Knee Replacement Surgery
Total knee replacement, also called total knee arthroplasty, is a surgical procedure in which the worn out or damaged surfaces of the knee joint are removed and replaced with artificial parts. The knee is made up of the femur (thigh bone), the tibia (shin bone), and patella (kneecap). These bony surfaces are covered with a layer of cartilage 2-3mm thick which allows for painless, smooth joint motion. Separate to this, the knee also has two cartilage ring-like structures called ‘meniscus’, which serve as a cushion between the femur and tibia and help absorb shock during motion. In a normal joint, articular cartilage allows for smooth movement within the joint, whereas in an arthritic knee the cartilage itself becomes thinner or completely absent. In addition, the bones become thicker around the edges of the joint and may form bony “spurs”.
All of these factors can cause pain, restrict range of motion in the joint and lead to difficulties in performing daily activities. Your doctor may recommend surgery if non-surgical treatment options have failed to relieve the symptoms.
Total knee replacement is a commonly performed, reliable procedure for the treatment of symptoms of knee arthritis. In Australia alone, over 65,000 knee replacements are performed every year and the numbers continue to grow every year. Total knee replacement is one of the most commonly performed surgeries and has been shown to have good longevity and provide good improvement in patient quality of life.
Total knee replacement surgery is commonly indicated for severe knee arthritis. Osteoarthritis is the most common form of knee arthritis in which the joint cartilage gradually wears away. It often affects older people. Other common types of knee arthritis include inflammatory arthritis conditions like rheumatoid arthritis, or after trauma or infection affecting the knee.
Dr Khatib may advise total knee replacement if you have:
The surgery is performed under spinal or general anaesthesia. Dr Khatib will make an incision in the skin over the affected knee to expose the knee joint. Then the damaged portions of the femur and tibia bones are cut at appropriate angles using specialized jigs. This removes the deformed parts of the bones and any bony growths and creates a smooth surface on which the implants can be attached. Depending on the pathology and the clinical picture, the inner surface of the patella may be cut and resurfaced with a plastic (polyethylene) patella component. The femoral and tibial components are attached to the end of the femur and the tibia with or without bone cement. Dr Khatib will place a plastic piece called an articular surface between the implants to provide a smooth gliding surface for movement. This plastic insert will support the body’s weight and allow the femur to move over the tibia. The femur and the tibia with the new components are then put together to form the new knee joint. With all the new components in place, the knee joint is tested through its range of motion. The entire joint is then irrigated and cleaned with a sterile solution. The incision is carefully closed, and a sterile dressing is placed over the incision.
Rehabilitation begins immediately following the surgery. A physical therapist will teach you specific exercises to strengthen your leg and restore knee movement. Ice is applied to the knee to decrease swelling. You will have an x-ray in recovery and once checked you will be able to walk with crutches or a walker. Your physical therapist will also provide you with a home exercise program to strengthen thigh and calf muscles. Antibiotics are given before and after-surgery to decrease the risk of infection. You will be given medication and calf pumps (calf-compressors) to decrease the chance of a clot (thromboembolism) in the legs or the lungs, but the best prevention is by getting the circulation moving and preventing stagnation of the blood through moving and performing certain exercises.
A blood transfusion is uncommon with modern anaesthetic and surgical techniques. Medication like Tranexamic acid (TxA) have reduced bleeding with joint replacement surgery and the need for blood transfusion afterward. Dr Khatib usually checks your haemoglobin levels after surgery and gives you iron and vitamin supplements so that your body can replace the blood lost during surgery.
Most patients are stable and ready to go home 3-5 days after surgery and continue with physiotherapy and rehabilitation as an outpatient or a physiotherapist may even attend to your house. Patients who live a split-level house, have many steps at home or who live alone may be more likely to need transfer to a rehabilitation facility for continued physiotherapy to get them to a safe level where they are ready for discharge home.
Risks and complications
As with any major surgery, possible risks and complications associated with total knee replacement surgery include: