Fracture-Related Infection Following Severe Open Lower Limb Fracture: Experience From a Linked Major Trauma Centre and Quaternary Bone Infection Unit

Introduction & Aim Open lower limb fractures are associated with a high risk of fracture-related infection (FRI). Timely bony fixation and soft tissue reconstruction using an orthoplastic approach may mitigate FRI risk. This study evaluated infection-related outcomes of these injuries at a Major Trauma Centre (MTC), with a focus on initial injury management and further management within the linked Bone Infection Unit (BIU). Methods A single-centre cohort study was conducted of adults with severe open tibial and/or fibular fractures, defined as those with a soft tissue defect requiring plastic surgical reconstruction with a flap or skin graft (April 2021–May 2025). Open fractures treated by fixation and direct closure were not included. Data included demographics, comorbidities, injury characteristics and operative details. The primary outcome was FRI, defined according to the international consensus definition; flap failure, BIU referral, secondary amputation and mortality were also reported. Logistic regression was used to explore factors associated with FRI and mortality. BOAST4 guideline compliance was evaluated as part of the fifth audit cycle in our unit. Results Among 150 patients, 99 (66.0%) underwent free flap reconstruction, 34 (22.7%) underwent loco-regional flap reconstruction, and 17 (11.3%) had split-thickness skin grafting alone. Fractures involved the tibia in 41 (27.3%) patients, the fibula in 9 (6.0%), and both tibia and fibula in 100 (66.7%). Injuries were Gustilo-Anderson Grade IIIB in 66 (44.0%) patients, Grade IIIA in 21 (14.0%), Grade II in 20 (13.3%) and Grade IIIC in 3 (2.0%), and the grade was not recorded in 40. There were 9 free flap failures (9.1%) and 3 loco-regional flap failures (8.8%); 11 of these 12 were salvaged with a further free flap. Soft tissue coverage within 72 hours, in accordance with BOAST4 guidelines, was achieved in 106 patients (70.7%). Twenty-seven patients (18.0%) received care from the BIU following initial treatment at the MTC. Fourteen patients (9.3%) developed FRI, including 3 of 66 (4.5%) with Grade IIIB injuries, and all were treated surgically. Gram-negative organisms predominated, most frequently Enterobacter cloacae . Other indications for BIU referral included superficial infections requiring antibiotics alone, delayed wound healing without infection, or chronic pain. Three patients required amputation (2.0%). Longer time to definitive surgery and flap failure were associated with FRI, although event numbers were small and both associations likely reflect injury severity. FRI was associated with mortality (4/14, 28.6%, vs 4/136, 2.9%, without FRI). