BACKGROUND: Patients with severe damage to the knee joint who suffer with progressive pain and impaired function may opt for total knee replacement. In the U.S., osteoarthritis is the most common reason for knee replacement. In a total knee replacement, the diseased knee joint is replaced with artificial parts. During the procedure, the end of the femur bone is removed and replaced with a metal shell. The end of the lower leg bone is also removed and replaced. Depending on the condition of the kneecap, a plastic button may also be added under the kneecap surface.
NEW TECHNOLOGY: Custom knee replacements use MRI scans and x-rays to get precise measurements of a patient’s knee. Data from these scans can guide the surgeon during the knee replacement procedure. They are placed into a computer, which uses special software to determine where the bone should be cut in order to preserve as much healthy bone and ligament tissue as possible. During surgery, specialized tools called jigs are used. Studies have found that custom-jig technology substantially improves accuracy. Custom knee replacements offer patients substantial benefits over standard surgical procedures, including:
- precise fit and alignment of the new joint
- faster recovery
- less blood loss
- decreased risk of infection
- less postoperative pain and discomfort
- faster return to normal activities
BEFORE SURGERY: Before surgery, doctors carefully evaluate the joints adjacent to the diseased knee, such as the hip and ankle, to ensure optimal outcome and recovery from the surgery. Replacing a knee joint that is adjacent to a severely damaged joint may not yield significant improvement in function. All medications that the patient is taking are also reviewed. Blood-thinning and anti-inflammatory medications such as aspirin may have to be adjusted or discontinued prior to surgery. Chest X-ray and EKG are performed to determine if there is any significant heart and lung disease that may prevent surgery or anesthesia. Since excess body weight puts the replaced knee at an increased risk of loosening and/or dislocation and makes recovery more difficult, a knee replacement surgery is less likely to have good long-term outcome if a patient’s weight is greater than 200 pounds. Younger patients may have an added risk since they tend to be more active, thereby adding trauma to the replaced joint.