Tape-Reinforced Graft Suturing and Retensioning of Adjustable-Loop Cortical Buttons Improve Quadriceps Tendon Autograft Biomechanics in Anterior Cruciate Ligament Reconstruction: A Cadaveric Study.

PURPOSE: To investigate the biomechanical effects of tape-reinforced graft suturing and graft retensioning for all-soft tissue quadriceps tendon (ASTQT) anterior cruciate ligament reconstruction (ACLR) in a full-construct human cadaveric model. METHODS: Harvested cadaveric ASTQT grafts were assigned to either (1) double-suspensory adjustable-loop cortical button device (ALD) fixation in which both graft ends were fixed with a suspensory fixation device with (n = 5) or without (n = 5) tape-reinforced suturing or (2) single-suspensory distal tendon fixation in which only the patellar end was fixed with an ALD (n = 5) or fixed-loop cortical button device (FLD) (n = 5). All specimens were prepared using a No. 2 whipstitch technique, and tape-reinforced specimens had an integrated braided tape implant. Graft preparation time was recorded for double-suspensory constructs. Samples were tested on an electromechanical testing machine using a previously published protocol simulating rehabilitative kinematics and loading. RESULTS: Tape-reinforced graft suturing resulted in greater graft load retention after cycling (11.9% difference, P = .021), less total elongation (mean [95% confidence interval (CI)], 5.57 mm [3.50-7.65 mm] vs 32.14 mm [25.38-38.90 mm]; P < .001), greater ultimate failure stiffness (mean [95% CI], 171.9 N/mm [158.8-185.0 N/mm] vs 119.4 N/mm [108.7-130.0 N/mm]; P < .001), and less graft preparation time (36.4% difference, P < .001) when compared with unreinforced specimens. Retensioned ALD constructs had less cyclic elongation compared with FLD constructs (mean total elongation [95% CI], 7.04 mm [5.47-8.61 mm] vs 12.96 mm [8.67-17.26 mm]; P = .004). CONCLUSIONS: Tape-reinforced graft suturing improves time-zero ASTQT ACLR construct biomechanics in a cadaveric model with 83% less total elongation, 44% greater stiffness, and reduced preparation time compared with a whipstitched graft without tape reinforcement. ALD fixation improves construct mechanics when compared with FLD fixation as evidenced by 46% less total elongation. CLINICAL RELEVANCE: Tape-reinforced implants and graft retensioning using ALDs improve time-zero ACLR graft construct biomechanics in a time-zero biomechanical model. Clinical studies will be necessary to determine whether these implants improve clinical outcomes including knee laxity and the incidence of graft rupture.

Preoperative 3-dimensional computed tomography bone density measures provide objective bone quality classifications for stemless anatomic total shoulder arthroplasty.

BACKGROUND: Reproducible methods for determining adequate bone densities for stemless anatomic total shoulder arthroplasty (aTSA) are currently lacking. The purpose of this study was to evaluate the utility of preoperative computed tomography (CT) imaging for assessing the bone density of the proximal humerus for supportive differentiation in the decision making for stemless humeral component implantation. It was hypothesized that preoperative 3-dimensional (3-D) CT bone density measures provide objective classifications of the bone quality for stemless aTSA. METHODS: A 3-part study was performed that included the analysis of cadaveric humerus CT scans followed by retrospective application to a clinical cohort and classification with a machine learning model. Thirty cadaveric humeri were evaluated with clinical CT and micro-CT (µCT) imaging. Phantom-calibrated CT data were used to extract 3-D regions of interest and defined radiographic scores. The final image processing script was applied retrospectively to a clinical cohort (n = 150) that had a preoperative CT and intraoperative bone density assessment using the "thumb test," followed by placement of an anatomic stemmed or stemless humeral component. Postscan patient-specific calibration was used to improve the functionality and accuracy of the density analysis. A machine learning model (Support vector machine [SVM]) was utilized to improve the classification of bone densities for a stemless humeral component. RESULTS: The image processing of clinical CT images demonstrated good to excellent accuracy for cylindrical cancellous bone densities (metaphysis [ICC = 0.986] and epiphysis [ICC = 0.883]). Patient-specific internal calibration significantly reduced biases and unwanted variance compared with standard HU CT scans (P < .0001). The SVM showed optimized prediction accuracy compared with conventional statistics with an accuracy of 73.9% and an AUC of 0.83 based on the intraoperative decision of the surgeon. The SVM model based on density clusters increased the accuracy of the bone quality classification to 87.3% with an AUC of 0.93. CONCLUSIONS: Preoperative CT imaging allows accurate evaluation of the bone densities in the proximal humerus. Three-dimensional regions of interest, rescaling using patient-specific calibration, and a machine learning model resulted in good to excellent prediction for objective bone quality classification. This approach may provide an objective tool extending preoperative selection criteria for stemless humeral component implantation.

