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Background: Given the complexity of arthroscopic rotator cuff repair (ARCR) and increasing prevalence, there is a need for comprehensive, large-scale studies that investigate potential correlations between surgeon-specific factors and postoperative outcomes after ARCR. This study examines how surgeon-specific factors including case volume, career length, fellowship training, practice setting, and regional practice impact two-year reoperation rates, conversion to total shoulder arthroplasty (anatomic or reverse), and 90-day post-ARCR hospitalization. Methods: The PearlDiver Mariner database was used to collect surgeon-specific variables and query patients who underwent ARCR from 2015 to 2018. Patient outcomes were tracked for two years, including reoperations, hospitalizations, and International Classification of Diseases, Tenth Revision codes for revision rotator cuff repair (RCR) laterality. Hospitalizations were defined as any emergency department (ED) visit or hospital readmission within 90 days after primary ARCR. Surgeon-specific factors including surgeon case volume, career length, fellowship training, practice setting, and regional practice were analyzed in relation to postoperative outcomes using both univariate and multivariate logistic regression. Results: 94,150 patients underwent ARCR by 1489 surgeons. On multivariate analysis, high-volume surgeons demonstrated a higher risk for two-year total reoperation (odds ratio [OR] = 1.06, 95% confidence interval [CI]: 1.01-1.12, P = .03) and revision RCR (OR = 1.06, 95% CI: 1.01-1.12, P = .02) compared to low-volume surgeons. Early-career surgeons showed higher rates of 90-day ED visits (mid-career surgeons: OR = 0.78, 95% CI: 0.73-0.83, P

Mechanical stimuli, such as stretch, shear stress, or compression, activate a range of biomolecular responses through cellular mechanotransduction. In the nervous system, studies on mechanical stress have highlighted key pathophysiological mechanisms underlying traumatic injury and neurodegenerative diseases. However, the biomolecular pathways triggered by mechanical stimuli in the nervous system has not been fully explored, especially compared to other body systems. This gap in knowledge may be due to the wide variety of methods and definitions used in research. Additionally, as mechanical stimulation techniques such as ultrasound and electromagnetic stimulation are increasingly utilized in psychological and neurorehabilitation treatments, it is vital to understand the underlying biological mechanisms in order to develop accurate pathophysiological models and enhance therapeutic interventions. This review aims to summarize the cellular signaling pathways activated by various mechanical and electromagnetic stimuli with a particular focus on the mammalian nervous system. Furthermore, we briefly discuss potential cellular mechanosensors involved in these processes.

Background: Anatomic total shoulder arthroplasty (ATSA) and reverse total shoulder arthroplasty (RTSA) reliably alleviate pain and restore shoulder function for a variety of indications. However, these procedures are not well-studied in patients with neurocognitive impairment. Therefore, the purpose of this study was to investigate whether patients with dementia or mild cognitive impairment (MCI) have increased odds of surgical or medical complications following arthroplasty. Methods: The PearlDiver database was queried from 2010 through October 2021 to identify a cohort of patients who underwent either ATSA or RTSA and had a minimum 2-year follow-up. Current Procedural Terminology and International Classification of Diseases codes were used to stratify this cohort into three groups: (1) patients with dementia, (2) patients with MCI, and (3) patients with neither condition. Surgical and medical complication rates were compared among these three groups. Results: The overall prevalence of neurocognitive impairment among patients undergoing total shoulder arthroplasty was 3.0% in a cohort of 92,022 patients. Patients with dementia had increased odds of sustaining a periprosthetic humerus fracture (odds ratio [OR] = 1.46, P

Abstract Background Macrophage polarization has been observed in the process of muscle injuries including rotator cuff (RC) muscle atrophy and fatty infiltration after large tendon tears. In our previous study, we showed that fibrogenesis and white adipogenesis of muscle residential fibro/adipogenic progenitors (FAPs) cause fibrosis and fatty infiltration and that brown/beige adipogenesis of FAPs promotes rotator cuff muscle regeneration. However, how polarized macrophages and their exosomes regulate FAP differentiation remains unknown. Methods We cultured FAPs with M0, M1, and M2 macrophages or 2 × 109 exosomes derived from M0, M1 and M2 with and without GW4869, an exosome inhibitor. In vivo, M0, M1, and M2 macrophages were transplanted or purified macrophage exosomes (M0, M1, M2) were injected into supraspinatus muscle (SS) after massive tendon tears in mice (n = 6). SS were harvested at six weeks after surgery to evaluate the level of muscle atrophy and fatty infiltration. Results Our results showed that M2 rather than M0 or M1 macrophages stimulates brown/beige fat differentiation of FAPs. However, the effect of GW4869, the exosome inhibitor, diminished this effect. M2 exosomes also promoted FAP Beige differentiation in vitro. The transplantation of M2 macrophages reduced supraspinatus muscle atrophy and fatty infiltration. In vivo injections of M2 exosomes significantly reduced muscle atrophy and fatty infiltration in supraspinatus muscle. Conclusion Results from our study demonstrated that polarized macrophages directly regulated FAP differentiation through their exosomes and M2 macrophage-derived exosomes may serve as a novel treatment option for RC muscle atrophy and fatty infiltration.

