as a new therapeutic option for symptomatic patients with obstructive hypertrophic cardiomyopathy (oHCM). Clinical trials revealed reduction of serum biomarkers, and left ventricular outflow tract (LVOT) obstruction, as well as an improvement in clinical symptoms and exercise capacity. Nevertheless, clinical experience and manageability of patients in a real-world setting is still lacking., Material and Methods: 22 patients with symptomatic oHCM (54.5% male, age 58.5 ± 16.2 years) and elevated LVOT gradients were started on mavacamten between March 2023 and June 2024. All patients were New York Heart Association (NYHA) class II or higher. Seven patients were excluded from primary analysis due to comedication with Angiotensin-converting-enzyme-inhibitors or Angiotensin-II receptor blockers. Cardiac imaging, laboratory work-up and clinical evaluation were assessed at three visits during the 12 weeks initiation phase; Dosing of mavacamten was adjusted according to manufacturer's recommendations., Results: At 12 weeks, the majority of patients described a significant improvement of their quality of life. Work-up at 12 weeks revealed a significant reduction of serum biomarkers and LVOT gradients. In four patients, mavacamten needed to be temporarily paused due to clinical complaints or transient left ventricular ejection fraction deterioration below 50% with subsequent full recovery., Conclusion: We provide first insights into the usage of mavacamten in oHCM patients during the titration period in a real-world setting. Clinical findings are in line with previous clinical trials. In accordance with current recommendations, we highlight the need for standardized follow-up of patients on mavacamten treatment., (© 2024. The Author(s).)

Purpose: The purpose of this study was to evaluate the perspective of orthopaedic surgeons on the impact of artificial intelligence (AI) and to evaluate the influence of experience, workplace setting and familiarity with digital solutions on views on AI., Methods: Orthopaedic surgeons of the AGA Society for Arthroscopy and Joint Surgery were invited to participate in an online, cross-sectional survey designed to gather information on professional background, subjective AI knowledge, opinion on the future impact of AI, openness towards different applications of AI, and perceived advantages and disadvantages of AI. Subgroup analyses were performed to examine the influence of experience, workplace setting and openness towards digital solutions on perspectives towards AI., Results: Overall, 360 orthopaedic surgeons participated. The majority indicated average (43.6%) or rudimentary (38.1%) AI knowledge. Most (54.5%) expected AI to substantially influence orthopaedics within 5-10 years, predominantly as a complementary tool (91.1%). Preoperative planning (83.8%) was identified as the most likely clinical use case. A lack of consensus was observed regarding acceptable error levels. Time savings in preoperative planning (62.5%) and improved documentation (81%) were identified as notable advantages while declining skills of the next generation (64.5%) were rated as the most substantial drawback. There were significant differences in subjective AI knowledge depending on participants' experience ( p  = 0.021) and familiarity with digital solutions ( p  < 0.001), acceptable error levels depending on workplace setting ( p  = 0.004), and prediction of AI impact depending on familiarity with digital solutions ( p  < 0.001)., Conclusion: The majority of orthopaedic surgeons in this survey anticipated a notable positive impact of AI on their field, primarily as an assistive technology. A lack of consensus on acceptable error levels of AI and concerns about declining skills among future surgeons were observed., Level of Evidence: Level IV, cross-sectional study., Competing Interests: Peter Angele is a consultant for Aesculap/TETEC and Arthrex. The remaining authors declare no conflict of interest., (© 2024 The Author(s). Journal of Experimental Orthopaedics published by John Wiley & Sons Ltd on behalf of European Society of Sports Traumatology, Knee Surgery and Arthroscopy.)

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: A variety of reconstruction techniques exist for the operative treatment of a ruptured acromioclavicular and coracoclavicular ligamentous complex. However, the complication rate remains high; between 5 and 89%. The intraoperative distance between the clavicle, acromion and coracoid is important for the refixation quality. In this study, the influence of scapular deflection on coracoclavicular and acromioclavicular distances was analysed., Methods: The ligamentous insertions of 24 fresh-frozen human scapulae were exposed. The coracoclavicular and acromioclavicular ligaments were referenced and captured in a rigid body system using a three-dimensional (3D) measurement arm. The inferior angle of the scapula was manually pulled into maximum anterior and posterior deflection, simulating a patient positioning with or without dorsal scapular support, respectively. Based on the rigid body system, the distances between the ligamentous insertions were calculated. Statistical evaluation was performed by setting the distances in anterior deflection to 100% and considering the other distances relative to this position., Results: The scapular deflection had a considerable impact on the distance between the ligamentous insertions. Concerning the conoid ligament, the mean distance was almost doubled when the inferior angle pointed posteriorly compared to anterior deflection (195.3 vs 100.0%; p = 0.028). The insertion of the acromioclavicular capsule also showed a significant association with the direction of deflection (posterior = 116.1% vs. anterior = 100%; p = 0.008)., Conclusion: Dorsal support shifting the inferior angle of the scapula anteriorly reduces the distance between the ligamentous insertions. Therefore, a patient position on a shoulder table with posterior support of the scapula is recommended to reliability reduce the acromioclavicular joint., (© 2022. The Author(s).)

Background: There exists a vast number of surgical treatment options for acromioclavicular (AC) joint injuries, and the current literature has yet to determine an equivocally superior treatment. AC joint repair has a long history and dates back to the beginning of the twentieth century., Main Body: Since then, over 150 different techniques have been described, covering open and closed techniques. Low grade injuries such as Type I-II according to the modified Rockwood classification should be treated conservatively, while high-grade injuries (types IV-VI) may be indicated for operative treatment. However, controversy exists if operative treatment is superior to nonoperative treatment, especially in grade III injuries, as functional impairment due to scapular dyskinesia or chronic pain remains concerning following non-operative treatment. Patients with a stable AC joint without overriding of the clavicle and without significant scapular dysfunction (Type IIIA) may benefit from non-interventional approaches, in contrast to patients with overriding of the clavicle and therapy-resistant scapular dysfunction (Type IIIB). If these patients are considered non-responders to a conservative approach, an anatomic AC joint reconstruction using a hybrid technique should be considered. In chronic AC joint injuries, surgery is indicated after failed nonoperative treatment of 3 to 6 months. Anatomic AC joint reconstruction techniques along with biologic augmentation (e.g. Hybrid techniques, suture fixation) should be considered for chronic high-grade instabilities, accounting for the lack of intrinsic healing and scar-forming potential of the ligamentous tissue in the chronic setting. However, complication and clinical failure rates remain high, which may be a result of technical failures or persistent horizontal and rotational instability., Conclusion: Future research should focus on addressing horizontal and rotational instability, to restore native physiological and biomechanical properties of the AC joint., (© 2022. The Author(s).)