Two-Year Retrospective Patient-Reported Outcomes Following Superior Capsular Reconstruction.

PURPOSE: The purpose of this study was to evaluate the short-term patient-reported outcomes of superior capsular reconstruction (SCR) and identify factors contributing to the success or failure of the procedure at 2 years. METHODS: A retrospective review was performed on data prospectively collected from the Surgical Outcomes System database. Patient-reported outcomes (PROMs) including American Shoulder and Elbow Surgeons (ASES) score, Single Assessment Numeric Evaluation (SANE) score, visual analog scale for pain, and Veterans RAND 12-Item Health Survey (VR-12) were evaluated at a minimum of 2 years postoperatively and reported using a minimal clinically important difference (MCID) and the percent of maximal possible improvement (MPI). In addition, preoperative and intraoperative variables were evaluated in patients with and without a postoperative improvement in ASES and SANE scores meeting the threshold of MCID. RESULTS: Two-year follow-up data were available for 350 patients. Statistically significant improvements were noted in all PROMs at 2-year follow-up. In total, 240 patients (68.8%) achieved an MCID improvement of >17.5 in ASES score, and 185 patients (52.9%) achieved an MCID of >29.8 improvement in the SANE score. Primary SCRs were associated with a higher MPI in the ASES score (60.1% ± 39.8% vs 40.4% ± 47.9%; P = .025) and VR-12 physical score (14.0% ± 13.8% vs 8.0% ± 14.7%; P = .028) compared to revision repairs. Only diabetes was identified as a predictor of SANE score improvement (64.5% vs 62.2%; P = .041). CONCLUSIONS: SCR is associated with improvement in patient-reported outcomes at short-term follow-up, with 53% to 69% of patients achieving an improvement considered to meet the MCID. Greater improvement is expected when SCR is performed as a primary procedure rather than as a revision procedure for failed rotator cuff repair. LEVEL OF EVIDENCE: Level III, retrospective comparative study.

Independent Suture Augmentation With All-Inside Anterior Cruciate Ligament Reconstruction Reduces Peak Loads on Soft-Tissue Graft. A Biomechanical Full-Construct Study.

PURPOSE: To evaluate the effect of suture augmentation (SA) of 7-mm and 9-mm diameter graft on load sharing, elongation, stiffness, and load to failure for all-inside anterior cruciate ligament reconstruction (ACLR) in a biomechanical Study was funded by Arthrex ID: EMEA-16020. full-construct porcine model. METHODS: Bovine tendon grafts, 7-mm and 9-mm diameter, with and without SA were tested using suspensory fixation (n = 8). The independent SA was looped over a femoral button and knotted on a tibial button. Preconditioned constructs were incrementally increased loaded (100N/1,000 cycles) from 100N to 400N for 4,000 cycles (0.75 Hz) with final pull to failure (50 mm/min). Isolated mechanical and optical measurements during construct loading of the SA allowed to quantify the load and elongation range during load sharing. Construct elongation, stiffness and ultimate strength were further assessed. RESULTS: Load sharing in 7-mm grafts started earlier (200N) with a significant greater content than 9-mm grafts (300N) to transfer 31% (125N) and 20% (80N) of the final load (400N) over the SA. Peak load sharing with SA reduced total elongation for 7-mm (1.90 ± 0.27 mm vs 4.77 ± 1.08 mm, P < .001) and 9-mm grafts (1.50 ± 0.33 mm vs 3.57 ± 0.54 mm, P < .001) and adequately increased stiffness of 7-mm (113.4 ± 9.3 N/mm vs 195.9 ± 9.8 N/mm, P < .001) to the level of augmented 9-mm grafts (208.9 ± 13.7N/mm). Augmentation of 7-mm (835 ± 92N vs 1,435 ± 228N, P < .001) and 9-mm grafts (1,044 ± 49N vs 1,806 ± 157N, P < .001) significantly increased failure loads. CONCLUSIONS: Load sharing with SA occurred earlier (200N vs 300N) in lower stiffness 7-mm grafts to carry 31% (7-mm) and 20% (9-mm) of the final load (400N). Loads until peak load sharing were transferred over the graft. Augmented constructs showed significantly lower construct elongation and increased stiffness without significance between variable grafts. Failure load of augmented grafts were significantly increased. CLINICAL RELEVANCE: Suture tape ligament augmentation may potentially protect biological grafts from excessive peak loading and elongation, thus reducing the risk of graft tears.

Independent Suture Tape Reinforcement of Tripled Smaller-Diameter and Quadrupled Grafts for Anterior Cruciate Ligament Reconstruction With Tibial Screw Fixation: A Biomechanical Full Construct Model.