Abstract Tears within the stabilizing muscles of the shoulder, known as the rotator cuff (RC), are the most common cause of shoulder pain—often presenting in older patients and requiring expensive advanced imaging for diagnosis. Despite the high prevalence of RC tears within the elderly population, there is no previously published work examining shoulder kinematics using markerless motion capture in the context of shoulder injury. Here we show that a simple string pulling behavior task, where subjects pull a string using hand-over-hand motions, provides a reliable readout of shoulder mobility across animals and humans. We find that both mice and humans with RC tears exhibit decreased movement amplitude, prolonged movement time, and quantitative changes in waveform shape during string pulling task performance. In rodents, we further note the degradation of low dimensional, temporally coordinated movements after injury. Furthermore, a logistic regression model built on our biomarker ensemble succeeds in classifying human patients as having a RC tear with > 90% accuracy. Our results demonstrate how a combined framework bridging animal models, motion capture, convolutional neural networks, and algorithmic assessment of movement quality enables future research into the development of smartphone-based, at-home diagnostic tests for shoulder injury.

Background: Both anatomic total shoulder arthroplasty (ATSA) and reverse total shoulder arthroplasty (RTSA) reliably improve pain and function for a variety of indications. However, there remain concerns about these procedures among elderly patients due to their general health, the potential for lesser functional gain, and the possible need for revision at an even older age. The purpose of this review is to compare the clinical outcomes, radiographic outcomes, and complications of ATSA and RTSA among patients older than 70 years. Methods: A systematic review was performed using searches of PubMed, Embase, and Cochrane databases. The inclusion criteria were studies with patients older than 70 years who were treated with a primary ATSA or RTSA and clinical results reported at a minimum of 2 years. All indications for primary RTSA except for tumor were included. Outcomes of interest included patient-reported outcomes (PROs), range of motion, patient satisfaction, radiographic changes, complication and revision rates, and implant survival. Results: A total of 24 studies met the inclusion criteria. At a mean follow-up of 3.4 years for ATSA and 3.1 years for RTSA, there were significant improvements in pain, range of motion, and PROs for both prostheses. Patients who underwent ATSA generally had better motion and functional outcomes compared to those who underwent RTSA, though these comparisons were made across different indications for arthroplasty. The satisfaction rate was 90.9% after ATSA and 90.8% after RTSA. Furthermore, 10.2% of ATSA patients and 9.9% of RTSA patients experienced a surgical complication, whereas 2.3% of ATSA and 2.2% of RTSA patients underwent a revision. Secondary rotator cuff tear was the most common complication after ATSA, occurring in 3.7% of patients, but only 1.1% of patients required revision surgery. Both ATSA and RTSA implant survivorship was reported to range from 93.1% to 98.9% at 5- and 8-year follow-up, respectively. Patient mortality was estimated to be 19.3% with a mean time to death of 6.1 years. Conclusions: Elderly patients with primary osteoarthritis and an intact rotator cuff can have predictable pain relief, restoration of functional range of motion, and significant improvement in PROs after ATSA with low complication rates. Secondary rotator cuff failure and revision arthroplasty occur infrequently at early to mid-term follow-up. Although elderly patients who underwent ATSA generally had better functional outcomes compared to those who underwent RTSA for differing indications, patient satisfaction after both procedures were similar.

