Gender and Racial Diversity Among the Head Medical and Athletic Training Staff of Women's Professional Sports Leagues.

Background: Despite increased awareness for promoting diversity, orthopaedics remains one of the least diverse specialties. Studying health care providers in women's professional sports provides a unique opportunity to analyze gender and racial diversity. Hypotheses: There would be low female and minority representation across the various women's professional sports leagues. There would be an increased number of female head certified athletic trainers (ATCs) when compared with head team physicians (HTPs). Study Design: Cross-sectional study. Methods: We evaluated the perceived race and sex of designated HTPs and ATCs in the Women's National Basketball Association, National Women's Soccer League, and National Women's Hockey League. Type of doctorate degree, specialty, and years in practice were also collected. Kappa (κ) coefficient measurements were used to determine interobserver agreement on race. Categorical and continuous variables were analyzed using chi-square and t tests, respectively. Results: There were significantly more female ATCs than female HTPs (74.1% vs 37.5%; P = .01). Minority representation between HTPs and ATCs was not significantly different (20.8% vs 40.7%; P = .13). Black HTPs (12.5%) and Black ATCs (22.2%) composed the largest proportion among the minority groups. There was high interobserver agreement of perceived race across HTPs (κ = 1.0) and ATCs (κ = 0.95). Conclusion: Although there were more female ATCs than HTPs in women's professional sports leagues, both cohorts lack perceived racial diversity. These data suggest an opportunity for diversification in medical and training staff of women's professional sports.

A novel mouse model of hindlimb joint contracture with 3D-printed casts.

Stiff joints formed after trauma, surgery or immobilization are frustrating for surgeons, therapists and patients alike. Unfortunately, the study of contracture is limited by available animal model systems, which focus on the utilization of larger mammals and joint trauma. Here we describe a novel mouse-based model system for the generation of joint contracture using 3D-printed clamshell casts. With this model system we are able to generate both reversible and irreversible contractures of the knee and ankle. Four- or 8-month-old female mice were casted for either 2 or 3 weeks before liberation. All groups formed measurable contractures of the knee and ankle. Younger mice immobilized for less time formed reversible contractures of the knee and ankle. We were able to generate irreversible contracture with either longer immobilization time or the utilization of older mice. The contracture formation translated into differences in gait, which were detectable using the DigiGait® analysis system. This novel model system provides a higher throughput, lower cost and more powerful tool in studying the molecular and cellular mechanisms considering the large existing pool of transgenic/knockout murine strains.

Current Perceptions of Diversity Among Head Team Physicians and Head Athletic Trainers: Results Across US Professional Sports Leagues.

BACKGROUND: Discrepancies in race, ethnicity, and sex among health care providers and their patients have been shown to affect the patient-provider relationship as well as the quality of care. Currently, minority and female representation among orthopaedic surgeons remains low. Given the large proportion of minority athletes and their degree of public visibility, professional sports serves as an important arena within which to analyze the diversity of health care providers. PURPOSE: To describe and evaluate the current level of diversity of head team physicians (HTPs) and head athletic trainers (ATCs), primarily in terms of race and sex, within men's professional sports leagues in the United States. STUDY DESIGN: Cross-sectional study. METHODS: Five major US professional sports leagues were evaluated: National Basketball Association, National Football League, National Hockey League, Major League Soccer, and Major League Baseball. Publicly available data were collected to identify the HTPs and head ATCs for each team within these leagues. Two independent observers analyzed photographs and names of these individuals to determine his or her perceived race and sex, with disagreements being resolved by a third independent observer. Other physician data collected included graduate degree(s), specialty, and number of years in practice. Kappa coefficients (κ) were employed to evaluate interobserver reliability. Chi-square, Fisher exact, and t tests were used for statistical comparisons across leagues. RESULTS: The κ values for perceived race were 0.85 for HTPs and 0.89 for head ATCs, representing near-perfect interobserver agreement. Minorities comprised 15.5% of HTPs and 20.7% of ATCs (P = .24). Women comprised 3.9% of HTPs and 1.3% of head ATCs (P = .017). The majority of HTPs were orthopaedic surgeons with medical doctorates. Female HTPs had significantly fewer years in practice compared with male HTPs (15.0 ± 4.9 vs 23.1 ± 9.6; P = .04). CONCLUSION: The lead physicians and athletic training providers for men's professional sports teams demonstrated low rates of minority and female representation, denoting a highly visible area for discussing the role of increased diversity in health care.

