This is a shoulder injury. It’s a compression fracture that creates a dent in the head of the humerus. That’s the ball of the arm bone that fits into your shoulder socket. The dent interferes with the motion of your shoulder.
A Hill-Sachs lesion is most often caused by a shoulder dislocation. It happens when the ball slips out of the socket and is then pressed against the socket’s rim. The ball gets damaged, leaving an indentation.
This injury causes shoulder pain and instability. You may lose your full range of motion. You may have popping, grinding or catching sensations when you move your arm. And, your shoulder may have a tendency to dislocate easily.
Treatment depends on your needs. Your shoulder may heal with rest, medications and physical therapy. Or, you may need surgery.