For people who suffer from chronic, disabling arthritis of the knee, joint replacement has become a most fulfilling surgical option to regain and restore quality of life. Knee replacement surgery can improve mobility and reduce chronic pain. There are several types of knee replacement procedures available, and each procedure is designed to treat a different level of degeneration.
Total Knee Replacement
In cases where the extent and severity of joint degeneration is such that there are virtually no normal surfaces left inside the knee, a total knee replacement procedure may be warranted. Total knee replacements are performed by using special cutting guides that help cut and remove the arthritic surfaces from the ends of the femur, or thigh bone; the tibia, or shin bone; and the patella, or knee cap.
After preparation with the cutting guides, implants are fitted over the cut surfaces. The finished product will consist of a metallic femoral component and a tibial prosthesis consisting of a metal tray and a plastic spacer. The knee cap is re-surfaced with an all plastic dome-shaped button to glide over the metallic femoral implant.
Partial Knee Replacement
Occasionally, younger people will develop arthritis in certain areas of the knee as a result of trauma or overuse. Because of their relatively younger age, the risk for full knee revision surgery is understandably higher.
Partial, or uni-compartmental, knee replacement procedures are typically designed to re-surface only one damaged femoral condyle, or knuckle portion of the thigh bone, as well as only the affected side of the tibia, or shin bone.
One variation of the uni-compartmental knee replacement prosthesis is called the Oxford uni-compartmental knee replacement. A defining feature is the Oxford's ability to have a movable plastic tibial spacer that literally slides and rotates on the flat tibial implant base, which is said to reduce wearing down of the polyethylene surface during bending, straightening and weight-bearing.
Quad Sparing
The quad sparing approach to total knee replacement incorporates the preservation of as much of the quadriceps, or thigh, muscle and tendon for better post-operative thigh muscle strength. This procedure type utilizes an approach in which the bones are shaved from the sides rather than from the front head-on.
This approach reduces the incision size as well as the amount of quadriceps, or thigh, muscle that is disturbed. In turn, the patient has more control of his leg after surgery and can actively lift the leg which allows for better rehabilitation much earlier.
The minimally invasive aspect of this surgery type is the smaller incision and the reduction of the amount of thigh muscle that is cut during surgery. This contributes to less post-operative pain and better leg function.
Mobile Bearing
Total knee replacement systems also incorporate the movable plastic or mobile bearing concept. Instead of only one side of the femur, or thigh bone, and one side of the tibia, or shin bone, being resurfaced, the entire knee is resurfaced as in a conventional knee replacement; however, the tibial platform allows for rotational movement of the plastic spacer. This is supposed to mimic the natural rotation that occurs between the femur and tibia during flexion, or bending, and extension, or straightening. It is also supposed to reduce the wear and tear of the plastic because the increased motion reduces friction.