Background: Recurrent shoulder instability is an orthopedic problem with potentially long-term functional ramifications. Although arthroscopic stabilization has become increasingly utilized over open stabilization, optimal surgical intervention to minimize recurrent instability remains controversial. Methods: The PearlDiver Mariner database was queried for all cases of open and arthroscopic shoulder stabilization from 2010 to 2019. Utilization trends were aggregated after identifying cohorts of 107,210 and 13,217 patients who respectively underwent arthroscopic or open stabilization using Current Procedural Terminology codes. Subsets from those cohorts with laterality-specific International Classification of Diseases, Tenth Revision codes for shoulder instability were used to evaluate 2-year rates of recurrent instability (presence of shoulder dislocation or revision open or arthroscopic stabilization). Linear regression and chi-squared analysis were used to analyze utilization trends and to compare recurrent instability. Results: Arthroscopic stabilization comprised 90% of all stabilization procedures with annual utilization continuing to increase into 2019. Latarjet utilization increased from 15% to 42% of all open stabilization procedures while open Bankart repair utilization decreased from 56% to 35%. The rate of recurrent instability was 10.2% after arthroscopic stabilization and 12.3% after open stabilization (P = .01). Rates of redislocation (4.0% vs. 2.6%, P

Background: Lipid deposition secondary to dyslipidemia (DLD) is shown to have a significant impact on tendon pathology, including tendon elasticity, fatty infiltration, and healing properties. Rotator cuff repair is a common procedure, susceptible to influence from many tear-related and patient-related characteristics. The purpose of this study was to determine the relationship between DLD and rotator cuff repair outcomes with analysis of retear risk and function. Methods: PubMed, Embase, and SPORTDiscus were searched for all English-language, peer-reviewed studies between 2000 and the present, which analyzed relationships between patient-related factors and outcomes of rotator cuff repair. Studies that explicitly examined the effect of DLD on rotator cuff repair outcomes were chosen for inclusion. Included studies were assessed for methodological quality, and data were extracted for meta-analysis. Results: Of the 3087 titles, 424 were screened by abstract, and 67 were reviewed in full. Inclusion criteria were met by 11 studies. Of these studies, 5 studies assessed retear, 2 studies measured function, 3 studies reported both retear and function, and 1 study evaluated the risk of retear necessitating a revision surgery. The studies report no significant difference in functional outcomes. Meta-analysis revealed that DLD patients had a significantly higher risk of retear after primary rotator cuff repair (odds ratio 1.32, 95% confidence interval 1.06-1.64). Conclusion: DLD leads to an increased risk of retear after rotator cuff repair, although function appears to be unimpaired. DLD should be considered among other risk factors when counseling patients regarding expected rotator cuff repair outcomes.

Background: Poor socioeconomic status (SES) is consistently associated with poor quality of health care, particularly in the field of orthopedics. Expanding insurance coverage has created a larger patient population by specifically making health care more accessible, translating to greater demand for care in the low-SES population. The purpose of this article is to provide a scoping review of literature observing access and outcomes of rotator cuff repair surgery among low-SES populations. Methods: We performed a systematic review of articles using PubMed, Embase, and EBSCO (May 2021) from 2010 onward. Peer-reviewed articles that recorded at least one SES measure specific to patients who underwent rotator cuff repair from the United States were included. SES measures were methodically defined as income, occupation, employment, education, and race. All data that aligned with these SES measures were extracted. Results: Of the 1009 titles reviewed, 109 studies were screened by abstract, 23 were reviewed in full, and 7 studies met criteria for inclusion. Of the 5 studies investigating access, all 5 found disparities among postoperative physical therapy, orthopedic consult, and surgery, using Medicaid status as a proxy for income in addition to other income measures. Of the 3 studies analyzing outcomes, 2 found that low-SES patients had worse pain and function, again based on Medicaid status and other income measures. Education did not have a significant impact on outcomes, as per the 1 study that included it. No studies included measures of occupation or employment. Conclusion: Patients of low SES face reduced access to cuff repair care and worse associated outcomes, despite federal and state government efforts to reduce health care disparity through health care reform. The small nature of this review reflects how measures of SES are often not examined in rotator cuff repair studies.

