Septic arthritis means an infection in the joint. Septic arthritis of the knee can develop by seeding of the joint by bacteria from outside or within the body. Outside bacteria can enter through a perforation wound following knee fractures, intra articular injections, surgical procedures.
Bacteria can also originate from another source of infection within the body like the teeth, gums, urine, skin, dental procedures, urinary catherization, infected toe nail, webspace infection etc.
Pus formation occurs. Pus can destroy the joint if it is not removed within forty eight hours. The diagnosis is made by aspirating fluid from the knee. Frank pus is diagnostic of infection. Doubtful cases can be confirmed by further tests. When the diagnosis is certain, it is imperative to treat the condition promptly.
When septic arthritis is detected earlier in a patient and debridement is indicated then it can be done arthroscopically. The scope is inserted through the antero- lateral or antero-medial portals and a shaver is introduced into the supr-apatellar pouch to break down soft adhesion. Multiple drains are left in situ and the patient is started on CPM (continuous passive mobilization). Antibiotics are administered for prolonged period.
When a knee arthroplasty gets infected, the treatment consists of open knee debridement. Arthroscopic debridement is not recommended in this condition.
If done early the knee implant can be salvaged. If not, a two stage revision knee replacement is the ideal treatment.