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To report patient characteristics, fracture types, treatment methods, early clinical outcomes and complications of children and adolescents treated for tibial tubercle fractures. Retrospective case series of patients 18 years old and younger treated for tibial tubercle fractures at a single institution from 1995 to 2015. Clinical and radiographic outcomes were reported at minimum six-month follow-up. In 228 patients, 236 tibial tubercle fractures were identified, of whom, 198 (87%) were males. Mean age and BMI was 14.3 years and 25.0, respectively. Pre-existing Osgood-Schlatter disease was identified in 31% cases and was most commonly associated with type I fractures (P < 0.001). Most fractures occurred while participating in athletics (86%). Initial treatment was surgical for 67% fractures. Type III fractures were most common (41%), followed by type I (29%). Type I fractures were most commonly treated nonoperatively (91%) and types II-V fractures were most commonly treated surgically (89%, P < 0.001). Compartment syndrome was identified in 4 (2%) patients, 3 of which had type IV fractures. Most patients returned to sports (88%). Tibial tubercle fractures are sports-related injuries and occur most commonly in adolescent males. They can be associated with pre-existing Osgood-Schlatter disease, a higher than average BMI, and a small but relevant risk of compartment syndrome. Following treatment, most patients return to sports participation.

Background: Patellofemoral instability (PFI) occurs most commonly in pediatric and adolescent patients, with evolving indications for surgery and changes in surgical techniques over the past decade. Purpose: To characterize the demographic, clinical, and radiologic characteristics of a large cohort of patients undergoing PFI surgery and investigate longitudinal trends in techniques utilized over a 10-year period at a tertiary-care academic center. Study Design: Case series; Level of evidence, 4. Methods: Electronic medical records of patients younger than 25 years of age who underwent primary surgery for lateral PFI from 2008 to 2017 at a single center by 1 of 5 different sports medicine surgeons were retrospectively reviewed. Demographic, clinical, and radiographic parameters of instability were analyzed. Routine surgical techniques included medial retinacular plication/reefing/repair (MRP), medial patellofemoral ligament reconstruction (MPFLR), tibial tubercle osteotomy (TTO), or a combination thereof, with or without lateral retinacular release (LR) or lateral retinacular lengthening (LRL). Exclusion criteria, selected for potentially altering routine surgical indications or techniques, included fixed/syndromic PFI, a formally diagnosed collagen disorder, cases in which a chondral/osteochondral shear fragment underwent fixation or was >1 cm in diameter, and body mass index >30 kg/m2. Results: Of the 492 study patients (556 knees; 71% female; median age, 15.2 years; 38% open physes), 88% were athletes, with the most common sports participated in being soccer, basketball, dance, football, gymnastics, and baseball/softball. While 91% of the cohort had recurrent dislocations, the 9% with primary dislocations were more likely to have small osteochondral fractures/loose bodies ( P < .001). Female patients were younger ( P = .002), with greater patellar tilt ( P = .005) than male patients. Utilization of MPFLR and TTO increased significantly over the study period, while use of MRP+LR decreased. Conclusion: Most patients younger than 25 years of age who underwent PFI surgery were skeletally immature, female, and athletes and had recurrent dislocations. The

Background: Anterior cruciate ligament (ACL) injuries demand individualized treatments based on an accurate estimation of the child’s skeletal age. Wrist radiographs, which have traditionally been used to determine skeletal age, have a number of limitations, including cost, radiation exposure, and inconvenience. Purpose: To evaluate the reliability and validity of a radiographic staging system using tibial apophyseal landmarks as hypothetical proxies for skeletal age to use in the preoperative management of pediatric ACL tears. Study Design: Cohort study (diagnosis); Level of evidence, 2. Methods: The study included children younger than 16 years of age who underwent ACL reconstruction between July 2008 and July 2018 and received both skeletal age radiography and knee radiography within 3 months of each other. Skeletal age was calculated from hand and wrist radiographs using the Greulich and Pyle atlas. Tibial apophyseal staging was categorized into 4 stages: cartilaginous stage (stage 1), apophyseal stage (stage 2), epiphyseal stage (stage 3), and bony/fused stage (stage 4). Data were collected by 2 independent assessors. The analysis was repeated 1 month later with the same assessors. We calculated descriptive statistics, measures of agreement, and the correlation between skeletal age and apophyseal stage. Results: The mean chronological age of the 287 patients included in the analysis was 12.9 ± 1.9 years; 164 (57%) of the patients were male. The overall Spearman r between skeletal age and tibial apophyseal staging was 0.69 (0.77 in males; 0.60 in females). The interrater reliability for the tibial apophyseal staging was substantial (Cohen κ = 0.66), and the intrarater reliability was excellent (Cohen κ = 0.82). The interrater reliability for skeletal age was excellent (intraclass correlation coefficient [ICC] = 0.93), as was the intrarater reliability (ICC = 0.97). Conclusion: The observed correlation between skeletal age and tibial apophyseal staging as well as observed intra- and interrater reliabilities demonstrated that tibial apophyseal landmarks on knee radiographs may be used to estimate skeletal age. This study supports the validity of knee radiographs in determining skeletal age and provides early evidence in certain clinical presentations to simplify the diagnostic workup and operative management of pediatric knee injuries, including ACL tears.

BACKGROUND Medial discoid meniscus (MDM) is an exceedingly rare anatomic abnormality that presents similarly to other meniscal pathologies. Symptomatic MDM is typically managed arthroscopically with mixed short-term and long-term outcomes, although the existing knowledge about MDM is limited. The purpose of this study was to describe the presentation and surgical treatment of MDM in pediatric and adolescent patients. METHODS Medical records of 12 knees with MDM in 8 pediatric and adolescent patients treated between 1991 and 2016 were reviewed retrospectively for patient characteristics, clinical manifestations, radiographic findings, operative techniques, and surgical outcomes. RESULTS Of the 446 knees diagnosed arthroscopically with discoid menisci, lateral discoid meniscus was noted in 434 knees (97.3%) and MDM was present in 12 knees (2.7%). The MDM series included 8 patients of mean age 13.8 years (range: 7.8 to 19.8), of which 5 were males (63%), and 4 (50%) had bilateral involvement. Of the 11 knees with available clinical records, all cases presented symptomatically (pain, mechanical symptoms); 10 (91%) had concurrent physical exam findings. On intraoperative examination, discoid morphologies were described as complete in 4/8 knees (50%) or incomplete in 4/8 (50%), with associated instability in 6/12 (50%). Meniscal tears were reported in 9 cases (75%)-primarily, horizontal cleavage tears. Saucerization was performed in 11 knees (92%), with medial meniscal repair in 7 (58%), when indicated. Retear of the medial meniscus occurred in 4/11 knees (36%) at a mean of 25.8 months postoperation; 2 knees required revisions. One knee developed arthrofibrosis and underwent arthroscopic lysis of adhesions. CONCLUSIONS MDM is a rare diagnosis, representing 3% of all discoid menisci, with a nonspecific clinical manifestation. Operative management of symptomatic MDM typically involves saucerization and meniscal repair, when indicated, for concurrent tears. Symptom resolution is common short-term, but long-term outcomes include recurrent meniscal tears. Subsequent observational studies are important to evaluate long-term outcomes, such as arthritic changes, with the advancement of arthroscopic techniques for meniscal preservation. LEVEL OF EVIDENCE Level IV-retrospective case series.

