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The purpose of this study was to review the outcome of patients with osteonecrosis of the humeral head, based on etiology and treatment with either hemiarthroplasty or total shoulder arthroplasty (TSA). Sixty-four shoulders, with an average age of 57 years, were evaluated at a mean of 4.8 years. Outcomes included L'Insalata and American Shoulder and Elbow Surgeons (ASES) scores, as well as range of motion (ROM). The overall ASES score was 67, average flexion was 127 degrees, and external rotation was 49 degrees. Outcomes did not differ based on etiology, but ROM was decreased with post-traumatic osteonecrosis. There was no difference in outcome or ROM between hemiarthroplasty and TSA. The complication rate was significantly higher with TSA (22%) than with hemiarthroplasty (8%). Achieving ROM in patients with post-traumatic osteonecrosis remains difficult. TSA was associated with a higher complication rate and decreased mobility and should be reserved for patients with stage V osteonecrosis.

DTI indices have been associated with cellular rejection in adult heart transplant recipients, but their predictive value in pediatric recipients is unknown. The purpose of this study was to evaluate DTI measures in the detection of cellular and AMR in pediatric heart transplant recipients. One hundred and forty-eight pediatric heart transplant recipients who had 267 cardiac catheterization procedures with EMB, echocardiogram with DTI, and BNP level performed on the same day were included in the study. For the mitral and tricuspid valves, the ratios (E/E') between the early diastolic inflow velocity by pulsed Doppler (E, m/s) and the early diastolic annular velocity by DTI (E', m/s) were obtained and compared between subjects with and without rejection. Of the 148 recipients, 30 subjects had a total of 37 episodes of rejection: 10 cellular (>or=1B), 17 AMR, and 10 biopsy-negative clinical rejection. Mitral and tricuspid valve E/E' ratios were significantly higher in rejectors than in non-rejectors (5.5 +/- 1.3 vs. 4.4 +/- 1.4, p < 0.001 and 4.9 +/- 2.1 vs. 4.1 +/- 1.5, p < 0.01, respectively). By multivariate linear regression, mitral valve E/E' was an independent predictor of rejection. Mitral and tricuspid valve E/E'

The combination of small-animal PET/CT scans and conventional imaging methods may enhance the evaluation of in vivo biologic interactions of murine models in the study of prostate cancer metastasis to bone.Small-animal PET/CT scans using (18)F-fluoride ion and (18)F-FDG coregistered with high-resolution small-animal CT scans were used to longitudinally assess the formation of osteoblastic, osteolytic, and mixed lesions formed by human prostate cancer cell lines in a severe combined immunodeficient (SCID) mouse tibial injection model. These scans were correlated with plain radiographs, histomorphometry, and soft-tissue measurements.Small-animal PET/CT scans were able to detect biologic activity of cells that induced an osteoblastic lesion 2 wk earlier than on plain radiographs. Furthermore, both the size and the activity of the lesions detected on PET/CT images significantly increased at each successive time point (P0.05). (18)F-FDG lesions strongly correlated with soft-tissue measurements, whereas (18)F-fluoride ion activity correlated with bone volume measured on histomorphometric analysis (P0.005). Osteolytic lesions were successfully quantified using small-animal CT, whereas lesion sizes measured on (18)F-FDG PET scans also strongly correlated with soft-tissue tumor burden (P0.05). In contrast, for mixed lesions, (18)F-fluoride ion and (18)F-FDG PET/CT scans detected only minimal activity.(18)F-FDG and (18)F-fluoride ion PET/CT scans can be useful tools in characterizing pure osteolytic and osteoblastic lesions induced by human prostate cancer cell lines. The value of this technology needs further evaluation to determine whether these studies can be used effectively to detect more subtle responses to different treatment regimens in animal models.

BackgroundPatellar maltracking is a leading cause of patellofemoral pain syndrome (PFPS). The aim of this study was to determine the inter- and intra-rater reliability of a semi-automated program for magnetic resonance imaging (MRI) based patellofemoral kinematics.MethodsSixteen subjects (10 with PFPS [mean age 32.3; SD 5.2; eight females] and six controls without PFPS 19 [mean age 28.6; SD 2.8; three females]) participated in the study. One set of T2-weighted, fat-saturated fast spin-echo (FSE) MRIs were acquired from each subject in full extension and 30° of knee flexion. MRI including axial T1ρ relaxation time mapping sequences was also performed on each knee. Following image acquisitions, regions of interest for kinematic MRI, and patellar and trochlear cartilage were segmented and quantified with in-house designed spline- based MATLAB semi-automated software.ResultsIntraclass Correlations Coefficients (ICC) of calculated kinematic parameters were good to excellent, ICC > 0.8 in patellar flexion, rotation, tilt, and translation (anterior -posterior, medial -lateral, and superior -inferior), and contact area translation. Only patellar tilt in the flexed position and motion from extended to flexed state was significantly different between PFPS and control patients (p=0.002 and p=0.006, respectively). No significant correlations were identified between patellofemoral kinematics and contact area with T1ρ relaxation times.ConclusionsA semi-automated, spline-based kinematic MRI technique for patellofemoral kinematic and contact area quantification is highly reproducible with the potential to help better understand the role of patellofemoral maltracking in PFPS and other knee disorders.Level of evidenceLevel IV.

Background:Early sport specialization is not a requirement for success at the highest levels of competition and is believed to be unhealthy physically and mentally for young athletes. It also discourages unstructured free play, which has many benefits.Purpose:To review the available evidence on early sports specialization and identify areas where scientific data are lacking.Study Design:Think tank, roundtable discussion.Results:The primary outcome of this think tank was that there is no evidence that young children will benefit from early sport specialization in the majority of sports. They are subject to overuse injury and burnout from concentrated activity. Early multisport participation will not deter young athletes from long-term competitive athletic success.Conclusion:Youth advocates, parents, clinicians, and coaches need to work together with the sport governing bodies to ensure healthy environments for play and competition that do not create long-term health issues yet support athletic competition at the highest level desired.

We report a case of suprapatellar fat pad impingement diagnosed and treated using musculoskeletal ultrasound. This report describes the utility of musculoskeletal ultrasound in making the diagnosis of suprapatellar fat pad impingement, which may potentially present as anterior knee pain, and more specifically, anterior superior knee pain. The importance of recognizing this entity on musculoskeletal ultrasound, especially when the imaging findings are subtle on prior MR imaging, is emphasized. Unconvincing suprapatellar fat pad edema on MR imaging, for example, should not preclude consideration of this entity at targeted ultrasound of the anterior knee in a patient with anterior knee pain. Furthermore, once the diagnosis is made using ultrasound, the suprapatellar fat pad impingement can be immediately and effectively treated with ultrasound-guided injection of steroid and anesthetic.

