Utility of Culturing Marginal Bone in Patients Undergoing Lower Limb Amputation for Infection.

Guidelines suggest culturing clinically uninfected bone at the margin after surgical resection for osteomyelitis, but little published evidence supports this procedure. To investigate whether culturing marginal bone after completing resection of infected bone affected antibiotic use or further surgical intervention, we collected data on sequential patients undergoing amputation for a foot infection at our tertiary care hospital between January 2014 and May 2015. We recorded patient age, sex, presence of diabetes mellitus, level of amputation, whether marginal bone was sent for culture, microbiology of any marginal bone specimens, type and duration of antibiotic therapy, and any further surgical resection. Among 132 patients, the mean age was 71.9 years, 103 (78.0%) were male, and 79 (59.8%) had diabetes. Treating surgeons sent marginal bone in 58 (43.9%) of these patients, 50 (86.2%) of which were culture positive. Patients with a positive bone culture were significantly more likely to undergo further surgical intervention (20.0% vs 6.1%, p = .047). For patients with diabetes, compared with those without, surgeons did not send marginal bone for culture more often (46% vs 42%, p = .72), nor did they undertake further surgical interventions more frequently (13.4% vs 10.1%, p = .89). Our results suggest that the clinicians used the marginal bone culture findings to make clinical decisions but do not clarify if there is a benefit to performing this procedure. Although patients whose proximal bone specimens were culture positive were more likely to undergo a surgical intervention, the reasons for, and benefit of, this additional surgery were unclear.