Background: Adolescent dancers may be a high-risk population for patellofemoral instability (PFI), but the condition remains under-investigated, to date, in this sub-group of athletes. Purpose: The purpose of this study was to (1) investigate the descriptive epidemiology of PFI in adolescent dancers, (2) analyze the efficacy of various patellar stabilization procedures within this population, and (3) compare PFI in dancers to a larger control group of matched, non-dancer athletes. Methods: A retrospective review of athletes, ages 10 to 19, who presented to a single tertiary care center with PFI between 2008 and 2017 was performed. Based on each patient’s primary sport, the cohort was divided into a dancer and a non-dancer control group. Demographics, clinical and radiologic features, surgical stabilization technique, and postoperative course and clinical outcomes were collected. Independent categorical groups were tested using chi squared and Fisher exact tests. Results: 258 adolescent athletes were included, 41 of whom were dancers, all females. This group was therefore matched with a control group of similarly aged, all-female athletes with PFI (Table 1). 54 athletes had bilateral PFI, yielding 285 knees for analysis. There was no difference between dancer and non-dancer athletes’ age, BMI, laterality, mechanism of injury, nor number of preoperative instability events. However, dancers had lower Dejour Classifications (p=0.044), smaller patella inclination angles (20.9±8.14 versus 25.0±9.84; p=0.004), and smaller Caton-Deschamps Indices (1.18±0.161 versus 1.25±0.189; p=0.041). Among dancers, there was no association between surgical stabilization technique and rates of recurrent instability (p=0.418) nor re-stabilization procedures (p=1.0) (Table 2). However, dancers who underwent tibial tubercle osteotomy (TTO) had higher rates of subsequent, non-stabilization procedures (66.7%), all for implant removal, compared to those undergoing isolated medial retinacular repairs (MRP) (3.8%) (pConclusions: Female dancers with PFI have similar demographic and clinical features as other female athletes with PFI, but have lower rates or less severe trochlear dysplasia, lateral tilt and patella alta. Therefore, the ligamentous laxity inherent in dancers may be a more powerful risk factor for PFI than other non-modifiable risk factors. Notably, the TTO was a powerful stabilization procedure for this sub-population with low rates of recurrent instability episodes and no revision stabilization procedures performed. Rates of implant removal surgery following TTO may be substantial, though this may be technique or surgeon dependent. Tables/Figures: [Table: see text][Table: see text]

Background: Previous studies have suggested that hip arthroscopy has been performed with increasing frequency. Few studies have examined this trend in the adolescent population. Purpose: The purpose of this study was to evaluate the trend in the frequency of hip arthroscopy in adolescents standardized by total orthopaedic surgeries in adolescents at pediatric hospitals in the United States. Methods: The Pediatric Health Information System (PHIS) database was queried for patients aged 10 to 19 years who underwent orthopaedic surgery at any of the PHIS-participating hospitals from 2008 to 2018. The subgroup of patients in this age cohort who underwent hip arthroscopy was identified using Current Procedural Terminology (CPT) procedure codes. The yearly rate was expressed as the number of hip arthroscopies per 1000 orthopaedic surgeries. A linear model was used to fit the data and illustrate the relative trend. Results: A total of 432309 orthopaedic surgeries including 9491 hip arthroscopies were performed for patients 10 to 19 years of age. Hip arthroscopies were performed at a yearly rate of 22 per 1000 orthopaedic surgeries. Over the 10-year period, the number of hip arthroscopies increased 6.2-fold, whereas the number of orthopaedic procedures increased 1.6-fold. There was a 3.9-fold increase in hip arthroscopies relative to total orthopaedic surgeries. Conclusion: The number of hip arthroscopic procedures in adolescent patients has increased by 3.9-fold times relative to total orthopaedic surgeries in adolescents over a 10-year span. This finding mirrors the trends in the adult population over similar time periods. This may be due to increasing participation in sports in the adolescent population as well as a better understanding of the diagnosis and treatment of femoroacetabular impingement and other sports-related hip pathologies. [Table: see text][Figure: see text]

Background: Historically, the most commonly utilized technique to address recurrent patellofemoral instability (PFI) was a combined proximal and distal realignment, specifically the tibial tubercle osteotomy (TTO) with a proximal medial retinacular plication/reefing/tightening/repair (MRP). Rising interest in the medial patellofemoral ligament reconstruction (MPFLR) over the last decade, now frequently performed as a more powerful isolated proximal realignment procedure, has prompted debate over the optimal technique to treat this common condition. Hypothesis/Purpose: The study hypothesis was that no difference would be detected in recurrent PFI rates or revision surgery rates between patients who underwent TTO-MRP vs. MPFLR. Methods: With cohorts derived from a large, single-center PFI database of 523 patients who underwent a variety of stabilization procedures, 114 eligible MPFLR patients were matched to 109 TTO patients based on age, gender, BMI, and TT-TG distance. Propensity score matching was conducted using logistic regression models to produce 1:1 matching, and a caliper of 0.2 standard deviations of the estimated propensity score was used to for the nearest neighbor matching algorithm. Final matching procedure resulted in 84 MPFLR patients and 84 TTO patients. These were compared on demographics and post-operative clinical results. Results: Demographic and radiologic comparisons of the cohorts are shown in Table 1, with the only difference between groups being an expected higher rate of patients with open physes in the MPFLR cohort. Table 2 shows the TTO-MRP group had longer follow up times, but comparable rates of return to sports. The MPFLR group had a higher rate of recurrent instability, but not to a significant degree, and a significantly higher incidence of revision patellar stabilization surgery (pConclusion: The TTO-MRP shows equivalent or superior results to the MPFLR for treatment of PFI. However, implant removal may be common with TTO, though this may be somewhat technique-dependent. In the current landscape of increasing interest and utilization of MPFLR as an all-encompassing PFI surgery, the influence of distal bony realignment to minimize recurrence should not be underappreciated. Tables/Figures: [Table: see text][Table: see text]

