A Machine Learning Model Demonstrates Excellent Performance in Predicting Subscapularis Tears Based on Pre-Operative Imaging Parameters Alone.

PURPOSE: To develop a machine learning model capable of identifying subscapularis tears before surgery based on imaging and physical examination findings. METHODS: Between 2010 and 2020, 202 consecutive shoulders underwent arthroscopic rotator cuff repair by a single surgeon. Patient demographics, physical examination findings (including range of motion, weakness with internal rotation, lift/push-off test, belly press test, and bear hug test), and imaging (including direct and indirect signs of tearing, biceps status, fatty atrophy, cystic changes, and other similar findings) were included for model creation. RESULTS: Sixty percent of the shoulders had partial or full thickness tears of the subscapularis verified during surgery (83% of these were upper third). Using only preoperative imaging-related parameters, the XGBoost model demonstrated excellent performance at predicting subscapularis tears (c-statistic, 0.84; accuracy, 0.85; F1 score, 0.87). The top 5 features included direct signs related to the presence of tearing as evidenced on magnetic resonance imaging (MRI) (changes in tendon morphology and signal), as well as the quality of the MRI and biceps pathology. CONCLUSIONS: In this study, machine learning was successful in predicting subscapularis tears by MRI alone in 85% of patients, and this accuracy did not decrease by isolating the model to the top features. The top five features included direct signs related to the presence of tearing as evidenced on MRI (changes in tendon morphology and signal), as well as the quality of the MRI and biceps pathology. Last, in advanced modeling, the addition of physical examination or patient characteristics did not make a significant difference in the predictive ability of this model. LEVEL OF EVIDENCE: Level III, diagnostic case-control study.

Meniscal extrusion consensus statement: A collaborative survey within the Meniscus International Network (MenIN) Study Group.

PURPOSE: The purpose of the present study was to perform a survey administered to members of the Meniscus International Network (MenIN) Study Group, seeking to delineate the most contentious aspects of meniscal extrusion classification and provide a foundation for new, more comprehensive definitions and treatments for these pathologies. METHODS: MenIN Study Group is a group of international experts treating and performing research on meniscus pathology and treatment. All MenIN Study Group members were asked to complete a survey aimed at establishing criteria for the optimal classification system for meniscal extrusion. Data obtained from the completed questionnaires were transferred into a spreadsheet and then analysed. All responses are presented as counts, percentages or means. RESULTS: Forty-seven (85.5%) MenIN Study Group members completed the survey and were included in this analysis. Key aspects recommended for inclusion in a comprehensive classification system for meniscal extrusion included laterality (93.6%), anatomical location (76.6%), patient age (76.6%), body mass index (BMI) (68.1%) and aetiology (68.1%). For classifying meniscal extrusion, 53.2% considered the distance in millimetres from the tibial plateau's outer margin as the most reliable measurement technique on imaging. Preferences for imaging modalities varied, with 44.7% favouring weight-bearing magnetic resonance imaging (MRI) and 36.2% opting for weight-bearing ultrasound due to its greater availability. Respondents advocated for a classification system addressing stability or progression of meniscal extrusion (66%), reducibility (53.2%), potential progression of knee osteoarthritis (OA) (83%), influencing treatment approaches (83%), a gradation system (83%), consideration of dynamic factors (66%), association with clinical outcomes and prognosis (76.6%) and investigation around centralization procedures (57.4%). CONCLUSIONS: In conclusion, the findings of this survey shed light on the global perspectives regarding meniscal extrusion classification. It was generally felt that a new classification of extrusion measured on MRI scans at the mid-tibial plateau should be developed, which considers factors such as laterality, anatomical location, age, BMI and aetiology. Additionally, the results support the integration of dynamic factors and clinical outcomes in MRI-based classifications to inform treatment approaches. LEVEL OF EVIDENCE: Level IV.

Increased risk for early revision with quadriceps graft compared with patellar tendon graft in primary ACL reconstructions.