The objective of the present study was to assess the ability of bone marrow cells expressing BMP-2 created via lentiviral gene transfer to heal a critical sized femoral defect in a rat model. Femoral defects in Lewis rats were implanted with 5x10(6) rat bone marrow stromal cells (RBMSC) transduced with a lentiviral vector containing either the BMP-2 gene (Group I), the enhanced green fluorescent protein (LV-GFP) gene (Group IV), or RBMSC alone (Group V). We also included femoral defects that were treated with BMP-2-producing RBMSC transduced with lentivirus, 8 weeks after infection (Group III), and a group with 1x10(6) RBMSC transduced with a lentiviral vector with the BMP-2 gene (Group II). All defects (10/10) treated in Group I healed at 8 weeks compared with none of the femora in the control groups (Groups IV and V). In Group II, only one out of 10 femora healed. In Group III, 5 out of 10 femora healed. Significantly higher amounts of in vitro BMP-2 protein production were detected in Groups I, II, and III when compared to that of the control groups (p

Currently available diagnostic techniques can be unreliable in the diagnosis of delayed fracture healing in certain clinical situations, which can lead to increased complication rates and costs to the health care system. This study sought to determine the utility of positron emission tomography (PET) scanning with (18)F-fluoride ion, which localizes in regions of high osteoblastic activity, and (18)F-fluorodeoxyglucose (FDG), an indicator of cellular glucose metabolism, in assessing bone healing in a rat femur fracture model.Fractures were created in the femurs of immunocompetent rats. Animals in group I had a fracture produced via a manual three-point bending technique. Group II animals underwent a femoral osteotomy with placement of a 2-mm silastic spacer at the fracture site. Fracture healing was assessed with plain radiographs, (18)F-fluoride, and (18)F-FDG PET scans at 1, 2, 3, and 4-week time points after surgery. Femoral specimens were harvested for histologic analysis and manual testing of torsional and bending strength 4 weeks after surgery.All fractures in group I revealed abundant callus formation and bone healing, while none of the nonunion femurs were healed via assessment with manual palpation, radiographic, and histologic evaluation at the 4-week time point. (18)F-fluoride PET images of group I femurs at successive 1-week intervals revealed progressively increased signal uptake at the union site during fracture repair. In contrast, minimal tracer uptake was seen at the fracture sites in group II at all time points after surgery. Data analysis revealed statistically significant differences in mean signal intensity between groups I and II at each weekly interval. No significant differences between the two groups were seen using (18)F-FDG PET imaging at any time point.This study suggests that (18)F-fluoride PET imaging, which is an indicator of osteoblastic activity in vivo, can identify fracture nonunions at an early time point and may have a role in the assessment of longitudinal fracture healing. PET scans using (18)F-FDG were not helpful in differentiating metabolic activity between successful and delayed bone healing.

Background Our purpose was to evaluate the diagnostic performance of magnetic resonance imaging (MRI) for the pre-operative detection of meniscus tears requiring operative intervention, and identify factors that determined accuracy of diagnosing meniscus tears, in the setting of anterior cruciate ligament (ACL) reconstruction. Methods Patients who underwent primary ACL reconstruction were retrospectively reviewed. A meniscus tear was classified as requiring treatment if it was debrided or repaired at the time of ACL reconstruction. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of pre-operative MRIs were determined for medial and lateral meniscus tears. Results Sensitivity, specificity, PPV, and NPV of MRI were 0.90, 0.75, 0.58, and 0.95 for medial meniscus tears, respectively, and 0.67, 0.81, 0.65, and 0.82 for lateral meniscus tears. MRI-diagnosed medial meniscus tears were associated with a longer time interval between initial injury and imaging compared to ACL tears without concomitant meniscus injury on MRI (p = 0.038). Vertical medial meniscus tears were less likely than other tear patterns to require treatment at the time of ACL reconstruction (p = 0.03). MRI showed a higher diagnostic performance for lateral meniscus tears when surgery was performed within 30 days of imaging. Conclusions This study demonstrates only moderate sensitivity and specificity of pre-operative MRI in the detection of meniscus tears requiring operative treatment in the setting of ACL injury. High rates of false diagnoses were observed, suggesting MRI may not be as accurate in predicting positive or negative meniscus findings at the time of ACL reconstruction as previously reported. Level of Evidence Level III

Purpose To report the prevalence of obesity in shoulder arthroscopy, determine a body mass index (BMI) threshold most predictive of complication within 30 days, and evaluate obesity as an independent risk factor for medical and surgical complications. Methods Using the National Surgical Quality Improvement Program database, we reviewed all patients who underwent shoulder arthroscopy during 2011 to 2013. Receiver operating characteristic and Youden coefficient were calculated to find an optimal BMI cutoff to predict complications within 30 days of surgery. A case-control matched analysis was then performed by stratifying patient BMI by this cutoff and matching patients one to one according to age, sex, type of shoulder arthroscopy, American Society of Anesthesiology rating, surgical setting, and 8 comorbidities. Operating time, complications, and readmissions were also compared. Results Of the 15,589 patients who underwent shoulder arthroscopy, 6,684 (43%) were classified as obese when using the optimal cutoff point of BMI = 30 according to the Youden coefficient. Obese patients had a higher risk of superficial site infection than nonobese patients (0.3% vs 0.0%; odds ratio [OR]: 6.00; 95% confidence interval [CI], 1.3 to 26.8; P = .015). Obese patients did not have significantly increased risk for overall early postoperative complication (1.2% compared with nonobese 0.8%; OR: 1.54; 95% CI, 1.0 to 2.4), readmissions (OR: 0.85; 95% CI, 0.5 to 1.5), or increased operating time ( P = .068). Conclusions Up to 43% of patients undergoing shoulder arthroscopy can be classified as obese, but early perioperative complications are uncommon. Higher patient BMI is associated with increased risk of superficial site infection but not an overall risk for complication, readmission, or increased operating time. Level of Evidence Level III, retrospective comparative study.

Background Recent studies report high hardware removal rates after plate fixation of midshaft clavicular fractures. Precontoured clavicle plates may decrease hardware-related complications while improving healing rates and patient-reported outcomes (PROs). Methods Using a private-payer national database, we identified 7826 patients who underwent clavicle open reduction and internal fixation (ORIF) in 2007 to 2011. Database patients were tracked for 2 years to assess hardware removal and revision fixation. In addition, we retrospectively identified 73 patients who underwent plate fixation of midshaft clavicular fractures at our institution. These patients completed the Disabilities of Arm, Shoulder and Hand (DASH) assessment, the EQ-5D (EuroQol, Rotterdam, The Netherlands) quality of life assessment, and a hardware-related outcomes survey. Results Among 7826 database patients, 994 (12.7%) underwent hardware removal and 78 (1%) required revision ORIF. The annual incidence of clavicle ORIF increased 61.5% between 2007 and 2011. In our institutional cohort, 56 patients (77%) were fixed with precontoured plates and 17 (23%) with standard plates. At a mean follow-up of 4.2 years, 11 patients (15%) underwent hardware removal and 1 patient (1.4%) experienced nonunion. Patients reported excellent outcomes, with average DASH of 4.0 ± 8.9 and EQ-5D of 0.89 ± 0.19. There were no differences in PROs, hardware removal, or union rate between plate types, although our study was underpowered for these outcomes. Patients who underwent hardware removal reported lower DASH, EQ-5D, satisfaction, and shoulder function compared with patients with hardware retained. Women were more likely to undergo hardware removal in the institutional ( P = .009) and the database ( P Conclusion Displaced midshaft clavicle fractures have high union rates with precontoured plate fixation. Women are 4 times more likely than men to have hardware removed. Patients undergoing clavicle hardware removal report worse long-term outcomes than patients with hardware retained.

Introduction rotator cuff tears (RCTs) are the most common tendon injury seen in orthopedic patients. Muscle atrophy and fatty infiltration of the muscle are crucial factors that dictate the outcome following rotator cuff surgery. Though less studied in humans, rotator cuff muscle fibrosis has been seen in animal models as well and may influence outcomes as well. The purpose of this study was to determine if the rotator cuff would develop muscle changes even in the setting of an acute repair in a sheep model. We hypothesized that fatty infiltration and fibrosis would be present even after an acute repair six months after initial surgery. Methods twelve female adult sheep underwent an acute rotator cuff tear and immediate repair on the right shoulder. The left shoulder served as a control and did not undergo a tear or a repair. Six months following acute rotator cuff repairs, sheep muscles were harvested to study atrophy, fatty infiltration, and fibrosis by histological analysis, western blotting, and reverse transcription polymerase chain reaction (RT-PCR). Results the repair group demonstrated an increase expression of muscle atrophy, fatty infiltration, and fibrosis related genes. Significantly increased adipocytes, muscle fatty infiltration, and collagen deposition was observed in rotator cuff muscles in the tendon repair group compared to the control group. Conclusions rotator cuff muscle undergoes degradation changes including fatty infiltration and fibrosis even after the tendons are repair immediately after rupture. Level of evidence Basic Science Study.

