Effect of intraarticular pressure on glenohumeral kinematics during a simulated abduction motion: a cadaveric study.

BACKGROUND: The current understanding of glenohumeral joint stability is defined by active restrictions and passive stabilizers including naturally-occurring negative intraarticular pressure. Cadaveric specimens have been used to evaluate the role of intraarticular pressure on joint stability, although, while the shoulder's negative intraarticular pressure is universally acknowledged, it has been inconsistently accounted for. HYPOTHESIS: During continuous, passive humeral abduction, releasing the native intraarticular pressure increases joint translation, and restoring this pressure decreases joint translations. STUDY DESIGN: Descriptive Laboratory Study. METHODS: A validated shoulder testing system was used to passively abduct the humerus in the scapular plane and measure joint translations for seven (n = 7) cadaveric specimens. The pressure within the glenohumeral joint was measured via a 25-gauge needle during passive abduction of the arm, which was released and subsequently restored. During motion, the rotator cuff muscles were loaded using stepper motors in a force feedback loop and electromagnetic sensors were used to continuously measure the position of the humerus and scapula. Joint translation was defined according to the instant center of rotation of the glenohumeral head according to the recommendations by the International Society of Biomechanics. RESULTS: Area under the translation versus abduction angle curve suggests that releasing the pressure within the capsule results in significantly less posterior translation of the glenohumeral head as compared to intact (85-90˚, p < 0.05). Posterior and superior translations were reduced after 70˚ of abduction when the pressure within the joint was restored. CONCLUSION: With our testing system employing a smooth continuous passive motion, we were able to show that releasing intraarticular pressure does not have a major effect on the path of humeral head motion during glenohumeral abduction. However, both violating the capsule and restoring intraarticular pressure after releasing alter glenohumeral translations. Future studies should study the effect of simultaneous external rotation and abduction on the relationship between joint motion and IAP, especially in higher degrees of abduction. CLINICAL RELEVANCE: Thoroughly simulating the glenohumeral joint environment in the cadaveric setting may strengthen the conclusions that can be translated from this setting to the clinic.

Combined MPFL reconstruction and tibial tuberosity transfer avoid focal patella overload in the setting of elevated TT-TG distances.

PURPOSE: Objectives are (1) to evaluate the biomechanical effect of isolated medial patellofemoral ligament (MPFL) reconstruction in the setting of increased tibial tuberosity-trochlear groove distance (TTTG), in terms of patella contact pressures, contact area and lateral displacement; (2) to describe the threshold of TTTG up to which MPFL reconstruction should be performed alone or in combination with tibial tuberosity transfer. METHODS: A finite element model of the knee was developed and validated. The model was modified to simulate isolated MPFL reconstruction, tibial tuberosity transfer and MPFL reconstruction combined with tibial tuberosity transfer for patella malalignment. Two TT-TG distances (17 mm and 22 mm) were simulated. Patella contact pressure, contact area and lateral displacement were analysed. RESULTS: Isolated MPFL reconstruction, at early degrees of flexion, restored normal patella contact pressure when TTTG was 17 mm, but not when TTTG was 22 mm. After 60° of flexion, the TTTG distance was the main factor influencing contact pressure. Isolated MPFL reconstruction for both TTTG 17 mm and 22 mm showed higher contact area and lower lateral displacement than normal throughout knee flexion. Tibial tuberosity transfer, at early degrees of flexion, reduced the contact pressure, but did not restore the normal contact pressure. After 60° of flexion, the TTTG distance was the main factor influencing contact pressure. Tibial tuberosity transfer maintained lower contact area than normal throughout knee flexion. The lateral displacement was higher than normal between 0° and 30° of flexion (< 0.5 mm). MPFL reconstruction combined with tibial tuberosity transfer produced the same contact mechanics and kinematics of the normal condition. CONCLUSION: This study highlights the importance of considering to correct alignment in lateral tracking patella to avoid focal patella overload. Our results showed that isolated MPFL reconstruction corrects patella kinematics regardless of TTTG distance. However, isolated MPFL reconstruction would not restore normal patella contact pressure when TTTG is 22 mm. For TTTG 22 mm, the combined procedure of MPFL reconstruction and tibial tuberosity transfer provided an adequate patellofemoral contact mechanics and kinematics, restoring normal biomechanics. This data supports the use of MPFL reconstruction when the patient has normal alignment and the use of combined MPFL reconstruction and tibial tuberosity transfer in patients with elevated TT-TG distances to avoid focal overload.

