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Authors: Richard P. Evans, M.D.

Title: Antibiotic Prosthetic Articulating Spacers For The Two-Stage Treatment Of Total Knee And Hip Sepsis

Address: Cherry Creek Orthopedic Specialists, 210 University Boulevard, Suite 210, Denver, Colorado 80206

Treatment outcomes of 70 consecutive chronic periprosthetic total knee and total hip infections were evaluated. All patients were treated with a two-stage reconstruction using articulating spacers made of antibiotic cement or cement covered components. Treatment success is compared to published reports. The advantages of articulating spacers for both knee and hip arthroplasty are described. Use of the McPherson staging system for periprosthetic sepsis was evaluated.

From January 1995 to March 2003, 70 consecutive periprosthetic total knee and hip infections were treated and are retrospectively evaluated. Thirty-nine septic total knee arthroplasties and thirty-one septic total hip arthroplasties underwent two-stage reimplantation protocol by a single surgeon (RPE) in a community setting. This protocol involved resection of the infected joint and foreign material and radical debridement of septic contiguous tissue. Treatment protocol was typical of two-stage treatment but also included implantation of hand molded articulating antibiotic laden cement prostheses and cement coated prostheses followed by six weeks of IV antibiotics. Except in the five Candida and two Mycobacterial infections four grams of vancomycin and four grams of tobramycin were mixed with each forty-gram batch of Palacos cement. Soft tissue augmentation was performed when indicated. A femoral knee mold was also employed. Second-stage permanent prosthetic implantation was performed after a two to six week window of no antibiotic treatment followed by joint aspiration, serial laboratory and physical exam evaluations. Second stage intraoperative evaluation with cell count, frozen section and culture was completed in each case.

Pain, range of motion, limb alignment and patient mobility during treatment was made. Postoperative restoration of functional result including postoperative knee range of motion was also evaluated. Retrospective McPherson staging of these infections was completed to determine if a correlation exists between staging and treatment failure. Antibiotic cement and cement coated total hip and knee prosthetic components were implanted in 70 patients including 39 total knees and 31 total hips. Combined success rate after second stage implantation of the final revision prosthetic components was 87.1% (90.3% hips and 84.6% knees). Girdlestone resection and hip disarticulation was the final result in two hips. Above knee amputation was required in six knees and one knee underwent permanent resection. All failures cultured resistant organisms; two with vancomycin resistant Enterococcus (VRE), seven with resistant Staphylococcus and five also had multiple organisms. Using the current McPherson staging system for periprosthetic joint infections, staging the failures in this series resulted in: one III-B-2, four III-B-3 and four III-C-3. Articulating antibiotic cement prosthetics at the first stage improved pain control and mobility prior to final implantation, facilitated the second operation and improved final functional outcome and range of motion.

Success rate in this series of total hip and knee sepsis two-stage treatment with antibiotic articulating spacers appears comparable to the two-stage treatment results in the literature. The use of articulating components did not seem to impair the success rate of treatment even though some areas of the components are not covered by antibiotic cement. Articulating components did reduce pain and improve mobility during treatment, facilitate reconstruction and result in improved range of motion. The staging system reveals that the failures occurred in systemically and locally compromised patients. As in other series total knee sepsis appears more common and difficult to treat than hips. All failures were infected with resistant organisms. The two VRE septic knees were treated at a time when the only antibiotics available are no longer on the market.

Use of articulating antibiotic cement and cement-coated prosthesis in both hips and knees can reduce the pain of treatment, facilitate final component implantation and improve functional result without impairing two-stage treatment success rate. There is no mention of resistant infection in the current staging system. Consideration of this plus other possible parameters should be considered for inclusion to improve the predictive power of the staging system.

Musculoskeletal Infecton Society
Musculoskeletal Infecton Society
PO Box 714
Rochester, MN 55903