PURPOSE: To compare the effect of independent suture tape reinforcement on the dynamic elongation and stiffness behavior as well as ultimate strength of tripled smaller-diameter and quadrupled soft-tissue grafts for anterior cruciate ligament reconstruction (ACLR) with tibial screw fixation in a biomechanical in vitro study. METHODS: Tripled smaller-diameter (8 mm) and quadrupled (9 mm) bovine tendon grafts with and without suture tape reinforcement (n = 8 in each group) were tested using femoral suspensory and tibial interference screw fixation. The suture tape was femoral sided and fixed independent from the graft by passing it through the suspensory button and securing the 2 open tibial strands with a secondary interference screw. Dynamic testing was performed in position and force control at 250 N and 400 N, followed by pull to failure with the mode of failure noted. Dynamic elongation, stiffness, and ultimate strength were analyzed. RESULTS: Tripled constructs showed a significantly worse structural performance than quadrupled constructs at higher loads. Reinforcement of tripled and quadrupled grafts substantially decreased total elongation by 56% (4.54 ± 0.75 mm vs 2.01 ± 0.50 mm, P < .001) and 39% (3.25 ± 0.49 mm vs 1.98 ± 0.51 mm, P < .001), respectively, by significantly increasing dynamic stiffness. No statistical significance was found between the reinforced groups. Failure loads of reinforced tripled (1,074 ± 148 N vs 829 ± 100 N, P = .003) and quadrupled (1,125 ± 157 N vs 939 ± 76 N, P = .023) grafts were also significantly improved. CONCLUSIONS: Independent reinforcement of soft-tissue grafts with suture tape strengthened the performance especially of tripled smaller-diameter grafts for ACLR with tibial screw fixation by significantly improving dynamic elongation at increased stiffness and ultimate strength. Quadrupled reinforced grafts showed no over-constraining and structurally behaved similarly to tripled grafts with reinforcement. CLINICAL RELEVANCE: Independent reinforcement for ACLR may provide an option for protecting autografts or allografts against irreversible lengthening during the maturation and remodeling phases of healing.

Two-millimetre diameter operative arthroscopy of the ankle is safe and effective.

PURPOSE: Technical innovation now offers the possibility of 2-mm diameter operative arthroscopy: an alternative to conventional arthroscopy that no longer uses inner rod-lenses. The purpose of this study was to assess whether all significant structures in the ankle could be visualized and surgically reached during 2-mm diameter operative arthroscopy, without inflicting iatrogenic damage. METHODS: A novel, 2-mm diameter arthroscopic system was used to perform a protocolled arthroscopic procedure in 10 fresh-frozen, human donor ankles. Standard anteromedial and anterolateral portals were utilized. Visualization and reach with tailored arthroscopic instruments of a protocolled list of articular structures were recorded and documented. A line was etched on the most posterior border of the talar and tibial cartilage that was safely reachable. The specimens were dissected and distances between portal tracts and neurovascular structures were measured. The articular surfaces of talus and tibia were photographed and inspected for iatrogenic damage. The reachable area on the articular surface was calculated and analysed. RESULTS: All significant structures were successfully visualized and reached in all specimens. The anteromedial portal was not in contact with neurovascular structures in any specimen. The anterolateral portal collided with a branch of the superficial peroneal nerve in one case but did not cause macroscopically apparent harm. On average, 96% and 85% of the talar and tibial surfaces was reachable respectively, without causing iatrogenic damage. CONCLUSION: 2-mm diameter operative arthroscopy provides safe and effective visualization and surgical reach of the anterior ankle joint. It may hold the potential to make ankle arthroscopy less invasive and more accessible.

Intraoperative Preconditioning of Fixed and Adjustable Loop Suspensory Anterior Cruciate Ligament Reconstruction With Tibial Screw Fixation-An In Vitro Biomechanical Evaluation Using a Porcine Model.