Recommended Musculoskeletal and Sports Ultrasound Terminology: A Delphi-Based Consensus Statement.

OBJECTIVES: The current lack of agreement regarding standardized terminology in musculoskeletal and sports ultrasound presents challenges in education, clinical practice, and research. This consensus was developed to provide a reference to improve clarity and consistency in communication. METHODS: A multidisciplinary expert panel was convened consisting of 18 members representing multiple specialty societies identified as key stakeholders in musculoskeletal and sports ultrasound. A Delphi process was used to reach consensus which was defined as group level agreement >80%. RESULTS: Content was organized into seven general topics including: 1) General Definitions, 2) Equipment and Transducer Manipulation, 3) Anatomic and Descriptive Terminology, 4) Pathology, 5) Procedural Terminology, 6) Image Labeling, and 7) Documentation. Terms and definitions which reached consensus agreement are presented herein. CONCLUSIONS: The historic use of multiple similar terms in the absence of precise definitions has led to confusion when conveying information between colleagues, patients, and third-party payers. This multidisciplinary expert consensus addresses multiple areas of variability in diagnostic ultrasound imaging and ultrasound-guided procedures related to musculoskeletal and sports medicine.

Lateral release associated with MPFL reconstruction in patients with acute patellar dislocation.

OBJECTIVE: Medial patellofemoral ligament (MPFL) injury occurs in the majority of the cases of acute patellar dislocation. The role of concomitant lateral retinaculum release with MPFL reconstruction is not clearly understood. Even though the lateral retinaculum plays a role in both medial and lateral patellofemoral joint stability in MPFL intact knees, studies have shown mixed clinical outcomes following its release during MPFL reconstruction surgery. Better understanding of the biomechanical effects of the release of the lateral retinaculum during MPFL reconstruction is warranted. We hypothesize that performing a lateral release concurrent with MPFL reconstruction will disrupt the patellofemoral joint biomechanics and result in lateral patellar instability. METHODS: A previously developed and validated finite element (FE) model of the patellofemoral joint was used to understand the effect of lateral retinaculum release following MPFL reconstruction. Contact pressure (CP), contact area (CA) and lateral patellar displacement were recorded. abstract. RESULTS: FE modeling and analysis demonstrated that lateral retinacular release following MPFL reconstruction with tibial tuberosity-tibial groove distance (TT-TG) of 12 mm resulted in a 39% decrease in CP, 44% decrease in CA and a 20% increase in lateral patellar displacement when compared to a knee with an intact MPFL. In addition, there was a 45% decrease in CP, 44% decrease in CA and a 21% increase in lateral displacement when compared to a knee that only had an MPFL reconstruction. CONCLUSION: This FE-based analysis exhibits that concomitant lateral retinaculum release with MPFL reconstruction results in decreased PF CA, CP and increased lateral patellar displacement with increased knee flexion, which may increase the risk of patellar instability.

Recommended musculoskeletal and sports ultrasound terminology: a Delphi-based consensus statement.

The current lack of agreement regarding standardised terminology in musculoskeletal and sports ultrasound presents challenges in education, clinical practice and research. This consensus was developed to provide a reference to improve clarity and consistency in communication. A multidisciplinary expert panel was convened consisting of 18 members representing multiple specialty societies identified as key stakeholders in musculoskeletal and sports ultrasound. A Delphi process was used to reach consensus, which was defined as group level agreement of >80%. Content was organised into seven general topics including: (1) general definitions, (2) equipment and transducer manipulation, (3) anatomical and descriptive terminology, (4) pathology, (5) procedural terminology, (6) image labelling and (7) documentation. Terms and definitions which reached consensus agreement are presented herein. The historic use of multiple similar terms in the absence of precise definitions has led to confusion when conveying information between colleagues, patients and third-party payers. This multidisciplinary expert consensus addresses multiple areas of variability in diagnostic ultrasound imaging and ultrasound-guided procedures related to musculoskeletal and sports medicine.