Background:. Surgical treatment options for proximal humeral fractures include hemiarthroplasty (HA), reverse shoulder arthroplasty (RSA), and open reduction and internal fixation (ORIF). The objectives of this study were to analyze the trends in surgical treatment of proximal humeral fractures across a decade and to compare complications, reoperation rates, and readmission rates between ORIF and RSA. Methods:. The PearlDiver MUExtr Database was used to identify patients with proximal humeral fractures who were treated with ORIF, HA, or RSA between 2010 and 2019 and analyze yearly trends. Complications, revision procedures, demographic characteristics, comorbidities, and emergency room visits and hospital readmissions within 90 days of the surgical procedure were compared between ORIF and RSA cohorts for patients who had at least 2-year follow-up data. Results:. In this study, 384,158 patients with proximal humeral fractures were identified in the 10-year period between 2010 and 2019. There was a significant increase in the frequency of RSA and a decrease in the frequency of ORIF and HA over time (p < 0.0001). Compared with patients who underwent ORIF or HA, patients who underwent RSA were more likely to be older (p < 0.0001), to be female, and to have a higher Charlson Comorbidity Index. Patients who underwent ORIF had higher complication rates (23.03% compared with 18.62%; p < 0.0001) and higher reoperation rates (20.3% compared with 10.3%; p < 0.0001) than patients who underwent RSA. Patients who underwent RSA had higher emergency room visit rates (20.0% compared with 16.7%; p < 0.001) and hospital readmission rates (12.9% compared with 7.3%; p < 0.0001) within 90 days of the surgical procedure compared with patients who underwent ORIF. Conclusions:. There has been an increasing trend in RSA utilization for the surgical treatment of proximal humeral fractures, along with a decreasing trend in HA and ORIF, over time. Patients who underwent ORIF for a proximal humeral fracture had higher complication and reoperation rates compared with patients who underwent RSA. Patients who underwent RSA had higher emergency room visit and hospital readmission rates within 90 days of the surgical procedure compared with patients who underwent ORIF, which may be attributable to the RSA cohort being older and having more comorbidities. Level of Evidence:. Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Musculoskeletal conditions impede patient biomechanical function. However, clinicians rely on subjective functional assessments with poor test characteristics for biomechanical outcomes because more advanced assessments are impractical in the ambulatory care setting. Using markerless motion capture (MMC) in clinic to record time-series joint position data, we implemented a spatiotemporal assessment of patient kinematics during lower extremity functional testing to evaluate whether kinematic models could identify disease states beyond conventional clinical scoring. 213 trials of the star excursion balance test (SEBT) were recorded by 36 subjects during routine ambulatory clinic visits using both MMC technology and conventional clinician scoring. Conventional clinical scoring failed to distinguish patients with symptomatic lower extremity osteoarthritis (OA) from healthy controls in each component of the assessment. However, principal component analysis of shape models generated from MMC recordings revealed significant differences in subject posture between the OA and control cohorts for six of the eight components. Additionally, time-series models of subject posture change over time revealed distinct movement patterns and reduced overall postural change in the OA cohort compared to the controls. Finally, a novel metric quantifying postural control was derived from subject specific kinematic models and was shown to distinguish OA (1.69), asymptomatic postoperative (1.27), and control (1.23) cohorts (p = 0.0025) and to correlate with patient-reported OA symptom severity (R = -0.72, p = 0.018). Time series motion data have superior discriminative validity and clinical utility than conventional functional assessments in the case of the SEBT. Novel spatiotemporal assessment approaches can enable routine in-clinic collection of objective patient-specific biomechanical data for clinical decision-making and monitoring recovery. Author summary Osteoarthritis (OA) is a leading cause of disability in the United States. Despite the relevance of biomechanical function as a marker of disease severity and as a target for therapeutic interventions, clinical assessments of biomechanical function are significantly limited by clinician subjectivity and poor test characteristics while more advanced methods are not feasible due to the need for specialized equipment and trained personnel. Coupling a single markerless motion capture camera with statistical modeling of posture change, we developed a practical system to perform advanced biomechanical assessments of lower extremity function during routine clinic visits. To validate our system, OA patients and healthy controls were assessed performing a functional balance task by clinicians according to conventional scoring and separately by our motion capture system using kinematic posture modeling. Although clinical scoring failed to distinguish OA patients and healthy controls, our kinematic modeling and dimensionality reduction techniques identified significant differences in both subject posture and motion trajectories throughout the assessment. Furthermore, OA patients reporting more severe symptoms exhibited worse postural control. Our results imply that novel motion capture approaches can enable routine in-clinic collection of objective patient-specific biomechanical data for clinical decision-making and monitoring recovery.