PURPOSE: To evaluate the effect of preconditioning according to intraoperative workflow on initial tension and elongation behavior for femoral adjustable loop devices (ALDs) and closed loop devices (CLDs) in suspensory anterior cruciate ligament reconstruction (ACLR) with tibial screw fixation in a biomechanical in vitro study. METHODS: Three ACLR groups with tibial screw fixation were biomechanically tested in a full-construct setup using porcine tibias. Groups (n = 8 per group) varied by femoral fixation method and consisted of a CLD (group 3) and ALD fixation with (group 2) and without simulated intraoperative preconditioning (group 1). The change in tension after screw insertion and the displacement to restore the initial loading situation were measured. Grafts underwent dynamic cycling (1,000 cycles at 0.75 Hz) using both a position and a force control mode. RESULTS: Data are presented as mean [standard deviation]. Placement of an interference screw induced a graft tension loss of 62% (49.4 [0.4] N vs 19.0 [10.0] N, P < .001) by introducing a laxity of 0.53 [0.26] mm. Intraoperative preconditioning led to a higher initial load level (228.3 [19.8] N) compared with unconditioned ALD (156.1 [25.5] N, P < .001) and CLD groups (156.6 [12.8] N, P < .001) with less force decrease over position-controlled cyclic loading. Furthermore, initial (-0.22 [0.16] mm) and dynamic elongation (0.88 [0.23] mm) were reduced compared with the unconditioned ALD (0.65 [0.35] mm, P < .001; and 1.56 [0.19] mm, P < .001) and CLD groups (0.16 [0.26] mm, P < .001; and 1.64 [0.24] mm, P < .001). CONCLUSIONS: ACLR with femoral ALD fixation and intraoperative preconditioning allows for restoration of time-zero screw-imparted slack and leads to significantly reduced cyclic elongation in accordance with native ACL function. Both ALD and CLD control groups behaved similarly, with total elongation less than 3 mm including time-zero slack. CLINICAL RELEVANCE: Although the clinical relevance of time-zero graft tension loss is uncertain, the use of an ALD in concert with tibial screw fixation may be favorable to allow for tension optimization.

Independent Suture Tape Reinforcement of Small and Standard Diameter Grafts for Anterior Cruciate Ligament Reconstruction: A Biomechanical Full Construct Model.

PURPOSE: To compare the dynamic elongation, stiffness behavior, and ultimate failure load of standard with small diameter soft tissue grafts for anterior cruciate ligament (ACL) reconstruction with and without high-strength suture tape reinforcement. METHODS: Both a tripled "small" diameter and a "standard" quadrupled tendon graft with and without suture tape reinforcement were tested using suspensory fixation (n = 8 each group). The suture tape was passed through the suspensory fixation button on the femur and tibia to ensure independent (safety belt) fixation from the graft in vitro. The testing of the constructs included position-controlled cyclic loading, force-controlled cyclic loading at 250 N and 400 N as well as pull to failure (50 mm/min). RESULTS: Reinforcement of a small diameter graft significantly reduced dynamic elongation of 38% (1.46 ± 0.28 mm vs 2.34 ± 0.44 mm, P < .001) and 50% (2.55 ± 0.44 mm vs 5.06 ± 0.67 mm, P < .001) after the 250 N and 400 N load protocol, respectively. Reinforcement of a standard diameter tendon graft decreased dynamic elongation of 15% (1.59 ± 0.34 mm vs 1.86 ± 0.17 mm, P = .066) and 26% (2.62 ± 0.44 mm vs 3.55 ± 0.44 mm, P < .001). No significant difference was found between both reinforced models. The ultimate failure loads of small and standard diameter reinforced grafts were 1592 ± 105 N and 1585 ± 265 N, resulting in a 64% (P < .001) and 40% (P < .001) increase compared with their respective controls. CONCLUSIONS: Independent suture tape reinforcement of soft tissue grafts for ACL reconstruction leads to significantly reduced elongation and higher ultimate failure load according to in vivo native ACL function data without stress-shielding the soft tissue graft. CLINICAL RELEVANCE: If in vitro results are translational to human knees in vivo, the suture tape reinforcement technique for ACL reconstruction may decrease the risk of graft tears, particularly in the case of small diameter soft tissue grafts.

Intraoperative Workflow for All-Inside Anterior Cruciate Ligament Reconstruction: An In Vitro Biomechanical Evaluation of Preconditioning and Knot Tying.

PURPOSE: To evaluate and compare the effect of preconditioning according to intraoperative workflow on the elongation behavior of single-side and fully knotted all-inside anterior cruciate ligament (ACL) reconstruction configurations in a biomechanical in vitro study. METHODS: Four full construct all-inside ACL reconstruction groups (n = 8 per group) were tested using porcine tibias and bovine tendons. Groups included both an all-inside configuration with one- (group 1) and both-side knotted adjustable loop-length devices (group 2), without and with performing intraoperative preconditioning (group 1-intraoperative preconditioned [IPC], group 2-IPC). Adjustable loop-length devices for control groups were knotted according to test configurations. Intraoperative preconditioning specimens were further precycled for 10 times at 0.5 Hz and manually retensioned before knotting. All groups underwent dynamic cycling in position and force control mode each for 1,000 cycles at 0.75 Hz according to in vitro loading parameters replicating the in vivo ACL environment. Finally, a load-to-failure test at 50 mm/min was performed. RESULTS: Intraoperative preconditioning increases initial graft tension for single- (242 ± 22 N vs 174 ± 13 N; P < .0001) and both-side knotted configurations (225 ± 15 N vs 159 ± 10 N; P < .0001) compared with controls and allows maintained graft tension at higher levels until reaching the end of position-controlled cyclic loading. Furthermore, dynamic elongation is reduced for one- (1.93 ± 0.28 vs 0.76 ± 0.12; P < .0001) and both-side knotted (1.84 ± 0.20 vs 0.96 ± 0.32; P < .0001) configurations by 61% and 47%, respectively. No intergroup (group 1 vs group 2 and group 1-IPC vs group 2-IPC) statistically significant differences could be found between one- and both-side knotted configurations. CONCLUSIONS: All-inside ACL reconstruction with preconditioning according to intraoperative workflow leads to a statistically significant improved mechanical behavior and may allow for optimizing initial graft tension and elongation for all-inside ACL reconstruction to reduce knee laxity. A single-side knotted configuration achieves similar stabilization strength to fully knotted constructs. CLINICAL RELEVANCE: Graft insertion until tunnel docking increases the intratunnel graft portion that may optimize graft incorporation. Eliminating a suture knot stack may improve intraoperative workflow and reduce postoperative knot irritation.