Purpose: To evaluate the effect of an isolated full-thickness supraspinatus (SSP) tear on glenohumeral kinematics and contact mechanics, as well as to quantify improvement following rotator cuff repair (RCR)., Methods: Ten fresh-frozen cadaveric shoulders (mean age: 63.1 ± 4.6 years) were tested using a dynamic shoulder simulator. A pressure-mapping sensor was placed between the humeral head and the glenoid. Each specimen underwent the following three conditions: 1) native, 2) isolated full-thickness SSP tear, and 3) RCR. Maximum abduction angle (MAA) and superior humeral head migration (SHM) were measured using 3D motion tracking software. Cumulative deltoid force (CDF) and glenohumeral contact mechanics, including contact area (GCA) and contact pressure (GCP), were assessed at the resting position, as well as at 15°, 30°, 45°, and 60° of glenohumeral abduction., Results: Compared to native, the SSP tear resulted in a significant decrease in MAA (Δ-8.3°; P < .001) along with a SHM of 6.4 ± 3.8 mm, while significantly increasing CDF (Δ20.5 N; P = .008), GCP (Δ63.1 kPa; P < .001), and peak GCP (Δ278.6 kPa; P < .001), as well as decreasing GCA (Δ-45.8 mm 2 ; P < .001) at each degree of abduction. RCR reduced SHM to 1.2 ± 2.5 mm, while restoring native MAA, CDF (Δ1.8 N), GCA (Δ4.5 mm 2 ), GCP (Δ-4.5 kPa) and peak GCP (Δ19.9 kPa) at each degree of abduction (P > .999, respectively)., Conclusion: In a dynamic biomechanical cadaveric model, increased glenohumeral joint loads due to a full-thickness SSP tear can be reversed with RCR. More specifically, RCR restored native glenohumeral contact area and contact pressure, while preventing superior humeral head migration and decreasing compensatory deltoid forces., Clinical Relevance: These time 0 observations indicate that undergoing rotator cuff repair may prevent the development of degenerative changes by significantly reducing glenohumeral joint loads and ensuring sufficiently stable joint kinematics., (Copyright © 2021 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.)

Background: Arthroscopic coracoplasty is a procedure for patients affected by subcoracoid impingement. To date, there is no consensus on how much of the coracoid can be resected with an arthroscopic burr without compromising its stability., Purpose: To determine the maximum amount of the coracoid that can be resected during arthroscopic coracoplasty without leading to coracoid fracture or avulsion of the conjoint tendon during simulated activities of daily living (ADLs)., Study Design: Controlled laboratory study., Methods: A biomechanical cadaveric study was performed with 24 shoulders (15 male, 9 female; mean age, 81 ± 7.9 years). Specimens were randomized into 3 treatment groups: group A (native coracoid), group B (3-mm coracoplasty), and group C (5-mm coracoplasty). Coracoid anatomic measurements were documented before and after coracoplasty. The scapula was potted, and a traction force was applied through the conjoint tendon. The stiffness and load to failure (LTF) were determined for each specimen., Results: The mean coracoid thicknesses in groups A through C were 7.2, 7.7, and 7.8 mm, respectively, and the mean LTFs were 428 ± 127, 284 ± 77, and 159 ± 87 N, respectively. Compared with specimens in group A, a significantly lower LTF was seen in specimens in group B ( P = .022) and group C ( P < .001). Postoperatively, coracoids with a thickness ≥4 mm were able to withstand ADLs., Conclusion: While even a 3-mm coracoplasty caused significant weakening of the coracoid, the individual failure loads were higher than those of the predicted ADLs. A critical value of 4 mm of coracoid thickness should be preserved to ensure the stability of the coracoid process., Clinical Relevance: In correspondence with the findings of this study, careful preoperative planning should be used to measure the maximum reasonable amount of coracoplasty to be performed. A postoperative coracoid thickness of 4 mm should remain., Competing Interests: One or more of the authors has declared the following potential conflict of interest or source of funding: L.F.H. was supported by a research scholarship from the Deutsche Vereinigung für Schulter und Ellenbogenchirurgie (German Society for Shoulder and Elbow Surgery). AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto., (© The Author(s) 2022.)

