Joint replacement surgery has rapidly become a mainstay operation for those who suffer from chronic, painful and debilitating arthritis. The two joints most commonly affected by the most common form of arthritis, osteoarthritis, are the hips and knees.
Knee replacement surgery can dramatically improve a person’s quality of life. There are different procedures that can be done in knee replacement surgery, and they are geared to a person’s specific pathology and needs.
Total Knee Replacement
In total knee replacement procedures, all surfaces that come in contact with each other are resurfaced: the femur or thigh bone, the tibia or shin bone and the patella or knee cap. The ends of each bone as well as the under-surface of the knee cap are shaved down to precise angles and shapes to remove the arthritic cartilage and prepare the bone for implantation of the parts.
Once the cut surfaces are prepared and are ready for implantation, the femur is fitted with a metallic prosthesis that literally mimics the shape of the condyles of the femur, or knuckles, that comprise the articular surfaces. This implant can be inserted and fixed with special bone cement or with a tight-fitting, bio in-growth, cementless version.
Next, the tibial is shaved and prepared to accept a flat, metallic tray of sorts, which will allow for a special plastic insert to be snapped onto it. This insert will be the spacer that separates the metallic components of the femur and tibia. The same technique is used on the knee cap and a special plastic, dome-shaped component is press-fitted or cemented into place.
As one of the final steps in the procedure, a plastic insert, or spacer, is chosen and comes in several thicknesses to properly restore the joint tensions. These spacers typically snap into place on the metal tibial plate.
Partial Knee Replacement
Partial knee replacement surgery, also known as uni-compartmental replacement, does just what its name implies: resurfaces just one side of the knee joint. This type of procedure is typically reserved for younger patients with higher physical demands, and most importantly very localized damage to only one knuckle of the femur and its corresponding tibial, or shin bone, surface. The procedure can be less invasive than total knee replacement surgery, thus translating into quicker rehabilitation times.
Mobile Bearing Uni-Compartmental Knee Replacement
One unique variation of the standard uni-compartmental knee replacement is the Oxford, mobile bearing partial knee replacement. In addition to being a uni-compartmental knee replacement, the Oxford offers a movable plastic insert known as a mobile bearing polyethylene insert, or spacer. This surgery can be done with a less invasive surgical technique, and resurfaces what damaged areas exist in a specific compartment of the knee.
Quad Sparing Knee Replacement
Another type of knee replacement procedure deals more with surgical approach than with implants. It is known as a minimally invasive, or quad-sparing, knee replacement.
Quad-sparing knee replacement surgery is built on the premise that violation of the muscles of the inner thigh area that also attach to the upper portion of the knee cap, called the quadriceps, is avoided in order to allow for a more rapid recovery after surgery with less tissue injury during surgical exposure.
This approach is typically less invasive than the standard total knee replacement incision and approach, thus causing less pain and immobility after surgery. The muscles of the thigh remain active with better strength and control of the leg during the early post-surgery time period.
References
- eOrthopod: A Patient's Guide to Unicompartmental Knee Replacement
- The American Association of Orthopedic Surgeons: Total knee replacement
- The Journal of Bone and Joint Surgery: The Oxford Knee Replacement
- UW Medicine Orthopaedics and Sports Medicine: Minimally-Invasive Surgery (MIS) Quadriceps-Sparing Total Knee Replacement
