Total vs. Reverse Shoulder Replacement: a Prospective Randomized Trial

The shoulder is the most mobile joint in the human body with a complex arrangement of structures working together to provide the movement necessary for daily life. Great mobility comes at the expense of stability. Several bones and a network of soft tissue (ligaments, tendons, and muscles) work together to produce shoulder movement. They also interact to keep the joint in place while it moves through extreme ranges of motion.

BONES The glenohumeral joint (shoulder joint) is a multiaxial, synovial ball and socket joint and involves articulation between the shoulder blade and the head of the humerus (upper arm bone). This makes it the most mobile joint of the human body.

SOFT TISSUE The rotator cuff is a group of muscles and their tendons that act to stabilize the shoulder. The four muscles of the rotator cuff are over half of the seven scapulohumeral muscles. These tendons can become torn following a trauma to the shoulder or it can occur through the "wear and tear" on tendons, most commonly the supraspinatus tendon found under the acromion. To be considered an equal candidate for both implants the rotator cuff must be grossly intact.

ARTHRITIS Glenohumeral (shoulder) arthritis is a common source of pain and disability that affects up to 20% of the older population. Damage to the cartilage surfaces of the glenohumeral joint (the shoulder's "ball-and-socket" structure) is the primary cause of shoulder arthritis.

SHOULDER REPLACEMENTS There are two types of total shoulder replacement systems: the conventional Total shoulder and the Reverse shoulder. The reverse was originally developed for use in patients with advanced high loss of shoulder function in conjunction with a damaged rotator cuff.