|History: The patient is a 22 year old rookie pitcher for a major league baseball team. During his rookie season, he developed anterior shoulder pain. The pain progressed over a period of time. He was treated with ice and modalities by the team trainer. Eventually the pain prevented him from active pitching. The team physician diagnosed possible rotator cuff tear. He was treated conservatively for eight weeks. The patient was then allowed to resume pitching on a gradual basis. When he was able to pitch at approximately 70% of full speed, a kinematic analysis was performed to determine if his pitching style was causing excessive shoulder stress and strain [Illustration I].|
Biomechanical Analysis addressed the relative joint positions and forces, in relation to his right shoulder at ball release. Graph I shows the relative speeds of his right hip, shoulder, elbow and wrist, prior to and at ball release. Note that while the peaks for linear hip, shoulder, elbow and wrist velocities are in proper sequence, there is a significant drop in elbow and wrist velocities, at 0.4 sec. before ball release.
Total Body Momentum [Graph II]. Both linear and rotational momenta should reach their peak simultaneously at ball release for maximum efficiency. Note that the linear momentum reaches its peak approximately at 0.3 sec. prior to ball release. This indicates a pre-release linear braking motion of the body and higher stress on the anterior of the shoulder joint.
Discussion: The subject's basic form is good but there is room for improvement in all aspects of his delivery. He is noted to have a premature braking action of forward momentum. This causes him to release the ball in a more erect posture that increases anterior shoulder capsule stress.
Conclusion: The patient's pitching technique is causing a chronic overuse/misuse syndrome in the anterior right shoulder.
Recommendation: To minimize shoulder stress, a recommendation was made for the patient to alter his pitching technique. He was taught to delay ball release somewhat until his body is more forward with the upper arm segment parallel to the ground. This shifted the shoulder maximum stress point to a higher position.
Outcome: The patient adjusted to his new pitching style over time. He became pain free and was pitching at 100% of capacity.