Background: Fractures of the proximal humerus are common. The most frequent surgical treatment option is open reduction and locking plate fixation. Multifragmentary fractures, including 3- and 4-part fractures, are especially challenging to treat because they correlate with an increased risk of fixation failure. In the past, several mechanisms of additional fixation were investigated, but none directly addressed the lesser tuberosity (LT). The goal of this study was to investigate the biomechanical impact of additional anterior fracture fixation in lateral locked plating (LLP) of 4-part proximal humeral fractures (PHFs)., Methods: Twenty-seven fresh frozen human shoulder specimens (mean age, 80 years) with intact rotator cuffs (RCs) were randomized into 4 groups: 3-part PHF with LLP and RC cerclage (n = 6); 4-part PHF with LLP and RC cerclage as standard of care (n = 7); 4-part PHF with LLP, RC cerclage, and 2 anterior 3.5-mm cortical screws (n = 7); and 4-part PHF with LLP, RC cerclage, and additional anterior one-third tubular plate (additional anterior plating [AAP], n = 7). Static load of the RC was simulated with weights. A force-controlled cyclic loading test was performed with a servo-hydraulic testing machine, followed by load-to-failure testing. An optical motion capture system recorded humeral head range of motion., Results: LLP of a 4-part PHF showed more humeral head motion than LLP of a 3-part PHF without fracture of the LT (P < .001). Fixing the LT to the humeral head with two 3.5-mm screws significantly reduced humeral head motion compared with LLP with RC cerclage alone (P < .006). Using AAP significantly increased the construct stiffness compared with the standard of care (P = .03)., Conclusion: LLP of a 4-part PHF is biomechanically less stable than LLP of a 3-part PHF without fracture of the LT. Additional screw fixation of the LT in 4-part PHFs improves stability compared with LLP alone. In case of metaphyseal comminution, AAP is favorable from a biomechanical perspective., (Copyright © 2021 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Purpose: To clinically evaluate patients who underwent a biologic augmentation technique in revision arthroscopic rotator cuff repair using an autologous fibrin scaffold and concentrated stem cells isolated from bone marrow aspirate (BMA) obtained from the proximal humerus., Methods: This is a retrospective review of prospectively collected data from patients who underwent biologic augmentation of revision arthroscopic rotator cuff repair using an autologous fibrin scaffold and BMA obtained from the proximal humerus between 2014 and 2015. Minimum follow-up was 12 months. Outcome measures were collected preoperatively and postoperatively including range of motion as well as American Shoulder and Elbow Surgeons Shoulder Form, Simple Shoulder Test, single assessment numeric evaluation, and visual analog score. In addition, BMA samples of each patient were assessed for the number of nucleated cells and colony-forming units. Regression analysis was performed to investigate whether the number of nucleated cells and colony-forming units had an influence on outcome and failure., Results: Ten patients who underwent biologic augmentation of revision arthroscopic rotator cuff repair using an autologous fibrin scaffold and concentrated BMA obtained from the proximal humerus between 2014 and 2015 were included. The mean follow-up time was 30.7 (range: 12-49) months. Four patients were revised at final follow-up. Postoperative clinical scores improved significantly: American Shoulder and Elbow Surgeons (28.1 ± 5.4 to 60.9 ± 9.0; P  < .01), single assessment numeric evaluation (6.6 ± 2.3 to 65.1 ± 10.9; P < .01), visual analog scale (7.2 ± 0.9 to 3.1 ± 0.9; P < .01), and Simple Shoulder Test (1.6 ± 0.5 to 10.3 ± 5.7; P < .01). Postoperative range of motion increased significantly with regard to flexion (97.0 ± 13.6 to 151.0 ± 12.2; P < .01) and abduction (88.0 ± 14.0 to 134.0 ± 15.1; P  = .038) but not with external rotation (38.0 ± 5.7 to 50.5 ± 6.5; P  = .16). Less pain was correlated to an increased number of nucleated cells ( P  = .026); however, there was no correlation between failure rate and number of nucleated cells ( P  = .430)., Conclusions: Patients who underwent biologic augmentation of revision arthroscopic rotator cuff repair using an autologous fibrin scaffold and concentrated BMA demonstrated a significant improvement in shoulder function along with reduction of pain. However, the overall revision rate for this procedure was 40%., Level of Evidence: Level IV, therapeutic case series., (© 2021 by the Arthroscopy Association of North America. Published by Elsevier Inc.)

Reverse shoulder arthroplasty (RSA) is a commonly performed salvage procedure for failed proximal humeral fracture fixation. The rate of intraoperative periprosthetic fractures is higher compared to primary RSA. The goal of this study was to investigate the biomechanical value of a protective cerclage during stem impaction in a revision surgery setting. Twenty-eight fresh-frozen human humeri were used to assess different configurations for steel wire and FiberTape cerclages. A custom-built biomechanical test setup simulated the mallet strikes during the stem impaction process with the Univers Revers prothesis stem. The mallet energy until the occurrence of a first crack was not different between groups. The total energy until progression of the fracture distally to the cerclage was significantly higher in the cerclage groups compared to the native humerus (9.5 J vs. 3.5 J, respectively; p = 0.0125). There was no difference between the steel wire and FiberTape groups (11.4 J vs. 8.6 J, respectively; p = 0.2695). All fractures were located at the concave side of the stem at the metaphyseal calcar region. This study demonstrates that a protective cerclage can successfully delay the occurrence of a fracture during stem impaction in reverse shoulder arthroplasty. A FiberTape cerclage is biomechanically equally efficient compared to a steel wire cerclage.

Purpose: To investigate the biomechanical effect of a glenolabral articular disruption (GLAD) lesion on glenohumeral laxity., Methods: Human cadaveric glenoids ( n  = 10) were excised of soft tissue, including the labrum to focus on the biomechanical effects of osteochondral surfaces. Glenohumeral dislocations were performed in a robotic test setup, while displacement forces and three-dimensional morphometric properties were measured. The stability ratio (SR), a biomechanical characteristic for glenohumeral stability, was used as an outcome parameter, as well as the path of least resistance, determined by a hybrid robot displacement. The impacts of chondral and bony defects were analyzed related to the intact glenoid. Statistical comparison of the defect states on SR and the path of least resistance was performed using repeated-measures ANOVA and Tukey's post hoc test for multiple comparisons ( P < .05). The relationship between concavity depth and SR was approximated in a nonlinear regression., Results: The initial SR of the intact glenoid (28.3 ± 7.8%) decreased significantly by 4.7 ± 3% in case of a chondral defect ( P  = .002). An additional loss of 3.2 ± 2.3% was provoked by a 20% bony defect ( P  = .004). The path of least resistance was deflected significantly more inferiorly by a GLAD lesion (2.9 ± 1.8°, P  = .002) and even more by a bony defect (2.5 ± 2.9°, P  = .002). The nonlinear regression with concavity depth as predictor for the SR resulted in a high correlation coefficient ( r  = .81)., Conclusions: Chondral integrity is an important contributor to the SR. Chondral defects as present in GLAD lesions may cause increased laxity, influence the humeral track on the glenoid during dislocation, and represent a biomechanical risk factor for a recurrent instability., Clinical Relevance: Cartilage deficiency corresponding to GLAD lesions may be a risk factor for impaired surgical outcomes., (© 2021 by the Arthroscopy Association of North America. Published by Elsevier Inc.)

Purpose: Surgical treatment of shoulder instability caused by anterior glenoid bone loss is based on a critical threshold of the defect size. Recent studies indicate that the glenoid concavity is essential for glenohumeral stability. However, biomechanical proof of this principle is lacking. The aim of this study was to evaluate whether glenoid concavity allows a more precise assessment of glenohumeral stability than the defect size alone., Methods: The stability ratio (SR) is a biomechanical estimate of glenohumeral stability. It is defined as the maximum dislocating force the joint can resist related to a medial compression force. This ratio was determined for 17 human cadaveric glenoids in a robotic test setup depending on osteochondral concavity and anterior defect size. Bony defects were created gradually, and a 3D measuring arm was used for morphometric measurements. The influence of defect size and concavity on the SR was examined using linear models. In addition, the morphometrical-based bony shoulder stability ratio (BSSR) was evaluated to prove its suitability for estimation of glenohumeral stability independent of defect size., Results: Glenoid concavity is a significant predictor for the SR, while the defect size provides minor informative value. The linear model featured a high goodness of fit with a determination coefficient of R 2  = 0.98, indicating that 98% of the SR is predictable by concavity and defect size. The low mean squared error (MSE) of 4.2% proved a precise estimation of the SR. Defect size as an exclusive predictor in the linear model reduced R 2 to 0.9 and increased the MSE to 25.7%. Furthermore, the loss of SR with increasing defect size was shown to be significantly dependent on the initial concavity. The BSSR as a single predictor for glenohumeral stability led to highest precision with MSE = 3.4%., Conclusion: Glenoid concavity is a crucial factor for the SR. Independent of the defect size, the computable BSSR is a precise biomechanical estimate of the measured SR. The inclusion of glenoid concavity has the potential to influence clinical decision-making for an improved and personalised treatment of glenohumeral instability with anterior glenoid bone loss., (© 2021. The Author(s).)

