Plastic and elastic biomechanical properties of anterior cruciate ligament autografts.

BACKGROUND: Anterior cruciate ligament (ACL) rupture is a common orthopedic injury, occurring in roughly 68.6 per 100,000 persons annually, with the primary treatment option being ACL reconstruction. However, debate remains about the appropriate graft type for restoring the native biomechanical properties of the knee. Furthermore, plastic graft elongation may promote increased knee laxity and instability without rupture. This study aims to investigate the plastic properties of common ACL-R graft options. METHODS: Patellar tendon (PT), hamstring tendon (HT), and quadriceps tendon (QT) grafts were harvested from 11 cadaveric knees (6 male and 5 female) with a mean age of 71(range 55-81). All grafts were mechanically tested under uniaxial tension until failure to determine each graft's elastic and plastic biomechanical properties. RESULTS: Mechanically, the QT graft was the weakest, exhibiting the lowest failure force and the lowest failure stress (QT < HT, p = 0.032). The PT was the stiffest of the grafts, having a significantly higher stiffness (PT > QT, p = 0.0002) and Young's modulus (PT > QT, p = 0.001; PT > HT, p = 0.041). The HT graft had the highest plastic elongation at 4.01 ± 1.32 mm (HT > PT, p = 0.002). The post-yield behavior of the HT tendon shows increased energy storage capabilities with the highest plastic energy storage (HT > QT, p = 0.012) and the highest toughness (HT > QT, p = 0.032). CONCLUSION: Our study agrees with prior studies indicating that the failure load of all grafts is above the requirements for everyday activities. However, grafts may be susceptible to yielding before failure during daily activities. This may result in the eventual loss of functionality for the neo-ACL, resulting in increased knee laxity and instability.

Arthroscopic Bankart with remplissage results in lower rates of recurrent instability with similar range of motion compared to isolated arthroscopic Bankart for anterior glenohumeral instability: A systematic review and meta-analysis.

PURPOSE: The addition of the remplissage procedure to an arthroscopic Bankart procedure has been shown to improve clinical outcomes, yet at the expense of potentially decreasing shoulder range of motion. The purpose of this study was to assess recurrent instability, range of motion, functional outcomes and rates of return to sport outcomes in patients undergoing an isolated arthroscopic Bankart repair compared to those undergoing arthroscopic Bankart repair in addition to the remplissage procedure. METHODS: According to the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) guidelines, a search was conducted using three databases (MEDLINE/OVID, EMBASE and PubMed). Retrieved studies were screened based on predefined inclusion and exclusion criteria for comparative studies. Data were extracted and meta-analysis performed using a random-effects model. RESULTS: A total of 16 studies (13 level III studies, 2 level II studies and 1 level I) were included with a total of 507 and 704 patients in the Bankart plus remplissage and isolated Bankart repair groups, respectively. No studies reported glenoid bone loss of >20% with the least percentage of glenoid bone loss reported among studies being <1%. There was a significantly increased rate of recurrent dislocations (odds ratio [OR] = 4.22, 95% confidence interval [CI]: 2.380-7.48, p < 0.00001) and revision procedures (OR = 3.36, 95% CI: 1.52-7.41, p = 0.003) in the isolated Bankart repair group compared to the Bankart plus remplissage group. Additionally, there were no significant differences between groups in terms of external rotation at side (n.s.), in abduction (n.s.) or at forward flexion (n.s.) at final follow-up. Furthermore, return to preinjury level of sport favoured the Bankart plus remplissage group (OR = 0.54, 95% CI: 0.35-0.85, p = 0.007). CONCLUSION: Patients undergoing arthroscopic Bankart plus remplissage for anterior shoulder instability have lower rates of recurrent instability, higher rates of return to sport, and no significant difference in range of motion at final follow-up when compared to an isolated arthroscopic Bankart repair. Further large, prospective studies are needed to further determine which patients and degree of bone loss would benefit most from augmentation with the remplissage procedure. LEVEL OF EVIDENCE: Level III.

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.

Return to Sport After Anterior Cruciate Ligament Reconstruction Requires Evaluation of >2 Functional Tests, Psychological Readiness, Quadriceps/Hamstring Strength, and Time After Surgery of 8 Months.