Purpose: To compare the incidence, patient demographics, complication rates, readmission rates, and reoperation rates of open and arthroscopic surgery performed for septic arthritis in native knee and shoulder joints. Methods: Records of patients who were diagnosed with native knee or shoulder septic arthritis and underwent open or arthroscopic irrigation and debridement (I&D) between 2015 and 2018 were queried from the PearlDiver Mariner Database. International Classification of Diseases 10th (ICD-10) diagnosis and procedure codes were used to identify patients and track reoperations. Reoperation procedures, including revision open and arthroscopic I&D, were analyzed at 1 month, 1 year, and 2 years. Complications, emergency department (ED) admissions, and hospital readmissions within 30 days were analyzed and compared between the open and arthroscopic cohorts. Results: The query resulted with 1,993 patients who underwent knee I&D (75.3% arthroscopic, 24.7% open, P < .001) and 476 patients who underwent shoulder I&D (64.8% arthroscopic, 35.2% open, P < .001). One-month complication rates (11.6-22.7%) and hospital readmission rates (15.8-19.6%) were similar for arthroscopic and open treatment for knee and shoulder septic arthritis. Reoperation rates for revision I&D of the knee were higher after open compared to arthroscopic treatment at 1 month, 1 and 2 years (20.9% vs. 16.7%, 32.5% vs 27.6% and 34.1% vs. 29.4%, P < .05, respectively). For shoulder septic arthritis 1-month, 1-year, and 2-year reoperation rates were similar for open and arthroscopic treatment (16.0% vs 11.7%, 22.0% vs 19.3%, and 22.7% vs 20.0%, P = .57, respectively). Lastly, 6.7% of patients with native septic knee arthritis underwent subsequent arthroplasty by 2 years. Conclusion: Arthroscopic treatment carries a lower reoperation rate than open surgery for knee septic arthritis, but in the shoulder, the risk for revision I&D is similar after arthroscopic or open surgery.

Purpose: To determine the incidence of preoperative shoulder imaging, explore the prevalence of obtaining multiple advanced imaging studies, and identify patient characteristics associated with specific imaging studies before anterior versus posterior shoulder stabilization surgery. Methods: The PearlDiver database was queried for patients who underwent anterior or posterior shoulder stabilization surgery from 2010 to 2019. The incidence of imaging studies within a year of surgery was collected. Patient characteristics were compared between groups using one-way analysis of variance or χ2 test. Results: In total, 10,252 patients underwent anterior shoulder stabilization surgery, and 1,108 patients underwent posterior shoulder stabilization surgery. Imaging use before anterior and posterior shoulder stabilization surgery included plain radiographs (69%, 70%, respectively), magnetic resonance imaging (MRI; 43%, 33%), and computed tomography (CT; 22%, 22%). In total, 1,098 patients (11%) received MRI and CT before anterior stabilization surgery and 85 patients (8%) received MRI and CT before posterior stabilization surgery. Over time, the incidence of obtaining MRI and CT increased before anterior (z = 2.54, P = .011) and posterior (z = 2.36, P = .018) stabilization surgery. Conclusions: This study highlights the increasing use of multiple imaging studies before shoulder stabilization surgery over recent years, including plain radiographs, MRI, and CT imaging. In total, 45% of anterior shoulder stabilization patients and 41% of posterior shoulder stabilization patients obtained more than 1 imaging study within a year of surgery, with a recent increase in patients obtaining both MR and CT scans preoperatively. Statement of Clinical Relevance: The increasing use of multiple preoperative imaging studies observed in this study highlights an opportunity for new imaging technology to streamline and improve the preoperative workup.

Background: Glenoid retroversion and humeral head subluxation have been suggested to lead to inferior outcomes after total shoulder arthroplasty (TSA). There are limited data to support this suggestion. We investigated whether preoperative glenoid retroversion and humeral head subluxation are associated with inferior outcomes after TSA and whether change of retroversion influences outcomes after TSA. Methods: Patients undergoing TSA with minimum 2-year follow-up were included from a prospectively collected institutional shoulder arthroplasty database. Retroversion and humeral head subluxation before and after surgery were measured on axillary radiographs. Postoperative radiographs were -evaluated for glenoid component loosening and compared between groups. Spearman correlations were determined between retroversion measurements and American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES) scores. Patients were analyzed in groups based on retroversion and humeral head subluxation. Results: There were 113 patients (50% follow-up rate) evaluated at 4.2 years postoperatively. The mean preoperative retroversion (15.3° ± 7.7°) was significantly higher than postoperative retroversion (10.0° ± 6.8°; P < .0001). There was no correlation between postoperative glenoid version or humeral head subluxation and ASES scores. For patients with preoperative retroversion of >15°, there was no difference in outcome scores based on postoperative retroversion. There were no differences in preoperative or postoperative version for patients with or without glenoid lucencies. Discussion: We observed no significant relationship between postoperative glenoid retroversion or humeral head subluxation and clinical outcomes in patients following TSA. For patients with preoperative retroversion >15°, change of retroversion during TSA had no impact on their clinical outcomes at short-term follow-up.

