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Stress Ultrasound May Identify Pitchers at Higher Risk of Ulnar Collateral Ligament Injury

A larger ulna-humerus gap under stress was associated with a higher risk of subsequent injury in professional baseball pitchers.

Jill Sakai, Contributor
Thursday, August 23, 2018


The motion of throwing a ball overhand places a high degree of stress on the ulnar collateral ligament (UCL), which runs between the humerus and the ulna and helps stabilize the elbow. Debilitating UCL injuries are common among baseball pitchers due to the repetitive stress on the joint. The UCL is typically assessed with MRI, a static visualization that may identify tears but provides no information about joint dynamics or injury risk.

A recent study in the Orthopaedic Journal of Sports Medicine assessed the use of stress ultrasound to measure UCL morphology and joint dynamics in professional baseball pitchers and evaluated whether these parameters can help identify players at higher risk of UCL injury. 70 pitchers for the Colorado Rockies professional baseball team were assessed during their spring training. Stress ultrasound was used to measure UCL thickness and the gap between the ulna and humerus when the joint was bent at 90 degrees, in both pitching and nonpitching elbows. The joints were imaged both at rest and under a stress load similar to the force applied during a baseball pitch.

Seven out of the 70 screened players sustained a UCL injury during the following season. The pitching arms of the subsequently injured players had a significantly larger pre-injury joint opening under stress than the players who remained uninjured, with an average gap of 6.5 millimeters compared to 5.3 millimeters. Pitchers whose elbow gapping under stress was greater than 5.6 millimeters had a sixfold higher risk of sustaining a future UCL injury than those with smaller gaps.

The results suggest that ultrasound assessment of pitchers’ elbows may be a rapid, dynamic and inexpensive way to help identify players at increased risk of UCL injury. The authors note the study is the first to link a larger elbow gap in the pitching arm to an increased risk of future UCL injury.

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