Your knee is a hinge joint where the end of the thigh bone (femur) meets the beginning of the large bone in your lower leg (tibia). A healthy knee has smooth cartilage that covers the ends of the femur and tibia. The smooth cartilage lets the surfaces of the two bones glide smoothly as you bend your knee. The muscles and ligaments around the knee joint support your weight and help move the joint smoothly so you can walk without pain. The smooth cartilage layers can wear down on the ends of the femur and tibia. When the smooth surfaces become rough, the surfaces are like sandpaper. Instead of the joint gliding when you move your leg, the bones grind and you have pain and / or stiffness. This degeneration can happen due to variety of reasons such as the following:
- Increased stress e.g., overuse, overweight, etc.
- Side effect from medicines, such as steroids
- Inactive lifestyle etc.
- Inflammation e.g., Rheumatoid arthritis
When pain in your knee or leg prevents you from doing your usual activities and your x-rays show irregular surfaces at the knee, your doctor might suggest that you have a knee replacement.
A revision knee replacement involves removing the old prosthesis and inserting a new one. These knee replacements usually feature a longer stem, which allows the component to be more securely fixed into the bone cavity. The components may also interlock in the centre of the knee to form a hinge to provide greater stability to the joint. Extra pieces of metal and/or plastic may be used to make up for any removed or badly damaged bone. All revision total knee replacement other than for infection are done in a single stage. When a revision operation is carried out for infection, often the revision procedure is done in two stages. In the first stage the infected prosthesis (and the bone cement if it was used to insert the first prosthesis) is removed. All infected material and soft tissue is cleared from the knee, and samples are taken to confirm which bacteria are causing the infection. A temporary spacer, shaped like a knee prosthesis, can be inserted, and often antibiotics are left inside the knee. The temporary spacer allows knee bending to right angles and weight bearing with crutches. After a period of at least six weeks (or more, depending on when the infection is eradicated), the second stage procedure is performed, when the new prosthesis is inserted. Post-operative care after knee revision surgery is very similar to the care of a primary knee replacement. This includes a combination of physical therapy, blood management, and pain medication as necessary. Antibiotics and some method of blood clot prevention will be continued in the postoperative period. A brace or splint may be used to protect the joint after the surgery. Therapy will usually continue for up to three months following the surgery. Assistive devices, such as a walker or crutches, will be used early in the convalescence period, and patients will progress to a cane or walking without any assistance as their condition improves. Revision TKR is a complex procedure that requires an experienced surgeon and proper pre-operative planning to achieve satisfactory outcomes.