Purpose: To precisely compare the questions and content between the most commonly cited knee-specific patient-reported outcome measurements (PROs) for anterior cruciate ligament (ACL) injury. Methods: A literature review through Medline from November 1, 2018, to November 1, 2020, was performed to find the most cited knee-specific PROs for assessment of ACL injuries. Each question was then classified as 1) identical, similar, or unique; 2) pertaining to 1 of 6 domains (pain, symptoms, functional activities, occupational activities, sports/recreation, and quality of life). The PROs were then compared to each other to assess question overlap and domain coverage. Results: A total of 133 questions were analyzed from the seven most common PROs: International Knee Documentation Committee (IKDC) form, Knee Injury and Osteoarthritis Outcome Score (KOOS), Lysholm Knee Scoring Scale, Tegner Activity Scale, Marx Scale, Knee Outcome Survey (KOS), and Cincinnati Knee Rating System (CKRS). The total distribution of identical (31.6%), similar (31.6%), and unique (36.8%) questions was found to be relatively even. However, this distribution varied within each PRO. KOS and Lysholm had the highest percentages of identical questions (64% and 62.5%, respectively). KOOS had the highest number of unique questions (26/42, 61.9%), while Tegner held the highest percentage (11/16, 68.8%). Sports/recreation was the only domain assessed by all PROs. Conclusion: Nearly two-thirds of questions overlap between the commonly used PROs for ACL injury. Although sports/recreation is assessed by all PROs, each has its own pattern of coverage across this and other domains. Level of Evidence: IV, cross-sectional study.

Purpose: To assess the use of anterior cruciate ligament (ACL) reconstruction in older adults and to compare postoperative complication and revision surgery rates between patients older than and younger than 50 years old. Methods: Retrospective data were obtained using the PearlDiver database for patients who underwent arthroscopic ACL reconstruction from January 2010 to December 2017. Trends in the annual performance of ACL reconstruction were determined using nonparametric test of trends of ranks. Patients in each age group were matched based on sex and the Charlson Comorbidity Index. The incidence of postoperative complications within 90 days and subsequent knee surgery within 2 years of ACL reconstruction was collected. Postoperative complication rates were compared between matched age groups using the χ2 test. Results: A total of 20,993 patients aged 50 years and older and 154,817 patients younger than 50 years underwent ACL reconstruction between 2010 and 2017. The use of ACL reconstruction in patients aged 50 years or older decreased over time (P = .044). Patients aged 50 years or older were more likely to experience at least 1 postoperative complication within 90 days compared to patients younger than 50 years (2.5% vs 2.1%, P = .007). Older patients were 1.3 times as likely to experience deep vein thrombosis (P = .002) and 1.8 times as likely to experience pulmonary embolism (P < .001). Younger patients were more likely to undergo subsequent ACL reconstruction and experience knee pain, stiffness, and wound infection postoperatively (P < .001, P < .001, P = .041). 1.6% of patients aged 50 years or older underwent total knee arthroplasty within 2 years. Conclusions: ACL reconstruction in patients aged 50 years or older is associated with greater complication rates but lower rates of subsequent knee surgery relative to patients younger than 50 years of age. Younger patients were more prone to surgical complications whereas older patients experienced more medical complications. The increased incidence of VTE in this population suggests that thrombotic prophylaxis may be considered. Level of Evidence: Level III, retrospective comparative observational trial.

Purpose: To use a large, contemporary database to perform a cross-sectional analysis of current practice trends in rotator cuff repair (RCR) for the treatment of full-thickness rotator cuff tear (RCT) and determine outcomes of arthroscopic and open RCR, including hospital readmissions and 2-year reoperation rates with accurate laterality tracking using International Classification of Diseases, Tenth Revision (ICD-10) codes. Methods: The PearlDiver Mariner dataset was used to query patients with full-thickness RCTs from 2010 to 2017. Propensity-score matching was performed to account for differences in age and comorbidities and allow for comparison between those undergoing open RCR and arthroscopic RCR. Subsequent procedures were tracked using ICD-10 codes to identify ipsilateral surgery within 2 years of index surgery. Hospital and emergency department admission within 30 days of surgery were investigated. Results: Of 534,076 patients diagnosed with full-thickness RCT, 37% underwent RCR; 73% of which were arthroscopic. From 2010 to 2017, arthroscopic RCRs increased from 65% to 80%, whereas open RCRs decreased from 35% to 20% (P < .0001). Younger patients underwent arthroscopic RCR more frequently, and patients who underwent open RCR had greater rates of 30-day emergency department (7.0%) and hospital readmission (2.0%) compared with arthroscopic RCR (6.3%, 1.0%, respectively) (P < .0001). For 24,392 patients with ICD-10 coding and 2-year follow-up, 10.4% of patients required reoperation, with the most common procedure being revision RCR, and 1.3% required conversion to arthroplasty. Open RCRs were more likely to require subsequent surgery (11.3%) compared with arthroscopic RCR (9.5%) (P < .0001). Patients aged 50 to 59 had the greatest rate of reoperation (14.0%), but no patients younger than age 40 years required reoperation, and no patients younger than age 50 years required conversion to arthroplasty. Conclusions: The frequency of arthroscopic RCR has continued to increase compared to open RCR. In this large cross-sectional analysis, arthroscopic RCR demonstrated lower 2-year reoperation rates and 30-day readmission rates compared to open RCR. Level of Evidence: III, cross-sectional study.