Over the past 15 years, there has been an increase in youth sports participation with a concomitant increase in early year-round training in a single sport. Many factors contribute to the desire of parents and coaches to encourage early single sport specialization, including the desire to give the young athlete an edge in competition, pursuit of scholarships, and potential professional status, and the ability to label a young athlete as elite at an early age. Despite these perceived advantages, some data suggest that early sport specialization does not lead to a competitive advantage over athletes who participate in multiple sports. Although the data are limited, there is some evidence that early sport specialization may put the young athlete at risk for overuse injuries. The focus of this review is to highlight the evidence regarding early sport specialization and risk for injury; discuss the risk factors for overuse injury in high-risk sports including ice hockey, swimming, gymnastics, and baseball; and discuss future potential research that would help define the risk of injury for young athletes who participate in early sport specialization.

Purpose To analyze and correlate the clinical, radiographic, and surgical presentation of subscapularis (SSc) tears treated with arthroscopic repair. Methods We retrospectively identified 455 patients who underwent rotator cuff tear repairs at our institution from 2010 to 2014. Of these patients, 139 underwent an SSc repair either in isolation or concurrently with other rotator cuff procedures. Tear size was classified arthroscopically by whether tears involved the superior one-third of the SSc tendon, superior two-thirds of the SSc tendon, or complete SSc tendon. Patient demographic characteristics, assessments of belly-press weakness and the lift-off test, magnetic resonance imaging (MRI) findings, and data on concurrent supraspinatus and biceps tendon pathology were collected and analyzed according to tear size. Results Our cohort had a mean age of 61.8 ± 12.5 years, with a male-female gender ratio of 1.7:1. There were 22 tears of the superior one-third of the SSc (16%), 96 tears of the superior two-thirds of the SSc (69%), and 21 complete SSc tears (15%). Overall, MRI diagnosis of SSc tears had a sensitivity of 83% and specificity of 70%. MRI sensitivity was associated with tear severity ( P = .02), with complete tears having an MRI sensitivity of 100%; superior two-thirds, 82%; and superior one-third, 67%. Physical examination sensitivity for belly-press weakness and the lift-off test was 61% and 63%, respectively, and did not correspond with tear size. Increased SSc tear size corresponded with a history of trauma ( P = .04) and the presence of concurrent supraspinatus tears ( P = .03) and biceps pathology ( P = .003). Conclusions The diagnosis of SSc tears remains challenging because of the limited sensitivity of MRI and physical examination. The diagnostic sensitivity of MRI is associated with SSc tear size, whereas physical examination is independent of tear size. Additional associations identified in this study include increased SSc tear size corresponding with a history of trauma, presence of concurrent supraspinatus tears, and presence of concurrent biceps tendon pathology. Level of Evidence Level III, retrospective comparative study.

Skeletal muscle injuries are among the most common sports-related injuries that result in time lost from practice and competition. The cellular response to muscle injury can often result in changes made to the muscle fibers as well as the surrounding extracellular matrix during repair. This can negatively affect the force and range of the injured muscle even after the patient’s return to play. Diagnosis of skeletal muscle injury involves both history and physical examinations; imaging modalities including ultrasound and magnetic resonance imaging (MRI) can also be used to assess the extent of injury. Current research is investigating potential methods, including clinical factors and MRI, by which to predict a patient’s return to sports. Overall, function of acutely injured muscles seems to improve with time. Current treatment methods for skeletal muscle injuries include injections of steroids, anesthetics, and platelet-rich plasma (PRP). Other proposed methods involve inhibitors of key players in fibrotic pathways, such as transforming growth factor (TGF)-s and angiotensin II, as well as muscle-derived stem cells.

Purpose: Our purpose was to evaluate the role of the posteromedial (PM) bundle of the native posterior cruciate ligament (PCL) in restraining posterior tibial translation and the effects of sectioning of the PM bundle on PCL forces. Methods: The PCL's femoral origin was mechanically isolated by use of a cylindrical coring cutter, and a cap of bone containing the ligament fibers was attached to a load cell that recorded resultant force in the ligament as the knee was passively extended from 120° to 0° without and with simulated tibial loading conditions. Anteroposterior laxity was also measured after load cell installation. The PM bundle was cut at its femoral origin, and all tests were repeated. Results: Cutting the PM bundle produced small but statistically significant increases in mean laxity at 0° (+1.06 mm) and 10° (+0.83 mm) of flexion; mean laxities at 30°, 45°, 70°, and 90° were unchanged. Forces in the remaining anterolateral bundle were not significantly different from those in the intact ligament for any mode of tibial loading, with the exception of the valgus moment, where sectioning of the PM bundle significantly reduced the PCL force at 0° and 5° of flexion. Conclusions: The relatively small increases in mean laxity after cutting of the PM bundle show that it plays a minor role in restraining posterior tibial translation. The minor changes in ligament force profiles after cutting of the PM bundle indicate that the remaining anterolateral bundle fibers continued to be loaded in a near-normal fashion. Clinical Relevance: This study helps to elucidate the function of the PM bundle in the native PCL. Because only small changes were seen in the biomechanical parameters tested, the rationale for reconstructing this bundle of the PCL could be questioned.

Background Objective results of posterior cruciate ligament reconstruction are often less than satisfactory, with many patients exhibiting excessive posterior laxity. Hypothesis Changes in the position of the femoral tunnel within the posterior cruciate ligament's femoral footprint will significantly affect anteroposterior laxities and graft forces. Study Design Controlled laboratory study. Methods The posterior cruciate ligament's femoral origin was mechanically isolated in 13 fresh-frozen knee specimens, and the bone cap containing the ligament's insertion was attached to a load cell that recorded resultant force during tibial loading tests. Anteroposterior laxity (at ± 200 N applied force) was also measured. Cast acrylic replicas of the bone cap were fabricated, with tunnels placed in anterolateral, central, and posteromedial regions of the footprint. A graft reconstruction was tested in each tunnel. Results Mean laxities with the anterolateral tunnel were + 0.9 mm to + 1.7 mm greater than normal between 0 ° and 45 ° of flexion. Mean laxities with the posteromedial tunnel were –2.4 mm to –3.7 mm less than normal between 10 ° and 45 ° of flexion. Mean laxities with the central tunnel were not significantly different from intact knee values, except at 0 ° (0.9 mm greater). Mean graft forces with the anterolateral tunnel were normal for most modes of loading, whereas there were significant increases in graft forces with the posteromedial and central tunnels. Conclusion The anterolateral tunnel reproduced normal posterior cruciate ligament force profiles but produced a knee that was more lax than normal between 0 ° and 45 ° of flexion. The central tunnel best matched intact knee laxities, but graft forces were higher than posterior cruciate ligament forces between 0 ° and 45 ° of flexion. The posteromedial tunnel overconstrained anteroposterior laxity approximately 2 to 4 mm between 0 ° and 45 ° of flexion and generated higher graft forces in the same flexion range. Clinical Relevance This study suggests that a posteromedial tunnel should not be used for single-bundle posterior cruciate ligament reconstruction.

A retrospective analysis of 90 patients (37 boys, 53 girls) with myelomeningocele was performed to determine the relationship between gender, presence of hydrocephalus, and level of myelomeningocele with skeletal maturity, as measured by bone age. Bone age was assessed using the Oxford method of skeletal maturity. A ventriculoperitoneal shunt was present in 56 of the 90 patients. The mean bone age was found to be significantly less in patients with a ventriculoperitoneal shunt. There was no difference in bone age when comparing gender or level of myelomeningocele. Identification of factors affecting skeletal maturity in patients with myelomeningocele is important in surgical planning for therapeutic operations such as osteotomies, timing of epiphysiodesis, and spinal fusion for scoliosis.