PURPOSE: Bone patella-tendon bone (BPTB) and hamstring tendon (HT) autografts are the most used grafts in primary anterior cruciate ligament (ACL) reconstructions (ACLR) in Norway. Quadriceps tendon (QT) autograft has gained more popularity during the past years. The purpose of this study is to compare revision rates and patient-reported outcomes of primary QT with BPTB and HT autograft ACL reconstructions in Norway at 2-year follow-up. It was hypothesized that there would be no difference in 2-year revision rates between all three autografts. METHODS: Data included primary ACLR without concomitant ligament surgeries, registered in the Norwegian Knee Ligament Register from 2004 through 2021. Revision rates at 2 years were calculated using Kaplan-Meier analysis. Hazard ratios (HR) for revision were estimated using multivariable Cox regression analysis with revision within 2 years as endpoint. Mean change in patient-reported outcome was recorded preoperatively and at 2 years through the Knee Injury and Osteoarthritis Outcome Score (KOOS) subcategories 'Sport' and 'Quality of Life' was measured for patients that were not revised and analysed with multiple linear regression. RESULTS: A total of 24,790 primary ACLRs were identified, 10,924 with BPTB, 13,263 with HT and 603 with a QT graft. Patients in the QT group were younger (23.5 years), more of them were women (58.2%) and over 50% had surgery <3 months after injury. The QT group had the highest prevalence of meniscal injuries (61.9%). Revision estimates at 2-years were 3.6%, 2.5% and 1.2% for QT, HT and BPTB, respectively (p < 0.001). In a Cox regression analysis with QT as reference, BPTB had a lower risk of revision (HR 0.4, 95% Cl 0.2-0.7, p < 0.001). No significant difference was observed in the revision risk between QT and HT (HR 1.1, 95% Cl 0.7-1.8, n.s.). The two most common reported reasons for revision were: traumatic graft rupture and nontraumatic graft failure. There were no differences between the groups in change of KOOS in subcategories 'Sport' and 'Quality of Life' at 2-years follow-up. CONCLUSION: The 2-year risk of revision after ACLR with QT was higher than BPTB and similar to HT. No difference was found between the groups in patient-reported outcomes. This study provides valuable insights for both surgeons and patients when making decisions about the choice of autografts in primary ACL reconstructions. LEVEL OF EVIDENCE: Level II.

Functional anterior cruciate ligament braces may have a role in select patient groups although there is presently limited evidence supporting or refuting their routine use: A scoping review of clinical practice guidelines and an updated bracing classification.

PURPOSE: The purpose of this study was to perform a scoping review of clinical practice guidelines (CPGs) concerning the use of functional anterior cruciate ligament (ACL) braces and to clarify the nomenclature for bracing relevant to ACL injury treatment in order to support prescribing clinicians. METHODS: A PubMed search for CPGs for the use of braces following ACL injury or reconstruction was performed. CPGs on the treatment of ACL injuries with sufficient attention to postoperative braces were included in this scoping review. The references used for supporting the specific CPG recommendations were reviewed. Specific indications for brace use including brace type, period of use following surgery and activities requiring brace use were collected. RESULTS: Six CPGs were identified and included this this review. Three randomised trials provided the evidence for recommendations on functional brace use following ACL reconstruction in the six CPGs. Functional ACL braces were the primary focus of the three randomised trials, although extension braces (postoperative knee immobilisers) were also discussed. A novel dynamic ACL brace category has been described, although included CPGs did not provide guidance on this brace type. CONCLUSIONS: Guidance on the use of functional ACL braces following ACL reconstruction is provided in six CPGs supported by three randomised trials. However, the brace protocols and patient compliance in the randomised trials render these CPGs inadequate for providing guidance on the use of functional ACL braces in the general and high-risk patient populations when returning to sport after ACL reconstruction. Functional ACL braces are commonly utilised during the course of ACL injury treatment although there is presently limited evidence supporting or refuting the routine use of these braces. Future studies are, therefore, necessary in order to provide guidance on the use of functional and dynamic ACL braces in high-risk patient populations. LEVEL OF EVIDENCE: Level II.

External validation of the Norwegian anterior cruciate ligament reconstruction revision prediction model using patients from the STABILITY 1 Trial.

PURPOSE: A machine learning-based anterior cruciate ligament (ACL) revision prediction model has been developed using Norwegian Knee Ligament Register (NKLR) data, but lacks external validation outside Scandinavia. This study aimed to assess the external validity of the NKLR model (https://swastvedt.shinyapps.io/calculator_rev/) using the STABILITY 1 randomized clinical trial (RCT) data set. The hypothesis was that model performance would be similar. METHODS: The NKLR Cox Lasso model was selected for external validation owing to its superior performance in the original study. STABILITY 1 patients with all five predictors required by the Cox Lasso model were included. The STABILITY 1 RCT was a prospective study which randomized patients to receive either a hamstring tendon autograft (HT) alone or HT plus a lateral extra-articular tenodesis (LET). Since all patients in the STABILITY 1 trial received HT ± LET, three configurations were tested: 1: all patients coded as HT, 2: HT + LET group coded as bone-patellar tendon-bone (BPTB) autograft, 3: HT + LET group coded as unknown/other graft choice. Model performance was assessed via concordance and calibration. RESULTS: In total, 591/618 (95.6%) STABILITY 1 patients were eligible for inclusion, with 39 undergoing revisions within 2 years (6.6%). Model performance was best when patients receiving HT + LET were coded as BPTB. Concordance was similar to the original NKLR prediction model for 1- and 2-year revision prediction (STABILITY: 0.71; NKLR: 0.68-0.69). Concordance 95% confidence interval (CI) ranged from 0.63 to 0.79. The model was well calibrated for 1-year prediction while the 2-year prediction demonstrated evidence of miscalibration. CONCLUSION: When patients in STABILITY 1 who received HT + LET were coded as BPTB in the NKLR prediction model, concordance was similar to the index study. However, due to a wide 95% CI, the true performance of the prediction model with this Canadian and European cohort is unclear and a larger data set is required to definitively determine the external validity. Further, better calibration for 1-year predictions aligns with general prediction modelling challenges over longer periods. While not a large enough sample size to elicit the true accuracy and external validity of the prediction model when applied to North American patients, this analysis provides more support for the notion that HT plus LET performs similarly to BPTB reconstruction. In addition, despite the wide confidence interval, this study suggests optimism regarding the accuracy of the model when applied outside of Scandinavia. LEVEL OF EVIDENCE: Level 3, cohort study.

