Partial knee replacement, also known as unicompartmental knee replacement, is a less invasive alternative to a total knee replacement. This procedure is designed to replace only one portion or compartment of the knee that has been damaged by arthritis, leaving the healthier areas intact. Partial knee replacement allows patients to benefit from less scarring, shorter recovery times and a fuller range of motion.
This procedure is commonly performed on younger, more active patients who do not wish to undergo a total knee replacement yet. Other good candidates often include patients whose arthritis is localized in one specific area of the knee. However, in some patients, arthritis may develop in a different part of the knee at a later point, which may lead to the necessity of another surgery.
To determine whether a partial knee replacement is the best course of treatment for a particular patient, the doctor will take a medical history and perform a physical examination. This can help the doctor evaluate precisely what area of the knee is producing the pain. In addition, imaging tests will likely be conducted, including X-rays and MRI scans. These tests can produce images that show the extent of damage to the cartilage and its location.
At the start of a partial knee replacement procedure, either general or spinal anesthesia is administered. The surgery generally takes one to two hours to complete. The doctor will make an incision at the front of the knee close to the area that is damaged. The structures of the knee are assessed to ensure that the nearby ligaments are healthy and that the damage is only contained within one area of the knee. If the arthritis is present in multiple areas of the knee, a total knee replacement procedure may be necessary instead.
Once the surgeon has determined that the damage is limited to one location, the partial knee replacement surgery will proceed. Using special surgical cutting devices, small pieces of cartilage and bone are removed from the affected portions of the femur, or thigh bone, and tibia, which is the larger bone in the lower leg. The segments of bone are replaced with metal prosthetics that are affixed in place with cement. The metal implants at the ends of the bones are separated by a plastic insert that allows for smooth, fluid motion of the joint after surgery.
Since only the precise location where the damage exists is disturbed, the bones and tissues of the other parts of the knee can remain untouched during a partial knee replacement procedure. This generally results in less bone loss and the recovery of a greater range of motion.
The recovery period following a partial knee replacement is often shorter and more comfortable than that of a total knee replacement. It is a less invasive procedure, performed through a smaller incision. However, a partial knee replacement does still typically require a hospital stay of one to three days.
Most patients require the use of an assistive device such as crutches or a walker for the first week or two following the procedure to prevent putting too much stress on the knee as it heals. Physical therapy is important as it can help the knee to regain strength and flexibility. After a partial knee replacement, many patients fully recover within six weeks and are still able to partake in low impact sports and other activities.
Partial knee replacement is considered a safe type of procedure. However, all surgeries do carry some risk. The risks that may be associated with a partial knee replacement include infection, development of blood clots, damage to blood vessels or nerves and lingering pain in the knee.