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:
Causes
- Arthritis
- Increased stress e.g., overuse, overweight, etc.
- Side effect from medicines, such as steroids
- Inactive lifestyle etc.
- Infection
- 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 Total Knee Replacement (TKR) or Total Knee Arthroplasty is a surgery that replaces the worn or damaged parts of your knee joint with artificial metal or plastic replacement parts called the 'prostheses'. The procedure is usually recommended for older patients who suffer from pain and loss of function from arthritis and have failed results from other conservative methods of therapy.
To create a new knee joint, the ends of the bones forming the joint are surgically removed. They are replaced with parts like the pieces shown in the following video animation. The parts of the prosthesis are made of metal and very strong plastic. The pieces may be cemented in place with a special bone cement, or the metal may have a porous surface that bone will grow into to create a tight fit.
Your orthopaedic surgeon, Dr. Pankaj Jain, will encourage you to use your new joint as soon as possible after your operation. Patients often stand and begin walking the day of or the day after surgery. Physiotherapy (PT) will begin in the afternoon of surgery or the day after.
Based on the surgery performed and what happens during your surgery, Dr. Pankaj will decide after surgery how much weight you can put on your surgical leg. This is called your Weight Bearing Status (WB Status). This may change throughout your hospital stay and your recovery from joint replacement surgery.
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.