PURPOSE: The purpose of this study was to examine the factors commonly used to determine readiness for return to sport (RTS) in the ACL reconstruction (ACL-R) patient population and assess which were most influential to successfully returning to sport and avoiding re-tear. METHODS: The PUBMED, EMBASE and Cochrane Library databases were queried for studies related to RTS in ACL-R. Inclusion and exclusion criteria were applied to identify studies with greater than 1-year outcomes detailing the rate of return and re-tear given a described RTS protocol. Data of interest were extracted, and studies were stratified based on level of evidence and selected study features. Meta-analysis or subjective synthesis of appropriate studies was used to assess more than 25 potentially significant variables effecting RTS and re-tear. RESULTS: After initial search of 1503 studies, 47 articles were selected for inclusion in the final data analysis, including a total of 1432 patients (31.4% female, 68.6% male). A meta-analysis of re-tear rate for included Level of Evidence 1 studies was calculated to be 2.8%. Subgroups including protocols containing a strict time until RTS, strength testing, and ≥2 dynamic tests demonstrated decreased RTS and re-tear heterogeneity from the larger group. Time to RTS, strength testing, dynamic functional testing, and knee stability were also found to be among the most prevalent reported criteria in RTS protocol studies. CONCLUSIONS: This study suggests a multifactorial clinical algorithm for successful evaluation of RTS. The "critical criteria" recommended by the authors to be part of the postoperative RTS criteria include time since surgery of 8 months, use of >2 functional tests, psychological readiness testing, and quadriceps/hamstring strength testing in addition to the modifying patient factors of age and female gender. LEVEL OF EVIDENCE: Level IV, systematic review of Level I-IV studies.

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.

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.

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.

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.

The Extensor Mechanism: Imaging and Intervention.

We present an overview of imaging and intervention of the extensor mechanism of the knee. Particular focus is placed on the evaluation of patellofemoral tracking disorders, patellar and quadriceps tendinosis and tears, patellar fracture, lateral patellar condyle patellar friction syndrome, and prepatellar bursitis. Anatomical and biomechanical factors contributing to these disorders are considered. Imaging evaluation is presented in a clinical context, and therapeutic options for these disorders are discussed. Image-guided therapy options for symptomatic patellar tendinosis are also described and illustrated.

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.

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.

Current Evidence Based Recommendations on Rehabilitation following Arthroscopic Shoulder Surgery: Rotator Cuff, Instability, Superior Labral Pathology, and Adhesive Capsulitis.

PURPOSE OF REVIEW: Arthroscopy has become increasingly popular for a addressing a wide variety of shoulder pathology. However, despite increasing interest, there is still much uncertainty and variability amongst providers regarding optimal post-operative rehabilitation. This review provides an overview of the evidence underlying common rehab protocols used following arthroscopic interventions for rotator cuff disease, shoulder instability, superior labral anterior to posterior (SLAP) tears and adhesive capsulitis. RECENT FINDINGS: For small and medium sized rotator cuff tears, early motion protocols do not seem to affect healing or retear rates, however there is no difference with regards to long term functional outcomes when compared to standard motion protocols. For larger tears (> 3 cm), early active motion may be associated with impaired tendon integrity. Early range of motion following arthroscopic Bankart repair has not been shown to increase rate of recurrence, however the data on return to sport requires more granularity to effectively guide care. Further research needs to be done to compare rehab protocols following SLAP repair and arthroscopic capsular release. Rehabilitation protocols following rotator cuff surgery and anterior shoulder stabilization have garnered the most research interest. However, there is still a need for larger higher-level studies examining the long-term effects of different rehab protocols. Regarding the arthroscopic management of other types of shoulder instability, SLAP tears and adhesive capsulitis, there is paucity of high-quality evidence. This knowledge gap likely underpins the variability in different rehab protocols seen in clinical practice, highlighting the need for more research.

A Passive Ankle Dorsiflexion Testing System for an In Vivo Model of Overuse-induced Tendinopathy.

Tendinopathy is a chronic tendon condition that results in pain and loss of function and is caused by repeated overload of the tendon and limited recovery time. This protocol describes a testing system that cyclically applies mechanical loads via passive dorsiflexion to the rat Achilles tendon. The custom-written code consists of pre- and post-cyclic loading measurements to assess the effects of the loading protocol along with the feedback control-based cyclic fatigue loading regimen. We used 25 Sprague-Dawley rats for this study, with 5 rats per group receiving either 500, 1,000, 2,000, 3,600, or 7,200 cycles of fatigue loads. The percentage differences between the pre- and post-cyclic loading measurements of the hysteresis, peak stress, and loading and unloading moduli were calculated. The results demonstrate that the system can induce varying degrees of damage to the Achilles tendon based on the number of loads applied. This system offers an innovative approach to apply quantified and physiological varying degrees of cyclic loads to the Achilles tendon for an in vivo model of fatigue-induced overuse tendon injury.