Background reduced mass (atrophy) and increased fat content (fatty infiltration) of rotator cuff muscles are common complications of large or massive rotator cuff (RC) tears, and are believed to be irreversible even after tendon repairs. Clinically, both muscle atrophy and fatty infiltration are important factors contributing to poor functional outcomes after tendon repairs. The molecular mechanism of RC muscle atrophy and FI remains undefined. In this study, we investigated the role of bone morphogenetic proteins (BMP) signaling in RC muscle atrophy and fatty infiltration using a rat model. Methods unilateral massive RC tears was induced in adult rats. RC muscles were harvested at 2 and 6 weeks after injury for BMP signaling analysis. In a separate experiment, BMP inhibitor (LDN-193189) was injected to rats through daily intraperitoneal injection. RC muscles from rats in the treated and control groups were harvested at 6 weeks after injury for biochemistry and histology analysis. Results we found significantly increased BMP-14 and BMP-7 expression in rotator cuff muscles after RCT. Inhibiting BMP signaling resulted in increased muscle atrophy and reduced fatty infiltration in rotator cuff muscle after RC tears. Conclusion this result suggests that BMP signaling inhibits RC muscle atrophy but promotes fatty infiltration.

Objectives: There are a variety of surgical techniques used for pediatric ACL reconstruction. With a majority of studies being small case series, there is limited data on the outcomes of surgery, frequency of complications, and rate of growth disturbance. The purpose of this meta-analysis is to review clinical outcomes following pediatric ACL reconstruction and the complications of growth disturbance. Methods: The PubMed and EMBASE databases were searched for clinical studies on ACL ruptures in the skeletally immature from 1985 to 2016. Full-text studies in English and performed on humans were included (n = 5718). Titles were included if they discussed operative intervention on skeletally immature patients with ACL tears (n = 160). The references from these studies were reviewed to ensure no studies were missed. Studies that discussed complications with ACL reconstruction that were specific to the pediatric population were included (growth disturbance). Complications that were not specific to the pediatric population (i.e. knee stiffness, pain) were excluded, as were studies that reported results of surgeon surveys. Data was extracted including demographics, graft type, surgical technique, follow up, growth disturbance, re-rupture, and patient reported outcome scores . This data was analyzed in aggregate. Results: Eighteen (18) studies meeting the inclusion criteria were identified (Table 1). There were a total of 225 patients with 226 knees who underwent pediatric ACL reconstruction. The average age at surgery was 12.5 years, 86% were male, and the mean post-operative follow up was 45.8 months. The majority of the grafts were hamstring autograft (169 of 226, or 75%). One hundred fifty eight patients (70%) underwent transphyseal reconstructions, 64 (28%) partial transphyseal, and 4 (2%) physeal sparing reconstructions. There were eight (3.5%) re-ruptures prior to skeletal maturity. Sixteen patients (7%) developed angular deformity, of which the majority was valgus deformity (n=13). One patient had valgus and flexion deformity. Two patients had recurvatum, and one patient had both varus and recurvatum deformities. Three patients required osteotomy for realignment and eight (72.7%) were observed. There were 10 patients with at least a 1 cm leg length discrepancy. Six patients with leg length discrepancy were treated with epiphysiodesis (66.7%) and 3 were observed. Two patients who had combined deformities (in multiple planes) were treated with osteotomy. Eight studies reported IKDC scores (range 81-100%) and grades (all either A or B). Five studies reported excellent Lysholm scores with mean scores greater than 94. Conclusion: Growth disturbance after ACL reconstruction in the skeletally immature is more common than what has been initially reported. This meta-analysis showed that even with hamstring autograft these occurrences do occur, particularly with transphyseal reconstructions. Of the complications noted, leg length discrepancy greater than 1cm was more likely to be surgically treated with epiphysiodesis. Angular deformity (valgus) occurred as well but was generally observed. Although there traditionally has been a concern for growth disturbance in very young patients (under 12 in males, under 10 in females) who undergo reconstruction, patients who are nearing skeletal maturity may actually be at higher risk of clinically significant growth disturbances due decreased ability for the body to respond to physeal insult. Table 1. Individual Studies Author Year Growth Disturbance Re-rupture Higuchi et al. 2009 MRI narrowing in 8, frank closure in 2 0 chotel et al. 2010 One with LLD 1.5em, one with valgus deformity and 1cm LLD 0 Liddle et al. 2008 One with valgus deformity 1 McIntosh et al. 2006 One with LLD of 1.5cm 2 Koman et al. 1999 One with valgus deformity 0 Andrews et al. 1994 Two patients > 10 mm LLD 1 Lipscomb et al. 1986 One LLD 1.3cm, one LLD 2cm 2 Lemaitre et al. 2014 Two with valgus deformity 0 Kohl et al. 2014 One with valgus deformity 0 Kumar et al. 2013 One with valgus deformity 1 Lawrence et al. 2011 One with valgus deformity after revision ACL 1 Robert et al. 2010 One with valgus deformity 0 Zimmerman et al. 2015 One with LLD of 2.8cm 0 Rozbruch et al. 2013 One with varus, recurvatum, and LLD of 4.5cm 0 Henry, et al. 2009 One with valgus deformity 0 Mauch et al. 2011 One with valgus-flexion deformity 0 Nathan et al. 2013 One with LLd of 2.7cn 0 Shifflett et al. 2016 Two with recurvatum, two with valgus deformity 0

We have compared three different methods of treating symptomatic non-traumatic tears of the supraspinatus tendon in patients above 55 years of age. A total of 180 shoulders (173 patients) with supraspinatus tendon tears were randomly allocated into one of three groups (each of 60 shoulders); physiotherapy (group 1), acromioplasty and physiotherapy (group 2) and rotator cuff repair, acromioplasty and physiotherapy (group 3). The Constant score was assessed and followed up by an independent observer pre-operatively and at three, six and twelve months after the intervention. Of these, 167 shoulders were available for assessment at one year (follow-up rate of 92.8%). There were 55 shoulders in group 1 (24 in males and 31 in females, mean age 65 years (55 to 79)), 57 in group 2 (29 male and 28 female, mean age 65 years (55 to 79)) and 55 shoulders in group 3 (26 male and 29 female, mean age 65 years (55 to 81)). There were no between-group differences in the Constant score at final follow-up: 74.1 (sd 14.2), 77.2 (sd 13.0) and 77.9 (sd 12.1) in groups 1, 2 and 3, respectively (p = 0.34). The mean change in the Constant score was 17.0, 17.5, and 19.8, respectively (p = 0.34). These results suggest that at one-year follow-up, operative treatment is no better than conservative treatment with regard to non-traumatic supraspinatus tears, and that conservative treatment should be considered as the primary method of treatment for this condition.

Background Muscle atrophy, fatty infiltration, and fibrosis of the muscle have been described as important factors governing outcome after rotator cuff injury and repair. Muscle fibrosis is also thought to have a role in determining muscle compliance at the time of surgery. The transforming growth factor-β (TGF-β) pathways are highly conserved pathways that exert a potent level of control over muscle gene expression and are critical regulators of fibrosis in multiple organ systems. It has been shown that TGF-β can regulate important pathways of muscle atrophy, including the Akt/mammalian target of rapamycin pathway. The purpose of this study was to evaluate the expression of TGF-β and its downstream effectors of fibrosis after a massive rotator cuff tear (RCT) in a previously established rat model. Methods To simulate a massive RCT, infraspinatus and supraspinatus tenotomy and suprascapular nerve transection were performed on Sprague-Dawley rats with use of a validated model. Two and 6 weeks after surgery, supraspinatus muscles were harvested to study alterations in TGF-β signaling by Western blotting, quantitative polymerase chain reaction, and histologic analysis. Results There was a significant increase in fibrosis in the rotator cuff muscle after RCT in our animal model. There was a concomitant increase in TGF-β gene and protein expression at both 2 and 6 weeks after RCT. Evaluation of the TGF-β signaling pathway revealed an increase in SMAD2 activation but not in SMAD3. There was an increase in profibrotic markers collagen I, collagen III, and α-smooth muscle actin. Conclusions TGF-β signaling is significantly upregulated in rat supraspinatus muscles after RCTs.