Lateral Release With Tibial Tuberosity Transfer Alters Patellofemoral Biomechanics Promoting Multidirectional Patellar Instability.

PURPOSE: The purpose of this study was to develop and validate a finite element (FE) model of the patellofemoral (PF) joint to characterize patellofemoral instability, and to highlight the effect of lateral retinacular release in combination with tibial tuberosity transfer with respect to contact pressures (CP), contact area (CA), and kinematics during knee flexion. METHODS: A comprehensive, dynamic FE model of the knee joint was developed and validated through parametric comparison of PF kinematics, CP, and CA between FE simulations and in vitro, cadaveric experiments. Using this FE model, we characterized the effect of patellar instability, lateral retinacular release (LR), and tibial tuberosity transfer (TTT) in the setting of medial patellofemoral ligament injury during knee flexion. RESULTS: There was a high level of agreement in CP, CA, lateral patellar displacement, anterior patellar displacement, and superior patellar displacement between the FE model and the in vitro data (P values 0.19, 0.16, 0.81, 0.10, and 0.36, respectively). Instability conditions demonstrated the greatest CP compared to all of the other conditions. During all degrees of flexion, TTT and concomitant lateral release (TTT + LR) decreased CP significantly. TTT alone shows a consistently lower CA compared to nonrelease conditions with subsequent lateral release further decreasing CA. CONCLUSIONS: The results of this study demonstrate that the FE model described reliably simulates PF kinematics and CP within 1 SD in uncomplicated cadaveric specimens. The FE model is able to show that tibial tubercle transfer in combination with lateral retinacular release markedly decreases patellofemoral CP and CA and increases lateral patellar displacement that may decrease bony stabilization of the patella within the trochlear groove and promote lateral patellar instability. CLINICAL RELEVANCE: The goal of surgical correction for patellar instability focuses on reestablishing normal PF kinematics. By developing an FE model that can demonstrate patient PF kinematics and the results of different surgical approaches, surgeons may tailor their treatment to the best possible outcome. Of the surgical approaches that have been described, the biomechanical effects of the combination of TTT with lateral retinacular release have not been studied. Thus, the FE analysis will help shed light on the effect of the combination of TTT with lateral retinacular release on PF kinematics.

A validated algorithm using current literature to judge the appropriateness of anatomic total shoulder arthroplasty utilizing the RAND/UCLA appropriateness method.

BACKGROUND: Currently, appropriateness criteria evaluating when to perform total shoulder arthroplasty (TSA) is lacking. In the absence of society guidelines and limited quality evidence, the RAND/University California in Los Angeles (UCLA) method provides a suitable alternative to evaluate appropriateness and assist in clinical decision making. Given the rise in utilization, appropriateness criteria for TSA have the potential to be an extremely powerful tool for improving quality of care and controlling costs. Thus, the goal of this study was to test explicit criteria to assess the appropriateness of TSA decision making using the RAND/UCLA appropriateness method. METHODS: A review of recent scientific literature to gather available evidence about the use, effectiveness, efficiency, and the risks involved in surgical intervention was performed by a shoulder/elbow fellowship trained physician. Based on pertinent variables including age, rotator cuff status, previous surgical management, mobility, symptomatology, and imaging classifications, 186 clinical scenarios were created. Appropriateness criteria for TSA were developed using a modified Delphi method with a panel consisting of American Shoulder and Elbow Surgeons (ASES) members. A second panel of ASES members rated the same scenarios, with reliability testing performed to compare groups. RESULTS: Panel members reached agreement in 40 (64%) indications. TSA was appropriate in 15 (24%) of indications. For patients with severe symptomatology, TSA was often appropriate for patients aged <75 years and inconclusive or inappropriate for patients aged >75 years. Among patients aged <65 years, TSA varied between appropriate and inconclusive, often dependent on Walch classification. For patients with moderate symptomatology, TSA was inappropriate or inconclusive for patients aged <65 or >75 years. When compared to the second panel's results, moderate agreement was obtained with a weighted kappa statistic of 0.56. CONCLUSIONS: Using the RAND/UCLA method, ASES members created an appropriateness decision tree for pertinent patient variables. This presents the data in a manner that streamlines the clinical decision-making process and allows for rapid and more reliable determination of appropriateness for practitioners. The decision tree is based on a combination of clinical experience from high-volume ASES-member surgeons and a comprehensive review of current evidence. This tool can be used as part of a broader set of factors, including individual patient characteristics, prior studies, and expert opinion, to inform clinical decision making, improve quality of care, and control costs.

