Total knee replacement surgery
Total knee replacement is one of the commonest procedures performed to address significant pain associated with knee arthritis. During total knee replacement the worn and damaged bearing surfaces of the knee are replaced with an artificial joint. In earlier stages of knee arthritis anti-inflammatory medications, physiotherapy and possibly arthroscopy (keyhole surgery) can help in pain relief but a total knee replacement is needed to relieve pain associated with advanced arthritis.
Type of anaesthesia for total knee replacement
The surgical procedure can either be carried out under a general anaesthetic (where you will be asleep) or a regional type of anaesthetic (spinal or epidural anaesthetic where your legs are numb for the duration of the operation). The appropriate anaesthetic is usually chosen after discussion with the anaesthetist and is based on pre-existing medical conditions.
What happens during knee replacement surgery?
The surgery is carried out under a tourniquet to limit the bleeding during your knee replacement surgery. A cut is made over the front of the knee and the knee capsule (covering of the knee) is opened to expose the arthritic knee. The arthritic bearing surfaces of the femur (thigh bone) and tibia (shin bone) are removed and metallic alloy components are fitted onto the ends of the bones using bone cement. A polyethylene bearing sits between the metallic components. A polyethylene button is sometimes placed on the underside of the kneecap. At the end of your knee replacement surgery the skin is closed with metal clips and a drain is used to drain the blood away from the knee after the knee surgery. Depending on the type of drain used the blood drained can be given back to you, reducing the need for a blood transfusion.
What happens after knee replacement surgery?
Following your knee replacement surgery you are given adequate pain relief. The day after your knee surgery the drain tubes are removed and you start exercising your knee with the help of a physiotherapist. Your knee is X-rayed after the operation to confirm accurate placement of the knee replacement and you are encouraged to walk and bend the knee, working with the physiotherapist. You should be able to go home within a week of your knee replacement surgery.
What happens after discharge from the hospital?
You need to continue with the exercises to improve the bend in your new knee and to regain the strength in your muscles around the knee. Two weeks following the surgery your skin clips will need to be removed. It does take around six weeks for the knee to settle down following the surgery and you may notice swelling and bruising in relation to the knee in this period. You will be reviewed in clinic at six weeks following your knee surgery to check your progress and you will be kept under review on a six monthly basis for the first year following the total knee replacement surgery.
What can I expect from my knee replacement surgery?
Following your knee replacement surgery you will be able to carry out most of your daily activities. Full bending of the knee is usually not possible following knee replacement surgery but you should get a bend around 100. You may find it difficult to kneel following your knee replacement surgery. Exercises and activities leading to impact on the artificial knee are generally not advisable. The knee replacement should last for about 10 years in 90% of the patients but may fail earlier in a younger and more active patient.
What are the risks of undergoing total knee replacement?
The significant and common risks are as follows:
- Infection (around 1%): every effort is undertaken to avoid infection by performing the knee surgery in sterile conditions (laminar air flow theatre) and by giving antibiotics around the time of operation. Despite this infection can still occur. Infection usually manifests by the incision becoming red, hot and painful, with possible discharge of fluid. If this infection is superficial (not going deep to the joint) this can usually be treated with antibiotics and an operation to wash the wound. In case of deep infection, which is fortunately rare, the artificial knee may need to be removed and replaced at a later date after the infection has been controlled.
- Deep vein thrombosis and pulmonary embolus: deep vein thrombosis (DVT) is a blood clot in the veins of the leg. The blood clot can go into the general circulation and go to the lungs, which is termed as a pulmonary embolus. To reduce the risk of DVT you will be given medications as well as stockings on your legs. One of the best ways to prevent a DVT is to get the leg muscles moving as quickly as possible following your knee replacement surgery.
- Loosening, wear and need for revision knee replacement: most knee replacements are expected to last for about 10 years or more. If there is loosening of the components or wearing of the polyethylene component of the knee replacement the knee may need to be changed (revised).
- Other less common complications include persistent pain following knee replacement surgery, knee stiffness, nerve damage and blood vessel damage.