Total and Partial Joint Replacement

The shoulder joint (aka glenohumeral joint) is like a ball and socket. A total shoulder replacement procedure involves exchanging the arthritic ball with a smooth metal ball that is fixed to the arm bone (humerus) by a stem that fits within it. At the same time, the arthritic socket (glenoid) is resurfaced with a high-density, polyethylene prosthesis. Of all the different surgical options available, this one provides the fastest and most comprehensive improvement in comfort and function for shoulders with arthritis, although the degree of success hinges on the technical expertise of the surgical team and the patient’s commitment to follow-up with physical therapy.

In a conventional shoulder replacement procedure, a plastic cup is fitted into the shoulder socket and a metal ball is attached to the upper arm bone, thus mimicking the normal anatomy of the shoulder. With a reverse total shoulder replacement, the ball is fixed to the socket while the cup is attached to the upper portion of the humerus. This procedure is recommended for those with a large rotator tear or cuff tear arthropathy because it relies on the deltoid muscle, instead of the rotator cuff, to move the arm.

In a total hip arthroplasty, damaged bone and cartilage are removed and replaced with prosthetic components. The femoral head is removed and replaced with a metal stem that is placed into the hollow center of the femur and either cemented or press fit into the bone. A metal or ceramic ball is placed on the upper end of the stem to replace the damaged femoral head. Also, the damaged cartilage surface of the socket is removed and replaced with a metal socket.

In addition, a plastic, ceramic, or metal spacer is inserted between the substitute ball and the socket. This allows for a smoother gliding surface for the artificial implant. There are several approaches to total replacement surgery, including anterior (front), posterior (from behind), lateral, and minimally invasive surgery. Robotic and computer-assisted surgical techniques are also available to help guide the surgeon and provide enhanced accuracy.

Knee arthroplasty is less about replacing the knee than resurfacing it, as only the surface of the bones is replaced. In this procedure, the damaged cartilage surfaces are removed along with a small portion of the underlying bone. Metal implants that recreate the surface of the joints are then attached to replace the damaged cartilage and bone. The undersurface of the patella (or kneecap) is cut and may be resurfaced with a plastic button. Lastly, a medical-grade plastic spacer is inserted between the metal components, thus creating a smooth gliding surface.

This minimally invasive procedure is an alternative to total knee replacement and is recommended for patients whose condition is limited to only one area of the knee. During the surgery, damaged bone and cartilage is resurfaced with metal and plastic components. Since the procedure is performed through a smaller incision, patients usually are required to spend less time in the hospital and can return to their normal activities sooner than with a total knee replacement. Also, since healthy bone, cartilage, and ligaments are unaffected, many patients report that partial knee replacement feels more natural.

MAKOplasty is a procedure that enables surgeons to plan and perform partial knee, total knee, or total hip replacement surgery using three-dimensional computer imaging based on a CT scan. The Robotic Arm Interactive Orthopedic (RIO®) System enables the surgeons to determine optimal implant size, position, and alignment for each patient, as well as accurately mapping out the areas of bone they need to remove. During the procedure, the robotic arm system provides visual, auditory, and tactile control, allowing the surgeons to dissect only the bone planned for removal. By taking the guesswork out of the surgery, this state-of-the-art tool delivers accurate and reproducible results.