What type of prostheses are fitted?

The prostheses used in these replacements attempt to replicate the normal movement of the knee. There are basically two types of prostheses:

• Unicompartmental prostheses. Unicompartmental prostheses (partial knee replacement) is performed in cases where cartilage degeneration affects only one of the three compartments that make up the knee. Therefore, only the affected compartment needs to be replaced, as the rest of the joint is well preserved. The correct selection of patients is essential to achieving a good outcome. In fact, this technique is only indicated in about 10% of cases.
• Full prostheses. In total knee replacement (knee arthroplasty), the bone ends of the femur and tibia are replaced with prosthetic components. These elements are connected to each other and to the kneecap, which is sometimes also replaced, depending on the deformities, damage or the surgeon's criteria. There are different types of total prostheses, and the choice will depend on the patient's characteristics, age, bone quality and structure, ligament laxity, etc.

Most prostheses are made of plastic (high-density polyethylene) and metal (chromium-cobalt alloy) components so that the parts slide against each other like healthy cartilage, allowing the patient to perform normal knee movements. The prosthetic components are attached to the bone using a ‘cement’ (polymethyl methacrylate) that provides immediate fixation of the prosthesis.