Background Context: The association between low back pain and lumbar disc degeneration is not fully characterized. One potentially overlooked factor of this process is the lumbar multifidus, which plays a role in segmental stabilization and locomotion. Previous reports have shown multifidus degeneration to be associated with disc degeneration. The goal of this study was to develop a mouse model of advanced lumbar disc degeneration to recapitulate the pathology of the human multifidus in patients with lumbar disc degeneration and low back pain. Methods: C57BL/6 mice underwent a left anterolateral approach to the lumbar spine and disc puncture with a micro scalpel at L5/6 and L6/S1. Mice underwent behavioral analysis and functional gait testing. A subset of mice underwent 14T T2-weighted MRI to assess disc degeneration and paraspinal muscle quality. At 6 and 15 weeks, mice were sacrificed, and the multifidus muscles were harvested and divided into proximal and distal segments relative to disc injury. Histological analysis was performed to assess muscle degeneration, fiber type, and macrophage density. Fibroadipogenic progenitors (FAPs) were isolated for gene expression analysis with qPCR. Results: MRI demonstrated decreased intervertebral disc signal and paraspinal muscle atrophy at 6 weeks, with progressive degeneration and atrophy at 15 weeks. Disc injury resulted in delayed functional recovery and impaired gait. Histology demonstrated progressive multifidus fibrofatty degeneration between 6 and 15 weeks. CD68+ macrophage density was increased at 6 weeks but not 15 weeks. FAPs exhibited increased fibrotic and adipogenic gene expression at 6 weeks compared to sham with less of a difference in gene expression by 15 weeks. Conclusions: We have developed a mouse model of disc injury-mediated paraspinal muscle degeneration that recapitulates features of degenerative muscle pathology observed in patients with lumbar disc degeneration, and highlights the role of FAPs in mediating fibrofatty muscle degeneration after disc injury.

Purpose: To determine whether range of motion (ROM) varies with the location and extent of labral tear seen in patients undergoing arthroscopic anterior shoulder stabilization. Methods: Consecutive patients undergoing arthroscopic anterior shoulder stabilization who were enrolled in the Multicenter Orthopaedic Outcomes Network Shoulder Instability database underwent a preoperative physical examination and intraoperative examination under anesthesia in which ROM was recorded. Intraoperatively, the location and extent of the labral tear was recorded using conventional clock-face coordinates. Patients were grouped by combinations of quadrants involved in the labral tear (G1-G7): G1 = anterior only, G2 = anterior + inferior, G3 = anterior + inferior + posterior, G4 = all quadrants, G5 = superior + anterior, G6 = superior + anterior + inferior, and G7 = posterior + superior + anterior. Statistical analyses were performed with the Kruskal–Wallis rank-sum test. When P < .05, a post-hoc Dunn’s test was performed. For categorical variables, the χ2 test was performed. We performed a series of bivariate negative binomial regression models testing pairwise combinations of ROM parameters predicting the count of labral tear locations (possible: 0-5) within each quadrant. Results: A total of 467 patients were included, with 13 (2.8%) in G1, 221 (47.3%) in G2, 40 (8.6%) in G3, 51 (10.9%) in G4, 18 (3.9%) in G5, 121 (25.9%) in G6, and 3 (0.6%) in G7. Multiple statistically significant differences were noted in ROM, specifically active internal rotation at side (IRS) (P = .005), active abduction (P = .02), passive IRS (P = .02), and passive external rotation in abduction (P = .0007). Regression modeling revealed a positive correlation between passive abduction and predicted count of labral tear locations in the superior quadrant and between passive IRS and predicted count of labral tear location in the inferior quadrant. Conclusions: In patients undergoing arthroscopic shoulder stabilization for anterior instability, ROM varies with location and extent of labral tear. However, the clinical relevance of such small ROM differences remains undetermined. Level of evidence: II, prospective comparative study.

