DOS 2018

DOS Kongressen 2018 · 203 Unexpected positive cultures in total hip arthroplasty revision increases re-revision risk: A national register study Nikolaj Milandt, Per Hviid Gundtoft, Søren Overgaard The Orthopaedic Research Unit, Odense University Hospital, Denmark; Department of Orthopaedic Surgery and Traumatology, Lillebaelt Hospital, Kolding, Denmark; Department of Orthopaedic Surgery and Traumatology, Odense University Hospital, Denmark Background: The diagnostic and prognostic value of unexpected positive intra- operative cultures remains unclear in diagnosing prosthetic joint infection (PJI) in total hip arthroplasty (THA) revisions. Purpose / Aim of Study: To study whether first-time aseptic revision of THA with unexpected bacterial growth in cultures of intraoperatively obtained biop- sies has increased risk for re-revision due to all causes and due to PJI. Materials and Methods: Cases reported to the Danish Hip Arthroplasty Register (DHR) as first-time aseptic loosening revisions performed during 2010 to 2016, were included. DHR data were merged with that of the Danish Microbiology Database, which contains data from all intraoperatively obtained cultures in Denmark. Revisions were grouped based on the number of unex- pected positive cultures growing the same bacterial genus: ≥2, 1, and 0 cul- tures. Positive cultures in presumed aseptic revision cases were defined as un- expected. The revisions were followed until re-revision, death, or end of the 1-year follow- up period. The relative risk for re-revision due to all causes and PJI was estimated. Findings / Results: We included 2,305 first-time aseptic revisions. Unexpected growth was found in 282 cases (12%), of which 170 (60%) grew the same bacteria in only 1 culture. Coagulase-negative staphylococcus accounted for 121 cases (71%). Re-revision was performed in 163 cases (7%), with PJI being the indication for revision in 43 cases (26%). The relative risk of re-revision was significantly higher for cases with 1 positive culture growing the same bacteria compared to culture-negative cases with both all-cause revision: 1.73 (95% CI 1.07; 2.80) and PJI revision: 2.63 (95% CI 1.16; 5.96). Conclusions: First-time aseptic THA revisions with unexpected growth in only 1 biopsy culture had an increased risk for re-revision, due to both all causes and PJI. 144.