The effect of residual osteomyelitis at the resection margin in patients with surgically treated diabetic foot infection.

The appropriate antibiotic treatment of surgically resected diabetic foot osteomyelitis is controversial. We conducted a retrospective cohort study to evaluate the prognostic impact of residual osteomyelitis at the surgical margin of surgically resected diabetic foot osteomyelitis, and to assess the effectiveness of postoperative antibiotic therapy for residual osteomyelitis after surgical resection of infected bone. Of the 111 patients included in the study, 39 (35.14%) had pathologically confirmed margins positive for residual osteomyelitis. The median total duration of antibiotic treatment was 19 (range 10-134) days in patients with positive margins, whereas it was 14 (range 2-63) days in those with negative margins (P = .01). No statistically significant difference (P = .695) was found in the primary outcome of definite failure, defined as pathologically or microbiologically confirmed infection relapse at the proximal amputation site, between 3 (7.69%) of 39 patients with positive margins and 4 (5.56%) of 47 patients with negative margins. A statistically significant difference (P = .001) in the secondary outcome, definite treatment failure, or the need for more proximal amputation was found between 17 (43.59%) of 39 patients with positive margins and 11 (15.28%) of 72 patients with negative margins. Residual osteomyelitis at the pathologic margin was associated with a higher rate of treatment failure, despite the longer duration of antibiotic therapy.