Background: Scapular notching is a radiographic finding of unknown clinical significance following reverse total shoulder arthroplasty (RTSA). The purpose of this study was to determine how baseplate position affects the incidence of scapular notching and measure the clinical outcomes. Hypothesis: We hypothesized that low base plate position on the glenoid and new prosthesis design with a higher humeral inclination angle would decrease the incidence of notching at 2 years follow-up. Materials and methods: A total of 54 patients with an average follow-up of 30 months met inclusion criteria and underwent radiographic analysis of scapular notching and radiographic measures to determine glenoid component placement. Clinical measures including visual analog score, American Shoulder and Elbow Surgeons (ASES) scores, and range of motion (ROM) were prospectively collected. Results: Thirty-nine of the 54 patients had no notching. 7 had Grade 1 notching, 7 had Grade 2 notching, one had Grade 3, and one had Grade 4 notching. Notching was associated with higher placement of the glenoid component as measured by peg-glenoid rim distance and base plate distance. All patients with no evidence of notching at 1-year, continued to have no notching after multi-year follow-up. Clinical outcome measures including ASES scores, ROM, and visual analog pain scores were improved at follow-up. Conclusion: We concluded that lower neck-shaft angle and low baseplate positioning led to a low incidence of significant scapular notching as only 6 out of 57 (16%) patients had notching Grade 2 and above. At short-term follow-up, this RTSA results in excellent clinical outcomes and a significantly lower scapular notching rate than traditional techniques.

Rotator cuff tears (RCTs) are among the most common musculoskeletal injuries seen by orthopaedic surgeons. Clinically, massive cuff tears lead to unique pathophysiological changes in rotator cuff muscle, including atrophy, and massive fatty infiltration, which are rarely seen in other skeletal muscles. Studies in a rodent model for RCT have demonstrated that these histologic findings are accompanied by activation of the Akt/mammalian target of rapamycin (mTOR) and transforming growth factor-β (TGF-β) pathways following combined tendon-nerve injury. The purpose of this study was to compare the histologic and molecular features of rotator cuff muscle and gastrocnemius muscle--a major hindlimb muscle, following combined tendon-nerve injury. Six weeks after injury, the rat gastrocnemius did not exhibit notable fatty infiltration compared to the rotator cuff. Likewise, the adipogenic markers SREBP-1 and PPARγ as well as the TGF-β canonical pathway were upregulated in the rotator cuff, but not the gastrocnemius. Our study suggests that the rat rotator cuff and hindlimb muscles differ significantly in their response to a combined tendon-nerve injury. Clinically, these findings highlight the unique response of the rotator cuff to injury, and may begin to explain the poor outcomes of massive RCTs compared to other muscle-tendon injuries.

Reverse total shoulder arthroplasty is an effective procedure for treatment of glenohumeral joint disease among patients with severe rotator cuff deficiency. Improvements in prosthetic design are the result of an evolved understanding of both shoulder and joint replacement biomechanics. Although modern generations of the reverse shoulder prosthesis vary in specific design details, they continue to adhere to Grammont's core principles demonstrated by his original Delta III prosthesis. This review article discusses the biomechanics of reverse total shoulder arthroplasty with a focus on elements of implant design and surgical technique that may affect stability, postoperative complications, and functional outcomes.

BACKGROUND Nuclear factor-kappaB (NF-kappaB) is a transcription factor that upregulates adhesion molecules ICAM-1, VCAM-1, and ELAM-1. We hypothesized the use of ex vivo pressure-mediated delivery of transcription factor decoys (TFD) to NF-kappaB binding sites would decrease expression of adhesion molecules, and decrease reperfusion injury, acute rejection, and graft coronary artery disease (GCAD) in rat cardiac allografts. METHODS Heterotopic heart transplants were performed on donor hearts treated with saline, 10 mg/kg LPS, 160 micromol/L NF-kappaB TFD, or 160 micromol/L scrambled sequence (NF-SC) TFD for 45 min at 78 psi (6 atm). Transfection efficiency was determined with FITC-labeled TFD. Reverse transcription-PCR and immunohistochemistry was used to analyze adhesion molecule mRNA and protein expression, respectively. Apoptosis was measured with DNA fragmentation analysis. Reperfusion injury was assessed with cardiac edema, neutrophil infiltration, and histology. Acute rejection was determined by daily palpation. Allografts were assessed at POD 90 for the development of GCAD by computer-assisted image analysis to determine intimal:medial ratio and myointimal proliferation. RESULTS Hyperbaric pressure was an effective method of NF-kappaB TFD delivery (P

Background.Our purpose was to optimize hyperbaric pressure as a vector for ex vivo transfection of antisense oligodeoxynucleotides (AS-ODN) to intercellular adhesion molecule-1 to limit reperfusion injury (RI) in cardiac allografts.We investigated the effects of increased pressure, incubation time

Reperfusion injury is an inflammatory cell-mediated response that causes tissue damage immediately following transplantation, and has been implicated in the development of acute and chronic rejection. NF-kappaB is a transcription factor that upregulates adhesion molecules ICAM-1, VCAM-1, and ELAM-1 following reperfusion. We hypothesized that treatment with sulfasalazine, a potent inhibitor of NF-kappaB, would decrease adhesion molecule expression, decrease reperfusion injury, and prolong allograft survival in rat cardiac transplants.Heterotopic rat heart transplants were performed. Donor allografts were treated with saline, sulfasalazine (SSA), or lipopolysaccharide (LPS), a potent inducer of NF-kappaB activity. Reperfusion injury was assessed with cardiac edema (percent wet weight), neutrophil infiltration (MPO activity), and histologic damage (contraction band necrosis). Immunohistochemistry was performed to analyze protein expression. Acute rejection was determined by daily palpation.Treatment with a single 100 mg/kg intraperitoneal injection of sulfasalazine decreased reperfusion injury compared to saline controls (MPO activity, saline: 2.1+/-0.3, SSA: 1.2+/-0.31, P0.005; % wet weight, saline 77.6+/-1.1%; SSA 75.8+/-1.0%, P0.005; contraction band necrosis, saline: 13.1+/-2.5%, SSA: 6.1+/-3.4%, P0.001). LPS administration increased all parameters of reperfusion injury. Treatment with sulfasalazine prior to LPS also decreased reperfusion injury compared to LPS and saline groups. Sulfasalazine treatment decreased ICAM-1 and VCAM-1 protein expression. Administration of 500 mg/kg sulfasalazine increased graft survival to 15.4+/-1.8 days compared to saline (6.8+/-1.4 days, P0.005).Treatment with sulfasalazine is an effective method to decrease reperfusion injury and prolong allograft survival in a rat cardiac transplantation model.

