Introduction: Direct exchange of total hip arthroplasty as a single stage revision procedure for aseptic loosening represents a significant proportion of the revision surgeon’s case load, accounting for 38% of cases in the Sheffield Lower Limb Arthroplasty Unit. In our unit current practice is to obtain preoperative negative hip aspirates and normal inflammatory markers and take 5 intraoperative deep tissue samples for microbiological culture. The aim of this retrospective, observational study was to evaluate the necessity of this technique.

Method: 100 consecutive direct exchanges to total hip replacements for aseptic loosening performed in our unit between 03/10/2005 and 31/07/2007 were identified using the arthroplasty database and their case notes reviewed. The microbiological results were evaluated by a microbiology consultant and the notes were examined. A minimum of 1 year follow-up was obtained in all patients.

Results: 42 patients were found to have one or more positive sample. Of these 37 were deemed by the microbiologist to be contaminants and 5 to have a significant growth. Of the 5 with significant growth, 2 patients were treated with systemic antibiotics as a result of microbial tissue sample growth. At the latest follow up appointment (range 22–33 months) these 5 patients were all clinically not infected.

Conclusion: The practice of obtaining routine deep tissue samples is essential for revision surgery performed for aseptic loosening. 5% of patients in our series had a significant bacterial growth despite being presumed to be aseptic which would otherwise not have been detected. The support of a microbiologist with dedicated arthroplasty interest is vital in determining the relevance of sample results.