Diagnosis and treatment strategies of the multiligament injured knee: a scoping review.

OBJECTIVE: To map the current literature evaluating the diagnosis and treatment of multiligament knee injuries (MLKIs). DESIGN: Scoping review. DATA SOURCES: Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for scoping reviews and Arksey and O'Malley frameworks were followed. A three-step search strategy identified relevant published literature comprising studies reporting on at least one aspect in the diagnosis or treatment of MLKI in adults. Data were synthesised to form a descriptive analysis and thematic summary. RESULTS: Overall, 417 studies were included. There was a substantial chronological increase in the number of studies published per year, with 70% published in the last 12 years. Of included studies, 128 (31%) were narrative reviews, editorials or technical notes with no original data. The majority of studies (n=239, 57%) originated from the USA; only 4 studies (1%) were of level I evidence. Consistent themes of contention included clinical assessment, imaging, operative strategy, timing of surgery and rehabilitation. There was a lack of gender and ethnic diversity reported within patient groups. CONCLUSIONS: There remains insufficient high-level evidence to support definitive management strategies for MLKI. There is considerable heterogeneity in outcome reporting in current MLKI literature, precluding robust comparison, interpretation and pooling of data. Further research priorities include the development of expert consensus relating to the investigation, surgical management and rehabilitation of MLKI. There is a need for minimum reporting standards for clinical studies evaluating MLKI.

International cooperation needed to improve national anterior cruciate ligament registries.

PURPOSE: The aim of this study is to illustrate an overview of the registries currently operative in many countries to support the introduction of new prospective registries in other countries. METHODS: The authors carried out a systematic web research in July 2021 to identify national ACL registries' annual reports and scientific literature on national ACL registries. The latest annual public registry reports were collected and analyzed in this study. RESULTS: There are currently established national ACL registries in Norway, Denmark, Sweden, Luxembourg, New Zealand, the United Kingdom (UK), and the Kaiser Permanente National Anterior Cruciate Ligament Reconstruction Registry in the United States (US). Some differences can be found among the various registries due to the local healthcare system structure, data management rules, and general national laws. CONCLUSION: It is possible to develop accessible, cost-effective and entirely web-based ACL registries-as demonstrated by the Danish and Swedish registries-respecting the national legislation of different countries. This study supports the introduction of new ACL prospective registries in other countries to obtain valuable information for implementing daily clinical practice. LEVEL OF EVIDENCE: IV.

Low rates of serious complications after open Latarjet procedure at short-term follow-up.

PURPOSE: To report on intraoperative and short-term postoperative adverse events after open Latarjet procedure in patients with recurrent anterior shoulder instability. These complications were classified into different grades of severity based on the treatment required and the learning curve of the procedure. METHODS: Ninety-six patients (102 shoulders) underwent open Latarjet procedure for recurrent post-traumatic anterior glenohumeral instability between 2012 and 2020. The minimum duration of patients' follow-up was 6 months. Adverse events were classified into 3 classes based on the severity and subsequent treatment. The complications in the first 50% of all cases were compared with the latter 50% to evaluate the role of learning curve on the complication rates. RESULTS: The mean follow-up was 7.2 ± 2.8 months. The patients' mean age was 26.7 ± 8.9 years and consisted of 83 (86.4%) male and 13 (13.6%) female patients. The total adverse events rate was 18.6%. Adverse events requiring no additional treatment (class 1) occurred in 6 cases (5.8%) including fibrous union (3.9%) and asymptomatic resorption of the graft (1.9%). Adverse events requiring additional or extended nonoperative management (class 2) occurred in 8 cases (7.8%), including coracoid fracture (2.9%), musculocutaneous nerve palsy (1.9%), axillary nerve palsy (0.9%), suprascapular nerve palsy (0.9%), and stiffness (0.9%). All the nerve palsies recovered without long-term sequelae. Adverse events requiring secondary operative procedures (class 3) occurred in 5 cases (4.9%), including symptomatic hardware (1.9%), medial healing of the graft (0.9%), screw loosening (0.9%), and deep infection (0.9%). The rate of adverse events in revision cases was higher than primary cases in 11.7% and 6.8%, respectively (P = .119). The complication rate was significantly higher in the first half of the surgeons' practice (14.7%) than in the second half (3.9%) (P ≤ .05). CONCLUSIONS: The overall complication rate reported in this open Latarjet series is 18.6%; however, the rate of class 3 adverse events that required additional surgery or long-term medical treatment was only 4.9%. Revision cases had a higher rate of complications than primary cases, and the learning curve has had a significant impact on the rate of adverse events.

