Sinatro, Alec M.

Background: A more detailed assessment of the anatomy of the entire medial ulnar collateral ligament complex (MUCLC) is desired as the rate of medial elbow reconstruction surgery continues to rise. Purpose: To quantify the anatomy of the MUCLC, including the anterior bundle (AB), posterior bundle (PB), and transverse ligament (TL). Study Design: Descriptive laboratory study. Methods: Ten unpaired, fresh-frozen cadaveric elbows underwent 3-dimensional (3D) digitization and computed tomography with 3D reconstruction. Ligament footprint areas and geometries, distances to key bony landmarks, and isometry were determined. A surgeon digitized the visual center of each footprint, and this location was compared with the geometric centroid calculated from the outline of the digitized footprint. Results: The mean surface area of the AB was 324.2 mm 2 , with an origin footprint of 32.3 mm 2 and an elongated insertional footprint of 187.6 mm 2 (length, 29.7 mm). The mean area of the PB was 116.6 mm 2 (origin, 25.9 mm 2 ; insertion, 15.8 mm 2 ), and the mean surface area of the TL was 134.5 mm 2 (origin, 21.2 mm 2 ; insertion, 16.7 mm 2 ). The geometric centroids of all footprints could be predicted within 0.8 to 1.3 mm, with the exception of the AB insertion centroid, which was 7.6 mm distal to the perceived center at the apex of the sublime tubercle. While the PB remained relatively isometric from 0° to 90° of flexion ( P = .606), the AB lengthened by 2.2 mm ( P < .001). Conclusion: Contrary to several historical reports, the insertional footprint of the AB was larger, elongated, and tapered. The TL demonstrated a previously unrecognized expansive soft tissue insertion directly onto the AB, and additional analysis of the biomechanical contribution of this structure is needed. Clinical Relevance: These findings may serve as a foundation for future study of the MUCLC and help refine current surgical reconstruction techniques.

Purpose The primary aims of this work were to (1) describe normal range of motion (ROM) profiles for elite pitchers, (2) describe the characteristics of shoulder and elbow injuries in professional pitchers over a 6‐year period in one Major League Baseball organization, and (3) identify ROM measures that were independently associated with a future shoulder or elbow injury. Methods Over 6 seasons (2010‐2015), a preseason assessment was performed on all pitchers invited to Major League Baseball Spring Training for a single organization. ROM measures included shoulder flexion, horizontal adduction, external rotation (ER), internal rotation, as well as elbow flexion and extension, were measured for both the dominant and nondominant arm, and total range of motion and deficits were calculated. All noncontact shoulder and elbow injuries were identified. Using multivariate binomial logistic regression analysis to control for age, height, weight, and all other ROM measures, the factors associated with an increased risk of subsequent shoulder or elbow injury were identified. Results A total of 53 shoulder (n = 25) and elbow (n = 28) injuries occurred during 132 pitcher seasons (n = 81 pitchers). The most significant categorical risk factor associated with increased elbow injury rates was the presence of a shoulder flexion deficit >5° (odds ratio [OR] 2.83; P = .042). For continuous variables, the risk of elbow injury increased by 7% for each degree of increased shoulder ER deficit (OR 1.07; P = .030) and 9% for each degree of decreased shoulder flexion (OR 1.09; P = .017). None of the measures significantly correlated with shoulder injuries. Conclusions Preseason shoulder ER and flexion deficits are independent risk factors for the development of elbow injuries during the upcoming season. Although prior work has supported the importance of reducing glenohumeral internal rotation deficits in pitchers, this study demonstrates that deficits in shoulder ER and flexion are more significant predictors of subsequent elbow injury. Level of Evidence Level III, retrospective comparative study.