The Shoulder Joint
The shoulder joint is a connection between two bones, the rounded head, or ball, of the upper arm bone (humerus) and the cup-like (socket) formation of the shoulder blade (scapula). The shoulder is the most flexible of all the joints in the body. While this flexibility gives us the ability to throw, reach, raise the arm and perform everyday tasks, as well as participate in sports and other activities, it is also susceptible to wear and tear and instability or dislocation.
The rotator cuff is a group of muscles and tendons in the shoulder, connecting the upper arm to the shoulder blade. The rotator cuff helps to lift the arm over the head and also helps to hold the ball (humeral head) in the socket (glenoid) of the shoulder.
A healthy shoulder has smooth cartilage covering where the bones of the upper arm and the shoulder meet, allowing them to move smoothly against each other. Cartilage can wear over time from arthritis, activity or injury. This causes the ends of the bones to rub against each other (bone-on-bone) leading to pain, stiffness, limited movement, and a decreased ability to perform activities of daily living. When this occurs it may be necessary to perform a shoulder replacement.
Why Choose Shoulder Replacement?
The main reason to have a shoulder replacement is to relieve your pain. If you need a shoulder replacement, Dr. Burns will choose one of the following procedures to repair your shoulder arthritis: anatomic total shoulder replacement, reverse shoulder replacement, or hemiarthroplasty (partial replacement, recommended in certain circumstances).
Anatomic Total Shoulder Replacement
Anatomic total shoulder replacement is a surgical procedure that removes the damaged ball and socket and replaces them with a new metal and plastic ball and socket. This also replaces the arthritic or “worn out” cartilage which has been causing your pain. This procedure works best for patients who have a normal and intact rotator cuff and who have not excessively ground down the remaining bone. Dr. Burns will make an incision on the front of your shoulder and remove the cartilage and bone that has been damaged by arthritis or injury. The upper arm bone (humerus) is resurfaced with a metal stem and ball made of titanium and cobalt chrome. The socket (glenoid) is resurfaced with a plastic liner. Often, this plastic liner will have a metal pin or tray to support it.
Reverse Total Shoulder Replacement
Reverse total shoulder replacement is a surgical procedure for patients who have significant arthritis and/or damage to their rotator cuff that cannot be repaired. Reverse shoulder replacement also works well for people who have major bone loss around their shoulder, which can occur from years of bone-on-bone grinding of the ball and socket. Reverse shoulder replacement also can be used to treat severe shoulder fractures. This procedure is called a “reverse” because the position of the ball and the socket are switched in this type of replacement. The socket (glenoid) is resurfaced with a metal base and a ball made of cobalt chrome. The upper arm bone (humerus) is resurfaced with a metal stem and plastic cup liner.
Partial Shoulder Replacement (Hemiarthroplasty)
Occasionally, Dr. Burns may select an option called hemiarthroplasty, which is a replacement of the ball at the upper end of the arm bone (humerus) only, which is why it’s known as a partial shoulder replacement. In this procedure the socket is not replaced with a metal and plastic part, although Dr. Burns will often rebuild or cushion the area with cadaver-donated tissue, called an allograft.