A s the authors of the current study eloquently state, ‘‘The teres minor seems to be a forgotten muscle in the evaluation and management of rotator cuff disorders.’’ This statement is especially true in the setting of massive rotator cuff tears. However, recent research has allowed us to gain an understanding of the importance of the teres minor as it relates to clinical and functional outcomes in massive cuff tears. Simovitch et al. [5] demonstrated that a functional teres minor with less fatty infiltration (Grade 0, 1, or 2) resulted in an improved Constant score and better external rotation after reverse shoulder arthroplasty. Further, a recent study [4] found that the teres minor will hypertrophy when there is an infraspinatus tear, suggesting an overlap of function and the potential to gain function for external rotation even in patients with large posterosuperior rotator cuff tears. The current study focuses on our ability as clinicians to detect the function of the teres minor in massive rotator cuff tears, and determine the role the teres minor has in clinical outcomes. With the data presented, it appears that external rotation lag sign is an excellent test for teres minor dysfunction and can be used to predict teres minor dysfunction and clinical outcomes after reverse shoulder arthroplasty. This is important in educating the patient in the expected post-operative function after reverse shoulder arthroplasty.

Background Despite the gold standard treatment of 2-stage exchange arthroplasty, reinfection after periprosthetic shoulder infections and periarticular osteomyelitis can be as high as 37%. This study describes a protocol to detect persistent deep shoulder infection before revision arthroplasty. Methods Patients who presented with periprosthetic shoulder infections and osteomyelitis after previous surgery were treated with a standardized protocol of irrigation and debridement (I&D), removal of implants, antibiotic cement spacer placement, and pathogen-directed antibiotic therapy for 6 weeks. After completion of antibiotics and resolution of clinical symptoms, specimens were obtained from an open biopsy performed in the operating room, followed by revision arthroplasty at a later date if final cultures were without evidence of infection. If evidence of infection persisted, then another course of I&D and antibiotic treatment was performed. American Shoulder and Elbow Surgeon scores were used to evaluate clinical outcomes. Results Eighteen patients were included between 2005 and 2012. The most common pathogens isolated were Propionibacterium acnes (44%), Staphylococcus epidermidis (39%), and S aureus (22%). Four patients (22%) had evidence of persistent infection on specimens from open biopsy and required subsequent rounds of I&D before replantation. The infecting pathogen in 75% of patients with persistent infection was P acnes , and 38% of patients with P acnes infection had recurrence. Mean follow-up of 24 months showed no signs of recurrent infection in any patient and an average American Shoulder and Elbow Surgeon score of 71. Conclusion Despite prior staged treatment for deep postoperative shoulder infections, specimens obtained from open biopsy before replantation detected a persistent infection rate of 22% in all patients and 38% in patients with P acnes infection, which may indicate a role for this procedure in the prevention of recurrent infections.

In studies of the biomechanics of joints, the representation of moments using the joint coordinate system has been discussed by several authors. The primary purpose of this technical brief is to emphasize that there are two distinct, albeit related, representations for moment vectors using the joint coordinate system. These distinct representations are illuminated by exploring connections between the Euler and dual Euler bases, the "nonorthogonal projections" presented in a recent paper by Desroches et al. (2010, "Expression of Joint Moment in the Joint Coordinate System," ASME J. Biomech. Eng., 132(11), p. 11450) and seminal works by Grood and Suntay (Grood and Suntay, 1983, "A Joint Coordinate System for the Clinical Description of Three-Dimensional Motions: Application to the Knee," ASME J. Biomech. Eng., 105(2), pp. 136-144) and Fujie et al. (1996, "Forces and Moment in Six-DOF at the Human Knee Joint: Mathematical Description for Control," Journal of Biomechanics, 29(12), pp. 1577-1585) on the knee joint. It is also shown how the representation using the dual Euler basis leads to straightforward definition of joint stiffnesses. Copyright © 2013 by ASME.

Ligamentous knee injuries are common and costly, both in financial terms and time missed from work and recreational activities. Furthermore, ligamentous injuries appear to predispose patients to future osteoarthritis and other morbidities. Therefore, prevention strategies are important in limiting the potential impact of these injuries. Knee braces are one of the most often prescribed devices in the billion-dollar orthotic industry. Despite widespread use of prophylactic and functional knee braces, the evidence supporting their efficacy in reducing and/or preventing injury remains limited. Knee braces have been shown to be more effective in preventing medial collateral ligament injuries than anterior cruciate ligament injuries in both cadaveric and clinical studies. The use of functional braces after anterior cruciate ligament reconstruction has been supported and refuted in both postoperative and long-term studies.

Background: Although shoulder arthroplasty procedures are more frequently performed in the United States, there is insufficient information on outcome measures such as hospital readmission rates or factors for readmission after surgery. Methods: The State Inpatient Database from 7 different states was used to identify patients who underwent hemiarthroplasty, total shoulder arthroplasty (TSA), or reverse total shoulder arthroplasty (RTSA) from 2005 through 2010. The database was used to determine the 90-day readmission rate, causes of readmission, and risk factors for readmission. Multivariate modeling and a Cox proportional hazards model were used to measure factors and risk for readmission. Results: Included were 26,218 patients receiving shoulder arthroplasty, with an overall 90-day readmission rate of 7.3%. RTSA had the highest rate (11.2%), followed by hemiarthroplasty (8.2%) and TSA (6.0%; P < .001). Medical complications contributed to 82% of readmissions, and surgical complications contributed to 18%. Osteoarthritis was the most common medical diagnosis (11%), followed by deep venous thrombosis or pulmonary embolism (4.4%) and pneumonia (3.9%). Infection was the most common surgical cause of readmission (4.8%), followed by dislocation (4.6%). There was a stepwise increase in risk of readmission with increasing age. Patients with Medicaid insurance had more than a 50% greater risk of readmission than patients with Medicare. Procedures performed at medium-volume and highvolume hospitals showed lower risk of readmission than low-volume centers. Conclusions: Patients undergoing RTSA had higher hospital readmission rates than those undergoing hemiarthroplasty or TSA, but most readmissions after shoulder arthroplasty were due to medical causes. Level of evidence: Level III, Retrospective Cohort Design, Treatment Study. 2014 Journal of Shoulder and Elbow Surgery Board of Trustees.

Numerous clinical cohorts are exposed to reduced skeletal loading and associated bone loss, including surgical patients, stroke and spinal cord injury victims, and women on bed rest during pregnancy. In this context, understanding disuse-related bone loss is critical to developing interventions to prevent fractures and the associated morbidity, mortality, and cost to the health care system. The aim of this pilot study was to use high-resolution peripheral QCT (HR-pQCT) to examine changes in trabecular and cortical microstructure and biomechanics during a period of non weight bearing (WB) and during recovery following return to normal WB. Surgical patients requiring a 6-week non WB period (n=12, 34.8±7.7 yrs) were scanned at the affected and contralateral tibia prior to surgery, after the 6-week non WB period, and 6 and 13 weeks after returning to full WB. At the affected ultradistal tibia, integral vBMD (including both trabecular and cortical compartments) decreased with respect to baseline (-1.2%), trabecular number increased (+5.6%), while trabecular thickness (-5.4%), separation (-4.6%), and heterogeneity (-7.2%) decreased (all p

Background: Patellofemoral pain (PFP) is a common condition and often presents without evidence of arthritis on radiographs. Magnetic resonance imaging (MRI) has shown good correlation between T1ρ and T2 relaxation times and changes in the cartilage matrix, but as of yet, there are limited data in the literature utilizing these modalities to evaluate the patellofemoral joint. Hypothesis: Patients with PFP and patellar tilt will show longer T1ρ relaxation times in the lateral facets of their patella but no difference in T2 values. Study Design: Cross-sectional study; Level of evidence, 3. Methods: A total of 20 patients aged 18 to 45 years with anterior knee pain, patellar tilt, and no evidence of osteoarthritis were identified and consented to undergo MRI including axial T1ρ and T2 relaxation time mapping sequences. Knee cartilage was segmented on spoiled gradient recalled acquisition in steady state (SPGR) images using a spline-based algorithm. These results were then compared with those of 10 age-matched controls. Results: The mean T1ρ values of the lateral facets were significantly elevated in patients with PFP compared with controls (46.33 ± 4.92 ms vs 42.32 ± 3.67 ms, respectively; P = .031), while no significant difference was observed in the medial facets (42.20 ± 5.55 ms vs 41.42 ± 4.09 ms, respectively; P = .69). Significantly higher mean T1ρ values were noted in the lateral facets of the patients with PFP (46.33 ms) compared with the medial facets (42.20 ms) ( P = .0001), while no significant differences in T1ρ values were observed between the medial and lateral facets of the controls ( P = .502). No significant differences were noted in T2 relaxation times. A high correlation was noted between the mean T1ρ values of the whole patella of patients with PFP and the degree of patellar tilt ( r = 0.72). Conclusion: There were significantly higher T1ρ values in the lateral facets of patients with PFP and patellar tilt that were not seen in control patients. These higher values approach the numbers seen in patients with early osteoarthritis.