Current state of unloading braces for knee osteoarthritis.

PURPOSE: Unicompartmental knee osteoarthritis (OA) is often treated with the prescription of an unloading knee brace to decrease pain and stiffness. Braces have been shown to improve the quality of life by applying an external moment to offset increased compressive tibiofemoral contact loads, but evidence regarding mechanical efficacy at the joint is controversial. Thus, the purpose of this study was to review the current state of unloading braces on knee mechanics, clinical impact, and long-term disease progression. METHODS: A literature search was performed through the PubMed MEDLINE database for the search terms "osteoarthritis," "knee," "brace," and derivatives of the keyword "unload." Articles published since January 1, 1980 were reviewed for their relevance. Evidence for the effectiveness of unloading braces for disease management both biomechanically and clinically was considered. RESULTS: While significant research has been done to show improvement in OA symptoms with the use of an unloading brace, current literature suggests a debate regarding the effectiveness of these braces for biomechanical change. Clinical findings reveal overall improvements in parameters such as pain, instability, and quality of life. CONCLUSION: Although clinical evidence supports brace use to improve pain and functional ability, current biomechanical evidence suggests that unloading of the affected knee compartment does not significantly hinder disease progression. LEVEL OF EVIDENCE: III.

High-load preconditioning of soft tissue grafts: an in vitro biomechanical bovine tendon model.

PURPOSE: No consensus exists regarding the optimal preconditioning protocol that will minimize postoperative elongation while creating a graft that is biomechanically equivalent to the native anterior cruciate ligament (ACL). It was hypothesized that a preconditioning protocol of specific mode and magnitude would create a graft with equivalent stiffness to the native ACL. METHODS: Thirty-six bovine extensor tendon grafts were randomly allocated among six preconditioning groups (n = 6 per group) including three cyclic (10 cycles at 0.5 Hz between 10-80, 100-300, and 300-600 N) and three static loading protocols (20 s at 80, 300, and 600 N). Grafts were then cyclically loaded between 50 and 250 N at 0.5 Hz for 500 cycles to simulate an early rehabilitation protocol. RESULTS: Cyclic 300-600 N and static 600 N loading protocols both demonstrated significantly less elongation during simulated rehabilitation when compared to lower, current clinical standard preconditioning levels of 10-80 N (-62% Δ) and 80 N (-69% Δ). The same high-load preconditioning protocols demonstrated statistical equivalence in stiffness when compared to the previously reported stiffness of the native ACL. CONCLUSIONS: In this experimental model, increased force applied to soft tissue grafts during preconditioning significantly decreased the subsequent elongation experienced during simulated early rehabilitation. A static load of 600 N removed the most graft elongation during preconditioning, had the least amount of cyclic displacement during simulated early rehabilitation, and was statistically equivalent to the native ACL stiffness. Implementation of high-load preconditioning of soft tissue grafts may help improve outcomes following ACL reconstruction by reducing residual knee laxity resulting from postoperative graft elongation and the intrinsic viscoelastic properties of the graft tissue while imparting biomechanical characteristics (e.g. stiffness) equivalent to the native ACL.

Lack of consensus regarding pretensioning and preconditioning protocols for soft tissue graft reconstruction of the anterior cruciate ligament.

