Total Knee Replacement

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). The meniscus, a bit of fibrocartilage between the femur and tibia, serves as a cushion or shock absorber, and helps distribute loads throughout 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. Your doctor may recommend surgery if non-surgical treatment options have failed to relieve the symptoms.

Indications

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 slowly wears away. It may be precipitated by injury to the cartilage (Post traumatic arthritis) however most often it is idiopathic (unknown cause).

In a normal joint, articular cartilage allows for smooth movement within the joint, whereas in an arthritic knee the cartilage itself becomes rougher and thinner or completely absent. The joint also may become swollen and have synovial thickening (Thickening of the lining of the joint). 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.

Your doctor 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, injections, physical therapy, or other conservative treatments.

  • A bow- legged knee deformity

Causes

The exact cause of osteoarthritis is not known, however there are a number of factors that are commonly associated with the onset of arthritis and may include:

  • Injury or trauma to the joint

  • Fractures at the knee joint

  • Increased body weight

  • Repetitive overuse

  • Joint infection

  • Inflammation of the joint

  • Connective tissue disorders

Diagnosis

Your doctor will diagnose osteoarthritis based on the medical history, physical examination, and X-rays. X-rays typically show a narrowing of the joint space in the arthritic knee.

Procedure

The goal of total knee replacement surgery is to relieve pain and restore the alignment and function of your knee.

The surgery is performed under spinal or general anaesthesia. Mr Damasena will make an incision in the skin over the affected knee to expose the knee joint. Then the damaged portions of the femur bone are cut at appropriate angles using specialized jigs positioned using a computer or robot . The femoral component is attached to the end of the femur with or without bone cement. Mr Damasena 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 creates a smooth surface on which the implants can be attached. Next, the tibial component is secured to the end of the bone with or without bone cement (Tis depends on the quality of your bone). A plastic liner is then inserted 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. To make sure the patella (knee cap) glides smoothly over the new artificial knee, if it is worn, its rear surface is also prepared to receive a plastic component. 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.

Post-operative care

Rehabilitation begins immediately following the surgery. A physiotherapist will teach you specific exercises to strengthen your leg and restore knee movement

In the first 2 weeks you should

  • Focus on reducing your swelling with regular icing and elevation.

  • Work together with your therapist to normalise the range of motion in the knee, aiming to be able to fully straighten it and bend it beyond 90 degrees before discharge.

  • Aim to normalise your walking using either a frame or crutches.

By week 4-6 you should

  • Be off strong pain killers and mainly use only panadol and an anti inflammatories regularly. You may need stronger medications for “breakthrough pain” as required.

  • Aim to be off crutches and walk without any aids.

  • Have a range of motion at least 0-90 degrees.

Risks and complications

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

  • Knee stiffness

  • Infection

  • Blood clots (deep vein thrombosis)

  • Nerve and blood vessel damage

  • Ligament injuries

  • Patella (kneecap) dislocation

  • Plastic liner wears out

  • Loosening of the implant

If you find difficulty in performing simple activities such as walking or climbing stairs because of your severe arthritic knee pain, then total knee replacement may be an option for you. It is a safe and effective procedure to relieve pain, correct leg deformity, and help you resume your normal activities of daily living.