Learning Curve for Arthroscopic Shoulder Latarjet Procedure Shows Shorter Operating Time and Fewer Complications with Experience.

PURPOSE: To evaluate the learning curve of the arthroscopic Latarjet procedure in a consecutive series of 103 shoulders in 102 patients by comparing the early clinical and radiologic outcomes and complications of the first 25 patients with the latter 25 patients. Our hypothesis was that the studied parameters would be enhanced over time. METHODS: A consecutive cohort of 103 shoulders in 102 patients treated with arthroscopic Latarjet procedure was prospectively registered from December 2014 until November 2019. Patients in this cohort represent the first cases of arthroscopic Latarjet for the 2 shoulder surgeons. All patients had a double screw fixation technique. The Western Ontario Shoulder Instability Index (WOSI) score preoperatively and at 1-year follow-up and 3-dimensional computed tomography scans preoperatively, postoperatively, and at 1-year follow-up were prospectively registered. Patient demographics, intraoperative data, complications, and reoperations were all recorded. In total, 85 of 103 shoulders (83%) had complete data sets. Patient demographics, WOSI scores, operating time, complications, satisfaction rate, and radiology scores in the first and last 25 patients were compared to evaluate learning curve. RESULTS: There was longer operating time in the early group compared with the latter (130 vs 105 minutes, P = .001) and number of complications was reduced with experience (16 vs 4, P = .0005). Serious complications requiring a reoperation were 4 (16%) in the early group compared to 1 (4%) in the latter group (P = .157). Clinical results were good with major improvement in WOSI scores and 84 % satisfaction rates in both groups. CONCLUSIONS: Arthroscopic Latarjet was associated with a learning curve where the early group had longer operating time and greater rates of complications. This is a procedure with few serious complications, acceptable surgery time and learning curve. LEVEL OF EVIDENCE: Level III, retrospective comparative observation trial.

Low annual hospital volume of anterior cruciate ligament reconstruction is not associated with higher revision rates.

PURPOSE: Surgery performed in low-volume centres has been associated with longer operating time, longer hospital stays, lower functional outcomes, and higher rates of revision surgery, complications and mortality. This has been reported consistently in the arthroplasty literature, but there is a paucity of data regarding the relationship between surgical volume and outcome following anterior cruciate ligament (ACL) reconstruction. The purpose was to compare ACL reconstruction failure rates between hospitals performing different annual surgical volumes. METHODS: All patients from the Norwegian Knee Ligament Register having primary autograft ACL reconstruction between 2004 and 2016 were included. Hospital volume was divided into quintiles based on the number of ACL reconstructions performed annually, defined arbitrarily as: 1-12 (V1), 13-24 (V2), 25-49 (V3), 50-99 (V4) and ≥ 100 (V5) annual procedures. Kaplan-Meier estimated survival curves and survival percentages were calculated with revision ACL reconstruction as the end point. Secondary outcome measures included (1) mean change in Knee Injury and Osteoarthritis Outcome Score (KOOS) Quality of Life (QoL) and Sport subsections from pre-operative to 5-year follow-up and (2) subjective failure defined as KOOS QoL < 44. RESULTS: Twenty thousand eight hundred and fifty patients met the inclusion criteria and 1195 (5.7%) underwent subsequent revision ACL reconstruction over the study period. Revision rates were lower in the lower volume hospitals compared with the higher volume hospitals (p < 0.001). There was no clinically significant difference in improvement between pre-operative and 5-year follow-up KOOS scores between hospital volume categories, but a higher proportion of patients having surgery at lower volume hospitals reported a subjective failure. Patients in the lower volume categories (V1-3) were more often male and older compared to the higher volume hospitals (V4-5). Concomitant meniscal injuries and participation in pivoting sports were most common in V5 compared with V1 (p < 0.001). Median operative time decreased as hospital volume increased, ranging from 90 min at V1 hospitals to 56 min at V5 hospitals (p < 0.001). CONCLUSION: Patients having ACL reconstruction at lower volume hospitals had a lower rate of subsequent revision surgery relative to higher volume hospitals. However, complications occurred more frequently, operative duration was longer, and the number of patients reporting a subjective failure of ACL reconstruction was highest at these lower volume hospitals. LEVEL OF EVIDENCE: Level III.

Machine learning algorithm to predict anterior cruciate ligament revision demonstrates external validity.

