The goal of total shoulder replacement surgery is to relieve shoulder pain and increase shoulder function by resurfacing the bones that meet at the shoulder's ball-and-socket joint, or glenohumeral joint. The surgeon removes the humeral head at the top of the arm bone (humerus), reshapes the shoulder socket (glenoid), and attaches prosthetic components to both bones.

Who performs this procedure? See Orthopedic Surgeon for Arthritis Treatment

Below is a step-by-step description of a typical total shoulder replacement surgery. A surgery usually lasts for 1 to 3 hours.

Total Shoulder Replacement Step-by-Step Description

Surgical procedures can vary depending on the patient's needs and the surgeon's preferences, but generally the steps are as follows:

  • The patient's blood pressure, heart rate, body temperature, and oxygenation levels are are checked before surgery can proceed. A mark is made on the shoulder undergoing surgery before the patients goes into the operating room to ensure that the correct shoulder is being operated on.
  • Anesthesia is administered. Typically, a patient receives general anesthesia (is put to sleep). Alternatively, some patients are given an additional regional anesthesia to block sensation in the arm and around the shoulder. The type of anesthesia a patient will receive is decided well ahead of the surgery.

    See Anesthesia for Orthopedic Surgery

  • The surgeon makes an incision approximately 6 inches long, starting at the top and front of the shoulder and curving along the deltoid muscle. The surgeon then cuts through deeper tissue, including one of the rotator cuff tendons to enter the shoulder joint.
  • The top of the upper arm bone, called the humeral head, is dislocated from the socket of the scapula, or glenoid.
  • The surgeon will examine the humeral neck, which is the area just below the rounded head of the humerus. The surgeon uses a tool called an osteotome to remove any bone spurs that may have developed on the humeral neck as the result of arthritis.
  • The surgeon uses a bone saw to remove the humeral head.
  • The surgeon prepares the humerus bone for the prosthetic humeral stem. The humeral stem is a narrow, tapered metal shaft that fits several inches down inside the humerus. The top of this stem is designed to hold a prosthetic ball that will replace the natural humeral head.
  • The surgeon uses a special tool called a reamer to smooth and shape the the shoulder socket (glenoid) and prepare it for its prosthesis.
  • The artificial socket, or glenoid prosthesis, is usually made of polyethelyne and has a smooth, slightly concave design to facilitate movement with the prosthetic humeral head. A new socket is usually backed by either a few short pegs or a flat, straight edge called a keel (which is shaped like the keel of a boat). The pegs or keel fits into the natural bone.
  • The prosthetics may be adhered to the natural bone with bone cement or they may be cementless (sometimes called "press fit") components. The fast-acting bone cement takes only about 10 minutes to set.

    See Cemented vs. Cementless Alternatives in Joint Replacement

  • After the humeral stem is secured in place, a temporary prosthetic ball is attached to its top. Different sizes of the temporary ball will be used to test the stability of the new joint before the final size is determined.
  • The artificial humeral head has a shape and size suited to the patient's existing anatomy, and is specially designed to move with the artificial socket. The exact model selected is based on the surgeon's pre-surgical planning and observations during surgery.
  • The surgeon inserts the temporary ball into the new socket and moves the shoulder around, checking to make sure the shoulder joint has ease of motion and does not dislocate.
  • The surgeon will then dislocate the joint, remove the temporary or trial component, and attach the final ball prosthetic. The surgeon inserts the ball into the new socket, checking again for ease of movement and dislocation.
  • The muscle and other soft tissues that were cut are repaired and the skin incision is stitched or stapled back together.

After surgery, a patient may be taken to a recovery room for observation while the surgical anesthesia wears off. Afterwards, the patient may be taken to a hospital room for the remainder of his or her hospital stay.

Many patients spend one or two nights in the hospital before being discharged, though this figure can vary depending on circumstances.

Dr. C. Benjamin Ma is an orthopedic surgeon and the Vice Chairman for Adult Clinical Operations in the Department of Orthopaedic Surgery at the University of California, San Francisco Medical Center. Dr. Ma has been practicing medicine for more than 15 years, specializing in sports medicine and knee and shoulder surgery.