Knee Replacement surgery is called as Knee Arthroplasty. Knee replacement is the surgical procedure in which weight bearing surfaces of the bones of the knee joint are replaced with artificial materials to relieve the patient of disability and excruciating pain. In some cases whole knee joint is replaced with artificial or prosthetic joint.  The prosthetics are made up of metal or metal and plastic both. Knee replacement surgery is performed on patients suffering from total or partial destruction of the knee joints.

CAUSES

The destruction of knee joint can take place due to diseases or physical injuries. Osteoarthritis, rheumatoid arthritis and gouty arthritis are the main diseases resulting in progressive joint destruction and pain. These diseases may cause complete joint immobility resulting in locomotory disability of the person along with causing severe pain. Joint destruction may also be caused due to old age related weakening of knee joint bones; femur and tibia or thinning of cartilages of the joint due to wear and tear. However, knee joint destruction in younger patients is mostly due to physical injuries resulting from mishaps and accidents that cause loss or deformations in the articulating surfaces of the bones- femur and tibia or permanent damage to cartilage of knee joint.

TYPES OF KNEE REPLACEMENT

Knee replacement surgeries are of two types depending upon how much part of knee joint is replaced- total knee replacement surgery and total knee replacement surgery.

1. Partial Knee Replacement: It is also known as Unicompartmental Knee Arthroplasty. It involves replacement of only one part of the damaged knee joint. It can replace either the inside part (medial), the outside part (lateral) or the knee cap part of the knee. It may involve replacement of articulating surfaces of the bones either femur or tibia or both; or replacement of cartilage cushion between femur and tibia bones or the knee cap. Partial knee replacement surgery is suggested to patients suffering from knee arthritis confined to limited part of the joint. Partial knee replacement requires smaller cut than total knee replacement and has shorter recovery period.

2. Total Knee Replacement: Total knee replacement is a surgical process in which the diseased or damaged joint is replaced with artificial prosthetic joint. Femur and tibia articulate with each other to form knee joint. In total knee replacement, the end of femur bone is removed and replaced with a metal shell and the end of tibia is replaced with a channeled plastic piece with a metal stem. Depending on the condition of knee cap bone (patella), a plastic button is added below its surface. Patients suffering with severe destruction of the knee joint associated with progressive pain and disability are advised total knee replacement.

TECHNIQUE

Knee replacement surgery is carried out by marking an incision on the knee of the patient. The knee joint is exposed by detaching a part of quadriceps muscle (vastus medialis) from the patella. The patella is displaced to one side exposing the distal end of femur and proximal end of tibia. The ends of these bones are then cut accurately to shape, to facilitate fitting of prosthetics. The cartilage and the anterior cruciate ligament, joining femur and tibia are removed; but the tibial and collateral ligaments are preserved. Metal prosthetics are then fixed onto the bones using PMMA (Polymethylmethacrylate) cement. Patients are given antibiotics and mild immunosuppressant pre and post surgery to avoid allergic response of the body towards the prosthetics.