Background: The factors that lead to patients failing multiple anterior cruciate ligament (ACL) reconstructions are not well understood. Hypothesis: Multiple-revision ACL reconstruction will have different characteristics than first-time revision in terms of previous and current graft selection, mode of failure, chondral/meniscal injuries, and surgical charactieristics. Study Design: Case-control study; Level of evidence, 3. Methods: A prospective multicenter ACL revision database was utilized for the time period from March 2006 to June 2011. Patients were divided into those who underwent a single-revision ACL reconstruction and those who underwent multiple-revision ACL reconstructions. The primary outcome variable was Marx activity level. Primary data analyses between the groups included a comparison of graft type, perceived mechanism of failure, associated injury (meniscus, ligament, and cartilage), reconstruction type, and tunnel position. Data were compared by analysis of variance with a post hoc Tukey test. Results: A total of 1200 patients (58% men; median age, 26 years) were enrolled, with 1049 (87%) patients having a primary revision and 151 (13%) patients having a second or subsequent revision. Marx activity levels were significantly higher (9.77) in the primary-revision group than in those patients with multiple revisions (6.74). The most common cause of reruptures was a traumatic, noncontact ACL graft injury in 55% of primary-revision patients; 25% of patients had a nontraumatic, gradual-onset recurrent injury, and 11% had a traumatic, contact injury. In the multiple-revision group, a nontraumatic, gradual-onset injury was the most common cause of recurrence (47%), followed by traumatic noncontact (35%) and nontraumatic sudden onset (11%) ( P < .01 between groups). Chondral injuries in the medial compartment were significantly more common in the multiple-revision group than in the single-revision group, as were chondral injuries in the patellofemoral compartment. Conclusion: Patients with multiple-revision ACL reconstructions had lower activity levels, were more likely to have chondral injuries in the medial and patellofemoral compartments, and had a high rate of a nontraumatic, recurrent injury of their graft.

Background and hypothesisRotator cuff tears are the most common injury seen by shoulder surgeons. Glenohumeral osteoarthritis develops in many late-stage rotator cuff tear patients as a result of torn cuff tendons, termed "cuff tear arthropathy." However, the mechanisms of cuff tear arthropathy have not been fully established. It has been hypothesized that a combination of synovial and mechanical factors contribute equally to the development of cuff tear arthropathy. The goal of this study was to assess the utility of this model in investigating cuff tear arthropathy.Materials and methodsWe used a rat model that accurately reflects rotator cuff muscle degradation after massive rotator cuff tears through either infraspinatus and supraspinatus tenotomy or suprascapular nerve transection. Using a modified Mankin scoring system, we found significant glenohumeral cartilage damage after both rotator cuff tenotomy and suprascapular nerve transection after only 12 weeks.ResultsCartilage degeneration was similar between groups and was present on both the humeral head and the glenoid. Denervation of the supraspinatus and infraspinatus muscles without opening the joint capsule caused cartilage degeneration similar to that found in the tendon transection group.ConclusionsOur results suggest that altered mechanical loading after rotator cuff tears is the primary factor in cartilage degeneration after rotator cuff tears. Clinically, understanding the process of cartilage degeneration after rotator cuff injury will help guide treatment decisions in the setting of rotator cuff tears.Level of evidenceBasic science study, animal model.

Little is known about the early changes in cartilage composition and tibiofemoral kinematics following partial meniscectomy. The purpose of this study was to determine the effects of partial meniscectomy on cartilage compositional properties using T1ρ and T2 relaxation time mapping and to assess changes in tibiofemoral kinematics. It is hypothesize that abnormal tibiofemoral kinematics and relaxation time elevation (a reflection of changes in cartilage biochemical composition) in the weight-bearing regions of the knees following meniscectomy will be observed. Nine patients (7 males and 2 females; mean age, 48.6 ± 10.8 years; BMI = 27.3 ± 3.8 kg/m2) with tears of the posterior horn of the medial meniscus underwent arthroscopic partial meniscectomy. Pre-surgical and 6 months post-surgical MRIs were obtained in all subjects to evaluate cartilage relaxation times and tibiofemoral kinematics. Paired t tests were performed to determine significant changes in cartilage relaxation times from baseline. T1ρ relaxation time in the region of the medial femoral condyle directly adjacent to the resection showed an increase of 7.4 % at 6 months (p = 0.02). T2 relaxation times in both the medial and lateral tibial plateaus showed significant elevation at 6 months. Consistent kinematic trends were not found in post-meniscectomized knees. These results suggest that arthroscopic partial meniscectomy affects the biochemical composition of articular cartilage in the knee in as early as 6 months. The largest responses were observed in the weight-bearing regions and the cartilage immediately adjacent to the resection. This suggests that the loading environment has been altered enough to result in cartilage compositional changes in a very brief period of time following meniscectomy. IV.

Background The purpose of this investigation is to evaluate the T1ρ relaxation times of articular cartilage surrounding focal defects in the tibiofemoral joint. Methods Quantitative cartilage assessment was performed using 3 T MRI with T1ρ mapping in 19 healthy individuals and 44 OA patients. Sagittal T2-weighted fast spin echo (FSE) images were acquired for lesion assessment. Differences were determined using analysis of variance (ANOVA). Results Cartilage lesions were found in 37% of controls, and 93% of OA patients. Meniscal tears were found in 16% of controls and 57% of OA patients. We observed no difference in T1ρ relaxation times when comparing cartilage immediately surrounding a focal defect, and the remaining cartilage within that compartment. The medial femoral condyle (MFC) had the highest incidence of cartilage defects. MFC and medial meniscus posterior horn T1ρ were higher in subjects having multiple focal lesions (p = 0.048, pb0.001 respectively) and extensive full thickness lesions (p = 0.009, pb0.001 respectively) compared to subjects with no MFC defects. Significant elevations in T1ρ of the adjacent compartment (medial tibia) and medial meniscus were observed in subjects with MFC lesions. Conclusion Increased relaxation times in the involved compartment as well as the adjacent compartment and associated meniscus underscore the interdependence of these structures at bearing load. However, no differences in cartilage composition immediately surrounding a defect were noted. Finally, an association was observed between cartilage defects and meniscal damage in advanced disease. Clinical Relevance Cartilage defects were not associated with degeneration in the immediately adjacent cartilage.

