A shoulder to cry on: Shoulder dislocation and instability

Remember that scene in Lethal Weapon where Mel Gibson dislocates his shoulder to free himself from a straightjacket? Well, every time a shoulder dislocates, or ‘pops’ out of the socket, it really does make it more likely to pop out again, because damage to the structure of the joint and the surrounding tissue causes it to become unstable. While it’s more common in athletes and young men, it can strike anyone at any time.

Anatomy: Chip on your shoulder

The shoulder is a ball and socket joint. The ball sits at the top part of the upper arm (humerus bone) and the socket is the shoulder area of the torso. The ball is held in its places by bone, ligaments and muscles. Seeing as you can’t buy this at the corner shop, you don’t want to be dislocating your shoulder too often.

The shoulder is actually the most mobile joint in the body, partly because the socket in which it lies is very shallow. This means it is the most likely joint in the body to dislocate. And because the socket is very shallow, it is mainly the ligaments and muscles that hold the shoulder in place, not the bone.

Ouch potatoes: Know your dislocation

There is more than one way to dislocate a shoulder, unfortunately.

Anterior shoulder dislocation is when the joint pops out of the socket in a forward direction. It is the most common type of dislocation – about 95% of shoulder dislocations are of this type. They usually occur in a person for the first time when their arm is extended above their head and additional force causes the arm to extend further up than it should, allowing the ball to pop out of its shallow joint. Ouch.

Posterior shoulder dislocations are those that involve the ball popping out of the socket in a backward direction. Double ouch.

Inferior dislocations are those in which the joint dislocates in a downward direction – they are more serious, but account for only 0.5% of all dislocations. Biggest ouch of all!

People who are double jointed have a higher risk of dislocating their shoulder in any of the above directions.

Blow this joint?

Dislocations can cause more than just pain. They can also damage the surrounding joint structure, including the bone, ligaments and muscles.

The force of the bone popping out may cause small sections of cartilage or bone from the shoulder socket to tear away or break off (fracture). Some sort of damage to the bone, ligaments or muscles occurs in most shoulder dislocations, and bone fractures occur in about a quarter of dislocations.

Once the joint has dislocated, the ball becomes jammed against the outer structure of the socket. The pressure created when the joint sits outside the socket can cause a dent in the ball. This generally occurs in about half of shoulder dislocations in people under 40.

Nerves of steel

Shoulder dislocation may also damage the blood vessels or nerves that supply the arm.

These injuries cause the shoulder joint to become less stable, which means that after the first shoulder dislocation, you’re far more likely to experience a second shoulder dislocation.

Having surgery to repair the damaged joint can considerably reduce the risk of future dislocations. So if you can pop your shoulder out like Mel, you may want to consider talking to a professional.

Shouldering the burden

Shoulder dislocations can mean ‘a whole lotta’, pain but there really isn’t any way to prevent them from happening. While the dislocation is not a serious injury in itself, it can be dangerous if it occurs in other situations, such as when someone is swimming. In fact, 15% of drowning deaths are thought to occur because of shoulder dislocation.

Further, dislocating your shoulder can increase the risk of future dislocation and arthritis in the shoulder joint. With modern medicine, there is no reason you need to shoulder this type of burden.

Don’t bogart the joint

First things first – never try to replace a dislocated shoulder yourself. You may cause further damage to the joint, and besides, DIY surgery is never a good idea.

Shoulder dislocation can be treated by replacing the shoulder joint into its socket. The doctor will x-ray the shoulder before replacement to assess the nature and extent of damage.

There are a number of ways to manipulate the joint back into place, which typically involve rotating and moving it. Don’t worry, painkillers are usually given. An x-ray may be taken afterwards to confirm correct relocation, and the arm is usually put in a sling.

Once the joint is replaced, muscles, nerve and ligament damage usually resolve. However, surgery to stabilise the joint has been shown to reduce the chance of a subsequent dislocation and may be necessary in cases where the joint has been damaged.

You may also need a little physiotherapy to help rehabilitate the joint.

Sock’et to me

Shoulder dislocation is common and can be treated effectively by replacing the ball back into its socket. As long as you let a doctor do this for you, the shoulder and you should be fine. Further assessment can tell you whether you may need surgery to stop further dislocations too. All in all, unless you need to escape a straightjacket – try to keep your ball in its socket.