Total Shoulder Replacement /Arthroplasty
The shoulder joint consists of the humerus (arm bone), the glenoid (part of the scapula bone), the labrum, and the surrounding tendons and ligaments. The humeral head sitting in the glenoid can be thought of as a “golf ball on a tee” because of the large humeral head and small labrum. The glenoid and the humeral head are both covered in cartilage, which provides a smooth gliding surface for the shoulder.
The four most important muscles and tendons that surround and stabilize the shoulder are the rotator cuff muscles: supraspinatus, infraspinatus, teres minor, and subscapularis. These muscles are covered by a bursa that helps lubricate the tendons and allow them to glide freely during motion. Together, these muscles with the help of the labrum, a ring of cartilage around the glenoid, hold the humeral head into the shoulder “socket” and stabilize the shoulder. It is important to recognize that unlike other joints that have strong bone and ligament stabilizers, the shoulder is primarily stabilized by muscles and tendons.
Injury to the cartilage in the shoulder results in arthritis. Like other joints, arthritis can be painful and complete loss of cartilage results in bone-on-bone rubbing between the humerus and glenoid. This is painful with any motion or activity. Although medications are often initially prescribed for symptoms of pain, there are currently no good treatments that can replace cartilage. Once the cartilage is lost, it is unlikely to return.
Instead of replacing cartilage in the shoulder, your orthopaedic surgeon can replace the humeral head (the “ball”) and the glenoid (the “golf tee”) to decrease your pain. This is called a total shoulder arthroplasty or shoulder joint replacement. There are different types of shoulder replacements, and the best option for you should be discussed with your surgeon. Generally speaking, by replacing the bone with a combination of metal and plastic, patients can expect to have a pain-free shoulder that still allows for functional range of motion. Importantly, patients should recognize that their shoulder will never return back to “full function” and will always have decreased motion.
Your physician will recommend a specific rehabilitation protocol to enhance your recovery to activities and decrease pain after surgery. This is especially important for regaining motion. The importance of physical therapy in the shoulder cannot be overstated since it is the muscles and tendons that primarily stabilize the joint and will become stiff after surgery. Exercises will consist of exercises for improving strength, maintaining motion, and re-training your muscles during the recovery phase. These exercises will typically progress in stages as the capsule and tendon heals and gets stronger. It is important to follow the protocol exactly as your surgeon recommends since going to fast may result in injury to the surgical repair and going too fast can result in stiffness and decreased motion. Exercises should be performed in a supervised setting, as well as at home on your own time. Your commitment to rehabilitation is key to a successful outcome.