PURPOSE: External validation of machine learning predictive models is achieved through evaluation of model performance on different groups of patients than were used for algorithm development. This important step is uncommonly performed, inhibiting clinical translation of newly developed models. Machine learning analysis of the Norwegian Knee Ligament Register (NKLR) recently led to the development of a tool capable of estimating the risk of anterior cruciate ligament (ACL) revision ( https://swastvedt.shinyapps.io/calculator_rev/ ). The purpose of this study was to determine the external validity of the NKLR model by assessing algorithm performance when applied to patients from the Danish Knee Ligament Registry (DKLR). METHODS: The primary outcome measure of the NKLR model was probability of revision ACL reconstruction within 1, 2, and/or 5 years. For external validation, all DKLR patients with complete data for the five variables required for NKLR prediction were included. The five variables included graft choice, femur fixation device, KOOS QOL score at surgery, years from injury to surgery, and age at surgery. Predicted revision probabilities were calculated for all DKLR patients. The model performance was assessed using the same metrics as the NKLR study: concordance and calibration. RESULTS: In total, 10,922 DKLR patients were included for analysis. Average follow-up time or time-to-revision was 8.4 (± 4.3) years and overall revision rate was 6.9%. Surgical technique trends (i.e., graft choice and fixation devices) and injury characteristics (i.e., concomitant meniscus and cartilage pathology) were dissimilar between registries. The model produced similar concordance when applied to the DKLR population compared to the original NKLR test data (DKLR: 0.68; NKLR: 0.68-0.69). Calibration was poorer for the DKLR population at one and five years post primary surgery but similar to the NKLR at two years. CONCLUSION: The NKLR machine learning algorithm demonstrated similar performance when applied to patients from the DKLR, suggesting that it is valid for application outside of the initial patient population. This represents the first machine learning model for predicting revision ACL reconstruction that has been externally validated. Clinicians can use this in-clinic calculator to estimate revision risk at a patient specific level when discussing outcome expectations pre-operatively. While encouraging, it should be noted that the performance of the model on patients undergoing ACL reconstruction outside of Scandinavia remains unknown. LEVEL OF EVIDENCE: III.

Full thickness quadriceps tendon grafts with bone had similar material properties to bone-patellar tendon-bone and a four-strand semitendinosus grafts: a biomechanical study.

PURPOSE: Despite increasing interest in utilizing quadriceps tendon (QT) grafts in anterior cruciate ligament reconstruction (ACLR), data on the optimal quadriceps graft thickness are limited. The purpose of this study was to characterize the mechanical properties for the quadriceps tendon, comparing full-thickness (FT) QT grafts with and without bone to a partial-thickness (PT) QT graft, and comparing the three QT grafts to four-stranded semitendinosus (4-SST) and bone-patellar tendon-bone (BTB) grafts and one experimental graft, the two-stranded rectus femoris (RF). METHODS: Forty-eight (n = 48) young cadaveric grafts (mean age 32 ± 6 years) were utilized for testing with N = 8 specimens in each of the following groups; (1) FT QT with bone, (2) FT QT without bone, (3) PT QT without bone, (4) BTB, (5) RF, and (6) 4-SST. Each specimen was harvested and rigidly fixed in custom clamps to a dynamic tensile testing machine for biomechanical evaluation. Graft ultimate load and stiffness were recorded. Independent groups one-factor ANOVAs and Tukey's pairwise comparisons were performed for statistical analyses. RESULTS: FT QT with bone and 4-SST grafts demonstrated similar ultimate loads to BTB grafts (both n.s), whereas PT QT demonstrate statistically significantly lower ultimate loads to BTB grafts (n.s) and 4-SST grafts (n.s). Furthermore, no statistically significant differences were observed between the ultimate loads of FT QT vs. PT QT grafts without bone (n.s) or between FT QT with vs. without bone (n.s). FT QT grafts with bone did not demonstrate statistically significantly greater ultimate loads than PT QT grafts without bone (n.s). The RF graft demonstrated statistically significantly lower ultimate loads to BTB grafts (p < 0.005) and 4-SST grafts (p < 0.014). CONCLUSIONS: Full thickness QT grafts with bone had similar material properties to BTB and a 4-SST grafts, while Partial thickness QT graft without bone had significantly lower material properties than BTB and 4-SST, in a biomechanical setting.

Preventative and Disease-Modifying Investigations for Osteoarthritis Management Are Significantly Under-represented in the Clinical Trial Pipeline: A 2020 Review.