Rotator cuff tear degeneration and the role of fibro-adipogenic progenitors.

The high prevalence of rotator cuff tears poses challenges to individual patients and the healthcare system at large. This orthopedic injury is complicated further by high rates of retear after surgical repair. Outcomes following repair are highly dependent upon the quality of the injured rotator cuff muscles, and it is, therefore, crucial that the pathophysiology of rotator cuff degeneration continues to be explored. Fibro-adipogenic progenitors, a major population of resident muscle stem cells, have emerged as the main source of intramuscular fibrosis and fatty infiltration, both of which are key features of rotator cuff muscle degeneration. Improvements to rotator cuff repair outcomes will likely require addressing the muscle pathology produced by these cells. The aim of this review is to summarize the current rotator cuff degeneration assessment tools, the effects of poor muscle quality on patient outcomes, the role of fibro-adipogenic progenitors in mediating muscle pathology, and how these cells could be leveraged for potential therapeutics to augment current rotator cuff surgical and rehabilitative strategies.

Intervertebral disc herniation effects on multifidus muscle composition and resident stem cell populations.

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<.001) and more SCs (3.4%±1.6% vs 0.08%±0.02%; P=.002) than the hamstring. FAPs had greater α Smooth Muscle Actin (αSMA) and adipogenic gene expression than FAPs from the hamstring. SCs from the multifidus displayed upregulated expression of stem, proliferation, and differentiation genes. CONCLUSION: The multifidus in patients with disc herniation contains large percentages of FAPs and SCs with different gene expression profiles compared to those in the hamstring. These results may help explain the tendency for the multifidus to atrophy and form FI and fibrosis as well as elucidate potential approaches for mitigating these degenerative changes by leveraging these muscle stem cell populations.

Human Rotator Cuff Tears Have an Endogenous, Inducible Stem Cell Source Capable of Improving Muscle Quality and Function After Rotator Cuff Repair.

BACKGROUND: The muscle quality of the rotator cuff (RC), measured by atrophy and fatty infiltration (FI), is a key determinant of outcomes in RC injury and repair. The ability to regenerate muscle after repair has been shown to be limited. PURPOSE: To determine if there is a source of resident endogenous stem cells, fibroadipogenic progenitor cells (FAPs), within RC injury patients, and if these cells are capable of adipogenic, fibrogenic, and pro-myogenic differentiation. STUDY DESIGN: Controlled laboratory study. METHODS: A total of 20 patients between the ages of 40 and 75 years with partial- or full-thickness RC tears of the supraspinatus and evidence of atrophy and FI Goutallier grade 1, 2, or 3 were selected from 2 surgeons at an orthopaedic center. During the surgical repair procedure, supraspinatus muscle biopsy specimens were obtained for analysis as were deltoid muscle biopsy specimens to serve as the control. FAPs and satellite cells were quantified using fluorescence-activated cell sorting. Muscle FI and fibrosis was quantified using Oil Red O and Masson trichrome staining. FAP differentiation and gene expression profiles were compared across tear sizes after culture in adipogenic, fibrogenic, and beta-3 agonist (amibegron) conditions. Analysis of variance was used for statistical comparisons between groups, with P < .05 as statistically significant. RESULTS: Histologic analysis confirmed the presence of fat in biopsy specimens from patients with full-thickness tears. There were more FAPs in the full-thickness tear group compared with the partial-thickness tear group (9.43% ± 4.25% vs 3.84% ± 2.54%; P < .01). Full-thickness tears were divided by tear size, with patients with larger tears having significantly more FAPs than those with smaller tears. FAPs from muscles with full-thickness tendon tears had more adipogenic and fibrogenic potential than those with partial tears. Induction of a beige adipose tissue (BAT) phenotype in FAPs was possible, as demonstrated by increased expression of BAT markers and pro-myogenic genes including insulin-like growth factor 1 and follistatin. CONCLUSION: Endogenous FAPs are present within the RC and likely are the source of FI. These FAPs were increased in muscles with in larger tears but are capable of adopting a pro-myogenic BAT phenotype that could be utilized to improve muscle quality and patient function after RC repair.

Surgical Stabilization of Shoulder Instability in Patients With or Without a History of Seizure: A Comparative Analysis.