PURPOSE: Pretensioning and preconditioning of soft tissue grafts are often performed to obviate graft stress relaxation and elongation due to viscoelastic graft properties following anterior cruciate ligament (ACL) reconstruction. It was hypothesized that a consensus could be identified in the current literature regarding the biomechanical effects and clinical benefits of an optimal protocol. METHODS: A systematic electronic literature search was performed by two independent reviewers to identify relevant publications. Only studies describing and/or comparing pretensioning or preconditioning protocols of soft tissue grafts or equivalent animal research models were eligible for inclusion. Study design, graft type, and protocol, including method, magnitude, mode (cyclic and/or static loading), and duration of load application, were compared. Research results and clinical conclusions were also evaluated for each study. RESULTS: Five studies, including four in vitro biomechanical investigations and one histological analysis of patient tissue, met the predefined criteria for inclusion. Studies described numerous pretensioning and/or preconditioning protocols with varying force, time, and application modalities for multiple soft tissue graft types and animal models. The majority of studies (80 %) utilized at least one pretensioning or preconditioning protocol between 80 and 89 N, while only one study investigated substantially higher loads (500 N). CONCLUSIONS: Despite common trends demonstrating the effects of pretensioning and preconditioning, no clear consensus regarding an optimal protocol, magnitude, or modality could be identified within the currently available relevant literature. Further multidisciplinary research is required before an optimal or consensus protocol can be established for soft tissue ACL reconstruction. Regardless, the current biomechanical literature demonstrates the potential clinically beneficial effects of pretensioning and preconditioning, including reduced graft elongation and greater preservation of graft tension and stiffness following fixation. LEVEL OF EVIDENCE: Systematic review, Level II.

Quantification of functional brace forces for posterior cruciate ligament injuries on the knee joint: an in vivo investigation.

PURPOSE: Counteracting posterior translation of the tibia with an anterior force on the posterior proximal tibia has been demonstrated clinically to improve posterior knee laxity following posterior cruciate ligament (PCL) injury. This study quantified forces applied to the posterior proximal tibia by two knee braces designed for treatment of PCL injuries. METHODS: The forces applied by two knee braces to the posterior proximal tibia and in vivo three-dimensional knee kinematics of six adult, male, healthy volunteer subjects (mean ± standard deviation: height, 182.5 ± 5.2 cm; body mass, 83.2 ± 9.3 kg; body mass index, 24.9 ± 1.5 kg/m(2); age, 25.8 ± 2.9 years) were measured using a custom pressure mapping technique and traditional surface marker motion capture techniques, while subjects performed three functional activities. The activities included seated unloaded knee flexion, squatting, and stair descent in a new generation dynamic force (DF) PCL brace and a static force (SF) PCL brace. RESULTS: During unloaded flexion at the lowest force level setting, the force applied by the DF brace increased as a function of flexion angle (slope = 0.7 N/°; p < 0.001) compared to the SF brace effect. Force applied by the SF brace did not significantly change as a function of flexion angle (slope = 0.0 N/°; n.s.). By 45° of flexion, the average force applied by the DF brace (48.1 N) was significantly larger (p < 0.001) than the average force applied by the SF brace (25.0 N). The difference in force continued to increase as flexion angle increased. During stair descent, average force (mean ± standard deviation) at toe off was significantly higher (p = 0.013) for the DF brace (78.7 ± 21.6 N) than the SF brace (37.3 ± 7.2 N). Similar trends were observed for squatting and for the higher force level settings. CONCLUSIONS: The DF brace applied forces to the posterior proximal tibia that dynamically increased with increased flexion angle. Additionally, the DF brace applied significantly larger forces at higher flexion angles compared to the SF brace where the PCL is known to experience larger in situ forces. Clinical studies are necessary to determine whether the loading characteristics of the DF brace, which more closely replicated the in situ loading profile of the native PCL, results in long-term improved posterior knee laxity following PCL injury. LEVEL OF EVIDENCE: II.

Biomechanical consequences of proximal biceps tenodesis stitch location: musculotendinous junction versus tendon only.

PURPOSE: The purpose of this study was to determine the biomechanical effects of placing the biceps tenodesis stitch at the musculotendinous junction versus in the tendon only. Placing the stitch at the musculotendinous junction was hypothesized to result in a significantly weaker repair than stitching in the tendon only. METHODS: Testing was performed on two groups of six matched pairs of long head of the biceps (LHB) with enclosed musculotendinous junction and muscle belly. Specimens were randomly distributed between two groups. The same baseball whipstitch configuration was performed using the same suture material in both groups. In group 1, the stitch configuration started 1 cm proximal of the musculotendinous junction (tendon tissue only). For contralateral specimens, the baseball whipstitching included the distal 1 cm of the musculotendinous junction. Specimens were pulled to failure at a rate of 60 mm/min. Ultimate failure load and failure pattern were recorded. RESULTS: Average ultimate failure load of group 2 was significantly higher than group 1 (mean increase 18.6 %, range -9.7 to 35.8 %; p = 0.046). A cut-through failure pattern was observed for all specimens in both groups. There were highly significant correlations between ultimate failure load and tendon thickness (p = 0.004, τ = 0.636), age of the specimen (p = 0.002, τ = 0.724), and gender (p = 0.004, τ = -0.739). No significant difference between the groups regarding tendon diameter was observed. CONCLUSIONS: Baseball whipstitching of the LHB including the distal part of the tendon and the musculotendinous junction was stronger than sutures placed in the tendon alone. These results suggest that suture pattern affects initial strength of repair, and therefore may affect decisions regarding early post-operative rehabilitation or ultimate clinical outcomes. Inclusion of the musculotendinous junction should be considered clinically for improved time zero strength of the repair construct.

