The lateral collateral ligament complex of the elbow: quantitative anatomic analysis of the lateral ulnar collateral, radial collateral, and annular ligaments.

BACKGROUND: Injury to the lateral ulnar collateral ligament (LUCL) complex of the elbow often results in posterolateral rotatory instability. Although surgical reconstruction of the LUCL is often required, gaps in our understanding of the LUCL complex remain. The purpose of this study was to provide a robust and accurate characterization of the lateral elbow ligamentous complex. METHODS: The LUCLs, radial collateral ligaments, and annular ligaments in 10 cadaveric elbows were 3-dimensionally digitized and reconstructed using computed tomography. Surface areas, origin and insertion footprint areas, distances between perceived footprint centers and geometric footprint centroids, distances to key landmarks, and ligament isometry were measured. RESULTS: The mean surface area of the LUCL was 229.3 mm2. The mean origin and insertion footprint areas were 26.0 mm2 and 22.9 mm2, respectively. The mean distance between the apparent centers and the geometric centroids of the footprints was 1 mm. The center of the LUCL origin was 10.7 mm distal to the lateral epicondyle and 8.2 mm from the capitellar articular margin. The center of the LUCL insertion was 3.3 mm distal to the apex of the supinator crest. The LUCL showed anisometric properties as elbow flexion increased (P < .001). CONCLUSIONS: The LUCL origin center was 10.7 mm from the lateral epicondyle, whereas the insertion center was 3.3 mm from the apex of the supinator crest. The visually estimated footprint centers were generally within 1 mm of the geometric centroid. These geometries and distances to key landmarks will be informative for surgeons seeking to perform anatomic ligament reconstruction procedures.

Quantitative Anatomic Analysis of the Medial Ulnar Collateral Ligament Complex of the Elbow.

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 mm2, with an origin footprint of 32.3 mm2 and an elongated insertional footprint of 187.6 mm2 (length, 29.7 mm). The mean area of the PB was 116.6 mm2 (origin, 25.9 mm2; insertion, 15.8 mm2), and the mean surface area of the TL was 134.5 mm2 (origin, 21.2 mm2; insertion, 16.7 mm2). 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.

Decreased Hip Internal Rotation Increases the Risk of Back and Abdominal Muscle Injuries in Professional Baseball Players: Analysis of 258 Player-seasons.

INTRODUCTION: The relationship of hip range of motion (ROM) to shoulder, elbow, abdominal, and back injuries remains undefined. METHODS: We assessed hip ROM on players reporting to Major League Spring Training for an organization over six seasons (2010 to 2015). Hip ROM was correlated with player abdominal, back, shoulder, and elbow injury status for those seasons using multivariate binomial logistic regression analysis. RESULTS: A total of 258 player-seasons (129 pitchers and 129 position players) resulted in 20 back and 35 abdominal injuries across all players and 28 elbow and 25 shoulder injuries in pitchers. Hip ROM did not correlate with shoulder or elbow injuries. Hip internal rotation deficit of 5° correlated with core injury (odds ratio [OR], 1.40; P = 0.024 for pitchers; OR, 1.35; P = 0.026 for position players) and back injury (OR, 1.160; P = 0.022 for pitchers). DISCUSSION: Hip internal rotation deficits were predictive of back and abdominal injuries but not shoulder or elbow injury.

Decreased Shoulder External Rotation and Flexion Are Greater Predictors of Injury Than Internal Rotation Deficits: Analysis of 132 Pitcher-Seasons in Professional Baseball.

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.