The shoulder joint is a ball-and-socket joint that allows for a wide range of motion. However, it is also susceptible to instability and dislocation, particularly in athletes and people who engage in repetitive overhead activities. Shoulder instability occurs when the ball of the humerus moves out of place and slides off the edge of the glenoid rim. This can cause pain, weakness, and a sensation of the shoulder "giving way." If the ball completely slides off the edge, the shoulder becomes dislocated. Once the shoulder has been dislocated, it has a tendency to become more unstable and can be easier to dislocate again.
Shoulder instability typically arises from a direct impact to the shoulder joint, especially when forcefully moving the arm above and behind the head. This is common in contact and overhead sports like AFL, rugby, and basketball, as well as in high-energy accidents such as falls from heights or motor vehicle collisions.
Individuals who frequently experience shoulder instability and dislocation are typically teenagers or young adults. These patients may exhibit joint hypermobility or increased ligament laxity. Once the shoulder has dislocated, the supporting soft tissues and bony structures may sustain irreversible damage, including ligament and labrum tears surrounding the shoulder joint, as well as fractures of the humerus and glenoid rim.
Shoulder instability and dislocation can lead to a range of signs and symptoms, including
To evaluate the extent of shoulder instability and the likelihood of further dislocations, a comprehensive medical history and physical examination are necessary. During this assessment, your Surgeon evaluates the overall ligament laxity in the shoulder and measures the arm's range of motion. Additional diagnostic tests may include:
