Two-stage revision arthroplasty for periprosthetic joint infections: What is the value of cultures and white cell count in synovial fluid and CRP in serum before second stage reimplantation?

INTRODUCTION: Besides CRP in serum, white cell counts and cultures of synovial fluid are routinely used to detect periprosthetic joint infections. But the sensitivities of these parameters do vary from 12 to 100 %. In two stage revision arthroplasty before the second stage surgeons have to decide if reimplantation is justified. Therefore, we investigated the value of cultures and white cell count from the synovial fluid with a polymethyl methacrylate spacer in place and CRP in serum before reimplantation to detect persistent infection in a standardized setting. METHODS: 115 patients with a two-stage revision hip or knee arthroplasty were included in this study. All patients had an antibiotic loaded polymethylmethacrylate spacer. Retrospectively synovial cultures, white blood count in synovial fluid and CRP in serum were assessed before reimplantation. RESULTS: The sensitivity of the synovial cultures was 5 % (95 % CI 0.13-24.87), with a specificity of 99 % (95 % CI 94.27-99.97). For white blood count in synovial fluid the sensitivity was 31.3 %, specificity was 39.1 %. Sensitivity for CRP in serum was 42.10 %, specificity was 84.21 %. CONCLUSION: Cultures from synovial fluid and white blood count in synovial fluid and CRP seem to be uncertain parameters to exclude persistent infection. We do not recommend joint aspiration before reimplantation anymore. Further research is necessary to find other markers to confirm or exclude persistent infection.

Two-stage hip revision arthroplasty with a hexagonal modular cementless stem in cases of periprosthetic infection.

BACKGROUND: Two-stage revision arthroplasty is today regarded as the gold standard treatment method for deep prosthetic joint infection. The aim of the present study was to evaluate clinical and functional outcomes with the Modular Universal Tumor And Revision System (MUTARS) RS stem in patients undergoing two-stage revisions. METHODS: The functional and clinical outcomes for 43 patients who had undergone two-stage revision procedures for PJI were analyzed in a retrospective study. The minimum follow-up period was 24 months. Shorter follow-up periods were only observed when there were complications such as loosening or recurrent infection. The mean follow-up period was 3.86 years (range 7 months to 11.6 years). RESULTS: The success rate with infection control for PJI was 93%. Reinfection occurred in four cases (7%). The risk of reinfection after MRSA infection was 20.5 times greater (P >0.01) than with sensitive or unknown bacteria. Two aseptic loosening occurred after 7 and 20 months. The average Harris Hip Score was 80 (range 62-93). CONCLUSION: This retrospective study showed a 93% rate of eradication using specific antibiotic therapy. With the modular MUTARS RS stem, there was a low rate of aseptic loosening of 4.6%. MRSA infection was identified as a risk factor for reinfection. The two-stage procedure with modular cementless implants used is therefore appropriate for treating periprosthetic infections associated with hip endoprostheses.

Distal femur and proximal tibia replacement with megaprosthesis in revision knee arthroplasty: a limb-saving procedure.

PURPOSE: The aim of the present study was to assess whether using megaprostheses in revision knee arthroplasty procedures allows limb salvage with an acceptable outcome and complication rate, in comparison with other limb-saving procedures. METHODS: Between 2000 and 2010, megaprosthesis implantation was required for non-oncologic indications in 20 patients (21 knees) (average age 73 years). Reconstructions involved the distal femur (n = 15), proximal tibia (n = 4), and both femur and tibia (n = 2). The indications, type, and numbers of previous operations and implants, as well as complications associated with megaprosthesis implantation, were reviewed, and the clinical and radiographic outcomes after an average follow-up period of 34 months (range 10-84 months) were evaluated. RESULTS: The indications for megaprosthesis implantation were periprosthetic infection (n = 5), fracture (n = 9), nonunion (n = 5), and aseptic loosening (n = 2). The types of implant placed before the megaprosthetic reconstruction were a cemented rotating-hinge arthroplasty (n = 16) and a primary total knee arthroplasty (n = 5). Six patients had an additional osteosynthesis of the distal femur. An average of 3.8 operations (range 1-7) had been carried out before megaprosthesis implantation. Complications developed in 11 patients. The Knee Society Score improved significantly, from 43 (± 15) to 68 (± 16.8); P < 0.05. CONCLUSIONS: Megaprosthesis implantation in revision knee arthroplasty is an exceptional indication. Despite the high complication rate, the patients can be spared amputation in most cases, and rapid mobilization with full weight-bearing is possible.

Patellar resurfacing as a second stage procedure for persistent anterior knee pain after primary total knee arthroplasty.

PURPOSE: Knee pain after total knee arthroplasty may be caused by an unresurfaced patella. Secondary isolated resurfacing of the previously unresurfaced patella in total knee arthroplasty remains controversial. The aim of this retrospective study was to evaluate the outcome after patellar resurfacing as a second stage procedure. METHODS: The study included 22 patients (13 female/nine male) who underwent resurfacing of the patella with a mean follow-up of 61.8 ± 39.2 months. The mean age of the patients was 60 ± 9.7 years at the time of operation. The average period between total knee arthroplasty and patellar resurfacing was 26.3 ± 15.2 months. The patient's subjective satisfaction was assessed by a custom-made questionnaire. RESULTS: The mean Knee Society Score improved significantly from 60.1 ± 8.3 to 77.0 ± 6.3 (p = 0.0063). The mean functional score also improved significantly from 42.7 ± 2.3 to 60.2 ± 3.9 (p = 0.001). Three patients (13.6%) needed further operative revision. CONCLUSIONS: Although clinical scores showed significant improvement some patients continued to have pain and remained dissatisfied without detecting a specific reason. Further studies are needed to better elucidate the benefit of patellar resurfacing as second stage procedure.