Hip arthroplasty needs to be performed in an emergency setting after intracapsular femur neck fracture, whereas pain makes preoperative skin preparation of the limb difficult and it may therefore be incomplete. To date no study has analyzed the patient's skin bacteriological status in these surgical conditions.

The skin's bacterial flora is quantitatively and qualitatively different in the trauma context compared to an elective scheduled arthroplasty for chronic hip disease.

Two groups of patients, undergoing hip arthroplasty and having the same preparation at the time of surgery but different skin preparation procedures the day before and the day of surgery, were prospectively compared: 30 patients operated on in an emergency setting for fracture (group A) had no skin preparation and 32 patients operated on in scheduled surgery (group B). Group A had no skin disinfection before going into surgery, whereas group B followed a predefined protocol the day before surgery. Skin samples were taken on gelose at three different stages of skin preparation at the time of surgery (before and after detersive cleaning, and at the end of the surgery) and on two sites (inguinal and greater trochanter). The bacteriological analysis took place after 48hours of incubation.

Before detersive cleaning, group A had 3.6times more bacteria than group B in the trochanter region and 2.7times more in the inguinal area. After detersive cleaning, the contamination rate in the trochanter area was similar in both groups (group A: 10%; group B: 12.5%), but different in the inguinal region (group A: 33%; group B: 3%; P=0.002). At the end of the surgery, no difference was identified. Coagulase-negative Staphylococcus and Bacillus cereus accounted for 44% and 37%, respectively, of the bacteria isolated. In addition, the frequency of pathogenic non-saprotrophic bacteria was higher in group A (38%) compared to group B (6%). At a mean follow-up of 9.7months (range: 8–11months), no infection of the surgical site was identified.

The dermal flora is more abundant and different when the patient is managed in an emergency context. Although effective in the trochanter area, cutaneous detersive cleaning in the operating room is insufficient in the inguinal area and the frequency of pathogenic bacteria warrants identical rigor in preoperative preparation in all situations.

III. Prospective case – control study.