Ultrasound Study of Season-Long Joint Changes to College Baseball Players

This study aims to use ultrasound imaging to assess the health of the ulnar collateral ligament (UCL) of the elbow, which acts as a major stabilizer in overhead throwing athletes and is often injured in baseball pitchers. The health of the UCL will be assessed by measured the amount of laxity in the UCL, identified as the distance between the end of the humerus (arm bone) where the UCL originates and the beginning of the ulna (forearm bone) where the UCL ends. An increase in this distance indicates an increase in laxity of the ligament, which is a risk factor for injury/tearing of the ligament with repetitive throwing seen in baseball pitchers. Measurements will be made at rest and under 3 pounds of valgus stress at 30 degrees of elbow flexion where the UCL acts as the main stabilizer of the elbow. Valgus stress is necessary for this procedure because damage to the ligament will be most clearly seen in this position when compared to the measurement at rest.

Measurements will be made to both the right and left elbows, as well as both the right and left knees. The purpose of including the knees in this protocol is so that the subjects are blinded to the true intention of the study. Due to the psychological harm that could occur if the subjects know the focus of the study is their UCL, the study will be presented to the subjects such that the research team is viewing all structures within the elbow and knee, and their overall flexibility, strength, and bony changes will be monitored throughout the season using ultrasound. Therefore, the ultrasound measurements of the knee will be sham measurements, and only measurements made at the elbow will be recorded.

In addition to ultrasound, measurements of range of motion will be performed at each testing session. Motions to be tested will be: shoulder flexion, extension, abduction, internal rotation, and external rotation; elbow flexion and extension; wrist flexion and extension; hip flexion, extension, abduction, internal rotation, and external rotation; knee flexion and extension. Recent studies have found significant results for deficits in range of motion correlating to UCL tears, so this data will be used in conjunction with measurements of laxity of the UCL as seen with ultrasound.

Ultrasound imaging and range of motion testing will be performed on the same 10 subjects four times throughout one baseball season: before the first game of the season, after 20 games have been played, after 40 games have been played, and after the last game of the season has been played. During this period, pitching data will be collected and recorded for each pitcher. Data to be collected includes number of pitches thrown, number of each type of pitch thrown, number of innings pitched, velocity of all pitches, time in days between pitching appearances.