Background Current advanced imaging classification systems for osteochondritis dissecans (OCD) of the knee grade severity of disease by identifying certain lesion characteristics. The most widely used are the Hefti and Nelson systems. A novel classification presents a simpler 3-group approach to diagnose knee OCD by magnetic resonance imaging (MRI), compared with the Hefti (5-group) and Nelson (4-group) classifications. The purpose of this study was to compare the reliability of this novel classification with that of the more complex, established systems-an initial step in establishing validity and clinical utility. Methods In total, 120 standardized knee MRIs of patients with established knee OCD were preselected to capture the spectrum of lesion types, with regard to both progression and location of the lesion. Each of the MRIs were independently classified by 2 readers into the novel, Hefti, and Nelson classification systems. A random sample was rereviewed by 1 rater 6 weeks after initial review. The inter-rater and intrarater agreements were evaluated by estimating Krippendorff α. Results In total, 106 knees were classified by the novel, Hefti, and Nelson classification systems, as 14 of the knees lacked the necessary MRI sequences. There were no differences in inter-rater and intrarater agreement across classification systems. Krippendorff α for inter-rater agreement was 0.51 (95% confidence interval, 0.33-0.66) for the Hefti classification, 0.50 (0.34-0.64) for the Nelson classification, and 0.49 (0.32-0.65) for the novel classification. The intrarater agreement was 0.88 (0.75-0.97) for the Hefti classification, 0.94 (0.86-0.99) for the Nelson classification, and 0.98 (0.94-1.00) for the novel classification system. Conclusions The novel classification for knee OCD demonstrated near-perfect intrarater agreement and moderate inter-rater agreement, consistent with the current, well-established classification systems. Pending a subsequent study on validity and clinical utility, this simpler classification system may offer an alternative, noninvasive diagnostic method to guide clinical treatment. Level of evidence Level IV.

Background: The early clinical course of COVID-19 can be difficult to distinguish from other illnesses driving presentation to hospital. However, viral-specific PCR testing has limited sensitivity and results can take up to 72 h for operational reasons. We aimed to develop and validate two early-detection models for COVID-19, screening for the disease among patients attending the emergency department and the subset being admitted to hospital, using routinely collected health-care data (laboratory tests, blood gas measurements, and vital signs). These data are typically available within the first hour of presentation to hospitals in high-income and middle-income countries, within the existing laboratory infrastructure. Methods: We trained linear and non-linear machine learning classifiers to distinguish patients with COVID-19 from pre-pandemic controls, using electronic health record data for patients presenting to the emergency department and admitted across a group of four teaching hospitals in Oxfordshire, UK (Oxford University Hospitals). Data extracted included presentation blood tests, blood gas testing, vital signs, and results of PCR testing for respiratory viruses. Adult patients (>18 years) presenting to hospital before Dec 1, 2019 (before the first COVID-19 outbreak), were included in the COVID-19-negative cohort; those presenting to hospital between Dec 1, 2019, and April 19, 2020, with PCR-confirmed severe acute respiratory syndrome coronavirus 2 infection were included in the COVID-19-positive cohort. Patients who were subsequently admitted to hospital were included in their respective COVID-19-negative or COVID-19-positive admissions cohorts. Models were calibrated to sensitivities of 70%, 80%, and 90% during training, and performance was initially assessed on a held-out test set generated by an 80:20 split stratified by patients with COVID-19 and balanced equally with pre-pandemic controls. To simulate real-world performance at different stages of an epidemic, we generated test sets with varying prevalences of COVID-19 and assessed predictive values for our models. We prospectively validated our 80% sensitivity models for all patients presenting or admitted to the Oxford University Hospitals between April 20 and May 6, 2020, comparing model predictions with PCR test results. Findings: We assessed 155 689 adult patients presenting to hospital between Dec 1, 2017, and April 19, 2020. 114 957 patients were included in the COVID-negative cohort and 437 in the COVID-positive cohort, for a full study population of 115 394 patients, with 72 310 admitted to hospital. With a sensitive configuration of 80%, our emergency department (ED) model achieved 77·4% sensitivity and 95·7% specificity (area under the receiver operating characteristic curve [AUROC] 0·939) for COVID-19 among all patients attending hospital, and the admissions model achieved 77·4% sensitivity and 94·8% specificity (AUROC 0·940) for the subset of patients admitted to hospital. Both models achieved high negative predictive values (NPV; >98·5%) across a range of prevalences (≤5%). We prospectively validated our models for all patients presenting and admitted to Oxford University Hospitals in a 2-week test period. The ED model (3326 patients) achieved 92·3% accuracy (NPV 97·6%, AUROC 0·881), and the admissions model (1715 patients) achieved 92·5% accuracy (97·7%, 0·871) in comparison with PCR results. Sensitivity analyses to account for uncertainty in negative PCR results improved apparent accuracy (ED model 95·1%, admissions model 94·1%) and NPV (ED model 99·0%, admissions model 98·5%). Interpretation: Our models performed effectively as a screening test for COVID-19, excluding the illness with high-confidence by use of clinical data routinely available within 1 h of presentation to hospital. Our approach is rapidly scalable, fitting within the existing laboratory testing infrastructure and standard of care of hospitals in high-income and middle-income countries. Funding: Wellcome Trust, University of Oxford, Engineering and Physical Sciences Research Council, National Institute for Health Research Oxford Biomedical Research Centre.