Purpose: To evaluate tunnel widening and its relationship in loss of reduction and clinical outcomes in patients undergoing anatomic coracoclavicular ligament reconstruction (ACCR) using free tendon grafts for chronic acromioclavicular (AC) joint injuries., Methods: A retrospective chart review was performed on patients undergoing ACCR for type III-VI AC joint injuries between January 2003 and December 2017. For radiographic analysis, pre- and post-operative coracoclavicular distance (CCD) and tunnel width of the medial and lateral clavicular bone tunnel were measured at the earliest (EPO) and latest postoperative follow-up (LPO). To determine the clinical relevance of improvement in clinical outcome score (American Shoulder and Elbow Surgeons score) substantial clinical benefit (SCB), and patient acceptable symptomatic state (PASS) thresholds were used., Results: Twenty-four patients with a mean clinical follow-up of 37 ± 35 months (mean age 44.7 ± 13.4) were included in the study. Both the medial (5.6 ± 0.2 mm EPO -6.6 ± 0.7 mm LPO; p < 0.001) and lateral (5.6 ± 0.5 mm EPO -6.8 ± 1 mm LPO ; p < 0.001) clavicular bone tunnel showed significant widening from EPO to LPO. There was a significant loss of reduction at LPO (CCD LPO 10.1 ± 4 mm) compared to EPO (CCD EPO : 6.2 ± 3.8 mm) (p < 0.001). No significant correlation between loss of reduction and medial (p = 0.45; r = - 0.06) or lateral (p = 0.69; r = - 0.06) tunnel widening was found. Alterations in tunnel width were shown having no influence on clinical outcomes., Conclusion: Patients who underwent ACCR using a free tendon graft for the treatment of chronic type III-VI ACJ injuries showed significant clavicular bone tunnel widening during the postoperative course. No correlation between tunnel widening and loss of reduction was shown with radiographic findings having no influence on clinical benefit and satisfaction., Study Design: Case Series; Level of evidence, IV.

Posttraumatic stiffness of the shoulder joint is a frequent and socioeconomically relevant result of injury; however, prior to making the diagnosis as the only cause of a persisting impairment of motion, it is necessary to rule out other sequelae of trauma. Even intensive conservative treatment is mostly accompanied by the stagnation of the impairments of movement. In many cases the treatment of choice is early arthroscopic arthrolysis with a standardized approach and intensive follow-up treatment. In the surgical treatment of proximal humeral fractures with humeral head preservation, arthroscopic arthrolysis with simultaneous implant removal is a form of planned second intervention for improvement of shoulder function in cases of persisting motion deficits after bony consolidation. Despite sometimes substantial limitations of movement, a clinically relevant and lasting improvement of shoulder function can be achieved with arthroscopic arthrolysis in posttraumatic shoulder stiffness.

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.

Background: Superior capsular reconstruction (SCR) for massive, irreparable rotator cuff tears has become more widely used recently; however, ideal tensioning of the graft and the influence on joint kinematics remain unknown., Purpose/hypothesis: The purpose of this study was to assess the effects of graft tensioning on glenohumeral joint kinematics after SCR using a dermal allograft. The hypothesis was that a graft fixed under tension would result in increased glenohumeral abduction motion and decreased cumulative deltoid forces compared with a nontensioned graft., Study Design: Controlled laboratory study., Methods: A total of 10 fresh-frozen cadaveric shoulders were tested using a dynamic shoulder simulator. Each shoulder underwent the following 4 conditions: (1) native, (2) simulated irreparable supraspinatus (SSP) tear, (3) SCR using a nontensioned acellular dermal allograft, and (4) SCR using a graft tensioned with 30 to 35 N. Mean values for maximum glenohumeral abduction and cumulative deltoid forces were recorded. The critical shoulder angle (CSA) was also assessed., Results: Native shoulders required a mean (±SE) deltoid force of 193.2 ± 45.1 N to achieve maximum glenohumeral abduction (79.8° ± 5.8°). Compared with native shoulders, abduction decreased after SSP tears by 32% (54.3° ± 13.7°; P = .04), whereas cumulative deltoid forces increased by 23% (252.1 ± 68.3 N; P = .04). The nontensioned SCR showed no significant difference in shoulder abduction (54.1° ± 16.1°) and required deltoid forces (277.8 ± 39.8 N) when compared with the SSP tear state. In contrast, a tensioned graft led to significantly improved shoulder abduction compared with the SSP tear state ( P = .04) although abduction and deltoid forces could not be restored to the native state ( P = .01). A positive correlation between CSA and maximum abduction was found for the tensioned-graft SCR state ( r = 0.685; P = .02)., Conclusion: SCR using a graft fixed under tension demonstrated a significant increase in maximum shoulder abduction compared with a nontensioned graft; however, abduction remained significantly less than the intact state. The nontensioned SCR showed no significant improvement in glenohumeral kinematics compared with the SSP tear state., Clinical Relevance: Because significant improvement in shoulder function after SCR may be expected only when the graft is adequately tensioned, accurate graft measurement and adequate tension of at least 30 N should be considered during the surgical procedure. SCR with a tensioned graft may help maintain sufficient acromiohumeral distance, improve clinical outcomes, and reduce postoperative complications., Competing Interests: One or more of the authors has declared the following potential conflict of interest or source of funding: The University of Connecticut Health Center/UConn Musculoskeletal Institute received direct funding and material support for this study from Arthrex. The company had no influence on study design, data collection, or interpretation of the results or the final manuscript. K.B. is a paid consultant for Arthrex. C.R.A. is an employee of Arthrex. A.D.M. has received research grants from Arthrex, consulting fees from Arthrex and Astellas Pharma, royalties from Arthrex, and honoraria from Arthrosurface. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto., (© The Author(s) 2020.)

