Using Pitch-Tracking Metrics to Identify Warning Signs Immediately Prior to Acute Ulnar Collateral Ligament Injuries...

Area of Science:

• Biomechanics
• Sports Medicine
• Baseball Analytics

Background:

• Ulnar collateral ligament (UCL) injuries are common in baseball pitchers.
• Previous research has not detailed the specific kinematic events leading to acute UCL failure.
• Understanding the pitch-by-pitch sequence preceding injury is crucial for prevention.

Purpose of the Study:

• To identify potential warning signs for acute UCL injuries in MLB pitchers using Statcast data.
• To analyze pitch-tracking metrics for deviations preceding ligamentous failure.

Main Methods:

• Retrospective case-control study of 7 MLB pitchers with acute UCL injuries.
• Analysis of Statcast data (velocity, spin rate, extension, arm angle, acceleration) from injury games and prior outings.
• Use of Mahalanobis distance (MD) to quantify deviations from baseline mechanics and identify outliers.

Main Results:

• Every injury pitch was a mechanical outlier (MD > 95th percentile).
• Injury pitches showed reduced velocity (mean 2.1 SD) and arm angle (mean 1.5 SD).
• 86% of injured pitchers exhibited elevated cumulative deviation in the 5 preceding fastballs, vs. 7% of controls (P < .001).

Conclusions:

• Acute UCL injuries in MLB pitchers are preceded by identifiable changes in pitch-tracking metrics.
• UCL failure may involve abrupt biomechanical decompensation rather than prolonged decline.
• Findings offer the first pitch-level characterization of UCL failure, potentially aiding in-game risk monitoring.