The operation to replace the arthritic shoulder with an artificial shoulder replacement may be done in one of two ways. If the socket portion of your shoulder is still in fairly good shape, meaning there is still some articular cartilage left on the surface, only the ball portion may be replaced. This is known as a hemiarthroplasty (“hemi” means half and “arthroplasty” means “reconstruction” of a joint). A hemiarthroplasty is commonly done following fractures of the shoulder – either right away instead of fixing the fracture or later if the ball portion looses its blood supply.
If the socket (glenoid) portion of your shoulder is worn away as well, you will need to have it replaced. When both the ball portion and the socket portion of the shoulder are replaced, it is referred to as a total shoulder arthroplasty. To perform an artificial shoulder replacement, you will most likely be placed under general anesthesia. It is difficult to perform any type of regional anesthesia (to just put the shoulder and arm to sleep) that will allow the surgeon to perform a major surgery such as shoulder replacement.
The operation begins by making an incision through the skin in the front of the shoulder.
This is called an anterior approach to the shoulder. Once through the skin, the nerves and major blood vessels are protected and moved to the side. The muscles are also moved to the side. Making an incision into the joint capsule that surrounds the shoulder joint cavity allows entry into the shoulder joint. The surgeon can now look at the surfaces of the joint as he prepares the bone to replace the shoulder joint surfaces.
The ball portion of the humeral head is removed with a bone saw. The hollow inside of the upper humerous (the arm bone) is prepared using a special rasp to allow for the humeral component to be inserted. This is where the metal stem will be placed that is attached to the ball portion of the artificial shoulder.
If the socket portion of your shoulder will be replaced as well, the socket is prepared by using a burr to remove any remaining cartilage on the surface. A hole is usually drilled with the burr to place the stem on the glenoid component into the bone of the scapula.
Finally, the artificial shoulder is inserted and the shoulder is tested to make sure the pieces fit properly. The glenoid component is inserted to replace the shoulder socket. The socket may be held in place with the epoxy cement if your surgeon has chosen to use a cemented type glenoid component.
When the surgeon has determined that everything is satisfactory, the shoulder capsule is sutured together, the muscles are returned to their correct positions and the skin is sutured together.