Purpose: The purpose of this study was to evaluate the number of colony-forming units (CFUs) derived from concentrated bone marrow aspirates (BMAs) that were processed following arthroscopic harvest from either the proximal humerus or the body of the ilium during biologic augmentation of the rotator cuff and acetabular labral repairs., Methods: Between November 2014 and January 2019, BMA was harvested from the proximal humerus (n = 89) and the body of the ilium (n = 30) during arthroscopic surgery. Following concentration of the aspirate, a 0.5-mL aliquot was further processed and the number of nucleated cells (NC) was counted. Each aliquot was cultured until CFUs were quantifiable. Fluorescence-activated cell sorting analysis and quantitative polymerase chain reaction was performed to confirm presence of mesenchymal stem cells. BMA harvest sites were prospectively assessed and evaluated for differences in age, sex, volume of aspirated BM, and CFUs per milliliter of BMA., Results: The prevalence (38.57 ± 27.92 ilium vs. 56.00 ± 25.60 humerus CFUs per 10 6 nucleated cells) and concentration (979.17 ± 740.31 ilium vs. 1,516.62 ± 763.63 humerus CFUs per 1.0 mL BMA) of CFUs was significantly higher (P < .001, respectively) for BMA harvested from the proximal humerus. Additionally, the estimated total number of cells was significantly higher (P = .013) in BMA from the proximal humerus (97,529.00 ± 91,064.01 ilium vs. 130,552.4 ± 85,294.2 humerus ). There was no significant difference between groups regarding BMA volume (91.67 ± 18.77 ilium vs. 85.63 ± 35.61 humerus mL; P = .286) and NC count (24.01 ± 5.13 ilium vs. 27.07 ± 6.28 humerus  × 10 6 per mL BMA; P = .061). The mean age was significantly lower (P < .001) in patients with BMA being harvested from the ilium (30.18 ± 7.63 ilium vs. 56.82 ± 7.08 humerus years). Patient sex and age had no significant influence on cellular measures within groups (P > .05, respectively)., Conclusion: Both proximal humerus and the body of the ilium can be considered reliable sources of bone marrow aspirate for the use in biologic augmentation during their respective arthroscopic surgery. Samples of bone marrow aspirate from the proximal humerus yielded a significantly higher amount of CFUs when compared with samples of BMA obtained from the ilium., Level of Evidence: Level II- prospective laboratorial study., (Copyright © 2020 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.)

Dual plating in fractures of the upper extremity is well established for the distal humerus. The indication for the use of dual plating has been expanded over the last few years. While dual plating was originally frequently used in revisions of non-unions, it is nowadays also used in primary fixation of diverse complex fractures of the upper extremity. The high biomechanical fixation strength of dual plating is advantageous in regions with high bending and torsional stresses, such as the humeral shaft. An additional anterior plate provides high fixation strength and reduces the risk of loss of reduction in complex proximal humeral fractures and allows for direct fixation of lesser tuberosity fragments. Low-profile plates have been introduced for complex proximal ulna fractures. In dual plating the improved mechanical stability is combined with a reduced risk of implant related soft tissue irritations. The present article provides an overview of current indications for dual plating of upper extremity fractures and outlines technical aspects as well as advantages over conventional fixation techniques., Competing Interests: The authors declare that they have no conflict of interest./Die Autoren geben an, dass kein Interessenkonflikt besteht., (Georg Thieme Verlag KG Stuttgart · New York.)

Double plating (DP) is an established treatment modality in traumatology. For certain indications, such as open reduction and internal fixation of bicondylar tibial plateau fractures and distal humeral fractures, DP is standard of care in the clinical routine. However, the principles of DP can be transferred to other anatomic regions and indications. In the past years, DP has been brought more and more into focus. For revision cases, such as the treatment of fracture non-unions, DP seems generally useful. In anatomical locations with high torsional stress and bending forces, but also in regions with traction forces by muscles and tendons DP provides multiplanar stability and therefore seems to have biomechanical advantages. Usually two smaller implants can replace one larger implant. Thus, the number of points of fixation can be increased, the stability can be improved and soft-tissue irritations by bulky implants can be minimized. Along with the established indication and application at the distal humerus, there is biomechanical evidence in the current literature for DP of clavicle fractures and humeral shaft fractures. Furthermore, DP provides mechanical advantages in the treatment of certain proximal humeral fractures and olecranon fractures. This review of the literature summarizes the published literature on biomechanics of upper extremity DP., Competing Interests: The authors declare that they have no conflict of interest./Die Autoren geben an, dass kein Interessenkonflikt besteht., (Georg Thieme Verlag KG Stuttgart · New York.)

Purpose: To biomechanically compare the effect of superior capsule reconstruction (SCR) using a 3- and 6-mm thick acellular dermal allograft for the treatment of irreparable rotator cuff tears., Methods: Eight fresh-frozen cadaveric shoulders were tested using a dynamic shoulder model. Maximum abduction angle (MAA), glenohumeral superior translation (ghST), subacromial peak contact pressure (sPCP), and cumulative deltoid force (cDF) were compared among 4 conditions: (1) intact shoulder, (2) simulated irreparable rotator cuff tear (RCT), (3) SCR using a 3-mm-thick acellular dermal allograft, (4) SCR using a 6-mm-thick acellular dermal allograft., Results: Compared with the intact state, simulated irreparable RCTs significantly decreased MAA (P < .001), while significantly increasing ghST (P = .001), sPCP (P < .001), and cDF (P < .001). SCR with a 3-mm-thick graft significantly increased MAA (P = .01) and decreased ghST (P = .01) compared with the RCT state, however, showed similar sPCP and cDF. Compared with the torn state, SCR with a 6-mm-thick graft significantly increased MAA (P < .001) and significantly decreased ghST (P < .001), sPCP (P < .001), and cDF (P = .001). Using a 6-mm-thick graft demonstrated similar MAA, ghST, sPCP, and cDF compared with the intact state. When comparing the 3-mm to the 6-mm thick graft, significant differences were found in ghST (P = .03), sPCP (P < .001), and cDF (P = .02)., Conclusions: SCR with a 6-mm-thick acellular dermal allograft better restored normal glenohumeral joint position and forces compared with a 3-mm-thick graft for the treatment of irreparable RCTs., Clinical Relevance: Graft thickness may affect the clinical success following SCR with commercially available dermal allografts. Using a thicker (>3 mm) graft was able to biomechanically better restore native glenohumeral joint properties., (Copyright © 2019 Arthroscopy Association of North America. All rights reserved.)

