Shoulder joint replacement procedures are mostly done for osteo-arthritis of joints. In the normal joint, cartilage covers both bony surfaces of the ball and socket. When this cartilage wears away bone is exposed and bone then grinds onto bone on the other side of the joint – this is why osteo-arthritis causes pain and stiffness in the shoulder joint.
If and when this shoulder pain becomes disabling, joint replacement procedures are done. The purpose is to place material between the bone-ends to avoid this painful contact by having two smooth surfaces in contact with each other. The most common joint replacement procedure is to place a metal surface on the ball and a plastic surface on the socket.
In general the following is the management of osteo-arthritis of the shoulder:
- Conservative management: This would consist of light exercise, anti-inflammatory medication and cortisone injections. This is often a question of “playing for time” to try and postpone any surgical procedures for as long as possible. The younger the person the more the doctor should try and postpone joint replacement surgery as prostheses do have a limited life span and if and when they wear out the person may be worse off than before.
- Arthroscopic soft tissue interposition: This is a newly developed technique where a “membrane” is placed arthroscopically (keyhole surgery) into the joint and fastened to the socket. This allows the body to grow in cartilage- like material onto this membrane and avoid the painful bony contact of the joint. The success rate of this has been satisfactory and it is a minimally invasive shoulder procedure.
- Metal resurfacing techniques: Metal disc types of prosthesis are available to put a smooth metal surface on the head of the humerus causing a smooth painless surface with the purpose of diminishing the pain and avoiding having to remove bone and cement a prosthesis in place.
- Total joint prosthesis: A metal ball is cemented into the humeral side and a polyethylene (plastic) prosthesis is cemented into the socket (glenoid).
- Reverse prosthesis: This prosthesis is used when the rotator cuff muscle and tendon has been torn for a considerable time. A standard prosthesis can therefore not be used as the essential rotator cuff muscles are now gone. The reverse prosthesis serves as a “hinge” enabling the powerful deltoid muscle to elevate the arm. This prosthesis is reserved for elderly patients as the prosthesis does not last as long as the other varieties.In most cases the above procedures may provide good pain relief and increased function for the person suffering from osteoarthritis of the shoulder. The joint replacement procedure should be reserved for the right indications as the prostheses last for a limited time. The activity level of a person with a prosthesis should also be considered as energetic type of activities may also lead to a shorter life-span of any joint replacement prosthesis.