PURPOSE: To conduct a review of active United States-based clinical trials investigating preventative, symptom resolution, and disease-modifying therapies for osteoarthritis (OA). METHODS: We conducted a review of currently active clinical trials for OA using data obtained from the ClinicalTrials.gov database as of August 2020. The inclusion criteria were active studies registered in the United States that involved the prevention, symptom resolution, or disease modification of OA. Descriptive statistics were recorded and summarized. RESULTS: A total of 3,859 clinical trials were identified, and 310 were included in the final analysis. Of the currently active trials, 89% (n = 275) targeted symptom resolution in patients with existing OA, 6% (n = 19) targeted OA disease-modifying therapeutics, and 5% (n = 16) targeted the prevention of OA in high-risk patients (P < .001). Primary interventions included medical devices (44%, n = 137), pharmaceutical drugs (14%, n = 42), surgical procedures (14%, n = 42), cellular biologics (13%, n = 41), and behavioral therapies (13%, n = 41). There was a significantly higher number of disease-modifying therapeutics for cellular biologics than pharmaceutical drugs (30% vs 14%) (P = .015). Most trials targeted the knee joint (63%, P = .042), with 38% of all trials evaluating joint arthroplasty. There were no significant differences between private sector and government funding sources (43% and 49%, respectively) (P = .288), yet there was a significantly lower rate of funding from industry (8%) (P = .026). CONCLUSIONS: There was a significantly higher number of clinical trials investigating symptomatic resolution therapy (89%) for existing OA in comparison to preventative (5%) and disease-modifying (6%) therapies. The most common interventions involved medical devices and joint replacement surgery, with the knee joint accounting for more than 60% of the current clinical trials for OA. There was a significantly higher number of disease-modifying therapeutics for cellular biologics than pharmaceutical drugs. Funding of clinical trials was split between the private sector and government, with a low rate of reported funding from industry partners. CLINICAL RELEVANCE: Identifying existing needs in the current market may help increase rates of research funding or optimize current funding pathways, in this study, specifically for targeting unaddressed focus areas in OA research. Our systematic review highlights the potential need for additional research and development regarding OA preventative and disease-modifying therapies.

Low rates of serious complications but high rates of hardware removal after high tibial osteotomy with Tomofix locking plate.

PURPOSE: The purpose of this study was to analyse adverse events encountered in medial opening wedge high tibial osteotomy (MOWHTO) utilizing contemporary surgical techniques with the Tomofix locking plate (DePuy Synthes, Raynham, MA, USA) and categorize them by their severity and need for further medical/surgical management. It was hypothesized that there would be low rates of serious complications after medial opening wedge high tibial osteotomy utilizing an internal locking plate fixator. METHODS: This study included 169 consecutive patients (200 knees) who underwent MOWHTO with a Tomofix locking plate at a single center, completing a minimum 2-year follow-up. Types of intra- and post-operative adverse events were retrospectively identified by an independent observer and categorized by their severity and further need of management. Additional surgery due to elective hardware removal was not included in the adverse event classification. RESULTS: There were in total 58 (29%) adverse events, the majority (13.5%) of which required no additional treatment (class 1). Class 1 events included lateral cortex hinge fractures that were observed in 8.5% (17 knees) and delayed wound healing 2% (4/200). Adverse events requiring additional or extended nonoperative management (class 2) were 9%. These included post-operative stiffness in 1% (2/200), low grade infection in 1.5% (3/200), delayed union in 5.4% (11/200), deep vein thrombosis 0.5% (1/200). One hundred and four knees (52%) underwent elective hardware removal. Serious adverse events requiring unplanned additional or revision surgery and/or long-term medical care (class 3) were the least reported (6.5%). Aseptic non-union was reported in 2.5%, deep infection requiring revision in 2% and limited hardware failure 1%. CONCLUSION: A low rate of serious complications (6.5%) requiring unplanned additional surgery (class 3) was found. The overall rate of complications following MOWHTO with Tomofix locking plate was 29% and the majority (13.5%) required no additional treatment (class 1). Lateral hinge fractures were the most common complication (8.5%) and these were associated with corrections over 12 mm. However, 52% knees required a further operation for elective hardware removal. LEVEL OF EVIDENCE: Level IV, prospective study without control group.

Editorial Commentary: Knee Lateral Femoral Osteochondral Allografts Are Not Recommended for Medial Femoral Condylar Defects: If the Shoe Doesn't Fit, Don't Wear It!

Treatment of large articular cartilage defects of the knee is challenging, particularly in young, high-demand patients. Osteochondral allograft (OCA) transplantation is a viable treatment option, providing fully mature articular cartilage during a single operation while avoiding donor site morbidity. Indications are symptomatic, full-thickness articular cartilage defects >3 cm2. Contraindications include a "kissing" lesion of the corresponding articular cartilage surface, uncorrected ligamentous instability, malalignment, peripheral osteophytes, joint-space narrowing, or absence of >50% of the meniscus in the affected compartment. Matching for size and contour is crucial; therefore, we use medial femoral condyle (MFC) allografts for MFC lesions and lateral femoral condyle (LFC) allografts for LFC lesions, and do not recommend LFC grafts for the MFC. Survival rates are 78.7% and 72.8% at 10 and 15 years, respectively.