Conservative versus accelerated rehabilitation after rotator cuff repair: a systematic review and meta-analysis.

BACKGROUND: The purpose of this systematic review and meta-analysis is to compare the conservative and accelerated rehabilitation protocols in patients who underwent arthroscopic rotator cuff repair in terms of clinical outcomes and range of motions at 3, 6, 12, and 24-month follow-up. METHODS: According to PRISMA guidelines, a systematic review of the literature was performed. For each included article, the following data has been extracted: authors, year, study design, level of evidence, demographic characteristics, follow-up, clinical outcomes, range of motions, and retear events. A meta-analysis was performed to compare accelerated versus conservative rehabilitation protocols after arthroscopic rotator cuff repair. The retear rate, postoperative Constant-Murley score and range of motions at 3, 6, 12, and 24 months of follow-up were the outcomes measured. RESULTS: The search strategy yielded 16 level I-II clinical studies. A total of 1424 patients, with 732 patients and 692 in the accelerated and conservative group, were included. The average age (mean ± standard deviation) was 56.1 ± 8.7 and 56.6 ± 9 in the accelerated and conservative group. The mean follow-up was 12.5 months, ranging from 2 to 24 months. The meta-analysis showed no statistically significant differences in terms of retear rate between the groups (P = 0.29). The superiority of the accelerated group was demonstrated in terms of external rotation (P < 0.05) at 3-month follow-up; in terms of forward elevation, external rotation, abduction (P < 0.05), but not in terms of Constant-Murley score at 6-month follow-up; in terms of forward elevation (P < 0.05) at 12-month follow-up. No significant differences between the two group were highlighted at 24-month follow-up. CONCLUSIONS: No statistically significant differences in the retear rate among the accelerated and conservative group have been demonstrated. On the other hand, statistically and clinically significant differences were found in terms of external rotation at 3 and 6 months of follow-up in favour of the accelerated group. However, no differences between the two groups were detected at 24 months follow-up.

Evolution of knowledge on meniscal biomechanics: a 40 year perspective.

BACKGROUND: Knowledge regarding the biomechanics of the meniscus has grown exponentially throughout the last four decades. Numerous studies have helped develop this knowledge, but these studies have varied widely in their approach to analyzing the meniscus. As one of the subcategories of mechanical phenomena Medical Subject Headings (MeSH) terms, mechanical stress was introduced in 1973. This study aims to provide an up-to-date chronological overview and highlights the evolutionary comprehension and understanding of meniscus biomechanics over the past forty years. METHODS: A literature review was conducted in April 2021 through PubMed. As a result, fifty-seven papers were chosen for this narrative review and divided into categories; Cadaveric, Finite element (FE) modeling, and Kinematic studies. RESULTS: Investigations in the 1970s and 1980s focused primarily on cadaveric biomechanics. These studies have generated the fundamental knowledge basis for the emergence of FE model studies in the 1990s. As FE model studies started to show comparable results to the gold standard cadaveric models in the 2000s, the need for understanding changes in tissue stress during various movements triggered the start of cadaveric and FE model studies on kinematics. CONCLUSION: This study focuses on a chronological examination of studies on meniscus biomechanics in order to introduce concepts, theories, methods, and developments achieved over the past 40 years and also to identify the likely direction for future research. The biomechanics of intact meniscus and various types of meniscal tears has been broadly studied. Nevertheless, the biomechanics of meniscal tears, meniscectomy, or repairs in the knee with other concurrent problems such as torn cruciate ligaments or genu-valgum or genu-varum have not been extensively studied.

Genetic basis of rotator cuff injury: a systematic review.

