Conflict of interest: A patent application (30435.354-US-P2) has been filed by BP, FAP, and AD on a method for generation of therapeutic pericytes from human pluripotent stem cells.

Massive tears of the rotator cuff (RC) are often associated with progressive and irreversible muscle degeneration due to fibrosis, fatty infiltration, and muscle atrophy. RC tears are common in individuals older than 60 years and the repair of these tears is amongst the most prevalent of orthopedic procedures. However, most current models of this injury are established in young animals, which may not accurately recapitulate the clinical condition. In this study, we used a murine model of massive RC tears to evaluate agerelated muscle degeneration following chronic injury. The expression of the fibro-adipogenic genes encoding collagen type III and leptin was higher in aged RC compared with matched injured young tissue at 2 weeks post-injury, and development of fibrosis was accelerated in aged mice within 5 days post-injury. Furthermore, the synthesis of collagens type I and III and fat tissue accumulation were significantly higher in injured RCs of aged mice. Similar frequency of fibro-adipogenic PDGFRβ + PDGFRα + progenitor cells was measured in noninjured RC of aged and young mice, but PDGFRβ + PDGFRα + cells contributed to significantly larger fibrotic lesions in aged RCs within 2 weeks post-injury, implying a more robust fibrotic environment in the aged injured muscle. Altogether, these findings demonstrate agedependent differences in RC response to chronic injury with a more profound fibro-adipogenic change in aged muscles. Clinically, cell therapies for muscular pathologies should not only consider the cell type being transplanted but also the recipient milieu into which these cells are seeded.

Small animal models of massive tears of the rotator cuff (RC) were introduced a decade ago and have been extensively used to study the pathophysiology of chronically injured RC. Transection of rodent suprascapular nerve and RC tendon results in progressive muscle atrophy, fibrosis and fat accumulation and affect the infraspinatus and supraspinatus muscles similarly to that seen in the setting

Background: There are few data on injuries suffered by collegiate water polo athletes. Purpose: To describe the epidemiology of injuries suffered by National College Athletic Association (NCAA) male and female water polo players by using injury surveillance data over a 5-year period. Study Design: Descriptive epidemiology study. Methods: Deidentified data on all water polo injuries and illnesses recorded in the Pac-12 Sports Injury Research Archive from July 2016 through June 2021 were obtained and analyzed. Three men’s and 4 women’s teams were observed for the entire 5-year period, and 1 men’s and 1 women’s team was observed from July 2018 through June 2021. Results: During the observation period, 729 injuries were recorded in the database, with no differences in overall injury rates between male and female athletes (relative risk [RR] = 1.0; 95% CI, 0.9-1.2); 33.7% of injuries required a physician encounter, and 3.6% required surgery. The shoulder was the most injured body part, making up 20.6% of all injuries, followed by the head/face (18.8%) and hand/wrist/forearm (11.7%). Shoulder tendinopathy was the most common shoulder injury diagnosis (4.5% of all injuries). Concussion was the most common injury diagnosis overall, making up 11.4% of injuries, and 81.9% of concussions occurred outside of competition. Male athletes were significantly more likely than female athletes to have a concussion in an off-season practice (RR, 3.25; 95% CI, 1.2-8.8) and via contact with another player (RR, 2.9; 95% CI, 1.3-6.4). Half of the 26 surgical procedures occurring over the observation period were for chronic joint trauma of the groin/hip/pelvis/buttock, with 9 of those 13 being for femoroacetabular impingement specifically. Conclusion: Among NCAA water polo athletes, the shoulder was the most injured body part; however, shoulder injuries rarely required missed time from sport or necessitated surgical intervention. Concussions were the most common injury diagnosis, had the worst return-to-play outcomes among common diagnoses, and were mostly sustained outside of competition. Femoroacetabular impingement was found to be the dominant diagnosis for which surgical intervention was required.

Orthopedic sports medicine surgeons are especially vulnerable to litigation, largely because of high patient expectations in the setting of complex surgeries. Understanding the factors associated with litigation may reduce physician risk as well as optimize patient satisfaction and outcomes. We used a national medicolegal database to search for medical malpractice verdicts and out-of-court settlements involving common sports injuries and their surgical management between January 1, 2000, and January 1, 2018. Univariate analysis was performed to identify predictors of case outcome and monetary awards. We identified 777 cases, but only 328 met the inclusion criteria. Of the 328 cases included in our study, 231 (70.4%) resulted in a defendant verdict, 75 (22.9%) resulted in a plaintiff verdict, and 22 (6.7%) resulted in a settlement. The most common reason for litigation was intraoperative error (183 cases, 55.8%). No statistically significant difference was found between monetary awards for plaintiff verdicts vs settlements (mean award of $1.29 million and $0.72 million, respectively, P =.07). Cases in which the plaintiff claimed neurovascular injury were significantly more likely to result in a higher monetary award (mean award of $2.37 million, P =.02). Cases involving an incorrect surgical site were significantly less likely to result in a defendant outcome, with 7 of 12 cases (58.3%) leading to a plaintiff outcome ( P =.047). With more than two-thirds of cases resulting in a defendant verdict, many suits result in a favorable outcome for practitioners. Intraoperative error is the most common reason for litigation, and neurovascular injury resulted in the highest monetary payouts. Vigilance to avoid these events may improve patient outcomes and decrease liability to practitioners. [ Orthopedics . 2022;45(1):e47–e52.]