Dynamic Stress Ultrasound Assessment of Professional Baseball Players' Elbows After Ulnar Collateral Ligament Reconstruction.

Background: There is a paucity of data analyzing dynamic stress ultrasound (SUS) findings in elite pitchers who have undergone ulnar collateral ligament (UCL) reconstruction (UCLR) and returned to sport.

Purpose: To identify longitudinal, perioperative changes in the elbows of professional baseball pitchers who have undergone UCLR and to compare these findings with a matched cohort of healthy pitchers.

Study Design: Cohort study; Level of evidence, 3.

Methods: This study used prospectively collected data from dynamic elbow SUS analyses of professional baseball pitchers within a single Major League Baseball organization. Pitchers were divided into 2 cohorts: a UCLR cohort and healthy cohort. The UCLR cohort eligibility included availability of (1) SUS from preseason of injury/UCLR and (2) SUS from ≥2 years after surgery. These players were 1:1 matched to players with no history of upper extremity injury to form the healthy cohort. Ligament thickness and ulnohumeral joint space at rest and under stress were directly measured. Joint laxity was calculated by subtracting joint space at rest from joint space under stress. The term "relative" was used to describe calculated differences where nondominant measurements were subtracted from dominant-side measurements.

Results: Eight pitchers were included in the UCLR group and matched to 8 healthy pitchers (mean age at initial SUS examination, 19.6 years). At a minimum follow-up of 2 years, there were no significant differences between groups in terms of relative or dominant arm rest space, stress space, or laxity. Longitudinally (final measurements - baseline measurements), the mean relative ulnohumeral rest space decreased in the UCLR group and increased in the healthy group (-0.36 mm vs +0.50 mm; = .032). The finding of increased UCL thickness in the UCLR group was expected, as UCL grafts are typically thicker than native ligaments.

Conclusion: Ulnhohumeral joint stability was achieved after UCLR as indicated by similar rest space, stress space, and joint laxity in dominant arms compared with a matched healthy cohort. A significant decrease in relative rest space after UCLR may represent the achievement of stability in surgery patients. Alternatively, the increase in ulnohumeral rest space seen in the healthy cohort may represent adaptive changes from pitching at a professional level.