Background: High-grade trochlear dysplasia (HGTD) has previously been identified as a risk factor for failure of surgical management of patellofemoral instability (PFI). However, limited data exists on the influence of the type of surgical procedure performed on postoperative outcomes in these patients. Hypothesis/Purpose: The purpose of this study was to identify the rates of failure of primary PFI surgery in patients with HGTD compared to those without HGTD and to assess the effect of the type of surgery on recurrent instability and return to OR. Methods: A retrospective review was performed on patients aged ≤19 years who underwent primary surgery for PFI at a single tertiary care center between 2008 and 2017. Patients underwent procedures including medial retinacular plication/reefing/advancement (MRP), graft-based medial patellofemoral ligament reconstruction (MPFLR), tibial tubercle osteotomy with or without MRP (TTO), or combined MPFLR + TTO. Exclusion criteria were BMI >30kg/m2, surgery for fixation of chondral fractures >1cm, and diagnosis of a syndromic disorder. Trochlear dysplasia was evaluated based on pre-operative MRI according to the Dejour classification system. Those with Dejour grade B or higher were designated as having HGTD. Comparisons were made between HGTD patients and non-HGTD patients, with logistic regression utilized to determine if surgery type was associated with recurrent PFI and revision PFI surgery. Results: 303 patients (mean age 15.1 years, 71% female) underwent primary surgical stabilization for PFI with median follow up time of 3.0 years. Approximately half (149/303, 49%) of the cohort had HGTD. Demographics were comparable between HGTD and non-HGTD patients (Table 1). HGTD and non-HGTD cohorts showed similar rates of post-operative instability, revision PFI surgery, and non-PFI secondary surgery. HGTD patients (Table 2) who underwent MPFLR had a 63% decrease in the odds of post-operative PFI compared to those who underwent MRP (OR=0.37; p=0.03). HGTD patients who underwent TTO had an 80% decrease in the odds of post-operative PFI compared to patients undergoing MRP (OR=0.20; p=0.002). Conclusion: Adolescents with PFI and HGTD have similar results after surgical stabilization to those patients without HGTD. Within the HGTD cohort, however, the type of surgery performed significantly influenced outcome. Patients with HGTD that underwent MRP had significantly more recurrent PFI and revision PFI surgery than patients that underwent other procedures, suggesting a limited role for this procedure in this sub-population of PFI patients. [Table: see text][Table: see text]

Background: Adolescents often benefit from surgical management of recurrent patellofemoral instability (PFI). However, the precise radiologic risk factors for failure of PFI surgery remains incompletely investigated. Hypothesis/Purpose: The purpose of this study was to determine the rate of failure, defined as recurrence of instability, in a large cohort of adolescent athletes undergoing primary surgery for PFI, and to identify preoperative radiologic risk factors for recurrence. Methods: A retrospective review was performed on patients aged ≤19 years who underwent primary surgery for PFI at a single tertiary care center between 2008 and 2017. Patients underwent procedures including medial retinacular plication/reefing/advancement (MRP), medial patellofemoral ligament reconstruction (MPFLR), tibial tubercle osteotomy with or without MRP (TTO), or combined TTO/MPFLR. Exclusion criteria were BMI >30kg/m2, surgery for fixation of chondral fractures >1cm, and diagnosis of a syndromic disorder. Preoperative magnetic resonance imaging (MRI) studies were reviewed, and radiologic parameters were recorded. Demographic and radiologic variables were compared between patients with and without subsequent PFI. Logistic regression was utilized to determine which imaging variables were associated with post-operative PFI. Results: 303 patients (mean age 15.1 years, 71% female) underwent surgery for PFI with median follow up time of 3.0 years. At final follow-up, 76/303 (25%) of patients experienced post-operative PFI, with 41 of these patients (54%; 14% overall) undergoing revision PFI surgery. Post-operative PFI patients were younger (14.3 vs 15.4 years; pConclusion: In conclusion, 25% of adolescents experienced post-operative PFI after primary patellofemoral stabilization surgery. However, such patients were more likely to be younger—a known risk factor for recurrence—and were more likely to undergo MRP, a procedure now largely replaced by MPFLR. Radiologic risk factors for failure included open physes, flatter trochlea, greater patellar tilt, and greater patella alta. Such data should guide treatment decisions and inform the risk of failure of surgical stabilization procedures in adolescents with PFI. [Table: see text][Table: see text]

Background Previous studies have suggested that hip arthroscopy has been performed with increasing frequency. Few studies have examined this trend in the adolescent population. The purpose of this study was to evaluate the trend in the frequency of hip arthroscopy in adolescents standardized by total orthopaedic surgeries in adolescents at pediatric hospitals in the United States. Methods The Pediatric Health Information System (PHIS) database was queried for patients aged 10 to 19 years who underwent orthopaedic surgery at any of the PHIS-participating hospitals from 2008 to 2018. The subgroup of patients in this age cohort who underwent hip arthroscopy was identified using Current Procedural Terminology procedure codes. The yearly rate was expressed as the number of hip arthroscopies per 1000 orthopaedic surgeries. A linear model was used to fit the data and illustrate the relative trend. Results A total of 432,309 orthopaedic surgeries including 9491 hip arthroscopies were performed for patients 10 to 19 years of age. Hip arthroscopies were performed at a yearly rate of 22 per 1000 orthopaedic surgeries. Over the 10-year period, the number of hip arthroscopies increased 6.2-fold, whereas the number of orthopaedic procedures increased 1.6-fold. There was a 3.9-fold increase in hip arthroscopies relative to total orthopaedic surgeries. Conclusions The number of hip arthroscopic procedures in adolescent patients has increased by 3.9-fold times relative to total orthopaedic surgeries in adolescents over a 10-year span, on the basis of data from PHIS-participating institutions. This finding mirrors the trends in the adult population over similar time periods. This may be because of increasing participation in sports in the adolescent population, and a better understanding of the diagnosis and treatment of femoroacetabular impingement and other sports-related hip pathologies. Level of evidence Level IV.

