PARTS OF KNEE REPLACEMENT PROSTHESIS
Total knee replacement is surgical procedure in which the damaged cartilage lining of bone is replaced with artificial components, thereby eliminating the pain caused by diseased joint.
The most common indication is completely worn out knee joint by osteoarthritis. Knee replacement is also considered in certain arthritic conditions like Rheumatoid arthritis.
The components of artificial knee replicate the shape of joint surface so as to allow smooth rolling and gliding movement. Structure and shape of knee joint varies from person to person and also across the genders. In order to address this, the implant companies manufacture artificial joints in different sizes so that the operating surgeon can choose the best fit.
There are also several designs of implant based on patient’s age, gender and lifestyle. It is the surgeon who can choose and suggest the best design and brand that best suits your need.
There are three main parts
-Femoral (thigh bone) component
-Tibial (Shin bone) component
-Plastic (Cushion) component
Femoral (Thigh bone) component:
The lower end of femur in knee joint is a curved surface with central groove allowing movement of knee cap. The prosthesis component is made up metal and is curved with central groove mimicking the natural surface of femur. Femoral component is made up Chrome cobalt alloy or Zirconium alloy or Oxinium .
Tibial (Shin bone) component:
The upper end of shin bone is replaced with flat metal platform which can accommodate Plastic (cushion). Tibial component is made of Titanium alloy or Chrome-cobalt alloy.
The plastic (Cushion) is also called as insert accommodates into the tibial metal platform. The plastic component has inbuilt curvature to accept the curvature of femoral component. If surgeon prefers to do a ligament sparing surgery the plastic has notch to accommodate the cruciate ligaments. In case cruciate ligaments are removed it has cam to take over the function. The material used in the manufacturing of plastic is High Molecular Weight Polyethylene (HMWP).
The back side of knee cap is also replaced by removing damaged cartilage with polyethylene button. Some absolute indications warrant’s patella replacement whereas in some cases its surgeons preference.