Infection after the surgery is of three varieties.
Superficial infection: This involves the coverings of the knee joint without extending into the joint itself. In a patient with a superficial infection, the wound leaks fluid excessively and skin around the surgical cut looks red and inflammed. The patients generally do not feel unwell in themselves. The infection can frequently be treated successfully by antibiotics.
Early deep infection: Infection of this type is more serious as it extends down to the artifical knee joint. A patient developing this complication is likely to feel unwell and have a temperature in addition to having an inflammed, hot, red wound which leaks fluid or pus. The knee is likely to be painful and walking may make the pain worse.
With this type of infection your specialist is likely to recommend surgery to wash out and clean the infection and also put you on intravenous antibiotics. Sometimes it is necessary to operate again to clean the infection a second time. The antibiotics will generally be continued for a period of 6 weeks and many deep infections can be cured successfully in this manner. Occasionally deep infection may not respond to this treatment and will then require to be treated as a late infection.
Late deep infection: This is deep infection that develops later than about 12 weeks after the surgery or occurs when the 'early' infection or superficial infection has not settled. Usually, this type of infection will not respond to antibiotics and operations to wash out the infection. This is because the germs that cause the infection get into tiny crevices of the artifical knee itself rather than just remaining in the living tissues. Also, some of the germs are able to produce a thin layer of slime around them into which the antibiotics cannot penetrate. Since the blood does not flow into the artifical joint, the antibiotics do not reach the germs and therefore become less effective.
The best chance of curing the infection is by removing the artifical knee components completely to wash out the infection and using antibiotics put directly inside the knee joint space and also intravenously. It is Mr. Trakru's practice to wash out the infection at least twice though many surgeons do this only once. In any case, intravenous antibiotics need to be given for 6 weeks. During this time the patient has no knee joint at all but is generally able to get about in a limited manner with the aid of two crutches. Of course he or she is not able to put any weight on the operated leg. There are some surgeons who have reported obtaining good results by carrying out the whole "exchange knee replacement" during one operation and others who, while using two procedures, leave only a week or two between.
The specialist is likely to carry out serial blood tests the results of which can give him some indication of whether the infection is being cured. At about 8 or 9 weeks after the start of the antibiotics, it will be necessary to put a needle into the knee joint to remove a sample of fluid. This is examined in the laboratory for any persistent infection and if none is found, that is a good indicator of the infection having been treated successfully.
The specialist will however also take into account the results of the blood tests and his physical assessment of the knee to advise the patient whether the infection has been eliminated. Once the infection has been successfully cleared, a new artificial knee may be implanted.