PURPOSE: To compare patients from a large multicenter cohort with a history of seizure and those without a history of seizure regarding preoperative and intraoperative findings and surgical procedures performed. METHODS: Patients undergoing shoulder stabilization from 2011 to 2018 at 11 orthopaedic centers were prospectively enrolled. Those with a history of seizure were identified and compared with non-seizure controls. Preoperative demographic, history, physical examination, and imaging findings were collected. Intraoperative findings and surgical procedures performed were recorded. The Mann-Whitney test, χ2 test, and logistic regression analysis were used to examine differences between the groups and define independent risk factors. Owing to the number of statistical tests performed, the false discovery method was used to determine adjusted P values to achieve α < .05. RESULTS: During enrollment, 25 of 1,298 shoulder stabilization patients (1.9%) had a history of seizure. The sex ratio and age were similar between groups, as was posterior instability incidence (23.2% in control group vs 28.0% in seizure group). Seizure patients more frequently had more than 5 dislocations in the year preceding surgery (P = .016) and had increased preoperative radiographic evidence of bone loss (P < .001). Intraoperatively, seizure patients had a higher prevalence of reverse Hill-Sachs lesions (P < .001) and large (>30% of glenoid fossa) bony Bankart lesions (P < .001). Arthroscopic Bankart repair was the most common procedure in both groups. However, open procedures were performed in 15.6% of controls and 40.0% of seizure patients (P = .001). These procedures were most commonly bony procedures. CONCLUSIONS: Seizure patients had more prior dislocations, had more preoperative bone loss, and underwent more open stabilization procedures than controls because of bone loss. Studies examining recurrence after stabilization will help establish appropriate management practices in this population. LEVEL OF EVIDENCE: Level III, retrospective review of prospectively collected cohort.

Beige FAPs Transplantation Improves Muscle Quality and Shoulder Function After Massive Rotator Cuff Tears.

Rotator cuff (RC) tears are a common cause of upper extremity disability. Any tear size can result in subsequent muscle atrophy and fatty infiltration (FI). Preoperative muscle degeneration can predict repair and postoperative functional outcomes. Muscle residential fibro-adipogenic progenitors (FAPs) are found to be capable of differentiating into beige adipocytes that release factors to promote muscle growth. This study evaluated the regenerative potential of local cell transplantation of beige FAPs to mitigate muscle degeneration in a murine massive RC tear model. Beige FAPs were isolated from muscle in UCP-1 reporter mice by flow cytometry as UCP-1+ /Sca1+ /PDGFR+ /CD31- /CD45- /integrin α7- . C57/BL6J mice undergoing supraspinatus tendon tear with suprascapular nerve transection (TT + DN) received either no additional treatment, phosphate-buffered saline injection, or beige FAP injection 2 weeks after the initial injury. Forelimb gait analysis was used to assess shoulder function with DigiGait. Mice were sacrificed 6 weeks after cell transplantation. FI, fibrosis, fiber size, vascularity were analyzed and quantified via ImageJ. Our results showed that beige FAP transplantation significantly decreased fibrosis, FI, and atrophy, enhanced vascularization compared with saline injection and non-treatment groups. Beige FAP transplantation also significantly improved shoulder function as measured by gait analysis. This study suggests that beige-differentiated FAPs may serve as a treatment option for RC muscle atrophy and FI, thus improving shoulder function in patients with massive RC tendon tears. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:1159-1166, 2020.

Beige fibro-adipogenic progenitor transplantation reduces muscle degeneration and improves function in a mouse model of delayed repair of rotator cuff tears.

BACKGROUND: Muscle atrophy and fatty infiltration (FI) are common occurrences following rotator cuff (RC) tears. Tears of all sizes are subject to muscle degeneration. The degree of muscle degeneration following RC tears is highly correlated with repair success and functional outcomes. We have recently discovered that muscle fibro-adipogenic progenitors (FAPs) can differentiate into uncoupling protein 1 (UCP-1)-expressing beige adipocytes and induce muscle regeneration. This study evaluated the potential of local cell transplantation of beige adipose FAPs (BAT-FAPs) to treat RC muscle degeneration in a murine model of RC repair. METHODS: BAT-FAPs were isolated from muscle in UCP-1 reporter mice by flow cytometry as UCP-1+/Sca1+/PDGFR+/CD31-/CD45-/integrin α7-. C57/BL6J mice underwent supraspinatus tendon tear with suprascapular nerve transection followed by repair 2 or 6 weeks after the initial injury. At the time of repair, mice received either no additional treatment, phosphate-buffered saline injection, or BAT-FAP injection. Functional outcomes were assessed by gait analysis. Mice were humanely killed at 6 weeks after cell transplantation. Supraspinatus muscle FI, fibrosis, muscle fiber size, and vascularity were analyzed and quantified via ImageJ. Analysis of variance with post hoc Tukey test and P <.05 was used to determine statistical significance. RESULTS: Cell transplantation diminished fibrosis, FI, and atrophy and enhanced vascularization in both delayed repair models. Cell transplantation resulted in improved shoulder function as assessed with gait analysis in both the delayed repair models. CONCLUSIONS: BAT-FAPs significantly reduced muscle degeneration and improved shoulder function after RC repair. BAT-FAPs hold significant promise as a therapeutic adjunct to repair for patients with advanced RC pathology.