Purpose: To identify an effective, nonenzymatic method for maximizing the yield of subacromial bursa-derived nucleated cells for augmenting rotator cuff repair., Methods: Subacromial bursa (minimum 0.2 g) was collected prospectively over the supraspinatus from patients (n = 7) with at least one full-thickness tendon tear undergoing arthroscopic primary rotator cuff repair. Samples were processed and analyzed prospectively using 4 different methods: (1) mechanical digestion with scissors (chopping), (2) collagenase digestion, (3) mechanical digestion with a tissue homogenizer, and (4) whole tissue with minimal manipulation. Tissue from each method were plated and cultured in a low oxygen tension, humidified incubator for 7 days. Following incubation, cellularity was assessed with nucleated cell count using a Coulter Counter. Flow cytometry was performed on the non-enzymatic method that demonstrated the greatest cell count to confirm the presence of mesenchymal stem cells (MSCs). The Kruskal-Wallis H test and post hoc Dunn's test were used for statistical analysis., Results: Following incubation, mean nucleated cell counts (cells/mL) were (1) 102,681 ± 73,249 for chopping, (2) 76,190 ± 66,275 for collagenase, (3) 31,686 ± 29,234 for homogenization, and (4) 11,162 ± 4016 for whole tissue. There was no significant difference between chopping and collagenase (P = .45) or between homogenization and collagenase (P = .52). Both chopping (P = .003) and collagenase (P = .03) produced significantly more cells when compared with whole tissue. Flow cytometry confirmed the presence of MSC markers on samples processed by chopping., Conclusions: Mechanical isolation of subacromial bursa-derived cells using a chopping technique demonstrated similar nucleated cell count compared with collagenase, along with the confirmed presence of MSCs., Clinical Relevance: This study demonstrated a nonenzymatic, mechanical method for isolating subacromial bursa-derived cells to potentially augment rotator cuff repair. Further clinical studies are required to assess its possible advent in the tendon-bone healing process., (Copyright © 2019 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.)

Following anterior cruciate ligament (ACL) reconstruction surgery, a staged repair response occurs where cells from outside the tendon graft participate in tunnel integration. The mechanisms that regulate this process, including the specific cellular origin, are poorly understood. Embryonic cells expressing growth and differentiation factor 5 (GDF5) give rise to several mesenchymal tissues in the joint and epiphyses. We hypothesized that cells from a GDF5 origin, even in the adult tissue, would give rise to cells that contribute to the stages of repair. ACLs were reconstructed in Gdf5-Cre;R26R-tdTomato lineage tracing mice to monitor the contribution of Gdf5-Cre;tdTom + cells to the tunnel integration process. Anterior-posterior drawer tests demonstrated 58% restoration in anterior-posterior stability. Gdf5-Cre;tdTom + cells within the epiphyseal bone marrow adjacent to tunnels expanded in response to the injury by 135-fold compared with intact controls to initiate tendon-to-bone attachments. They continued to mature the attachments yielding zonal insertion sites at 4 weeks with collagen fibers spanning across unmineralized and mineralized fibrocartilage and anchored to the adjacent bone. The zonal attachments possessed tidemarks with concentrated alkaline phosphatase activity similar to native entheses. This study established that mesenchymal cells from a GDF5 origin can contribute to zonal tendon-to-bone attachments within bone tunnels following ACL reconstruction., (© 2019 New York Academy of Sciences.)

Background: Little is known about the strains at the glenoid near the bone-implant interface in reverse shoulder arthroplasty. The purpose of the current study was to evaluate the strains on the glenoid bone under a compressive load after implantation of three different sizes of metal-backed baseplates in either inferior or superior position in combination with three different sizes of glenospheres and three different glenosphere designs., Methods: Three sizes of baseplates (small, medium, large) were implanted in thirty-six paired human cadaveric scapulae either inferior, flush with the glenoid neck, or with a 5 mm superior offset. Glenospheres were available in three sizes (36 mm, 39 mm, 42 mm) and designs (standard, 4 mm lateralized, 2.5 mm inferiorized). Specimens were mounted in a servo-hydraulic testing apparatus at a 60° angle between the glenoid and actuator holding the humeral component. Four strain-gauge rosettes were placed around the glenoid rim to measure strains transferred to the scapular bone under a compressive load (750 N) relative to the various baseplate-glenosphere combinations. Following repeated compression, a load-to-failure test was performed., Results: Mean overall registered strains were 161με (range: - 1165 to 2347) at the inferior sensor, -2με (range: - 213 to 90) at the superior sensor, -95με (range: - 381 to 254) at the anterior sensor, and 13με (range: - 298 to 128) at the posterior sensor. Measured bone strains did not show any significant differences across tested baseplate and glenosphere design, size, or positioning combinations (p > 0.05 for all sensors). Furthermore, linear regression analysis did not identify any of the evaluated parameters as an independent influential factor for strains (p > 0.05 for all sensors). Mean load-at-failure was significantly higher in the group of inferior (3347.0 N ± 704.4 N) compared to superior (2763.8 N ± 927.8 N) positioned baseplates (p = 0.046)., Conclusion: Different baseplate positions, baseplate sizes, glenosphere sizes, and glenosphere design or various combinations of these parameters did not significantly influence the measured bone strains at the glenoid near the bone-implant interface in a contemporary reverse shoulder arthroplasty system., Level of Evidence: Basic Science Study, Biomechanical Study.

Purpose: Treatment of failed primary reconstruction of the unstable acromioclavicular (AC) joint remains challenging for orthopaedic surgeons. When approaching revision cases, the reason for failure has to be precisely identified. The purpose of this manuscript was to perform a critical review of the literature regarding treatment options for failed AC joint stabilization techniques and to provide a treatment algorithm for salvage procedures., Methods: A thorough search included electronic databases for articles published up to April 15th, 2019. Inclusion criteria were set as (1) studies that reported on clinical outcomes following surgical or conservative treatment of AC joint dislocation; (2) studies reporting on failure or complications of primary treatment; (3) chronic instabilities caused by delayed or secondary treatment as well as (4) revision and salvage procedures., Results: The search strategy identified a total of 3269 citations. The final dataset comprised 84 studies published between 1954 and 2019. A total of 5605 patients (9.63% females) were involved with a mean age of 34.5 years. Overall, complication rates varied between 5 and 88.9% in patients with AC joint instability., Conclusion: In the current literature, evidence for treatment of revision AC joint instability is still lacking, however, surgical treatment continues to evolve. The importance of failure analysis and clinically relevant algorithms were highlighted in this review. Adequately restoring native joint biomechanics is needed for ensuring an optimal healing environment that will translate into patient satisfaction and long-term stability., Level of Evidence: V.