BackgroundRapid identification of COVID-19 is important for delivering care expediently and maintaining infection control. The early clinical course of SARS-CoV-2 infection can be difficult to distinguish from other undifferentiated medical presentations to hospital, however for operational reasons SARS-CoV-2 PCR testing can take up to 48 hours. Artificial Intelligence (AI) methods, trained using routinely collected clinical data, may allow front-door screening for COVID-19 within the first hour of presentation.MethodsDemographic, routine and prior clinical data were extracted for 170,510 sequential presentations to emergency and acute medical departments at a large UK teaching hospital group. We applied multivariate logistic regression, random forests and extreme gradient boosted trees to distinguish emergency department (ED) presentations and admissions due to COVID-19 from pre-pandemic controls. We performed stepwise addition of clinical feature sets and assessed performance using stratified 10-fold cross validation. Models were calibrated during training to achieve sensitivities of 70, 80 and 90% for identifying patients with COVID-19. To simulate real-world performance at different stages of an epidemic, we generated test sets with varying prevalences of COVID-19 and assessed predictive values. We prospectively validated our models for all patients presenting or admitted to our hospital group between 20th April and 6th May 2020, comparing model predictions to PCR test results.ResultsPresentation laboratory blood tests, point of care blood gas, and vital signs measurements for 115,394 emergency presentations and 72,310 admissions were analysed. Presentation laboratory tests and vital signs were most predictive of COVID-19 (maximum area under ROC curve [AUROC] 0.904 and 0.823, respectively). Sequential addition of informative variables improved model performance to AUROC 0.942.We developed two early-detection models to identify COVID-19, achieving sensitivities and specificities of 77.4% and 95.7% for our ED model amongst patients attending hospital, and 77.4% and 94.8% for our Admissions model amongst patients being admitted. Both models offer high negative predictive values (>99%) across a range of prevalences (ConclusionArtificial intelligence techniques perform effectively as a screening test for COVID-19 in emergency departments and hospital admission units. Our models support rapid exclusion of the illness using routinely collected and readily available clinical measurements, guiding streaming of patients during the early phase of admission.BriefThe early clinical course of SARS-CoV-2 infection can be difficult to distinguish from other undifferentiated medical presentations to hospital, however viral specific real-time polymerase chain reaction (RT-PCR) testing has limited sensitivity and can take up to 48 hours for operational reasons. In this study, we develop two early-detection models to identify COVID-19 using routinely collected data typically available within one hour (laboratory tests, blood gas and vital signs) during 115,394 emergency presentations and 72,310 admissions to hospital. Our emergency department (ED) model achieved 77.4% sensitivity and 95.7% specificity (AUROC 0.939) for COVID-19 amongst all patients attending hospital, and Admissions model achieved 77.4% sensitivity and 94.8% specificity (AUROC 0.940) for the subset admitted to hospital. Both models achieve high negative predictive values (>99%) across a range of prevalences (

Aims The COVID-19 pandemic presents an unprecedented burden on global healthcare systems, and existing infrastructures must adapt and evolve to meet the challenge. With health systems reliant on the health of their workforce, the importance of protection against disease transmission in healthcare workers (HCWs) is clear. This study collated responses from several countries, provided by clinicians familiar with practice in each location, to identify areas of best practice and policy so as to build consensus of those measures that might reduce the risk of transmission of COVID-19 to HCWs at work. Methods A cross-sectional descriptive survey was designed with ten open and closed questions and sent to a representative sample. The sample was selected on a convenience basis of 27 senior surgeons, members of an international surgical society, who were all frontline workers in the COVID-19 pandemic. This study was reported according to the Standards for Reporting Qualitative Research (SRQR) checklist. Results Responses were received by all 27 surgeons from 22 countries across six continents. A number of the study respondents reported COVID-19-related infection and mortality in HCWs in their countries. Differing areas of practice and policy were identified and organized into themes including the specification of units receiving COVID-19 patients, availability and usage of personal protective equipment (PPE), other measures to reduce staff exposure, and communicating with and supporting HCWs. Areas more specific to surgery also identified some variation in practice and policy in relation to visitors to the hospital, the outpatient department, and in the operating room for both non-urgent and emergency care. Conclusion COVID-19 presents a disproportionate risk to HCWs, potentially resulting in a diminished health system capacity, and consequently an impairment to population health. Implementation of these recommendations at an international level could provide a framework to reduce this burden.

Background: The arthroscopic “bony Bankart bridge” (BBB) repair technique was recently shown to successfully restore shoulder stability at short-term follow-up, but longer-term outcomes have not yet been described. Purpose: To report the outcomes at minimum 5-year follow-up after BBB repair for anterior shoulder instability with a bony Bankart lesion. Study Design: Case series; Level of evidence, 4. Methods: Patients were included if they sustained a bony Bankart lesion, were treated with a BBB technique, and were at least 5 years postoperative. Patients were excluded if they underwent concomitant rotator cuff repair or an open bone fragment reduction. All patients were assessed with the following measures preoperatively and at final evaluation: QuickDASH (Quick Disabilities of the Arm, Shoulder and Hand), American Shoulder and Elbow Surgeons, Single Assessment Numeric Evaluation, and 12-Item Short Form Health Survey (SF-12) Physical Component Summary. Results: From 2008 to 2012, 13 patients who underwent BBB met the inclusion criteria with a mean age of 39.6 years (range, 19.1-68.8 years) and a mean follow-up of 6.7 years (range, 5.1-9.0 years). Mean time from most recent injury to surgery was 6.3 months (range, 1 day–36 months). The mean glenoid bone loss was 22.5% (range, 9.1%-38.6%). Mean SF-12 scores demonstrated significant improvement from 45.8 (SD, 9.7) preoperatively to 55.1 (SD, 5.9) at a mean follow-up of 6.7 years. At final follow-up, the mean American Shoulder and Elbow Surgeons score was 93.1 (range, 68.3-100); the mean QuickDASH score, 6.2 (range, 0-25); and the mean Single Assessment Numeric Evaluation score, 92.8 (range, 69-99). None of the patients progressed to further shoulder surgery. Three of 13 patients (23%) reported subjective recurrent instability. At final follow-up, 9 of 12 (75%) patients indicated that their sports participation levels were equal to their preinjury levels. Median patient satisfaction at final follow-up was 10 of 10 points (range, 3-10). Conclusion: The arthroscopic BBB technique for patients with anterior bony Bankart lesions can restore shoulder stability, yield durable improvements in clinical outcomes, and provide a high return-to-sport rate at a minimum 5-year follow-up. Three of 13 patients experienced postoperative symptoms of instability but did not undergo further stabilization surgery.