BACKGROUND: Rotator cuff disease is a widespread musculoskeletal pathology and a major cause of shoulder pain. Studies on familial predisposition suggest that genetic plays a role in the pathogenesis of rotator cuff disease. Several genes are responsible for rotator cuff disease. The aim of this study was to perform a systematic review on genetic association between rotator cuff disease and genes variations. METHODS: A systematic review of the literature was performed, in accordance with the PRISMA guidelines. PubMed, Medline, CINAHL, Cochrane, Embase and Google Scholar databases were searched comprehensively using the keywords: "Rotator cuff", "Gene", "Genetic", "Predisposition", "Single-nucleotide polymorphism" and "Genome-wide association". RESULTS: 8 studies investigating genes variations associated with rotator cuff tears were included in this review. 6 studies were case-control studies on candidate genes and 2 studies were GWASs. A significant association between SNPs and rotator cuff disease was found for DEFB1, FGFR1, FGFR3, ESRRB, FGF10, MMP-1, TNC, FCRL3, SASH1, SAP30BP, rs71404070 located next to cadherin8. Contradictory results were reported for MMP-3. CONCLUSION: Further investigations are warranted to identify complete genetic profiles of rotator cuff disease and to clarify the complex interaction between genes, encoded proteins and environment. This may lead to individualized strategies for prevention and treatment of rotator cuff disease. LEVEL OF EVIDENCE: Level IV, Systematic Review.

Changes in Contact Area in Meniscus Horizontal Cleavage Tears Subjected to Repair and Resection.

PURPOSE: To assess the changes in tibiofemoral contact pressure and contact area in human knees with a horizontal cleavage tear before and after treatment. METHODS: Ten human cadaveric knees were tested. Pressure sensors were placed under the medial meniscus and the knees were loaded at twice the body weight for 20 cycles at 0°, 10°, and 20° of flexion. Contact area and pressure were recorded for the intact meniscus, the meniscus with a horizontal cleavage tear, after meniscal repair, after partial meniscectomy (single leaflet), and after subtotal meniscectomy (double leaflet). RESULTS: The presence of a horizontal cleavage tear significantly increased average peak contact pressure and reduced effective average tibiofemoral contact area at all flexion angles tested compared with the intact state (P < .03). There was approximately a 70% increase in contact pressure after creation of the horizontal cleavage tear. Repairing the horizontal cleavage tear restored peak contact pressures and areas to within 15% of baseline, statistically similar to the intact state at all angles tested (P < .05). Partial meniscectomy and subtotal meniscectomy significantly increased average peak contact pressure and reduced average contact area at all degrees of flexion compared with the intact state (P < .05). CONCLUSIONS: The presence of a horizontal cleavage tear in the medial meniscus causes a significant reduction in contact area and a significant elevation in contact pressure. These changes may accelerate joint degeneration. A suture-based repair of these horizontal cleavage tears returns the contact area and contact pressure to nearly normal, whereas both partial and subtotal meniscectomy lead to significant reductions in contact area and significant elevations in contact pressure within the knee. Repairing horizontal cleavage tears may lead to improved clinical outcomes by preserving meniscal tissue and the meniscal function. CLINICAL RELEVANCE: Understanding contact area and peak contact pressure resulting from differing strategies for treating horizontal cleavage tears will allow the surgeon to evaluate the best strategy for treating his or her patients who present with this meniscal pathology.

Corticosteroid Injections for Adhesive Capsulitis: A Review.

OBJECTIVE: Adhesive capsulitis is a self-limiting condition in a majority of patients and is often treated nonoperatively. However, symptoms may take 2 to 3 years to resolve fully. A small, but significant, portion of patients require surgical intervention. The purpose of this systematic review is to evaluate the efficacy of corticosteroid injections for the treatment of adhesive capsulitis (AC). DATA SOURCES: A review of articles indexed by the United States National Library of Medicine was conducted by querying the PubMed database for studies involving participants with AC, frozen shoulder, stiff shoulder, or painful shoulder. Articles that included corticosteroids, glucocorticoids, steroids, and injections were included. MAIN RESULTS: Corticosteroid injections provide significant symptom relief for 2 to 24 weeks. Injections can be performed intra-articularly or into the subacromial space. Evidence suggests that a 20 mg dose of triamcinolone may be as effective as a 40 mg injection. It remains unclear whether image-guided injections produce a clinically significant difference in outcomes when compared with landmark-guided (blind) injections. Corticosteroids may be less beneficial for diabetic patients. Patients using protease inhibitors (antiretroviral therapy) should not receive triamcinolone because the drug-drug interaction may result in iatrogenic Cushing syndrome. CONCLUSIONS: Corticosteroid injections for AC demonstrate short-term efficacy, but may not provide a long-term benefit. More high quality, prospective studies are needed to determine whether corticosteroid injections using ultrasound guidance significantly improve outcomes.

