Knee joints undergo degeneration (wear and tear) within the aging patient. This is called osteoarthritis. During this process the cartilage becomes thin and weak till eventually the underlying bone is exposed. Contact of bone on bone in joints cause pain and swelling, especially with activities. Previous trauma, infection or inflammatory diseases lead to earlier degeneration of the joint.
When the pain and swelling and stiffness interfere with the patient’s ambulation, activities or work, it needs to be treated. Symptoms can be brought under control for short periods with medication, but eventually patients will need surgery in the form of replacement surgery.
During a total knee replacement, the joint surfaces of the upper and lower leg are replaced or resurfaced with metal prosthesis with a polyethylene (hard plastic) bearing surface in between. These prostheses are usually fixed with bone cement. For isolated 1 compartment degeneration, unicondylar or partial replacements can also be done. Some of these prostheses can even be fixed without cement.
The worst complication of replacement surgery is infection, either early or late. Fortunately, it is rare (< 1% world-wide). Therefore, numerous tests are performed before surgery to identify a possible focus of infection and to treat beforehand.
Blood thinning drugs such as Disprin/Ecotrin need to be stopped 5 days before surgery. Ask your surgeon if you are unsure about this. Patients are admitted on the day of surgery or sometimes a day before.
Post-operatively patients stay in hospital 3-4 days until they can ambulate adequately. Sometimes they will stay 1 night in High Care. Mobilization starts on the same day or the day after surgery. It includes ambulation with crutches or walking frame for 4-6 weeks as well of mobilization of knee joint (bending). A Physiotherapist will help with this in hospital and monitor post-operative. Drainage tubes are usually removed on day 1 and the drip on day 1 – 2. The wound is closed with dissolvable stitches. It is preferred that patients rather shower than bath for 4-6 weeks after operation. Patients can drive their cars independently after 4-6 weeks. Follow up of patients occur at 2 and 6 weeks and then after 6-12 months.
For 6 weeks post-operative there is a higher change of blood clot formation (DVT). This can cause severe swelling and pain in the leg and does not get better with elevation and medication. Prophylactic therapy against DVT includes early mobilization, compression socks for 4-6 weeks, Clexane injections in hospital and Pradaxa/Xarelto tablets for 2 weeks after discharge.
Antibiotics should be taken before any future surgery especially dental and urogenital procedures. The dosage will be a single treatment 1 hour before procedure e.g. Augmentin 1g or Clindamycin 300mg for Penicillin allergy. Contact your surgeon beforehand.
Under no circumstances should anyone insert a needle into the operated knee for aspiration or infiltration before consultation with your surgeon.
In a minority of cases the range of movement will still be inadequate at 6-12 weeks. A manipulation under anaesthesia will then be considered.
It is normal to feel or hear clicks in the knee. This is usually painless. There will also be an area of decreased sensation on the outside of the knee. This will improve over 6-12 months but will probably never be normal.
Knee function will improve for 12-18 months post-operative. The normal life span for the prosthesis is on average 20 years. It will provide a painless functional joint and patients can participate in low demand sport such as bowls, cycling, golf, doubles tennis and walking.
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