The purpose of this study was to investigate clinical outcomes following Achilles tendon allograft-augmented latissimus dorsi tendon transfer (LDTT) for the treatment of irreparable posterosuperior rotator cuff tears with a minimum of 2 years post-operative follow-up. We hypothesized that patients would show significant improvement in outcomes scores with a low failure rate. Patients who were treated with Achilles tendon allograft-augmented LDTT for irreparable posterosuperior rotator cuff tears with a minimum follow-up of 2 years were included. Patient-reported outcomes scores, including ASES, QuickDASH, SANE, SF-12 PCS, and satisfaction, were collected pre- and post-operatively. Pre- and post-operative scores were compared with a Wilcoxon test. Revision to reverse total shoulder arthroplasty (RTSA) was considered as failure. Between March 2006 and November 2014, a total of 16 patients with a mean age of 49 years (range 34–57 years) were included. Minimum 2-year outcomes data were available for 14 of the 16 patients (87.5%) with a mean follow-up of 5.5 years (range 2.1–10.5 years). Two patients (12.5%) advanced to RTSA at a mean of 1.1 years following LDTT. Postoperative median subjective outcomes scores improved, but did not reach statistical significance (SF-12 PCS: 35.4–46.4, P = 0.182; ASES: 47.5–69.9, P = 0.209; QuickDASH: 57.9–31.8, P = 0.176; SANE: 40.0–39.5, P = 0.273). Median post-operative patient satisfaction was 5 on a 10-point scale (range 1–10). Patients with irreparable rotator cuff tears treated with Achilles tendon allograft-augmented latissimus dorsi tendon transfer did not experience significant post-operative improvement in patient-reported outcomes. Thus, the use of an additional allograft-augmentation remains questionable. Retrospective case series, level IV.

The production of lovastatin by Aspergillus terreus PU-PCSIR-1 was studied using submerged fermentation technique. Effects of pH, incubation temperature, incubation time, and the media components on the production of lovastatin were investigated. Maximum lovastatin yield (198.90 mg/L) was achieved after 14 days of incubation at temperature 28°C and pH 7.4. Peptonized milk, linoleic acid, glucose, yeast extract, and trace elements had a positive impact on the production of lovastatin by A. terreus.

Interest in the therapeutic potential of bone marrow aspirate concentrate (BMAC) has grown exponentially. However, comparisons among studies and their processing methods are challenging because of inconsistent reporting of protocols, as well as poor characterization of the composition of the initial bone marrow aspirate and of the final products delivered. The purpose of this study was to perform a systematic review of the literature to evaluate the level of reporting related to the protocols used for BMAC preparation and the composition of BMAC utilized in the treatment of musculoskeletal diseases in published clinical studies.A systematic review of the literature was performed by searching PubMed, MEDLINE, the Cochrane Database of Systematic Reviews, and the Cochrane Central Register of Controlled Trials from 1980 to 2016. Inclusion criteria were human clinical trials, English language, and manuscripts that reported on the use of BMAC in musculoskeletal conditions.After a comprehensive review of the 986 identified articles, 46 articles met the inclusion criteria for analysis. No study provided comprehensive reporting that included a clear description of the preparation protocol that could be used by subsequent investigators to repeat the method. Only 14 (30%) of the studies provided quantitative metrics of the composition of the BMAC final product.The reporting of BMAC preparation protocols in clinical studies was highly inconsistent and studies did not provide sufficient information to allow the protocol to be reproduced. Moreover, comparison of the efficacy and yield of BMAC products is precluded by deficiencies in the reporting of preparation methods and composition. Future studies should contain standardized and stepwise descriptions of the BMAC preparation protocol, and the composition of the BMAC delivered, to permit validating and rationally optimizing the role of BMAC in musculoskeletal care.

Focal articular cartilage injuries in the knee are common and can cause severe morbidity and reduced function. The articular cartilage is avascular and has limited ability to heal, and hence, patients with cartilage injuries have increased risk of progressing to osteoarthritis. Most of the cartilage injuries are located on the femoral condyles. Engaging focal cartilage injuries involving the trochlea are challenging because of the morbidity caused by these injuries and the limited treatment options. Osteochondral allograft transplantation is emerging as a promising treatment for full-thickness articular cartilage defects. Recent studies have reported high success rates with the use of osteochondral allografts. This article reports our technique of osteochondral allograft transplantation for the treatment of a focal full-thickness defect of the trochlea.

BackgroundThe distinction between normal and pathological extra-axial cerebrospinal fluid (CSF) spaces is unclear, with the use of the term benign external hydrocephalus (BEH) not being well defined in clinical practice. This study aimed to establish a distribution of metrics of the subarachnoid space in a population of children diagnosed as normal, and investigate the clinical use of the term BEH.MethodsA retrospective case-control study on magnetic resonance image scans was performed on 150 children diagnosed as normal and 10 children diagnosed with BEH. Measurements were taken in the axial plane for CSF width (CSFW), and interhemispheric width (IHW).ResultsNormal controls had a mean age of 11.1 ± 7.6 months (78 male, 72 female) and the BEH sample had a mean age of 10.6 ± 7.8 months (six male, four female). Mean CSFW was 7.96 ± 4.79 mm in the BEH sample compared to 4.58 ± 2.25 mm in the normal sample ( p ConclusionThe absence of diagnostic criteria for BEH means reporting is variable. Patients being diagnosed with BEH who have no other clinical defects may represent the extreme of the normal population rather than a distinct clinical entity.

Os acromiale occur frequently in the population and can be a cause of significant shoulder dysfunction and rotator cuff impingement. When symptomatic os acromiale fail conservative management, surgical intervention may become necessary. The purpose of this article is to describe our preferred surgical technique for osteosynthesis of os acromiale using cannulated screws and tension-band wiring.

Chronic anterior shoulder instability due to structural failure of the subscapularis muscle and the anterior capsule is a rare and challenging diagnosis for surgeons to manage because poor-quality capsular, labral, and rotator cuff tissue often limits effective treatment options. If primary repair is not possible because of retraction and poor tissue quality, reconstruction with an allograft or autograft may be the only joint-preserving option. The purpose of this article is to describe a surgical technique for anterior capsular reconstruction using a human acellular dermal allograft for the treatment of irreparable subscapularis tears.