Magnetic resonance imaging is comparable to computed tomography for determination of glenoid version but does not accurately distinguish between Walch B2 and C classifications.

BACKGROUND: Computed tomography (CT) scan is the standard for the preoperative assessment of glenoid version and morphology before total shoulder arthroplasty. However, the capacity of magnetic resonance imaging (MRI) to visualize bone morphology has improved with advancing technology. The purpose of this study was to compare the accuracy of MRI to CT for assessment of glenoid version and Walch classification. METHODS: Three fellowship-trained shoulder surgeons assessed glenoid version and Walch classification of 30 patients with primary shoulder osteoarthritis who received both CT and MRI scans before total shoulder arthroplasty. Version measurements, Walch classification, and observer agreement were compared. RESULTS: Mean glenoid version was -15.5° and -18.6° by CT and MRI, respectively (P = .17). Interobserver reliability coefficients were good for both imaging modalities (CT, 0.73; MRI, 0.62). Intraobserver coefficients were good to excellent for CT (range, 0.76-0.87) and good for MRI (range, 0.75-0.79). For Walch classification, interobserver reliability for both modalities was merely fair, whereas intraobserver reliability was moderate to good. Although identification of type A1, A2, and B1 was nearly identical between CT and MRI, there was observer disagreement on type B2 (P = .001) and C glenoids (P = .03). Specifically, MRI underidentified type B2 and overidentified type C compared with CT. CONCLUSIONS: MRI is largely comparable to CT scan for evaluation of the glenoid, with similar measurements of version and identification of less extreme Walch glenoids. However, MRI is less accurate at distinguishing between type B2 and C glenoids.

Evaluating Nonoperative Treatments for Adhesive Capsulitis.

Patients commonly present with shoulder complaints to the primary care and orthopaedic setting. The differential includes rotator cuff tears, subacromial impingement, osteoarthritis, and adhesive capsulitis, also known as frozen shoulder. Despite the prevalence of adhesive capsulitis, it is commonly misdiagnosed and management remains unclear. This article reviews the presentation of adhesive capsulitis, presents an overview of the pathophysiology of this poorly understood disease, and evaluates nonoperative treatment options for adhesive capsulitis. (Journal of Surgical Orthopaedic Advances 26(4):193-199, 2017).

Influence of disruption of the acromioclavicular and coracoclavicular ligaments on glenohumeral motion: a kinematic evaluation.

BACKGROUND: Changes to the integrity of the acromioclavicular (AC) joint impact scapulothoracic and clavicular kinematics. AC ligaments provide anterior-posterior stability, while the coracoclavicular (CC) ligaments provide superior-inferior stability and a restraint to scapular internal rotation. The purpose of this cadaveric study was to describe the effect of sequential AC and CC sectioning on glenohumeral (GH) kinematics during abduction (ABD) of the arm. We hypothesized that complete AC ligament insult would result in altered GH translation in the anterior-posterior plane during abduction, while subsequent sectioning of both CC ligaments would result in an increasing inferior shift in GH translation. METHODS: Six cadaveric shoulders were studied to evaluate the impact of sequential sectioning of AC and CC ligaments on GH kinematics throughout an abduction motion in the coronal plane. Following an examination of the baseline, uninjured kinematics, the AC ligaments were then sectioned sequentially: (1) Anterior, (2) Inferior, (3) Posterior, and (4) Superior. Continued sectioning of CC ligamentous structures followed: the (5) trapezoid and then the (6) conoid ligaments. For each group, the GH translation and the area under the curve (AUC) were measured during abduction using an intact cadaveric shoulder. Total translation was calculated for each condition between ABD 30° and ABD 150° using the distance formula, and a univariate analysis was used to compare total translation for each axis during the different conditions. RESULTS: GH kinematics were not altered following sequential resection of the AC ligaments. Disruption of the trapezoid resulted in significant anterior and lateral displacement of the center of GH rotation. Sectioning the conoid ligament further increased the inferior shift in GH displacement. CONCLUSION: A combined injury of the AC and CC ligaments significantly alters GH kinematics during abduction. Type III AC separations, result in a significant change in the shoulder's motion and may warrant surgical reconstruction to restore normal function.

