[Risk of deep infection in first-intention total hip replacement. Evaluation concerning a continuous series of 790 cases].

OBJECTIVE: Deep infections of the operative site is a rare but serious complication of first intention total hip arthroplasties. French data on infections are sparse. We studied the incidence, characteristics and potential risk factors for these infections in a consecutive series of 790 total hip arthroplasties performed as first intention implantations in a University Hospital in France.

PATIENTS AND METHODS: All patients undergoing first intention total hip arthroplasty surgery between November 1995 and May 1999 were included in this study. Demographic, clinical, therapeutic and surgical data were collected. Deep infection was defined as proven presence of microorganisms in at least two preoperative samples during revision surgery. Patients were followed for 1 month to 4 years. Potential risk factors were identified with univariate analysis. Chi square and exact Fisher test were used.

RESULTS: The overall incidence of deep infections was 1.11 per 100 implantations (95% CI 0.84-2.70). Delay to development ranged from 14 days to 32 months. Eleven infections were proven within the first year and 3 after one year. Two risk factors were identified: absence of systemic antibiotic prophylaxis (RR = 4.74, p = 0.03) and drainage discharge after 48 hours (RR = 3.62, p = 0.02). Other variables associated with infection with a relative risk greater than 2 were obesity, corticosteroid therapy, development of a hematoma, or difficult postoperative wound healing.

CONCLUSION: The incidence observed in this series is slightly higher than generally reported in the world literature. It would be important to write an antibiotic prophylaxis protocol with prescription of systemic antibiotics for all operated patients in order to reduce this incidence. Other measures that could improve the quality of care should also be taken: re-evaluation of preoperative skin preparation protocols, systematic screening of patients carrying Staphylococcus aureus before implantation and proper care for these patients.