Editorial Commentary: Early Surgery and Restricted Rehabilitation Are Recommended for High-Grade Acromioclavicular Joint Dislocation.

Despite acromioclavicular (AC) joint injuries being common, there are still controversies about the treatment; nonoperative versus surgical, who to operate, when to operate, which technique to use, and which rehabilitation protocol to use. Orthopaedic surgeons are often faced with these patients fearing not regaining normal function and to some degree acceptable cosmetic outcomes. Despite increasing interest in surgical management of type 3 AC joint injuries, surgical management has not been demonstrated to yield superior functional outcomes compared with nonoperative treatment. Interestingly, studies have demonstrated that good outcomes are achieved with most surgical techniques even though they are all associated with loss of initial reduction. This brings into question whether surgery is necessary in the early phase and how we can mitigate the effects of gravity to maintain reduction. Studies that can aid surgeons in patient selection for treatment protocols (nonoperative versus surgical) and timing of surgery are needed. We recommend early surgery, and restricted rehabilitation, for high-grade acromioclavicular joint dislocation.

Biomechanical comparison of tension band wiring and plate fixation with locking screws in transverse olecranon fractures.

BACKGROUND: Tension band wiring (TBW) is the standard method for treating transverse olecranon fractures, but high rates of complications and reoperations have been reported. Plate fixation (PF) with locking screws has been introduced as an alternative method that may retain the fracture reduction better with a higher load to failure. METHODS: Twenty paired cadaveric elbows were used. All soft tissues except for the triceps tendon were removed. A standardized transverse fracture was created, and each pair was allocated randomly to TBW or PF with locking screws. The triceps tendon was mounted to the materials testing machine with the elbow in 90° of flexion. Construct stiffness was compared 3 times. Then, the elbows underwent a chair lift-off test by loading the triceps tendon to 300 N for 500 cycles. Finally, a load-to-failure test was performed, and failure mechanism was recorded. RESULTS: The construct stiffness of PF was higher in the first of 3 measurements. No difference was observed in the cyclic test or in load to failure. Hardware failure was the failure mechanism in 8 of 10 TBW constructs, and all failures occurred directly under the twists of the metal wire. Hardware failure was the cause of failure in only 1 elbow in the PF group (P < .01). CONCLUSION: There was no difference in fracture displacement following fixation with TBW and PF with locking screws in transverse olecranon fractures. However, assessment of the mode of hardware failure identified the metal cerclage twist as the weakest link in the TBW construct.

Re-revision Anterior Cruciate Ligament Reconstruction: An Evaluation From the Norwegian Knee Ligament Registry.

PURPOSE: To identify the rate of re-revision anterior cruciate ligament reconstruction (ACLR) to estimate the influence of patient-related factors on the risk of re-revision ACLR. The secondary aim of the study was to report the intra-articular findings and patient-related factors at the time of revision ACLR and to compare these with the findings in a matched controlled group of primary ACLR. METHODS: Patients with primary ACLR without a subsequent need of revision and patients with a revision ACLR identified in the Norwegian Knee Ligament Registry from June 2004 through September 2016 were included. Using age at operation, sex, activity at injury, and year of ACLR as covariates, a propensity score matched control group of primary ACLR patients for the revision ACLR patients was identified. For the revision ACLR patients, re-revision ACLR rates at 1, 2, 5, and 8 years were estimated with Kaplan-Meier analysis; the hazard ratio for a re-revision ACLR was estimated using a multivariable Cox regression model. RESULTS: The cumulative estimated proportion of patients undergoing a re-revision ACLR at 1, 2, 5, and 8 years after the original revision ACLR was 0.4%, 3.0%, 6.5%, and 9.0% respectively. There was no significant difference between the control and revision ACLR groups regarding cartilage injury (P = .72) or associated ligament injury (P = .17). Revision ACLR patients did have fewer meniscal injuries (P < .001). There were no intraoperative findings or surgical techniques identified as a predictor for a higher risk of re-revision ACLR. CONCLUSIONS: Based on a review of a large ligament reconstruction registry,one can expect 9% of patients to undergo a re-revision ALCR at 8 years of follow up. Revision ACLR did not have an increase in cartilage injuries or associated ligament injuries and had significantly fewer meniscal injuries compared with a primary ACLR control group. LEVEL OF EVIDENCE: Level III, retrospective comparative study.

Acromioclavicular and Coracoclavicular Ligament Reconstruction for Acromioclavicular Joint Instability: A Systematic Review of Clinical and Radiographic Outcomes.

