The shoulder is made up of three bones: the humerus (arm bone), the scapula (shoulder blade), and the clavicle (collar bone). The top of the humerus bone is a ball shape and meets the region of the scapula called the glenoid (socket). The joint made by these two bones is typically referred to as the shoulder joint or the glenohumeral joint. This is considered a ball and socket type joint, allowing for the largest range of movement and rotation of any joint in the body. This motion provides patients with the ability to perform activities over their head, in front of their body, and behind their back using the arm. The shoulder motion also allows patients to participate in sports that require throwing, serving, or other overhead motions.
To allow for this large range of mobility, the shoulder is less stable than other joints in the body. This is due, in part, to the fact that the shoulder relies on many soft tissue structures to provide stability (glenohumeral ligaments, capsule, labrum) rather than relying on how the bones fit together. The glenohumeral ligaments surround the shoulder and blend with the shoulder capsule. This forms a “sling” effect around the shoulder to keep it in place. These ligaments attach to a rim of cartilage the surrounds the socket (glenoid) called the labrum to provide stability to the joint. The labrum increases the depth of the socket and helps to keep the ball centered in the proper position.
What is a Shoulder Dislocation
When the ball and socket (the humeral head and glenoid) become separated the injury is called a shoulder dislocation. During a dislocation the humeral head can dislocate forwards, backwards or downward. When the shoulder dislocates, the force of the event typically causes a tear in the labrum, ligaments, and capsule. In certain instances the dislocation can cause damage to the bone on the glenoid (called a Bony Bankart lesion) or on the humeral head (called a Hill-Sachs lesion). Shoulder specialist Dr. Robert Boykin focuses on the treatment of shoulder dislocations and shoulder instability for patients in Asheville, Arden, Fletcher and surrounding North Carolina communities.
Athletes who compete in physically demanding contact sports such as football, hockey, rugby, and basketball are at a heightened risk of this particular shoulder injury. In addition, athletes requiring overhead activity for their sport, such as in gymnastics, baseball, tennis, and volleyball may also be at an increased risk. A shoulder dislocation can also be caused by a traumatic event such as a direct fall on the shoulder. Certain patients considered to be “double” or “loose” jointed or those that have connective tissue disorders may be at a heightened risk for suffering from dislocations of multiple joints including the shoulder.
When a young active adult suffers from a dislocation caused by trauma, the risk of a repeat dislocation or future shoulder instability is extremely high. The risk of further dislocations is less in patients who are older when they sustain their dislocation or those who are less active.
Symptoms of a Shoulder Dislocation
Symptoms of a shoulder dislocation are:
- Immediate and severe pain
- Inability to move or lift the arm
- Numbness and tingling in the fingers
- A popping sound and/or feeling
- Visual deformity (abnormal appearance) of the shoulder
- Loss of range of motion