Supplemental material, DS_10.1177_0363546520914632 for Predictive Modeling to Determine Functional Outcomes After Arthroscopic Rotator Cuff Repair by Salvatore Frangiamore, Grant J. Dornan, Marilee P. Horan, Sandeep Mannava, Erik M. Fritz, Zaamin B. Hussain, Gilbert Moatshe, Jonathan A. Godin, Jonas Pogorzelski and Peter J. Millett in The American Journal of Sports Medicine

INTRODUCTION Despite the widespread use of arthroscopic double-row transosseous-equivalent (TOE) rotator cuff repair (RCR) techniques, midterm outcome data are limited. The purpose of this article was to assess midterm clinical outcomes of patients following arthroscopic TOE RCR using either a knotless tape bridge (TB) repair or knotted suture bridge (SB) repair technique. We hypothesized that there would be significant improvements in patient-reported outcomes with TOE RCR that would be durable over time. We also hypothesized that the knotless TB technique would yield equivalent clinical results to the knotted SB technique, but that there would be differences in retear types between the two TOE techniques. METHODS Patients included were a minimum of 5 years from an index arthroscopic double-row TOE repair using either a knotless TB or knotted SB technique for one, two, or three tendon full-thickness rotator cuff tears involving the supraspinatus tendon. Preoperative and postoperative American Shoulder and Elbow Surgeons, Short-Form 12 Physical Component Summary, Quick Disabilities of the Arm, Shoulder, and Hand, Single Assessment Numeric Evaluation, and satisfaction scores were collected. Scores were also stratified and compared based on primary and revision repair, tear location, and tear chronicity. Outcomes between techniques were contrasted, and survivorship analysis was conducted, with failure defined as progression to revision surgery. RESULTS One-hundred ninety-two shoulders were included with a mean follow-up of 6.6 years (range, 5.0 to 11.0 years). Fifteen shoulders (7.8%) underwent revision cuff repair. All scores improved significantly for TB repair (P < 0.001). For SB repair, all scores improved, but only American Shoulder and Elbow Surgeons and Short-Form 12 Physical Component Summary scores (P < 0.05) demonstrated statistical significance. No statistically significant differences were found between the repair techniques when stratified by primary and revision repairs, tear location, or chronicity. Postoperative clinical survivorship was 96.6% and 93.6% for knotted SB repairs and 96.7% and 93.9% for knotless TB repairs at 2 and 5 years, respectively. CONCLUSION TOE RCR results in significant clinical improvement and excellent survivorship at a minimum of 5 years of follow-up, using either knotted SB or knotless TB repair techniques in primary and revision cases and in small and large tears. Equivalent results were obtained with both TOE techniques. Patients undergoing repair with a TOE showed significant improvements in patient-reported outcomes that were durable at a minimum of 5 years postoperatively.

Background: Previous studies have examined factors related to the increased use of opioids after hip arthroscopy in adults. However, few have focused on the adolescent population. Purpose: The purpose of this study was to compare the opioids prescribed to opioids consumed after hip arthroscopic procedures in adolescent and young adult patients, and to determine patient or surgical factors associated with increased postoperative opioid use. Methods: Adolescent and young adult patients who underwent hip arthroscopy and associated arthroscopic interventions between January 2017 and January 2020 were included. Patients with a diagnosed pain syndrome or history of chronic pain, as determined by the patient taking opioid medications prior to surgery, were excluded. Daily postoperative opioid intake was recorded via pain-control logbooks. The outcome of the study was defined as the average total number of opioid tablets consumed postoperatively. Results: Fifty-eight patients returned completed logbooks, 72% of whom were female patients. The average age was 21.30 years (range, 14.9 – 34.2). Most patients (73%) were prescribed 30 oxycodone tablets. The median amount of tablets consumed was 7 (range, 0-41) over a median duration of 7 days (range, 1-22). The median ratio of tablets consumed to prescribed was 20% and the 95th percentile of opioids consumed was 28 tablets. Bivariate analysis showed that patient age at surgery was positively correlated to the total amount of tablets consumed (r=0.28, p=0.04) and to the ratio of tablets consumed to prescribed (r=0.30, p=0.03). Duration of surgery was negatively correlated to the number of days tablets were consumed (r=-0.31, p=0.03). Multivariate analysis showed that patients who were prescribed more than 30 tablets took on average 7.8 more tablets overall compared to those prescribed 30 or fewer tablets (p=0.003), and that for each additional year of age, the ratio of tablets consumed to prescribed increased by 1% (p=0.02). Conclusion: After undergoing hip arthroscopy and associated arthroscopic procedures, adolescents and young adult patients are commonly overprescribed opioids, consuming on average only one-fifth of the tablets prescribed. This finding mirrors trends in the pediatric knee arthroscopy literature and provides an opportunity to reassess current opioid prescribing behaviors in the adolescent and young adult populations. [Table: see text][Table: see text][Table: see text][Table: see text][Table: see text]

Background: Osteochondritis dissecans(OCD) is an idiopathic condition primarily involving the subchondral bone with secondary articular cartilage changes, commonly occurring in the knee. The true prevalence of bilateral OCD in patients presenting with unilateral OCD symptoms is unknown. Hypothesis/Purpose: The goals of this study are to determine the prevalence and characteristics of bilateral OCD in patients with unilateral symptoms and compare to those with unilateral disease. Methods: An electronic medical record database was queried from 2003-2016 to identify and retrospectively review patients 18 years or younger presenting to a single pediatric institution with a diagnosis of OCD of the knee and strictly unilateral knee pain. Contralateral knee imaging of the asymptomatic knee within one year of initial presentation was required. Lesion characteristics were evaluated on both x-ray and magnetic resonance imaging(MRI) assessing size, location, and Hefti staging. Treatment(both surgical and non-operative) and outcomes were recorded. Patients with unilateral OCD were compared with those with bilateral disease using appropriate statistical analyses. Results: Eighty consecutive patients, 63 males(79%) and 17 females(21%), average age of 13.1 years old (range:8-18), were included. 71% of symptomatic lesions were located on the medial femoral condyle and 14% on the lateral femoral condyle with 20 lesions(25%) deemed stable on MRI evaluation. A positive correlation was found between increasing lesion size and severity of MRI/Hefti grade(Figure-1). Twelve patients(15%) were found to have bilateral OCD on contralateral imaging, with five of the contralateral lesions(42%) considered stable on MRI. There was no significant difference in skeletal maturity between patients with bilateral vs. unilateral disease. Fifty-two patients(77%) with unilateral disease underwent surgical intervention, while 9(75%) of those with bilateral disease underwent a surgical procedure on either knee. In patients discovered to have an asymptomatic contralateral lesion, 67% ultimately underwent surgical intervention on the contralateral knee. Comparing patients with unilateral and bilateral disease, no statistical differences were found in terms of patient demographics or lesion characteristics. Conclusion: In patients presenting with unilateral OCD symptoms, there was a 15% prevalence of bilateral disease. There was no difference in age, sex, physeal status or lesion characteristics between patients with unilateral vs. bilateral OCD lesions, and we found no difference in rates of surgical intervention. A consistent relationship between lesion size and Hefti classification was appreciated. Given the prevalence of asymptomatic contralateral lesions and required intervention, our study supports the recommendation for bilateral radiologic knee evaluation for pediatric and adolescent patients presenting with unilateral knee OCD. [Figure: see text]

