Outcomes of free flaps in patients with diabetes mellitus and open lower limb fractures: a retrospective cohort study

INTRODUCTION: High-energy open fractures are complex orthoplastic problems. Limb salvage surgical goals include achieving bony stabilisation and adequate soft tissue coverage, while minimising bone and soft tissue complications. Soft tissue coverage often requires free flap coverage due to thin overlying native soft tissue. Successful free flaps depend on multiple factors, including diabetes mellitus (DM), a prevalent modifiable disease in Singapore that represents a unique host factor. The objective of the study was to elucidate the effect of DM on the outcomes of free flaps done for open lower limb fractures. The primary outcome was the presence of partial or complete flap failure. Secondary outcomes included length of stay, osteomyelitis (OM) status, vascular intervention and requirement of bone reconstruction. METHODS: A retrospective cohort study was performed in patients with open lower limb fractures requiring free flap coverage over a 3-year period from March 2018 to December 2021 in Khoo Teck Puat Hospital, Singapore. Relevant parameters were obtained from the hospital's electronic medical records for statistical analyses to investigate primary and secondary outcomes. RESULTS: We obtained statistically significant data showing that the rates of flap failure (P < 0.01) and postoperative free flap complications (P < 0.05) were higher in diabetic patients. Statistically significant correlations were observed between DM and rates of OM, vascular interventions and requirement of bone reconstruction (P < 0.05), while increased length of stay was not statistically significant (P > 0.05). CONCLUSION: Patients with DM have statistically significant increased rates of flap failure and surgical complications. Holistic multidisciplinary perioperative optimisation of DM can potentially improve surgical outcomes.