Indolent infection in nonunion of the distal femur.

In the treatment of nonunions of the distal femur, infection should be excluded. However, it is difficult to determine whether the nonunion is infected or not with negative history and signs of infection. The purpose of this study was to investigate indolent infection as a cause of presumptive aseptic distal femur nonunion. All presumptive aseptic distal femur nonunions treated from 1998 to 2008 were retrospectively reviewed. Any patient with suspected of having an infection clinically was excluded. Multiple tissue cultures were performed at the nonunion site. The main outcomes were to analyze the rate of positive cultures in presumptive aseptic distal femur nonunion and to compare the rate of secondary surgery in positive and negative culture groups. Of the 22 patients, 3 (13.6%) had positive culture results. The organisms cultured were Staphylococcus aureus, Staphylococcus epidermidis, and Enterobacter cloacae. The overall rate of infection was 9.1% (2/22), and one patient underwent a secondary procedure. In the open fracture group, 2 of 10 patients (20%) had positive cultures; all developed infection. In the closed fracture group, 1 of 12 patients (8.3%) had positive culture results, but Infection did not occur in the patient with a 3-week intravenous antibiotic treatment. The postoperative infection rate was 67% (2/3) in patients with positive intraoperative cultures, while 0% (0/18) in the group with negative intraoperative cultures (p<0.001). The presence of indolent infection can be verified in patients with presumptive aseptic nonunion of distal femoral fractures by obtaining intraoperative biopsy tissue cultures. Positive intraoperative culture results were related with postoperative infection.