The effect of body mass index on internal rotation and function following anatomic and reverse total shoulder arthroplasty.

BACKGROUND: The exact relationship between body mass index (BMI) and internal rotation (IR) before and after total shoulder arthroplasty has not been studied to date. The purpose of this study was to determine the effects of BMI on the preoperative and postoperative shoulder range of motion and function in anatomic (aTSA) and reverse total shoulder arthroplasty (rTSA), and specifically how IR affects patient ability to perform IR-related activities of daily living (ADLs). METHODS: Patients from a prospective multicenter international shoulder arthroplasty registry who underwent primary rTSA (n=1171) and primary aTSA (n=883) were scored preoperatively and at latest follow-up (2-10 years, mean = 3 years) using the Simple Shoulder Test, University of California-Los Angeles shoulder score, American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form, Constant score, and Shoulder Pain and Disability Index patient-reported outcome measures (PROMs). Measured active abduction, forward flexion, IR, and active and passive external rotation were recorded, and BMI was evaluated as a predictor of motion and patient-reported outcomes. Patient responses to questions regarding the difficulty level of IR-related ADLs were studied. The relationships between BMI, IR, and ability to perform IR-related ADLs were quantified through analysis of variance with post hoc comparisons by Tukey honestly significant difference tests, where significance was denoted as P < .05. RESULTS: BMI was found to be inversely correlated with IR in patients undergoing both aTSA and rTSA, both preoperatively (P < .001 and P = .002) and postoperatively (P < .001 and P < .001). BMI affected the range of motion parameters of forward flexion abduction and external rotation but to a lesser extent than that of IR. Nonobese patients demonstrated significantly greater IR than overweight, obese, and morbidly obese patients postoperatively for aTSA (P < .001). For rTSA, nonobese patients had a significantly greater postoperative IR than obese and morbidly obese patients (P < .001 and P = .011, respectively). For both aTSA and rTSA patients, mean IR scores significantly differed between patients reporting normal function vs. patients reporting slight difficulty, considerable difficulty, or inability to perform IR-related ADLs. Increasing IR demonstrated a significant, positive correlation with all PROMs for both aTSA and rTSA patients (Pearson correlation, P < .001). CONCLUSIONS: BMI is an independent predictor of IR, even when controlling for age, gender, glenosphere size, and subscapularis repair. BMI was inversely correlated with the degree of IR, and decreased IR significantly negatively affected the ability to perform IR-related ADLs. CLINICAL RELEVANCE: Increasing BMI adversely affects shoulder ROM, particularly IR. IR is correlated with the ability to perform ADLs requiring IR in both aTSA and rTSA patients.

Pitch count adherence and injury assessment of youth baseball in South Carolina.

INTRODUCTION: Overuse injury in youth overhead athletes remains a concern. The introduction of pitch count guidelines was designed to limit the number of pitches per game. South Carolina is considered a warm weather climate which has been proven to expose overhead athletes to higher risk for injury. The purpose of this study was to detect baseline rates of arm pain and sequelae (injury, surgery, impact on participation) among southern youth baseball/softball players to better counsel players, parents, coaches and league administration on the prevention of arm injury. METHODS: A survey was distributed to 14 pediatric practices within the South Carolina Pediatric Practice Research Network. The 2-page survey included 28 closed-ended and descriptive questions that investigated physical and psychosocial responses during and after play. Additional questions were conducted on adherence and understanding of USA Baseball guidelines and pitch counting behavior. RESULTS: Two hundred and seventy three surveys were completed by parents of baseball/softball players. The players' average age was 11.6 years, who played on an average of 1.78 teams/leagues for 5.2 months each year. Only 26% of baseball players answered "Sometimes", "Often" or "Always" to their arm hurting. Arm fatigue, older age, parent/coach frustration with play, and months played were statistically significantly associated with arm pain. The survey revealed 58.9% of families were familiar with pitch count guidelines. DISCUSSION: Arm pain is relatively prevalent among the South Carolina youth baseball community and worse in older players and experience fatigue. This survey found lower percentage of youth overhead athletes experiencing arm discomfort when compared to prior studies. It is important for warm weather climate athletes to abide by guidelines, as they are more susceptible to arm injury. Increased recognition, education and compliance with pitch count guidelines will help protect these youth athletes from overuse injury. LEVEL OF EVIDENCE: IV, Descriptive Epidemiology Study.

The Effect of Screw Design and Cortical Augmentation on Insertional Torque and Compression in Coracoid-Glenoid Fixation in a Sawbones Model.

PURPOSE: To compare screw insertional torque and coracoid-glenoid compression from 4 fixation techniques with different screw design parameters and cortical augmentation for the Latarjet procedure. METHODS: Simulated Latarjet procedures were performed with 4 fixation techniques using laminated polyurethane blocks with dimensions similar to the coracoid-glenoid construct. The groups included DePuy Synthes Mitek 3.5-mm partially threaded screws with top hats, Arthrex 3.75-mm fully threaded screws with a 2-hole plate, Arthrex 3.75-mm fully threaded screws, and Smith & Nephew 4.0-mm partially threaded screws. Screws were inserted using a digital torque-measuring screwdriver to determine maximum insertional torque. Pressure-sensitive film was used to measure the maximum contact pressure and the effective pressure distribution (EPD) between the coracoid and glenoid; the EPD represents the percentage of the film's surface area that experienced pressure greater than 10 MPa. One-way analysis of variance and post hoc tests were used for statistical analysis. RESULTS: Significant differences were found between the 4 fixation groups for each variable measured. The 2 cortically augmented systems produced significantly higher maximum insertional torque than the non-cortically augmented systems (P < .001 for both). The 3.75-mm screws with a 2-hole plate yielded significantly higher contact pressures than the 4.0-mm screws (P = .028). This group also had a high EPD, with a mean value more than double the values of the non-cortically augmented systems (P = .037 and P < .001). CONCLUSIONS: Cortically augmented fixation methods showed higher maximum insertional torque, maximum contact pressure, and EPD between the surfaces of the coracoid and glenoid in this Sawbones model. CLINICAL RELEVANCE: Various implants are available for the Latarjet procedure, but their biomechanical characteristics have not yet been fully elucidated. Graft fracture and nonunion represent 2 modes of failure that may be related to insertional torque and coracoid-glenoid compression. This study compared screw insertional torque and compression achieved using 4 fixation techniques with different screw design parameters and cortical augmentation in a Sawbones model.

Racial and sex disparities in utilization rates for shoulder arthroplasty in the United States disparities in shoulder arthroplasty.

PURPOSE: To investigate racial disparities in shoulder arthroplasty (SA), accounting for demographic factors such as sex and age. METHODS: Data for SAs (2011-2014) was queried from the Healthcare Cost and Utilization Project Nationwide Inpatient Sample. Population-adjusted SA utilization rates, racial and sex differences by age, length of stay, insurer, and comorbidities were calculated. RESULTS: Caucasians aged 45-64 are 54% more likely than African-Americans and 74% than Hispanics to receive surgery. For patients aged 65-84, the disparity is wider for African-Americans and narrower for Hispanics. CONCLUSIONS: Policymakers and physicians should focus on further national efforts to alleviate healthcare disparities.