The infected knee arthroplasty

Sammanfattning: The Swedish Knee Arthroplasty Register (SKAR) was used to identify 478 cases that underwent a first-time revision with exchange or removal of the prosthesis due to infection during the years 1986–2000. 30% of the infections were diagnosed within 3 months from primary operation and two-thirds were diagnosed within 2 years. These cases frequently had a history of wound complication after the primary arthroplasty. Acute haematogenous infection accounted for 22% and was more common in rheumatoid than in osteoarthritic patients. The most common pathogen in cases infected within 2 years from the primary arthroplasty was coagulase-negative staphylococcus (CNS) and in acute haematogenous infections it was Staphylococcus aureus. Only 1 case of methicillin resistant S. aureus (MRSA) was found, while resistance to methicillin was common in CNS and increased during the study period. Two-stage revision arthroplasty was performed in 60% and one-stage in 9%. Almost 30% were treated with poorer functional alternatives, i.e. arthrodesis, extraction of the implant, or above-the-knee amputation. After a two-stage revision arthroplasty, only half of those with failure to eradicate infection were re-revised, the cumulative re-revision rate at 2 years being 9.4% and the cumulative rate of failure to eradicate infection being 17.8%. The only factor that predicted failure to eradicate infection after a one- and two-stage revision arthroplasty was a history of wound complication after the primary operation. In a separate study the timing of administration of the first dose of perioperative antibiotic prophylaxis was studied and was found to be suboptimal in 55% of the 114 cases studied at Lund University Hospital, and in 47% of 198 cases randomly selected from the SKAR. Awareness of the fact that most infections arise early, are associated with wound complications, and often caused by CNS should encourage use of judicious postoperative care to allow early diagnosis and adequate treatment. To improve the results of revision surgery it is recommended that the treatment is centralised to units where specialists in orthopaedics and infectious diseases are working in a team.