PURPOSE: To perform a systematic review of the available literature on clinical and radiographic outcomes after surgical treatment for acromioclavicular (AC) joint instability. METHODS: A systematic review was performed according to PRISMA guidelines. Inclusion criteria were AC joint and coracoclavicular (CC) ligament reconstruction outcomes, English language, human studies, more than 10 patients in the study and a 2-year minimum follow-up. Exclusion criteria were animal studies, cadaveric studies, clinical studies without reported follow-up period or patient-reported outcomes, clinical studies of nonoperative treatment, AC reconstructions with concurrent lateral clavicle fracture, editorial articles, abstracts, presentations, reviews, case reports, and surveys. RESULTS: The systematic review identified 34 studies (939 patients) after inclusion and exclusion criteria application. Postoperative American Shoulder and Elbow Surgeons (ASES) scores ranged from 93.8 to 96, 81.8 to 97.8, and 88.1 for free tendon graft, suspensory devices, and modified Weaver-Dunn techniques, respectively. Postoperative Constant scores were 76.4 to 96.0, 82.6 to 97.8, 85.9 to 97.0, 81 to 96 and 83.0 to 94.6 for free tendon graft, suspensory devices, synthetic ligament devices, modified Weaver-Dunn, and hook plate/K-wires techniques, respectively. All treatment modalities improved patient outcomes; however, hook plates and K-wires had the highest rate of complications (26.3%). Unplanned reoperation rates were 1.2%, 2.8%, 0.9%, 5.4%, and 2.6% in free tendon graft, suspensory devices, synthetic ligament devices, modified Weaver-Dunn, and hook plate/K-wires techniques, respectively. CONCLUSIONS: Comparable subjective outcomes after surgical treatment of AC joint instability was reported for all modalities, with relatively low unplanned reoperation rates. Treatment with hook plate/K-wires was associated with the highest complication rates, and modified Weaver-Dunn had the highest unplanned reoperation rates. LEVEL OF EVIDENCE: Level IV, systematic review of Level I-IV studies.

Quantitative Assessment of the Coracoacromial and the Coracoclavicular Ligaments With 3-Dimensional Mapping of the Coracoid Process Anatomy: A Cadaveric Study of Surgically Relevant Structures.

PURPOSE: To perform a quantitative anatomic evaluation of the (1) coracoid process, specifically the attachment sites of the conjoint tendon, the pectoralis minor, the coracoacromial ligament (CAL), and the coracoclavicular (CC) ligaments in relation to pertinent osseous and soft tissue landmarks; (2) CC ligaments' attachments on the clavicle; and (3) CAL attachment on the acromion in relation to surgically relevant anatomic landmarks to assist in planning of the Latarjet procedure, acromioclavicular (AC) joint reconstructions, and CAL resection distances avoiding iatrogenic injury to surrounding structures. METHODS: Ten nonpaired fresh-frozen human cadaveric shoulders (mean age 52 years, range 33-64 years) were included in this study. A 3-dimensional coordinate measuring device was used to quantify the location of pertinent bony landmarks and soft tissue attachment areas. The ligament and tendon attachment perimeters and center points on the coracoid, clavicle, and acromion were identified and subsequently dissected off the bone. Coordinates of points along the perimeters of attachment sites were used to calculate areas, whereas coordinates of center points were used to determine distances between surgically relevant attachment sites and pertinent bony landmarks. RESULTS: The CAL had a single consistent acromial attachment (mean area 77 mm [51.9, 102.2]) and then bifurcated into 2 bundles, anterior and posterior, that separately inserted on the lateral aspect of the coracoid. The footprint areas were 54.4 mm2 [31.7, 77.2] and 30.6 mm2 [23.4, 37.7] for the anterior and posterior CAL bundles, respectively. These anterior and posterior bundles attached 10.6 mm [8.4, 12.9] and 24.8 mm [12.3, 27.4] medial and proximal to the apex of the coracoid process, respectively. The minimum distance between the coracoid apex and the trapezoid ligament was 25.1 mm [22.1, 28.1] and was noted to be different in males (28.1 mm [25.1; 31.2]) and females (22.0 mm [18.2, 25.9]). The most lateral insertion of the CC ligaments on the clavicle the AC joint was 15.7 mm [13.1, 18.3]. The distance between the most medial to the most lateral point of the CC ligaments on the clavicle was 25.6 mm [22.3, 28.9], which accounted for 18.2% [15.8, 20.6] of the clavicle length. CONCLUSIONS: In contrast to previous findings, 2 different coracoid attachments (anterior and posterior bundles) of the CAL were consistently identified in all specimens. Moreover, a coracoid osteotomy for a bone graft for the Latarjet procedure should be performed at less than 28.1/22 mm from the apex of the coracoid in male/female patients, respectively. The CC ligaments' attachments on the clavicle were located 15.7 mm from the AC joint, which should be considered for reconstruction. CLINICAL RELEVANCE: During the Latarjet technique, to maintain the integrity of the CC ligaments, precise knowledge of differences between male and female anatomy is necessary during a coracoid osteotomy. Furthermore, when reconstructing the AC joint, the distance from the lateral aspect of the clavicle and the size of the attachments areas should be considered to better replicate the native anatomy.