A quantitative analysis of hip capsular thickness.

PURPOSE: The purpose of this study was to provide a comprehensive quantitative analysis of capsular thickness adjacent to the acetabular rim in clinically relevant locations. METHODS: Dissections were performed and hip capsular measurements were recorded on 13 non-paired, fresh-frozen cadaveric hemi-pelvises using a coordinate measuring device. Measurements were taken for each clock-face position at 0, 5, 10 and 15 mm distances from the labral edge. RESULTS: The capsule was consistently thickest at 2 o'clock for each interval from the labrum with a maximum thickness of 8.3 at 10 mm [95 % CI 6.8, 9.8] and 15 mm [95 % CI 6.8, 9.7]. The capsule was noticeably thinner between 4 and 11 o'clock with a minimum thickness of 4.1 mm [95 % CI 3.3, 4.9] at 10 o'clock at the labral edge. Direct comparison between 0 and 5 mm between 9 and 3 o'clock showed that the hip capsule was significantly thicker at 5 mm from the labrum at 9 o'clock (p = 0.027), 10 o'clock (p = 0.032), 1 o'clock (p = 0.003), 2 o'clock (p = 0.001) and 3 o'clock (p = 0.001). CONCLUSIONS: The hip capsule was thickest between the 1 and 2 o'clock positions for all measured distances from the acetabular labrum and reached its maximum thickness at 2 o'clock, which corresponds to the location of the iliofemoral ligament.

Iatrogenic injury of the anterior meniscal root attachments following anterior cruciate ligament reconstruction tunnel reaming.

PURPOSE: To determine whether reaming of anterior cruciate ligament (ACL) reconstruction tibial tunnels with a 10-mm-diameter reamer would result in injury to the anterior roots of the medial and lateral menisci in an in vitro model when using a tibial aiming device at two settings (40° and 60°). METHODS: Three-dimensional footprints of the ACL and the anterior roots of the menisci were measured for 12 human cadaveric tibias. Measurements were taken before and after attempted reaming of an ACL tibial reconstruction tunnel in the calculated ACL centre using a tibial aiming device set at two angles (40° and 60°). RESULTS: Iatrogenic injury to the anterior root of the medial meniscus caused by overlap with the reamed tibial tunnel was found in 3/6 specimens in Group 1 (40°) and 0/6 specimens in Group 2 (60°). The average area of iatrogenic injury in Group 1 was 9.6 mm(2) (8.6 % of the root). There was iatrogenic injury to the anterior root of the lateral meniscus in 4/6 specimens for both groups. The average area of iatrogenic injury was 20.5 mm(2) (28.8 %) for Group 1 and 16.2 mm(2) (25.9 %) for Group 2. CONCLUSIONS: Reaming of ACL tibial reconstruction tunnels carries a risk of iatrogenic injury to the anterior meniscus roots, even when tunnels are reamed based on guide pin placement in the calculated centre of the ACL. Reaming at varying tibial aiming device angle settings can affect the obliquity of the tunnel aperture and cause iatrogenic injury to the anterior meniscal roots. Caution should be exercised clinically to avoid iatrogenic injury to both the anterior meniscal roots while reaming tibial tunnels during ACL reconstructions.

A qualitative and quantitative analysis of the attachment sites of the proximal hamstrings.

PURPOSE: Proximal hamstring tears represent a challenge. Surgical repair of such tears has been reported utilizing both open and endoscopic techniques. It was hypothesized that the proximal attachments of the hamstring muscle group could be reproducibly and consistently measured from pertinent bony anatomical reference landmarks. METHODS: Fourteen fresh-frozen, human cadaveric specimens were dissected, and measurements were taken regarding the proximal attachments of the hamstring muscle group in reference to bony landmarks. A highly precise coordinate measuring device was used for three-dimensional measurements of tendon footprints and bony landmarks, and relevant distances between structures were calculated. RESULTS: The semitendinosus and long head of the biceps femoris shared a proximal origin (conjoined tendon), having an oval footprint with an average area of 567.0 mm(2) [95 % CI 481.0-652.9]. The semimembranosus (SM) footprint was crescent-shaped and located anterolateral to the conjoined tendon, with an average area of 412.4 mm(2) [95 % CI 371.0-453.8]. The SM footprint had an accessory tendinous extension that extended anteromedially forming a distinct footprint. A consistent bony landmark was found at the medial ischial margin, 14.6 mm [95 % CI 12.7-16.5] from the centre of the conjoined tendon footprint, which coincided with the distal insertion of the sacrotuberous ligament. CONCLUSION: The conjoined tendon was the largest attachment of the proximal hamstring group. Two other distinct attachment footprints were identified as the SM footprint and the accessory tendinous extension. The sacrotuberous ligament insertion served as a bony landmark. The anatomical data established in this study may aid in better restoring the anatomy during repair of proximal hamstring tears.