Purpose: The acromioclavicular ligament complex (ACLC) is the primary stabilizer against horizontal translation with the superior ACLC providing the main contribution. The purpose of this study was to evaluate the specific regional contributions in the superior half of ACLC, where the surgeon can easily access and repair or reconstruct, for posterior translational and rotational stability., Methods: The superior half of ACLC was divided into three regions; Region A (0°-60°): an anterior 1/3 region of the superior half of ACLC, Region B (60°-120°): a superior 1/3 region of the superior half of ACLC, and Region C (120°-180°): a posterior 1/3 region of the superior half of ACLC. Fifteen fresh-frozen cadaveric shoulders were used. Biomechanical testing was performed to evaluate the resistance force against passive posterior translation (10 mm) and the resistance torque against passive posterior rotation (20°) during the following the four conditions. (1) Stability was tested on all specimens in their intact condition (n = 15). (2) The ACLC was dissected and stability was tested (n = 15). (3) Specimens were randomly divided into three groups by regions of suturing. Stability was tested after suturing Region A, Region B, or Region C (n = 5 per group). (4) Stability was tested after suturing additional regions: Region A + B (0°-120°), Region B + C (60°-180°), or Region A + C (0°-60°, 120°-180°, n = 5 per group)., Results: The translational force increased after suturing Region A when compared with dissected ACLC (P = 0.025). The force after suturing Region A + B was significantly higher compared to the dissected ACLC (P < 0.001). The rotational torque increased after suturing Region A or Region B compared with dissected ACLC (P = 0.020, P = 0.045, respectively). The torque after suturing the Region A + C was significantly higher compared to the dissected ACLC (P < 0.001)., Conclusion: The combined Region A + B contributed more to posterior translational stability than Region B + C or Region A + C. In contrast, combined Region A + C contributed more to posterior rotational stability than Region A + B or Region B + C. Based on these findings, surgical techniques restoring the entire superior ACLC are recommended to address both posterior translational and rotational stability of the AC joint.

Reasons for failure of anterior cruciate ligament (ACL) reconstructions are manifold and require a multifactorial explanatory approach. In addition to technical failures, many modifiable and non-modifiable risk factors for a new ACL injury have to be considered. Technical failures primarily include non-anatomical tibial and femoral tunnel position. In comparison to the transtibial drilling technique, the tibial tunnel-independent technique results in a more anatomical position of the femoral tunnel and should therefore be preferred. One can differentiate between non-modifiable and modifiable risk factors. At the same time, the combination of more than one risk factor increases the risk of injury significantly. Non-modifiable risk factors include genetic predisposition, female sex, young age and ligament hyperlaxity. Young age at the time of the first injury is the most important risk factor for graft failure. Modifiable risk factors include high body mass index (BMI), deficits in jump landing mechanics, a steep posterior tibial slope and narrow intercondylar notch width. Neuromuscular training or additional surgical procedures modify these risk factors and reduce the probability of further injuries. A high tibial osteotomy (HTO) is the surgical procedure of choice for a reduction in the posterior tibial slope and anterior tibial translation. In case of a tibial slope over 12°, this procedure should be considered. In revision anterior cruciate ligament reconstructions with remaining anterolateral rotatory instability, additional lateral extraarticular tenodesis should be taken into account. This is also recommended for patients participating in pivoting sports, having concomitant hyperlaxity or additional injury of peripheral structures with insufficiency of the ACL. In addition, the surface of the pitch can be modified and thus influence the risk of an ACL injury. In summary, a substantiated failure analysis is required to initiate specific and individualised therapy - not only in the case of ACL rerupture. These factors should already be considered in risk assessment during patient information., Competing Interests: The authors declare that they have no conflict of interest./Die Autoren geben an, dass kein Interessenkonflikt besteht., (Georg Thieme Verlag KG Stuttgart · New York.)

Purpose: To assess whether preoperative subpectoral tenderness in patients with rotator cuff tears was associated with arthroscopic findings of tendinopathy of the long head of the biceps, as well as whether they had resolution of their subpectoral tenderness postoperatively after tenodesis or tenotomy., Methods: Patients presenting between 2011 and 2016 undergoing arthroscopic rotator cuff repair were evaluated preoperatively with the subpectoral biceps test (SBT). This test is performed with the arm adducted and internally rotated to allow palpation of the biceps as it courses under the pectoralis major tendon. Preoperative SBT findings determined operative management with either tenodesis or tenotomy during rotator cuff repair. Patients were followed up postoperatively to assess resolution of subpectoral tenderness with a repeated SBT. Preoperative and postoperative Single Assessment Numeric Evaluation (SANE), American Shoulder and Elbow Surgeons, and Constant-Murley scores were recorded in all patients., Results: A total of 128 patients were enrolled in the study, with a mean age of 58 years (range, 33-82 years). Patients with a positive preoperative SBT (n = 68) had significantly lower SANE and Constant-Murley scores preoperatively (P < .01) than patients with a negative SBT (n = 60). All patients with a positive preoperative SBT underwent either tenodesis or tenotomy, with 94% of patients (n = 64) having resolution of subpectoral pain and tenderness at final follow-up. Intraoperatively, 93% of patients with a positive SBT showed gross pathologic changes in the tendon (fraying, erythema, tears, or subluxation) compared with only 65% of patients with negative preoperative examination findings (P < .01). American Shoulder and Elbow Surgeons, Constant-Murley, and SANE scores were significantly increased postoperatively in all patients (P = .02)., Conclusions: In this group of patients with rotator cuff tears surgically treated with concomitant biceps tenodesis or tenotomy, 94% had resolution of their subpectoral tenderness. A positive SBT was associated with gross pathologic changes of the biceps in 93% of patients., Level of Evidence: Level III, prospective comparative study., (Copyright © 2019 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.)