Rotator Cuff Fibro-Adipogenic Progenitors Demonstrate Highest Concentration, Proliferative Capacity, and Adipogenic Potential Across Muscle Groups.

Fatty infiltration (FI) of rotator cuff (RC) muscles is common in patients with RC tears. Studies have demonstrated that fibro-adipogenic progenitors (FAPs), a population of resident muscle stem cells, are the main contributors of FI, which adversely affects muscle quality and RC repair success. Although FI is common in RC injuries, it is not frequently reported after other musculotendinous injuries. Additionally, studies have shown the development of different pathology patterns across muscle groups suggestive of intrinsic differences in cellular composition and behavior. This study evaluates FAP distribution and differentiation properties across anatomic locations in mice. Muscles from seven different anatomic locations were harvested from PDGFRα-eGFP FAP reporter mice. FAPs were quantified using histology and FACS sorting with BD Aria II with CD31- /CD45- /Integrinα7- /Sca-1+ and PDGFRα reporter signal (n = 3 per muscle). The cells were analyzed for adipogenesis using immunocytochemistry and for proliferation properties with Brdu-Ki67 staining. In a separate group of mice, RC and tibialis anterior muscles received glycerol injection and were harvested after 2 weeks for FI quantification (n = 4). One-way analysis of variance was used for statistical comparisons among groups, with significance at p < 0.05. FAPs from the RC, masseter, and paraspinal muscles were more numerous and demonstrated greater proliferative capacity and adipogenic potency than those from the tibialis anterior and gastrocnemius. The RC demonstrated significantly greater levels of FI than the tibialis anterior after glycerol-injection injury. Clinical Significance: This study suggests differences in FAP distribution and differentiation characteristics may account for the propensity to develop FI in RC tears as compared with other musculotendinous injuries. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:1113-1121, 2020.

MicroRNA-425 and microRNA-155 cooperatively regulate atrial natriuretic peptide expression and cGMP production.

AIMS: Atrial natriuretic peptide (ANP), secreted primarily by atrial cardiomyocytes, decreases blood pressure by raising cyclic 3',5'-guanosine monophosphate (cGMP) levels and inducing vasorelaxation, natriuresis, and diuresis. Raising the level of ANP has been shown to be an effective treatment for hypertension. To advance the future development of an anti-microRNA (miR) approach to increasing expression of ANP, we investigated the regulation of NPPA expression by two miRs: miR-425 and miR-155. We examined whether miR-425 and miR-155 have an additive effect on the expression and function of ANP. METHODS AND RESULTS: Human embryonic stem cell-derived cardiomyocytes (hESC-CMs) were transfected with miR-425, miR-155, or a combination of the two miRs. Two days later, NPPA expression was measured using real time qPCR. Each of the miRs decreased NPPA expression over a wide range of concentrations, with a significant reduction at concentrations as low as 1 nM. The combination of miR-425 and miR-155 reduced NPPA expression to a greater extent than either miR-425 or miR-155 alone. An in vitro assay was developed to study the potential biological significance of the miR-induced decrease in NPPA expression. The cooperative effect of miR-425 and miR-155 on NPPA expression was associated with a significant decrease in cGMP levels. CONCLUSIONS: These data demonstrate that miR-425 and miR-155 regulate NPPA expression in a cooperative manner. Targeting both miRNAs with anti-miRs (possibly at submaximal concentrations) might prove to be a more effective strategy to modulate ANP levels, and thus blood pressure, than targeting either miRNA alone.

Novel MicroRNA Regulators of Atrial Natriuretic Peptide Production.

