The shoulder joint is a highly flexible ‘ball and socket’ joint situated where the arms meet the upper body. It is formed from the rounded end of the humerus, or upper arm bone, and a curved recess in the scapula, or shoulder blade. The joint is strengthened and stabilised by ligaments and tendons.
Shoulder replacement surgery is the third most common joint replacement after hip and knee replacements. Like a hip replacement, shoulder replacement surgery can involve the reconstruction or replacement of the ball, the socket, or both. This is generally done following damage due to an accident, or because of the impact of degenerative disease. Unlike hip replacement, where the main purpose is to enhance movement and to enable someone to be able to walk easily again, shoulder replacement surgery is generally undertaken for pain relief.
Why is shoulder replacement surgery done?
Shoulder replacement surgery is usually undertaken to correct damage that has resulted from either disease or trauma:
- Damage due to disease: the most common disease that affects the shoulder joint is arthritis. This damages the thick layer of cartilage that normally protects the end of the humerus and the socket in which it sits. As the cartilage breaks down, the bare ends of the bones grind together and do not move as smoothly as they normally would. This in turn results in painful swelling and inflammation around the joint. If this does not respond to anti-inflammatory treatments, then shoulder replacement surgery can be performed to alleviate the pain.
- Damage due to trauma: even healthy, well-protected shoulder joints can be knocked out of alignment by an accident or injury, causing unprotected areas of the bones to rub together. This needs to be corrected by shoulder replacement surgery as the grinding will only make the injury worse. The joint is more likely to deteriorate, resulting in increasing pain and stiffness.
What types of shoulder replacement are available?
Shoulder replacement surgery replaces one or more elements of the shoulder joint with a prosthetic joint. The head of the humerus and the socket in the scapula are replaced with either metal or hi-tech plastic compounds. These are designed to function as naturally as possible, mimicking the structure of the original shoulder joint. Shoulder replacement surgery can take several forms, including:
- Partial shoulder replacement: the socket remains intact and healthy, so only the head of the humerus is replaced. This is known as shoulder hemiarthroplasty.
- Shoulder resurfacing: there is limited damage, so the bones can be resurfaced. This is usually achieved with metal resurfacing on the head of the humerus and the use of a plastic composite to line the scapula socket.
- Total shoulder replacement: when both the ball and socket are significantly damaged, they can both be completely replaced with prosthetics. This is known as shoulder arthroplasty.
- Reverse shoulder replacement: where there is considerable damage to the surrounding muscles and tendons of the shoulder, known as the rotator cuff, it may be necessary to rebuild the shoulder the opposite way around. This involves placing the prosthetic socket on the end of the arm bone and the prosthetic ball within the shoulder blade.
How is it done?
Shoulder replacement surgery is done in hospital under general anaesthetic. The surgeon carefully cuts through the skin and moves aside the muscles and connective tissue above the shoulder joint to expose the bones.
The bones of the joint are separated, or dislocated, to allow access to the damaged sections, which are then cut away and replaced with prosthetics. These are held in place with either specialist cement or screws.
The shoulder joint ligaments are checked and adjusted to ensure maximum flexibility and function of the joint before the wound is stitched closed. A small tube may be left in place to drain fluids from the wound site for the first few hours.
After the surgery
You will need to spend a few days in hospital following your shoulder replacement surgery and attend physiotherapy for several months after you are discharged. You will be asked to wear a sling for the first few days to keep the weight off your new shoulder and you should avoid any lifting for around six weeks. You should also steer clear of any form of contact sports for at least six months.
What are the benefits?
Shoulder replacement surgery rarely results in the full range of movement that you get with a healthy joint, and you may not be able to raise your arm much higher than level with your shoulder. However, you should experience significantly less pain than before, and an increase in movement, function and flexibility.
The success of your shoulder replacement surgery will depend on the extent of the original damage, the skill of your surgeon and your own dedication to physiotherapy after your operation.
What are the associated risks?
As with any major surgery, there are established risks associated with a general anaesthetic. Shoulder replacement surgery also carries risks of wound infection, bleeding and blood clots leading to cardio-vascular problems. However, these risks are rare. Your surgeon and anaesthetist will talk to you before your operation to make you fully aware of the risks and benefits so that you can make an informed choice.