OBJECTIVES/GOALS: For shoulder osteoarthritis (OA), the understanding of the patient-specific factors that determine success of both non-operative and operative treatment options is limited. This study aims to identify key factors associated with the response and the heterogeneity of outcomes for both types of treatment. METHODS/STUDY POPULATION: Patients diagnosed with shoulder OA and treated with either reverse/anatomic total shoulder arthroplasty (rTSA/TSA) or non-operative management at the University of California, San Francisco were enrolled in this study. They were followed for a year to ascertain phenotypic traits and patient-reported outcomes (PROs). Magnetic Resonance Imaging (MRI) was used to calculate the Shoulder Osteoarthritis Severity (SOAS) score, a semi-quantitative global assessment of shoulder OA, and to measure fat fractions of rotator cuff muscles. A Microsoft Kinect camera was used to determine the Reachable Workspace (RWS). Linear regression models were used to assess the associations between baseline demographic and radiographic factors on outcomes related to shoulder function. RESULTS/ANTICIPATED RESULTS: It is anticipated that the pre-operative MRI-based SOAS score will be inversely correlated with the magnitude of improvement in PROs 1 year after rTSA/TSA and non-operative management of shoulder OA for the surgical replacement and non-operative cohorts, respectively. Additionally, the non-operative patients who convert to rTSA/TSA within 1 year of observation will have higher SOAS scores compared to patients who continue with non-operative management. The surgical replacement patients with an infraspinatus fat fraction of more than 5% will have worse shoulder function, as measured by RWS, compared to patients with an infraspinatus fraction less than 5%. DISCUSSION/SIGNIFICANCE: MRI may be a novel technique to better predict prognosis of shoulder OA management. This will allow for the development of appropriate algorithms in the prescription of treatments and may be used to counsel patients regarding their expected outcomes or to recommend alternative treatments.

Tears of the subscapularis tendon can be challenging to diagnose and treat. Because the subscapularis plays an important role in shoulder function, careful arthroscopic evaluation and treatment are necessary to restore function. Previous surgical techniques have ranged from full open repairs to complex arthroscopic procedures needing suture passer and/or retriever devices. We describe an arthroscopic surgical technique of subscapularis repair through a single anterior portal using only penetrating graspers. This approach can be used for partial upper-border subscapularis tears, as well as complete and retracted subscapularis tendon tears.

Absract Background Paraspinal muscles are crucial for vertebral stabilization and movement. These muscles are prone to develop fatty infiltration (FI), fibrosis, and atrophy in many spine conditions. Fibro‐adipogenic progenitors (FAPs), a resident muscle stem cell population, are the main contributors of muscle fibrosis and FI. FAPs are involved in a complex interplay with satellite cells (SCs), the primary myogenic progenitor cells within muscle. Little is known about the stem cell composition of the multifidus. The aim of this study is to examine FAPs and SCs in the multifidus in disc herniation patients. Multifidus muscle samples were collected from 10 patients undergoing decompressive spine surgery for lumbar disc herniation. Hamstring muscle was collected from four patients undergoing hamstring autograft ACL reconstruction as an appendicular control. Multifidus tissue was analyzed for FI and fibrosis using Oil‐Red‐O and Masson's trichrome staining. FAPs and SCs were visualized using immunostaining and quantified with fluorescence‐activated cell sorting (FACS) sorting. Gene expression of these cells from the multifidus were analyzed with reverse transcription‐polymerase chain reaction and compared to those from hamstring muscle. FI and fibrosis accounted for 14.2%± 7.4% and 14.8%±4.2% of multifidus muscle, respectively. The multifidus contained more FAPs (11.7%±1.9% vs 1.4%±0.2%; P

The role of hip arthroscopy in the management of femoroacetabular impingement (FAI) has been advancing rapidly. In this case report, we describe the use of hip arthroscopy to successfully treat a femoral neck osteochondroma that caused a symptomatic labral tear in a 37 year old woman. Hip arthroscopy offers several advantages to surgical dislocation of the hip in the management of intra articular pathology and FAI. Hip arthroscopy is minimally invasive without the significant trauma to hip musculature, is useful in treatment of labral tears generated by FAI, and can be used to resect small lesions on the femoral head.