Knees and Hips
Computer-Assisted Total Knee Replacement
Jason E. Lang, MD, an orthopaedic surgeon at Wake Forest Baptist Medical Center, performs a computer-assisted total knee replacement. William G. Ward, Sr., MD, an orthopaedic surgeon who also performs joint replacements, narrates the procedure.
Lang's areas of expertise include partial and total knee and hip replacement, minimally invasive joint replacements including uni-compartmental or partial knee replacement and anterior approach to total hip replacement, and revision surgery of the hips and knees.
About Computer-Assisted Total Knee Replacement
The knee is the largest joint in the human body. It also is the strongest. The bottom ends of the femur or thigh bone and the top ends of the tibia or shin bone are covered with cartilage and cushioning, allowing for motion, support, and flexibility. Working properly, the knee joint slides smoothly.
A knee with congenital conditions, sports injuries, wear and tear and arthritis can cause tremendous pain, even lack of sleep and inability to walk. A total knee replacement is one means to replace that damaged joint by resurfacing the bone ends of the thigh and shin bone, capping them each with metal pieces and placing plastic in between to ensure support, flexibility and motion, without the pain.
Computer-assisted surgery allows the physician an additional measure of care by providing alignment of the knee joint with the bones and with the body, which will allow the joint to work better and last longer.
Knee replacement surgery is for patients who have extreme knee pain and disabilities caused by congenital defects, trauma, osteoarthritis or rheumatoid arthritis. Either through trauma or degeneration, cartilage may have worn away where the patient’s thigh and shin bones rub directly against each other. Knee replacement patients have already tried the non-steroidal anti-inflammatory drugs, cortisone injections, physician therapy and possible less invasive surgeries to relieve their discomfort.
To prepare for surgery, in addition of medical history and physical exam, additional scanning may be needed such as bone scans or MRIs or CTs.
Numerous designs of knee joints are available and the design chosen by the patient and the physician will depend on the patient’s age, weight, activity, health and condition. The patient may choose general anesthesia or a more localized version.
During the surgery, the physician trims off about one third of an inch of the ends of the thigh bone and then cements a curved metal femoral component that covers the end of the thigh bone. About a third of an inch of the shin bone is trimmed away at the top and replaced with a flat and stemmed tibial plate that is cemented onto the top of the shin bone. The plate has a polyethylene cushion that allows for movement. Another piece replaces the patella or kneecap.
The metal pieces are typically titanium- or cobalt chromium-based alloys. These replacement joints have a 95% chance of lasting 10 to 20 years or more. Before and during surgery, the physician uses the computer to take measurements that guide the size, design and placement of the knee joint.
Just as important as the surgery is the process is rehabilitation, Lang said. As soon as possible, patients are encouraged to get up and walk. Physical therapy starts right away. Joint replacement patients are cared for by physicians, physical therapists, nurses and staff who all have special training in joint replacement care. In addition to the high volume of hip and knee replacements, resurfacings, repairs and preservations, Wake Forest Baptist Medical Center also does research and trains future surgeons.
In addition to Lang, the other orthopaedic surgeons who are part of the comprehensive joint program in the Department of Orthopaedic Surgery include Riyaz H. Jinnah, Gary G. Poehling, David F. Martin, and Scott C. Wilson.