Biomechanical evaluation of internal fixation techniques for unstable meso-type os acromiale.

BACKGROUND: Several internal fixation surgical techniques have been described for the treatment of symptomatic os acromiale. The purpose of this study was to compare the biomechanical characteristics of different internal fixation techniques for the operative treatment of unstable meso-type os acromiale in a cadaveric model. METHODS: Testing was performed on 12 matched pairs of cadaveric acromia with simulated meso-type os acromiale. Twelve specimens were prepared with 2 cannulated 4.0-mm screws only (SO group), inserted in the anterior-posterior direction. Contralateral specimens were repaired with screws and a tension band (TB group). An inferiorly directed load to the anterior acromion was applied at a rate of 60 mm/min until failure. Ultimate failure load, stiffness, and fracture pattern were recorded and analyzed. RESULTS: Ultimate failure load was significantly higher for the TB group (mean, 336 N ± 126 N; range, 166-623 N; P = .01) than for the SO group (mean, 242 N ± 57 N; range, 186-365 N). In contrast, no significant difference in stiffness was found between the SO group (mean, 22.1 N/mm ± 4.7 N/mm; range, 13.0-33.3 N/mm; P = .94)) and the TB group (mean, 22.2 N/mm ± 2.9 N/mm; range, 18.2-26.6 N/mm). CONCLUSION: Surgical repair of simulated unstable meso-type os acromiale by a combination of cannulated screws with a tension band leads to significantly higher repair strength at time zero in a cadaveric model compared with cannulated screws alone.

The ability of massive osteochondral allografts from the medial tibial plateau to reproduce normal joint contact pressures after glenoid resurfacing: the effect of computed tomography matching.

BACKGROUND: Current techniques for resurfacing of the glenoid in the treatment of arthritis are unpredictable. Computed tomography (CT) studies have demonstrated that the medial tibial plateau has close similarity to the glenoid. The purpose of this study was to assess contact pressures of transplanted massive tibial osteochondral allografts to resurface the glenoid without and with CT matching. METHODS: Ten unmatched cadaveric tibiae were used to resurface 10 cadaveric glenoids with osteochondral allografts. Five cadaveric tibiae and glenoids were CT matched and studied. An internal control group of 4 matched pairs of glenoids, with the contralateral glenoid transplanted to the opposite glenoid, was also included as a best-case scenario to measure the effects of the surgical technique. All glenoids were tested before and after grafting at different abduction and rotation angles, with recording of peak contact pressures. RESULTS: Peak contact pressures were not different from the intact state in the autografted group but were increased in both allografted groups. CT-matched tibial grafts had lower peak pressures than unmatched grafts. Peak pressures were on average 24.8% (range [18.3%, 29.6%]) greater than in the native glenoids for unmatched allografts, 21.8% ([17.0%, 25.5%]) greater for the matched allografts, and 4.9% ([3.8%, 5.5%]) greater for matched autografts. CONCLUSION: Osteochondral grafting from the medial tibial plateau to the glenoid is feasible but results in increased peak contact pressures. The technique is reproducible as defined by the autografted group. Contact pressures between native and allografted glenoids were significantly different. The clinical significance remains unknown. Peak pressures experienced by the glenoid seem highly sensitive to deviations from the native glenoid shape.

Epidemiology, identification, treatment and return to play of musculoskeletal-based ice hockey injuries.

UNLABELLED: Ice hockey is a high contact sport where players are inherently at an increased risk for traumatic and time-loss injury. With its increasing popularity and high incidence of injury, further research is necessary to understand the risks and injuries associated with the sport and to develop performance-based outcome measures to guide return to play. This review, tailored to the practicing sports medicine team physician, focuses on the stepwise identification, treatment, time loss, return to play and subsequent risk of injury for the most common areas of injury: the head, shoulder, hip and knee. Injuries were categorised into upper and lower extremity with an emphasis on glenohumeral and acromioclavicular joint injuries, femoroacetabular impingement, medial collateral ligament tears, and high ankle sprains. With return to play a primary goal for these high-level athletes, recovery in ice hockey becomes a complex issue with efficient protocols tailored to the requirements of the sport vital to the athlete and clinician alike. By reviewing the treatments and sport-specific care, athletes can be better managed with the ultimate goal of returning to their preinjury level of play. LEVEL OF EVIDENCE: Level IV.