[Treatment of Acute Periprosthetic Infections with DAIR (Debridement, Antibiotics and Implant Retention) - Success Rate and Risk Factors of Failure]. / Lécba akutních periprotetických infekcí postupem DAIR (debridement, antibiotics and implant retention) ­ úspesnost a rizikové faktory selhání.

ABSTRACT

PURPOSE OF THE STUDY Revision surgery with implant retention and exchange of mobile prosthetic parts is considered to be the method of first choice in acute periprosthetic infections with a stable endoprosthesis and good condition of soft tissues, where the symptoms did not last longer than 3 weeks. The aim of the study was to evaluate the long-term outcomes and to identify the factors affecting the success rate of this procedure. MATERIAL AND METHODS This unicentric retrospective study evaluated the results of 18 surgeries with implant retention performed at the Department of Orthopaedics of Ceské Budejovice Hospital in the period 2009-2016. The failure of the procedure was defined as the presence of at least one of the following criteria removal or replacement of endoprosthesis within 2 years after the DAIR procedure, detection of the same pathogen during the DAIR procedure and in the later performed revision surgery, necessity of chronic suppressive antibiotic therapy, death related to periprosthetic infection. The cured patients were invited for a clinical check-up. The postoperative condition was assessed using the Knee Society Score and the Harris Hip Score. RESULTS The overall success rate of the procedure reached 61.1%. Hematogenic dissemination was the cause of periprosthetic infection in 13 followed-up cases (72.2%), with the average time after the implantation of 153.2 weeks. Treatment through the DAIR procedure was successful in 53.8%. Early postoperative complications were observed in 5 cases (27.8%), in 4 of which, i.e. 80%, they were successfully managed by a surgery with implant retention. The most frequently identified etiological agents were Staphylococcus aureus and Staphylococcus epidermidis strains. In primo-implanted endoprostheses the success rate reached 90.9% (in case of early postoperative infections even 100%), whereas surgeries in repeatedly operated joints were successful in 14.3% only. The mean value of the Knee Society Score in patients after a successful knee joint surgery was 81.2 of the maximum score of 100 (σ= 8.5), the Function Knee Society Score was 70 of 100 (σ= 34.6). In the case of the Harris Hip Score in patients after the hip replacement, the mean hip function score was 89.8 of the maximum of 100 (σ= 7.3). The patients with knee and hip joint endoprosthesis after the performed DAIR procedure were satisfied on average to the level of 82.5% and 90%, respectively, while 28.6% of patients experienced certain functional decline during daily activities. Postoperatively, 25% of patients reported continuing stronger pain as compared to the past medical history. No patient experienced any change in terms of a limited range of motion or decreased joint stability. DISCUSSION The overall success rate of the DAIR procedure of 61.1% corresponds with the values stated in the literature. A significantly higher success rate was achieved in early postoperative complications. This can be explained by a lower specificity in determining the actual pathogenesis of late periprosthetic infections and potentially longer lasting colonisation of endoprosthesis. The medical history of previous surgeries performed on the affected joints for septic arthritis or with a surgical instrument retention was identified as an important risk factor of failure of the subsequently performed DAIR procedure. Significant effects of pathogenicity of the detected agent or systemic comorbidities on the success rate of the procedure were not confirmed in our group. Successful performance of the DAIR procedure results in maintaining a very good function of endoprosthesis as well as subjective satisfaction of patients. CONCLUSIONS The DAIR technique is an ideal solution in correctly and early diagnosed acute periprosthetic infections. The results suggest that it is particularly appropriate in early postoperative infections of primary total joint replacements. Its indication in late periprosthetic infections, especially of repeatedly operated joints, shall be carefully considered. Key wordsacute periprosthetic joint infections, PJI, DAIR, implant retention, risk factors, success rate.