Dear Doctor: I’m a 53-year-old woman, and I’ve been athletic all my life. I’m in a soccer league and have a grinding pain in my right knee. I’ve had knee injuries in the past, and now I’m told I might need a partial knee replacement. Why would that be? What does it entail?
Dear Reader: The knee is the largest and most complex joint in the body. It consists of the lower end of the thigh bone, or femur; the upper end of the tibia, or shin bone; and the kneecap, or patella. The knee joint itself is divided into three compartments. The inside part of the knee is known as the medial compartment, the outside forms the lateral compartment and the area between the kneecap and femur is called the patellofemoral compartment.
When the tissues that form the compartments of the knee become damaged or worn out, knee replacement can become an option. This is a surgery in which portions of the knee joint are replaced with artificial components. The primary reason for this type of surgery is osteoarthritis, a condition in which continued wear and tear has eroded the cartilage that cushions the joint and reduces friction. Rheumatoid arthritis, which is an inflammatory condition, and knee injuries can also require a knee replacement.
This type of surgical repair falls into two main categories: total knee replacement and partial knee replacement. In a total knee replacement, also known as arthroplasty, the surfaces of the tibia, femur and patella are all replaced. When damage to the knee joint is limited to just one area of the knee, a partial replacement is possible. Known as a unicompartmental knee replacement, only one of the three compartments of the knee is resurfaced.
In order to know if a knee replacement would be beneficial and which form of the surgery may be required, you would consult with an orthopedic surgeon. They will take a medical history, ask about injuries and pain and evaluate the range of motion, strength and stability of your knee joint. X-rays, and possibly other forms of imaging, are used to visualize the location and extent of damage. You will also be advised of possible complications, which include blood clots, infection, nerve damage, problems with prosthetics and a reduced range of motion.
The surgery itself, which typically takes place under general anesthesia, lasts between one and two hours. The surgeon makes an incision, removes damaged bone and cartilage and replaces it with prosthetic parts. A smooth plastic spacer, which mimics the cushion of cartilage that has been removed, will also be inserted. In most cases, the person returns home the same day.
Recovery from a partial knee replacement takes several months. You will receive a customized recovery plan that includes pain management, wound care, mobility guidelines and exercises. Many patients find working with a physical therapist to be extremely helpful. Patients are often back to a normal routine within six weeks. The lifespan of a partial knee replacement is about 10 years. In some cases, a total replacement may become necessary in the future.
(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10960 Wilshire Blvd., Suite 1955, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)
