Histopathological Analysis from Proximal Bone Samples During Minor Amputations for Diabetes-related Foot Infections: A Single-center, Retrospective Study.

Abstract

Minor amputations, defined as resection of bone below the ankle, are important procedures for managing diabetes-related foot infections (DFI). The optimal method to determine the presence of residual bone infection is unclear and unplanned reoperation rates are common. Although international guidelines endorse the use of histopathology, this approach has not been universally adopted. We evaluated the utility of histopathological analysis from samples collected from 'proximal' or 'marginal' bone during minor amputations. A retrospective, single-center study was conducted at Sir Charles Gairdner Hospital, in Perth, Western Australia. The primary outcome of interest was treatment success at six months, defined as being alive and no unplanned reoperation at the original operation site. Of 67 cases, 22 (33%) had positive histopathology. Patients with positive margins were less likely to have treatment success compared to those with negative margins (50% versus 82%; P=0.006). Antibiotic duration was significantly shorter in patients with negative histopathological margins compared to patients with positive histopathological margins (median 14 vs 42 days; P=0.0003). The concordance between histopathology and microbiology was 51%. Positive histopathology was associated with lower rates of treatment success, despite receiving longer antibiotic durations. Positive culture from the same samples were not predictive of outcome. Larger, prospective studies are needed to define optimal sampling methods and antibiotic therapy following minor amputation.