PARTIAL KNEE REPLACEMENT – MAKO
Patients who have arthritis have developed advanced wear of the articular cartilage that lines the bones in the knee. Articular cartilage lines all three bones in the knee (the femur, tibia, and patella). Cartilage is smoother than ice and lacks nerve endings. People with healthy articular cartilage generally have excellent motion and do not have pain. On the other hand, the bone underneath cartilage has free nerve endings and is rough. Therefore, as the smooth cartilage lining over bone wears down, patients with arthritis feel pain, stiffness, and other symptoms. Some patients may have success with non-surgical management; however other patients may require surgery if symptoms are severe.
The knee has three main spaces or “compartments:” the inside (medial compartment), the outside (lateral compartment), and the space under the kneecap (anterior compartment). In those patients who have advanced damage to articular cartilage in one compartment of the knee, the best surgical option may be partial knee replacement.
Partial knee replacement is a surgical technique that has been available for decades. Many different companies have developed implants for partial knee replacement. There is ample evidence in the orthopaedic journals that partial knee replacement helps eliminate pain from arthritis and may enable patients to return to an active lifestyle. Another advantage of partial knee replacement is that the healthy tissue in the knee is preserved. In a total knee replacement, the entire knee is reconstructed; even healthy tissue is sacrificed. For example, the ACL is preserved in patients who have a partial knee replacement. In those patients who have a total knee replacement, the ACL is removed.
Recently, a few companies have developed robotic-assisted knee replacement surgery. Dr. Welch prefers and strongly endorses robotic-assisted partial knee replacement for patients with arthritis in one or two compartments of the knee that have failed non-operative treatment. One company, MAKO, was recently acquired by Stryker. Dr. Welch had extensive training using the MAKO system as a fellow at the Kerlan Jobe Orthopaedic Clinic in Los Angeles. The benefit of MAKO robotic-assisted surgery is that it helps eliminate human error during surgery and enables surgeons to position the implants extremely accurately.
If Dr. Welch recommends MAKO surgery, a CT scan is required. The CT scan gives Dr. Welch a 3-dimensional view of the new and allows him to plan the surgery. During surgery, Dr. Welch makes an incision over the center of the knee and uses the robotic arm to remove the appropriate area of damaged cartilage and bone in the knee. The MAKO robotic arm is very accurate and ensures that Dr. Welch only removes the damaged area in the knee. Dr. Welch then resurfaces the damaged area in the knee with a metal implant on the femur bone, a titanium implant on the tibia bone, and a plastic implant in between the metal surfaces.
Following surgery, patients are encouraged to place their weight on the affected extremity. Some patients may require crutches or a cane for the first few days after surgery. When the patient is sitting or lying down, Dr. Welch encourages knee range of motion exercises with heel slides or with a passive motion machine. Dr. Welch also recommends intermittent icing and straight leg raise exercises to strengthen the quadriceps muscles for the first 2-3 weeks. Dr. Welch recommends starting physical therapy 1-2 days after surgery. Physical therapy focuses on reducing swelling in the knee, restoring full range of motion, and eventually, restoring strength to the knee. Most patients have full range of motion and excellent function within approximately three months following surgery.
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