I am the coach of a high school baseball team. Two of my best pitchers are out with injuries. One has a Hill-Sachs lesion. The other has a SLAP tear. What's the difference between these two problems?

A Hill-Sachs lesion occurs with an injury that causes damage to the head of the humerus (the round ball at the end of the upper arm bone). This type of lesion is linked with a shoulder dislocation. When the shoulder dislocates, the smooth cartilage surface of the humeral head hits against the shallow socket (the glenoid cavity). An X-ray confirms the diagnosis.

The SLAP lesion is an injury to the labrum. The labrum is a rim of cartilage that forms a cup for the head of the humerus to move within. A SLAP lesion is a specific type of labral tear. This describes a Superior Labral tear from Anterior (front) to Posterior (back). The SLAP lesion occurs at the point where the top of the biceps tendon connects to the labrum. The injury is seen most often after a fall onto an outstretched arm.

Slap injuries don't show up well with imaging studies (X-rays, CT scans, or MRIs). Surgery may be needed to find the problem.