The effect of the rotator interval on glenohumeral kinematics during abduction.

BACKGROUND: The rotator interval (RI) has been exploited as a potentially benign point of entry into the glenohumeral (GH) joint. Bounded by the supraspinatus, subscapularis and coracoid process of the scapula, the RI is believed to be important in the shoulder's soft tissue balancing and function. However, the role of the RI in shoulder kinematics is not fully understood. The purpose of this study is to describe the effect of the RI on GH motion during abduction of the arm. METHODS: Six shoulders from three cadaveric torsos were studied to assess the impact of changes in the RI during abduction under four conditions: Intact (Baseline), Opened, Repaired (repaired with side-to-side tissue approximation, no overlap) and Tightened (repaired with 1 cm overlap). For each group, the GH translation and area under the Curve (AUC) were measured during abduction using an intact cadaveric shoulder (intact torso). RESULTS: GH kinematics varied in response to each intervention and throughout the entire abduction arc. Opening the RI caused a significant change in GH translation. The Repair and Tightened groups behaved similarly along all axes of GH motion. CONCLUSIONS: The RI is central to normal GH kinematics. Any insult to the tissue's integrity alters the shoulder's motion throughout abduction. In this model, closing the RI side-to-side has the same effect as tightening the RI. Since suture closure may offer the same benefit as tightening the RI, clinicians should consider this effect when treating patients with shoulder laxity. This investigation provides an improved perspective on the role of the RI on GH kinematics during abduction. When managing shoulder pathology, surgeons should consider how these different methods of RI closure affect the joint's motion. In different circumstances, the surgical approach to the RI can be tailored to address each patient's specific needs.

Biomechanical evaluation of an all-inside suture-based device for repairing longitudinal meniscal tears.

PURPOSE: A device for all-inside suture-based meniscal repairs has been introduced (NovoStitch; Ceterix, Menlo Park, CA) that passes the suture vertically through the meniscus, thereby encircling the tear, and does not require an additional incision or extra-capsular anchors. Our aim was to compare this all-inside suture-based repair with an inside-out suture repair and an all-inside anchor-based repair (FasT-Fix 360°; Smith & Nephew, Andover, MA). METHODS: Longitudinal tears were created in 36 fresh-frozen porcine menisci. Repairs were performed using an all-inside suture-based meniscal repair device, an all-inside anchor-based repair, and an inside-out suture repair. They were tested with cyclic loading and load-to-failure testing. The displacement, response to cyclic loading (100, 300, and 500 cycles), and mode of failure were recorded. The stiffness of the constructs was calculated as well. RESULTS: The all-inside suture-based repairs and the inside-out repairs showed significantly higher loads to failure than the all-inside anchor-based repairs. The stiffness values for the 3 repairs were not different. There were no differences in initial displacement. After 100, 300, and 500 cycles, the inside-out repair had higher gap formation (displacement) than the other 2 groups. Suture failure was the predominant mode of failure across all repair techniques. CONCLUSIONS: The all-inside suture-based repairs and inside-out repairs did not exhibit different load-to-failure values. In addition, the all-inside suture-based repairs and the all-inside anchor-based repairs did not exhibit different displacement values during cyclic loading. CLINICAL RELEVANCE: When addressing a longitudinal meniscal tear, surgeons should consider biomechanical data of various repair devices and techniques in their decision-making process to maximize the mechanical strength and healing probability of the repair.

Analysis of a new all-inside versus inside-out technique for repairing radial meniscal tears.

