Primary Total Knee Replacement

Overview

Primary total knee replacement, also called total knee arthroplasty, is a surgical procedure in which the worn out or damaged surfaces of the knee joint is removed and replaced with artificial parts. The knee is made up of the femur (thigh bone), the tibia (shin bone), and patella (kneecap). The meniscus, the soft cartilage between the femur and tibia, serves as a cushion and helps absorb shock during motion.  Arthritis (inflammation of the joints), injury, or other diseases of the joint can damage this protective layer of cartilage, causing extreme pain and difficulty in performing daily activities. Orthopaedic surgeon Dr Klar may recommend surgery if non-surgical treatment options have failed to relieve your symptoms.

Indications for surgery

Total knee replacement surgery is commonly indicated for severe osteoarthritis of the knee. Osteoarthritis is the most common form of knee arthritis in which the joint cartilage gradually wears away. It often affects older people. Other forms of arthritis exist such as rheumatoid arthritis. 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 and restricted range of motion in the joint. Dr Klar may advise total knee replacement if you have:

• Severe knee pain which limits your daily activities (such as walking, getting up from a chair or climbing stairs).
• Moderate to severe pain that occurs during rest or awakens you at night.
• Chronic knee inflammation and swelling that is not relieved with rest or medications.
• Failure to obtain pain relief from medications, physical therapy, or other conservative treatments.
• A bow-legged or knocked-knee deformity of the leg.
• Poor quality of life and significant functional limitation.

Knee Replacement Surgery

The goal of total knee replacement surgery is to relieve joint pain and restore the alignment and function of your knee. The surgery is performed under spinal and/or general anaesthesia. Dr Klar will make an incision in the skin over the affected knee to expose the knee joint. Dr Klar uses the Zimmer Nex Gen and Persona TKR components and the I-Assist computer navigation system for all primary knee replacements. This represents the best-surviving implants currently available on the market as proven on the National Joint Replacement Registry NJRR. Computer navigation ensures the components are optimally fitted and aligned in your knee. The damaged portions of the femur bone are cut at appropriate angles using specialized jigs.

Dr Klar then cuts or shaves the damaged area of the tibia (shinbone) and the cartilage. This removes the deformed part of the bone and any bony growths, as well as creating a smooth surface on which the implants can be attached. Dr Klar 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, similar to the original meniscus cartilage. The femur and the tibia with the new components are then put together to form the new knee joint and all components are cemented into position with antibiotic bone cement. To make sure the patella (knee cap) glides smoothly over the new artificial knee, its rear surface is also prepared to receive a plastic component or button. 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, an injection of local anaesthetic (to stop bleeding inside the knee) is infiltrated into the joint and a sterile dressing is placed over the incision.

Post operation

Rehabilitation begins immediately following the knee replacement surgery.  A physical therapist will teach you specific exercises to strengthen your leg and restore knee movement, and your physiotherapist will come to walk you briefly at about 4 hours after the operation to minimise your risk of blood clots. 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. Blood transfusion is occasionally needed after total knee replacement surgery but is less likely these days. Most patients stay in hospital 3-5 days after a primary knee replacement.

Risks and complications

As with any major surgery, possible risks and complications exist and those associated with total knee replacement surgery include:

• Knee stiffness or arthrofibrosis
• Infection in the artificial knee joint
• Blood clots (deep vein thrombosis) or lung clots
• Nerve and blood vessel damage
• Ligament injuries
• Patella (kneecap) dislocation or fracture
• Plastic liner wearing out
• Ongoing pain of uncertain origin in up to 10% of patients
• Loosening of the implants
• Unsightly or thickened scar
• Complex regional pain syndrome