Two-staged exchange arthroplasty with an antibiotic-impregnated PMMA cement spacer in-between two stages has a success rate of 85% to 95% in eradication of infection. Use of vancomycine in high doses has a high potential for complications due to nephrotoxicity. The aim of this study was to evaluate the results of two-staged exchange arthroplasty in infected hip arthroplasty using low-dose vancomycine-impregnated PMMA cement as an interim spacer between stages. Thirty-five (20 females, 15 males, average age: 60) patients with a confirmed infected total hip arthroplasty who were treated between 1999 and 2005 were the subjects of the study. In the first stage after removal of the prosthesis and debridement, a spacer made of 40 grams of PMMA cement impregnated with 1 gr vancomycine was placed in the infected joint space. Postoperatively, patients were treated with 6 weeks of intravenous antibiotics in consultation with an infectious disease consultant. When CRP and ESR returned to normal levels, revision surgery with cementless components was performed. The average follow-up after the second stage was 4 years. The ESR and CRP decreased significantly before the second stage with this treatment protocol (from 81.28 to 17.54 mm/h p<
0.001 and 10.05 to 0.64 mg/dl respectively, p<
0.001). The mean interval between the two stages was 193.3 days. A second debridement was needed in 4 patients (10.8 %) because they did not respond to treatment. Two patients (5.4 %) had recurrent infections after reimplantation and underwent a resection arthroplasty. None of the patients suffered from antibiotic toxicity. Two-stage exchange arthroplasty using a low dose vancomycine-impregnated cement spacer was an effective method in treating infected hip replacements. With using a lower dose than previously reported, we were able to avoid antibiotic toxicity while effectively treating our patients with the same success rate.
As expected, the generated forces at the bike pedal were low (20–25% body-weight) calling for little muscle activity and low compressive joint forces. However, with a mean maximum flexion angle of 131.5°, the observed motion ranges were higher than expected. Prostheses not designed for high flexion activities could lose tibio-femoral contact during cycling with detrimental effects on wear. Still, the measured range of rotation in the transverse plane indicates that despite its posterior-stabilized design rotation is taking place with approximately the same amount as it occurs in normal subjects. This may have detrimental effects on the post at the tibial plateau and could explain the previously observed rotational damage patterns on retrieved posterior stabilized TKA specimens. Data are suggesting that leisure activities should be considered to determine the appropriate TKA design. This study will provide useful data for future design and wear testing scenarios.