The shoulder is a complex of bones, ligaments, muscles and tendons that allow the arm a great range of movement while remaining stable. Because it’s so complex, the shoulder is vulnerable to a range of insults, including fractures, torn tendons and ligaments or dislocations and subluxations. A condition called avascular necrosis causes the shoulder’s blood supply to be cut off, which destroys the bone. Arthritis of the shoulder is fairly common as the cushioning between the bones of the joint starts to wear down. Though surgery or immobilization can help in some cases, in other cases the shoulder is so damaged or so painful that it needs to be replaced.
The patient who seeks shoulder replacement will have a consultation with the surgeon to make sure they’re a good candidate for the operation. The doctor will explain the different types of surgery in order to ask, “Why not try these out?” The doctor takes the patient’s medical history to learn about their overall health, examines the shoulder and orders X-rays. X-rays reveal how much damage was done to the shoulder and help the doctor determine the best way to repair it. Sometimes, the doctor also orders bone scans, blood tests or an MRI of the shoulder.
Ball and socket surgery consists of the doctor cementing or press fitting a stemmed metal ball into a plastic socket. The technique depends on the strength of the bone. If the bone is still strong, the doctor may press fit the ball and stem into it. They cement the prosthesis if the bone is weak. The doctor most often uses bone cement to implant the socket part of the prosthesis. However, the socket may not be implanted if the patient’s natural socket still has healthy cartilage, if the socket is too deteriorated or if the tendons in the shoulder’s rotator cuff can’t be repaired. The rotator cuff is a structure of muscles and tendons that allow the arm to move freely. Sometimes, only the ball and its stem are replaced. This operation is called stemmed hemiarthroplasty. Surgeons opt for this when the ball of the humerus is badly broken or arthritic but the socket is still intact and healthy. It’s also done if the patient’s socket has soft bone or if they have a badly damaged rotator cuff. In another operation called resurfacing hemiarthroplasty, just the surface of the ball is replaced with a stemless cap. This is an option if the cartilage in the socket is healthy, if the head or neck of the humerus bone is not fractured, and the patient and doctor want to preserve the humerus. A patient with a ruptured rotator cuff or a patient who’s had a previous shoulder replacement that failed may opt for a reverse total shoulder replacement. In this operation, the doctor switches the position of the ball and socket, which allows the patient to lift their arm without pain.
About 53,000 people have shoulder replacement every year in the United States. For the majority of them, it restores the functioning of their shoulder and arm. Shoulder replacement surgery greatly improves the quality of their lives.