Knee Replacement

There are two types of knee replacement surgery: Partial knee replacement (PKA) Total knee replacement (TKA)[2] The knee joint is divided into 3 compartments Medial (inside of knee joint), lateral (outside of knee joint), patellofemoral (joint between knee cape and thigh bone).most patient have involvement of two or more compartments requiring total knee replacement whereas a minority(highly debatable ten to thirty percent ) have involvement of single compartment (mainly medial compartment),in which partial knee replacement can be considered[3]. In general, both types consist of replacing damaged or diseased joint surfaces of the knee joint with metal or plastic prosthesis depending upon patient age, weight, physical activity, knee size and shape and overall health. The surgery involves exposure of the front of the knee, with detachment of part of the quadriceps muscle (vastus medialis) from the patella. The patella is displaced to one side of the joint, allowing exposure of the distal end of the femur and the proximal end of the tibia. The ends of these bones are then accurately cut to shape using cutting guides oriented to the long axis of the bones. The cartilages and the anterior cruciate ligament are removed; the posterior cruciate ligament may also be removed [4] but the tibial and fibular collateral ligaments are preserved. Whether the posterior cruciate ligament is removed or preserved depends on the type of implant used, although there appears to be no clear difference in knee function or range of motion favouring either approach[5]. Metal components are then impacted onto the bone or fixed using polymethylmethacrylate (PMMA) cement. Alternative techniques exist that affix the implant without cement. This cement-less techniques may involve osseointegration, including porous metal prostheses.