Atrial natriuretic peptide (ANP) has a central role in regulating blood pressure in humans. Recently, microRNA 425 (miR-425) was found to regulate ANP production by binding to the mRNA of NPPA, the gene encoding ANP. mRNAs typically contain multiple predicted microRNA (miRNA)-binding sites, and binding of different miRNAs may independently or coordinately regulate the expression of any given mRNA. We used a multifaceted screening strategy that integrates bioinformatics, next-generation sequencing data, human genetic association data, and cellular models to identify additional functional NPPA-targeting miRNAs. Two novel miRNAs, miR-155 and miR-105, were found to modulate ANP production in human cardiomyocytes and target genetic variants whose minor alleles are associated with higher human plasma ANP levels. Both miR-155 and miR-105 repressed NPPA mRNA in an allele-specific manner, with the minor allele of each respective variant conferring resistance to the miRNA either by disruption of miRNA base pairing or by creation of wobble base pairing. Moreover, miR-155 enhanced the repressive effects of miR-425 on ANP production in human cardiomyocytes. Our study combines computational, genomic, and cellular tools to identify novel miRNA regulators of ANP production that could be targeted to raise ANP levels, which may have applications for the treatment of hypertension or heart failure.

Acute Metabolic Influences on the Natriuretic Peptide System in Humans.

BACKGROUND: The cardiac natriuretic peptides (NPs), atrial natriuretic peptide (ANP) and B-type natriuretic peptide (BNP), have central roles in sodium and blood pressure regulation. Extracardiac factors (e.g., obesity and diabetes) influence NP production, potentially altering cardiovascular responses to volume and pressure stress. OBJECTIVES: This study examined the effects of acute carbohydrate intake on the NP system in humans, and investigated underlying mechanisms. METHODS: Normotensive subjects (N = 33) were given a high-carbohydrate shake. Venous blood was sampled to measure N-terminal (NT)-proANP and NT-proBNP levels. Human embryonic stem cell-derived cardiomyocytes (hESC-CMs) and HepG2 cells were treated with glucose, and expression levels of NPs and micro ribonucleic acid 425 (miR-425), a negative regulator of ANP, were examined. The role of nuclear factor kappa B (NF-κB) in the glucose-mediated effects was investigated using a NF-κB inhibitor and expression plasmids encoding NF-κB subunits. RESULTS: We observed a 27% reduction in the levels of circulating NT-proANP (p < 0.001, maximal at 6 h) after carbohydrate challenge, with no effect on NT-proBNP levels in our human subjects. Glucose treatment of hESC-CMs for 6 h and 24 h increased levels of the primary transcript of miR-425 (pri-miR-425) and mature miR-425. A corresponding decrease in NPPA messenger RNA levels was also observed at both time points. Overexpression of NF-κB subunits in H9c2 cardiomyocytes increased miR-425 levels, whereas inhibition of NF-κB abrogated the glucose-mediated increase in pri-miR-425 levels in HepG2 cells. CONCLUSIONS: Acute carbohydrate challenge is associated with a reduction in ANP production. The mechanism appears to involve a glucose-induced increase in the expression of miR-425, mediated by NF-κB signaling.

Repeat Manipulation Under Anesthesia For Persistent Stiffness After Total Knee Arthroplasty Achieves Functional Range of Motion.

Poor range of motion may decrease a patient's ability to participate in activities of daily living after total knee arthroplasty. Manipulation under anesthesia has been shown to improve range of motion; however, some patients have persistent stiffness even after manipulation. The goal of this study was to evaluate the outcomes and complications of patients who underwent a second manipulation under anesthesia for persistent stiffness after total knee arthroplasty. The review of surgical records of two joint arthroplasty surgeons identified 226 knees in 210 patients who underwent a manipulation under anesthesia for poor range of motion after total knee arthroplasty. Of these patients, 16 patients underwent a second manipulation under anesthesia. For patients undergoing two manipulations under anesthesia procedures, at latest follow up (mean 539 days), mean extension improved from 10.50° to 2.50° (p=0.001) and mean flexion improved from 87.50° to 112.69° (p=0.001) respectively. SF-12 scores were available for 12 of 16 knees with a mean score of 34.42. Two of 16 patients (12.5%) experienced a complication. Three of 16 (18.8%) patients who underwent a second manipulation required a revision arthroplasty procedure. In conclusion, a second manipulation under anesthesia can achieve functional range of motion that is sustained after total knee arthroplasty.