The shoulder is the most mobile joint of the human body, with a wide range of motion. The shoulder consists of
- the ball on top of the upper arm bone (humerus)
- the socket (glenoid) of the shoulder blade (scapula) in which the ball of the humerus fits
- a rim of cartilage in the scapula (labrum) to make the glenoid a little deeper
- surrounding ligaments (joint capsule)
- surrounding muscles and tendons spanning from the scapula to the humerus (rotator cuff) to stabilize the upper arm bone and hold it tightly into the glenoid
What happens when a shoulder dislocates?
Most commonly, the ball of the humerus bone rolls out of the glenoid when the arms are struck while the elbows are held out (i.e. collisions in football).
Dislocation can also happen when if the ball of the humerus is forced backwards.
- Landing on an outstretched hand to break a fall
- Direct blow to the front of the shoulder
Who is at risk for a shoulder dislocation?
- Athletes in contact sports, such as football or hockey
- Athletes in sports that involve frequent falling, such as gymnastics, skiing or volleyball
- Active people between the ages of 18 and 25
- Older people with weaker ligaments or a greater tendency to fall down
What are the symptoms of a shoulder dislocation?
- A visibly deformed shoulder
- Swelling or bruising
- Extreme pain
- Inability to move the arm
- Numbness, weakness, or tingling around the neck or down the arm
- Painful muscle spasms around the shoulder