Total Knee Replacement
Total knee replacement (TKR) is a surgical procedure in which the worn out or damaged surfaces of the knee joint are removed and replaced with new artificial components.
The knee is made up of the femur (thigh bone), the tibia (shin bone), and patella (kneecap). Two menisci located between the femur and tibia, are soft cartilage structures that serve as cushions to help 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, stiffness, instability and difficulty in performing daily activities. A doctor may recommend TKR if non-surgical treatment options have failed to relieve knee symptoms.
The goal of TKR surgery is to relieve pain and restore the alignment and function of the knee.
- TKR is performed under anaesthesia
- The surgeon makes an incision in front of the affected knee or usesold scars, exposing the knee joint
- The surgeon removes the damaged portions of the femur and tibia using special instruments and cutting equipment. Standard jigs, Computer Navigation, Patient Matched guides and even Robotics can aid in making more accurate cuts
- The femoral and tibial componentsare attached to the femur with or without bone cement
- The surgeon will place a plastic piece called a spacer (polyethylene insert) between the implants to enable smooth gliding movements. This plastic insert will support the body’s weight and allow the femur to move over the tibia similar to the original cartilage (meniscus)
- The femur and the tibia with the new components are put together to form the new knee joint
- Usually, to make sure the patella (knee cap) glides smoothly over the new artificial knee; its rear surface is prepared to receive a plastic component. Usually cemented
- With all the new components in place, the knee joint is tested through its range of motion
- The aim is an aligned, stable, balanced equally in flexion and extension, with a good range of movement and the patella tracking well
- The entire joint will be irrigated with a sterile saline solution. The knee is then carefully closed in layers. A suction drain may be inserted. The knee wound is dressed and bandaged
Goals and outcomes
TKR’s are a successful operation when performed well. Eradication of pain, return of painfree functional movement and a stable, aligned knee is the goal. Outcomes are however not as predictable as hip replacements. Current literature suggests that approximately 80% of TKR’s will have a good to excellent outcome, the so-called forgotten knee. 15%fair outcome, with a possibility of some pain, stiffness, clicking, instability, swelling or other symptoms that make the patient aware of the knee daily. Unfortunately, 5% of patients may have a poor outcome despite a well performed TKR with a good X-ray.
As part of the preparation for surgery, the better informed and prepared the patient is, the better the likely outcome. Signing an informed consent is a vital part of preparing for surgery. Attending a preadmission clinic is helpful. Many steps and actions are taken to reduce the risks of surgery and to aid in an uneventful full post-operative recovery.
Post-operative pathway usually include:
- The patient beingmonitored regularly
- Pain will be managed in a multi-modality style
- Drugs will be administered to avoid blood clots, prevent infections and prevent bleeding
- Urinary catheters usually remain in for 1-2 days
- Patients usually stay 3-5 days in the acute care ward
- Patients will be given specific instructions regarding exercises and activity. Starting on the day of surgery. The physiotherapist will guide these
- Knee and leg swelling is common after knee surgery. Ice and elevation of the leg are recommended to minimize swelling and pain
- Foot or calf pumps, early mobilising and hydration will be utilised to prevent calf and lung clots
- If progress is slow, a referred to in or out patient rehabilitation will be arranged
- Eating a healthy diet and not smoking will promote healing
Risks and complications
As with any major surgery, possible risks and complications associated with total knee replacement surgery include, but are not limited to:
- Knee pain
- Wound breakdown and oozing
- Knee stiffness
- Infection, superficial and deep
- Blood clots (deep vein thrombosis, pulmonary embolus)
- Fractures around the knee joint
- Nerve and blood vessel damage
- Numbness around the scar
- Patella (kneecap) dislocation
- Plastic liner wears out
- Loosening of the implant
- Bone loss from wear debris
The patient is a very important part of the pathway pre and post surgery. Patients need to be responsible for there own health and follow instructions. Informing the doctor or appropriate professional if there is a concern. Early diagnosis and treatment of complications will improve the success of treatment.
Total Knee Replacement