Accuracy of intraoperative cultures in primary total hip arthroplasty.

The aim of this investigation was to assess the diagnostic accuracy of intraoperative cultures for the early identification of patients who are at risk of infection after primary total hip arthroplasty.Four or six swabs were obtained immediately before the wound closure in 263 primary total hip replacements. Patients with a maximum of one positive culture were denoted as patients with a normal profile and did not receive any treatment. Patients with two or more positive cultures, with the same organism identified, were denoted as patients with a risk profile and received treatment with a specific antibiotic as determined by the antibiogram for six weeks. The follow-up ranged from a minimum of one year to five years and eleven months, concentrating on the presence or absence of infection, which was defined as discharge of pus through the surgical wound or as a fistula at any time after surgery. The accuracy of this procedure (number of cases correctly identified in relation to the total number of cases) in the group of 152 arthroplasties in which 4 swabs per patient were collected was 96%. In the group of 111 arthroplasties in which 6 swabs per patient were collected the accuracy was 95.5%.We conclude that the collection of swabs under the conditions described is a method of high accuracy (above 95%) for the evaluation of risk of infection after primary total hip arthroplasty.