Purpose: To compare a conventional single-row (SR) repair technique and 2 double-row (DR) repair techniques to restore and protect the superolateral aspect of the subscapularis (SSC) tendon and ensure SSC leading-edge reconstruction in a cadaveric model., Methods: The native footprint was measured in 15 pairs of human cadaveric shoulders (N = 30) with a mean age of 67.2 years. According to the Fox-Romeo classification, a 25% defect or 50% defect in a superior-inferior direction was created. Specimens were mounted onto a servohydraulic test system to analyze contact variables at 0° and 20° of abduction with a force-controlled ramped program up to 50 N. In addition, each specimen was cyclically loaded (10-100 N, 300 cycles). The tears were repaired with 1 of 3 constructs: a 2-anchor medially based conventional SR construct, a 2-anchor-based hybrid DR construct, or a 3-anchor-based DR construct. The outcome variables were ultimate tensile load, displacement, and pressurized footprint coverage., Results: All reconstructions resulted in stable constructs with peak loads exceeding 450 N (P = .68). The overall displacement during cyclic loading was between 1.2 and 3.0 mm (P = .70). A significant difference was seen when the 2 arm positions of 0° and 20° of abduction were compared, showing a constant reduction of pressurized footprint coverage with the arm abducted (P = .01). Analyzing footprint coverage with respect to the region of interest-the leading edge of the SSC-we observed a significant difference between the SR construct and a construct using a superolaterally placed anchor (25% defect, P = .01; 50% defect, P = .01), whereas no statistical differences were detectable between the hybrid DR construct and the DR construct., Conclusions: The leading edge of the SSC tendon can best be restored by using a superolateral anchor, whereas no statistical difference in load to failure in comparison with an SR construct or with the addition of a third anchor was detectable., Clinical Relevance: The SSC is critical for proper shoulder function. Without an increase in the number of implants, a significantly better footprint reconstruction can be achieved by placing an anchor superior and lateral to the native footprint area close to the entrance of the bicipital groove., (Copyright © 2019 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.)

Background: The concept of dynamic anterior shoulder stabilization (DAS) combines a Bankart repair with the additional sling effect of the long head of the biceps (LHB) tendon to treat anterior glenohumeral instability. This surgical technique was created to close the gap between the indications for isolated Bankart repair and those requiring bone transfer techniques., Purpose: To biomechanically investigate the stabilizing effects of the DAS technique in comparison with the standard Bankart repair in different defect models., Study Design: Controlled laboratory study., Methods: Twenty-four fresh-frozen cadaveric shoulders (mean ± SD age, 60.1 ± 8.6 years) were mounted in a 6 degrees of freedom shoulder testing system. With cross-sectional area ratios, the rotator cuff muscles and LHB tendon were loaded with 40 N and 10 N, respectively. Anterior and inferior glenohumeral translation was tested in 60° of abduction and 60° of external rotation (ABER position) while forces of 20 N, 30 N, and 40 N were applied to the scapula in the posterior direction. Total translation and relative translation in relation to the native starting position were measured with a 3-dimensional digitizer. Maximal external rotation and internal rotation after application of 1.5-N·m torque to the humerus were measured. All specimens went through 4 conditions (intact, defect, isolated Bankart repair, DAS) and were randomized to 1 of 3 defect groups (isolated Bankart lesion, 10% anterior glenoid defect, 20% anterior glenoid defect). The DAS was performed by transferring the LHB tendon through a subscapularis split to the anterior glenoid margin, where it was fixed with an interference screw., Results: Both surgical techniques resulted in decreased anterior glenohumeral translation in comparison with the defect conditions in all defect groups. As compared with isolated Bankart repair, DAS showed significantly less relative anterior translation in 10% glenoid defects at translation forces of 20 N (0.3 ± 1.7 mm vs 2.2 ± 1.8 mm, P = .005) and 30 N (2.6 ± 3.4 mm vs 5.3 ± 4.2 mm, P = .044) and in 20% glenoid defects at all translation forces (20 N: -3.2 ± 4.7 mm vs 0.8 ± 4.1 mm, P = .024; 30 N: -0.9 ± 5.3 mm vs 4.0 ± 5.2 mm, P = .005; 40 N: 2.1 ± 6.6 mm vs 6.0 ± 5.7 mm, P = .035). However, in 20% defects, DAS led to a relevant posterior and inferior shift of the humeral head in the ABER position and to a relevant increase in inferior glenohumeral translation. Both surgical techniques did not limit the rotational range of motion., Conclusion: In the context of minor glenoid bone defects, the DAS technique demonstrates less relative anterior translation as compared with an isolated Bankart repair at time zero., Clinical Relevance: The new DAS technique seems capable of closing the gap between the indications for isolated Bankart repair and bone transfer techniques.

Background: The objective of this biomechanical study is to compare two variations of single-row knotless techniques (Knotless repair and Rip-stop Knotless repair) against a single-row double-loaded anchor (DL) repair, focused on evaluating contact pressure and contact area amongst three different single-row techniques for rotator cuff repairs., Methods: A total of 24 fresh frozen human shoulders were tested. Specimens were randomly assigned into one of the three single-row (SR) repair groups: A Knotted single-row double-loaded anchor (DL) repair, a Knotless (K) repair, or a Knotless Rip-Stop (KRS) repair. The footprint was measured after complete detachment of the supraspinatus tendon from the greater tuberosity, introducing pressure sensors between bony footprint and detached rotator cuff, and finally reconstructing it. All specimens were mounted onto a servohydraulic test system to analyze contact variables at 0° and 30° of abduction with 0 N, 30 N and 50 N of tension., Results: Groups did not differ significantly in their footprint sizes: DL group 359.75 ± 58.37 mm 2 , K group 386.5 ± 102.13 mm 2 , KRS group 415.87 ± 93.80 mm 2 (p = 0.84); nor in bone mineral density: DL group 0.25 ± 0.14 g/cm 2 , K group 0.32 ± 0.19 g/cm 2 , KRS group 0.32 ± 0.13 g/cm 2 , (p = 0.75) or average age. The highest mean pressurized contact area measured for the K repair was 248.1 ± 50.9 mm 2 , which equals a reconstruction of 67.1 ± 19.3% at 0° abduction and a 50 N supraspinatus load. This reconstructed area was significantly greater compared with the DL repair 152.8 ± 73.1 mm 2 , reconstructing 42.0 ± 18.5% on average when under the same conditions (p = 0.04). The mean contact pressure did not significantly differ amongst groups (p = 1.0): DL group 30.8 ± 17.4 psi, K group 30.9 ± 17.4 psi and KRS group 30.0 ± 10.9 psi. Neither the 30° abduction angle nor the supraspinatus load had a significant influence on the contact pressure in our study., Conclusion: Both single-row knotless techniques resulted in significantly higher footprint reconstruction, providing larger contact area and a more uniform pressure distribution when compared with the single-row Knotted techniques. The mean contact pressure did not differ among groups significantly. These knotless techniques may be an alternative if the surgeon decides to perform a single-row rotator cuff repair., Level of Evidence: Basic Science Study, Biomechanics.