Background: Recurrent patellar instability is a common condition often requiring surgical stabilization in adolescents. Obesity, defined as body mass index (BMI) greater than 30 kg/m2 in adults, has been associated with poorer outcomes with many procedures including ACL reconstruction, spinal fusion, and joint arthroplasty. Data is limited regarding the results of surgery for patellar instability in adolescent patients with BMI > 30 kg/m2. Purpose: The purpose of this study was to report on rates of recurrent patellar instability following surgical management in adolescents with BMI >30 kg/m2 and to compare the rates of recurrent instability between different surgical procedures. Methods A retrospective review of patients who underwent surgical management of patellar instability at our institution was performed. Inclusion criteria included patients aged 19 and younger, with BMI >30 kg/m2 who were followed for least 12 months post procedure. Patients with underlying collagen or systemic disorders, a history of prior ipsilateral knee surgery, or an osteochondral fragment greater than 10mm were excluded. Complications were defined as any recurrent subluxation or dislocation, or need for subsequent instability surgery. A subgroup analysis was performed to compare recurrent instability rates within our cohort between patients who underwent medial retinacular plication versus all other procedures. Categorical variables were compared using Fisher’s exact test. Statistical significance of pResults: Fifty-five patients were identified. Mean age was 15.6±2.4 years. Mean BMI for this cohort was 34.9± 4.3 kg/m2. 72.7% of patients were female. All patients underwent either medial retincular plication, tibial tubercle osteotomy, MPFL reconstruction or combined procedures (Table 1). At a mean of 3.8 years, 16.4% of all patients had any recurrent subluxation or dislocation including 12.7% who had a recurrent dislocation, and 7.3% who required a revision patellar stabilization procedure. Subgroup analysis revealed that obese patients who underwent isolated medial retinacular plication had higher rates of recurrent subluxation or dislocation (24% vs 10%, p=0.272) including recurrent dislocation (20% vs 6.7%, 0.226), and had significantly higher rates of subsequent instability surgery (16% vs 0%, p=0.037) (Table 2). Conclusion: Adolescents with BMI > 30 who undergo patellar stabilization surgery have notable rates of recurrent subluxation or dislocation and subsequent instability surgery though comparable to results in non-obese patients. Obese patients who underwent medial retinacular plication had higher rates of postoperative instability and significantly higher rates of revision instability surgery compared to those who underwent MPFL reconstruction, tibial tubercle osteotomy or combined procedures. Tables/Figures: [Table: see text][Table: see text]

Clavicle fractures are among the most common fractures occurring in the general population, and the vast majority are localized in the midshaft portion of the bone. Management of midshaft clavicle fractures remains controversial. Although many can be managed nonoperatively, certain patient populations and fracture patterns, such as completely displaced and shortened fractures, are at risk of less optimal outcomes with nonoperative management; surgical intervention should be considered in such cases. The purpose of this article is to demonstrate our technique of midshaft clavicle fixation using minimally invasive intramedullary fixation.

Tightness or contracture of the pectoralis minor muscle can cause significant scapular dysfunction and is typically seen in patients with scapular dyskinesis and abnormal scapular protraction. When nonoperative treatment in these patients has failed, pectoralis tenotomy aims to resect the pectoralis minor tendon from the medial aspect of the coracoid process in order to decrease the force on the scapula, thereby improving scapular dynamics.

Rupture of the pectoralis major tendon typically occurs following violent, eccentric contraction of the muscle. Tendon repair is indicated in healthy, active individuals with complete or high-grade partial tears involving the humeral insertion of the muscle. Repair is achieved with unicortical buttons and sutures which are tensioned to bring the tendon stump down to its native footprint.

Background: Patients are staying active longer and expect to return to sports or continue participating in recreational activities after total shoulder arthroplasty (TSA) for primary glenohumeral osteoarthritis. Purpose/Hypothesis: The purpose of this study was to assess the ability of patients to return to recreational sports following TSA. We hypothesized that TSA would allow a high rate of return to recreational sports. Study Design: Case series; Level of evidence, 4. Methods: All patients who underwent primary TSA by a single surgeon and were at least 2 years out from surgery were included and were studied for their ability to return to recreational activity following surgery between December 2005 and January 2015. Patient-reported outcomes were obtained, including the 12-Item Short Form Health Survey–Physical Component Summary (SF-12 PCS); Single Assessment Numeric Evaluation (SANE); Quick Disabilities of the Arm, Shoulder, and Hand (QuickDASH) questionnaire; American Shoulder and Elbow Surgeons (ASES) score; and satisfaction scores (10-point scale), preoperatively and at a minimum of 2 years postoperatively. Return-to-sport rates were assessed using a standardized patient-reported outcome questionnaire. Results: A total of 165 patients (186 shoulders) that received TSA met the inclusion criteria for the study. Preoperatively, 139 patients (157 shoulders) were involved in recreational sports; 16 (8.6%) shoulders required additional surgical intervention after the index TSA procedure. A significant postoperative increase was noted in the mean ASES (from 48.3 to 87.0; P < .001), QuickDASH (from 41.0 to 15.8; P < .001), SANE (from 49.1 to 81.2; P < .001), and SF-12 PCS scores (from 38.6 to 48.9; P = .004). Of the 157 shoulders in the recreational sports cohort, responses to the survey examining recreational sporting activities after surgery were available for 112 shoulders. The overall rate of return to sport or recreational activity following TSA was 93.7% (105/112 shoulders). The rate of return to recreational sporting activity equal to or better than the preinjury level was 69.7% (78/112 shoulders), while 6.3% (7/112 shoulders) of our cohort reported that they were unable to compete in recreational sports following TSA. Of the patients who participated in predominantly upper extremity sporting activities after TSA, 49% had to modify their postoperative recreational sporting activity because of lifestyle change, pain, weakness, or decreased range of motion. Conclusion: Patients undergoing TSA showed excellent postoperative improvement in their outcome scores, satisfaction, and return to athletic activities. Despite the expected decrease in activity levels with the slow progression of osteoarthritis over time until TSA was performed, almost 94% of patients successfully returned to various recreational sporting activities postoperatively. This study showed that return to recreational sports can be achieved at participation levels that are comparable with preoperative levels, but athletes in some sports such as tennis or swimming, which require more intense levels of exercise, are less likely to return to the same participation levels.