Resting T cells express very low levels of c-Myb protein. During T-cell activation, c-myb expression is induced and much of the increase in expression occurs at the transcriptional level. We identified a region of the c-myb 5' flanking sequence that increased c-myb expression during T-cell activation. In vivo footprinting by ligation-mediated PCR was performed to correlate in vivo protein binding with functional activity. A protein footprint was visible over this region of the c-myb 5' flanking sequence in activated T cells but not in unactivated T cells. An electrophoretic mobility shift assay (EMSA) with nuclear extract from activated T cells and an oligonucleotide of this binding site demonstrated a new protein-DNA complex, referred to as CMAT for c-myb in activated T cells; this complex was not present in unactivated T cells. Because the binding site showed some sequence similarity with the nuclear factor of activated T cells (NFAT) binding site, we compared the kinetics of induction of the two binding complexes and the molecular masses of the two proteins. Studies of the kinetics of induction showed that the NFAT EMSA binding complex appeared earlier than the CMAT complex. The NFAT protein migrated more slowly in a sodium dodecyl sulfate-polyacrylamide gel than the CMAT protein did. In addition, an antibody against NFAT did not cross-react with the CMAT protein. The appearance of the CMAT binding complex was inhibited by both cyclosporin A and rapamycin. The CMAT protein appears to be a novel inducible protein involved in the regulation of c-myb expression during T-cell activation.

Introduction Rotator cuff (RC) tears are common tendon injuries. Clinically, both muscle atrophy and fatty infiltration have generally been attributed to poor functional outcomes. Matrix metalloproteinase-13 plays a crucial role in extracellular matrix remodeling in many physiological and pathological processes. Nevertheless, its role in rotator cuff muscle atrophy and fatty infiltration remains unknown. The purpose of this study is to define the functional role of MMP-13 in rotator cuff muscle atrophy and fatty infiltration using a mouse RC tears model. Materials and methods Unilateral complete supraspinatus and infraspinatus tendon transection and suprascapular nerve transection was performed on nine of MMP-13 (-/-) knockout and nine of MMP-13 (+/+) wildtype mice at 3 months old. Mice were sacrificed 6 weeks after surgery. Supraspinatus (SS) and infraspinatus (IS) muscles were harvested for histology and gene expression analysis with RT-PCR. Results Six weeks after RC surgery, no significant difference in muscle atrophy and fibrosis between MMP-13 knockout and wild type mice was observed. However, there was a significant increase in the amount of fatty infiltration in MMP-13 knockout mice compared to the wild types. Muscles from MMP-13 knockout mice have significantly higher expression of fatty infiltration related genes. Discussion Results from this study suggest that MMP-13 plays a crucial role in rotator cuff muscle fatty degeneration. This novel finding suggests a new molecular mechanism that governs RC muscle FI and MMP-13 may serve as a target for therapeutics to treat muscle FI after RC tears.

To evaluate how body mass index (BMI) affects rates of 30-day complication, hospital readmissions, and mortality in patients undergoing knee arthroscopy.Patients undergoing knee arthroscopy procedures between 2006 and 2013 were identified in the American College of Surgeons National Surgical Quality Improvement Program database. Patient demographics and preoperative risk factors including BMI were analyzed for postoperative complications within 30 days. Cochran-Armitage testing was performed to detect differences in complication rates across BMI categories according to World Health Organization classification. The independent risk of BMI was assessed using multivariate regression analysis.Of 41,919 patients with mean age 48 years undergoing knee arthroscopy, 20% were classified as normal weight (BMI 18.5 to 24), 35% overweight (BMI 25 to 29), 24% obese class I (BMI 30 to 34), 12% class II (BMI 35 to 40), and 9% class III (BMI ≥40). Risk of complication increased significantly with increasing BMI (normal: 1.5%, overweight: 1.6%, obese class I: 1.7%, obese class II: 1.8%, obese class III: 1.9%, P = .043). On multivariate analysis, there was no increased risk of postoperative complication directly attributed to patient BMI. Independent risk factors for medical and surgical complications after knee arthroscopy included American Society of Anesthesiologists (ASA) rating (class 4 v class 1 odds ratio [OR]: 5.39 [95% confidence interval: 3.11-9.33], P.001), functional status for activities of daily living (dependent v independent OR: 2.13 [1.42, 3.31], P.001), history of renal comorbidity (presence v absence OR: 5.10 [2.30, 11.29], P.001), and previously experienced history of wound infection prior to current surgery (presence v absence OR: 4.91 [2.88, 8.39], P.001).More than 40% of knee arthroscopy patients qualify as obese. Although univariate analysis suggests that obesity is associated with increased postoperative complications within 30 days of surgery, BMI alone does not predict complications. Independent predictors of complications include patients with high ASA classification, dependent functional status, renal comorbidities, and a recent history of wound infection.Level IV, prognostic case series.

Introduction The purpose of this study was to evaluate the changing incidence of hip arthroscopy procedures among newly trained surgeons in the United States, the indications for hip arthroscopy, and the reported rate of post-operative complications. Methods The ABOS database was used to evaluate the annual incidence of hip arthroscopy procedures between 2006–2010. Procedures were categorized by indication and type of procedure. The rate of surgical complications was calculated and compared between the published literature and hip arthroscopy procedures performed for femoroacetabular impingement (FAI)/osteoarthritis (OA) and for labral tears among the newly trained surgeon cohort taking the ABOS Part II Board exam. Results The overall incidence of hip arthroscopy procedures performed by ABOS Part II examinees increased by over 600% during the 5-year period under study from approximately 83 in 2006 to 636 in 2010. The incidence of hip arthroscopy for FAI/OA increased steadily over the time period under study, while the incidence of hip arthroscopy for labral tears was variable over time. The rate of surgical complications was 5.9% for hip arthroscopy procedures for a diagnosis of FAI/OA vs. 4.4% for a diagnosis of labral tear ( P =0.36). Conclusions The incidence of hip arthroscopy has increased dramatically over the past 5years, particularly for the indication of FAI/OA. Reported surgical complication rates are relatively low, but appear higher than those rates reported in previously published series. Appropriate indications for hip arthroscopy remain unclear.

Rotator cuff tears (RCTs) are among the most common injuries seen in orthopedic patients. Chronic tears can result in the development of muscular atrophy and fatty infiltration. Despite the prevalence of RCTs, little is known about the underlying molecular pathways that produce these changes. Recently, we have shown that mammalian target of rapamycin (mTOR) signaling plays an important role in muscle atrophy that results from massive RCTs in a rat model. The purpose of this study was therefore to extend our understanding of mTOR signaling and evaluate its role in fatty infiltration after a combined tendon transection and suprascapular nerve denervation surgery. Akt/mTOR signaling was significantly increased and resulted in the up-regulation of two transcription factors: SREBP-1 and PPARγ. We also saw an increase in expression of adipogenic markers: C/EBP-α and FASN. Upon treatment with rapamycin, an inhibitor of mTOR, we observed a decrease in mTOR signaling, activity of transcription factors, and reduction in fatty infiltration. Therefore, our study suggests that mTOR signaling mediates rotator cuff fatty infiltration via SREBP-1 and PPARγ. Clinically, our finding may alter current treatment methods to address rotator cuff fatty infiltration. © 2012 Orthopaedic Research Society.

Rotator cuff pathology is the most common shoulder problem seen by orthopedic surgeons. Rotator cuff muscle fatty infiltration and muscle atrophy are common in larger tears and are considered predicting factors for the prognosis of cuff repair. Clinically, MRI is the gold standard in determining fatty infiltration and muscle atrophy; however, analysis for MRI imaging is primarily qualitative in nature with the results lacking further validation. We have recently developed a mouse model of rotator cuff tears. The goal of this study is to quantify and verify rotator cuff muscle atrophy and fatty infiltration using high-resolution MRI in our mouse model. The rotator cuff muscles were analyzed for fat using a triglyceride quantification assay (TQA), muscle volume was measured through water displacement (WD), and histology. The study revealed that MRI had a high correlation with fat as measured with histology and TQA (R(2) =098). MRI also correlated well with atrophy measured with WD and wet weight. This suggests that MRI is a reliable modality in evaluating the progression of fatty infiltration and muscle atrophy following rotator cuff tears in a small animal model.