PURPOSE: The purpose of this study was to compare gap formation, strength, and stiffness of repaired radial tears of the meniscus treated using a new all-inside technique versus a traditional inside-out suture technique. METHODS: Radial tears were created in 36 fresh-frozen porcine menisci. Repairs were performed using a novel all-inside suture-based meniscal repair device or an inside-out technique. The repairs were tested for cyclic loading and load to failure. The displacement, response to cyclic loading (100, 300, and 500 cycles), and mode of failure were recorded, and the construct's stiffness was calculated. RESULTS: The all-inside repairs using the novel device resulted in a significantly lower displacement (gap formation) after 100, 300, and 500 cycles (P = .002, P = .001, and P = .001, respectively). The ultimate load to failure was significantly greater for the all-inside repairs (111.61 N v 95.01 N; P = .03). The all-inside repairs showed greater stiffness (14.53 N/mm v 11.19 N/mm; P = .02). The all-inside repairs failed most often by suture breakage (suture failure). The inside-out repairs failed most commonly when the suture pulled through the tissue (tissue failure) (P < .001). CONCLUSIONS: For repair of radial tears of the meniscus, the vertical suture configuration created by the all-inside technique resulted in lower displacement, higher load to failure, and greater stiffness compared with the horizontal inside-out technique. CLINICAL RELEVANCE: In a porcine specimen meniscus repair model, the biomechanical properties of a vertical all-inside technique were superior to that of a horizontal inside-out technique. Future studies of biomechanical and clinical outcomes in human meniscal repairs with this device are warranted to explore whether this repair method is valuable to clinical practice and patient outcomes.

Biomechanical characterization of unicortical button fixation: a novel technique for proximal subpectoral biceps tenodesis.

PURPOSE: Proximal biceps tenodesis is one method for treating biceps-related pain. Tenodesis protects the length-tension relationship of the biceps muscle, maintains strength, and provides a better cosmetic appearance than tenotomy. The purpose of this investigation was to compare the mechanical properties of a unicortical metal button and an interference screw in proximal biceps tenodesis. METHODS: Six pairs of fresh-frozen shoulders were dissected, leaving the proximal biceps tendon as a free graft. On each pair of shoulders, a biceps tenodesis was performed using an interference screw or a unicortical metal button. The specimens were mounted and a cyclic load (10-60 N) was applied at 1 Hz for 200 cycles, followed by an axial load to failure. The displacement, ultimate load to failure, and mode of failure were recorded. RESULTS: Displacement in response to cyclic loading was 3.7 ± 2.2 mm for the interference screw and 1.9 ± 1.0 mm for the cortical button (P = 0.03). Load at failure for the interference screw was 191 ± 64 N (stiffness: 24 ± 11 N/mm) and 183 ± 61 N (stiffness: 24 ± 7. N/mm) for the unicortical button (P = n.s. for both cases). CONCLUSIONS: As a novel technique for subpectoral biceps tenodesis, a unicortical button demonstrated significantly less displacement in response to cyclic loading than the interference screw. The ultimate load to failure and stiffness for the two methods were not different. In this way, a unicortical button may provide a reliable alternative method of fixation with a potentially lower risk of post-operative humeral fracture and a construct that permits early mobilization following biceps tenodesis.

Return to driving after arthroscopic rotator cuff repair: patient-reported safety and maneuverability.

This survey investigated patients' return to driving after rotator cuff surgery, to determine whether pain, weakness, sling use, and narcotics correlate with self-assessed safety and maneuvering. Fifty-four patients (80.6% of those eligible) were surveyed 4 months after surgery. Return to driving ranged widely from same day to 4 months, with two not driving at 4 months; 12% reported narcotics use and 33% reported sling use. Drivers reporting weakness were more likely to feel unsafe (p = .02) and more likely to report difficulty maneuvering (p <.01). Drivers reporting pain were more likely to feel unsafe (p < .01) and more likely to report difficulty maneuvering their vehicle (p < .01). Patient-reported return to driving does not correspond to perceived safety; pain and weakness correspond with feeling unsafe and difficulty maneuvering. Although subjective, clinicians may find these self-assessments predictive when counseling patients on return to driving.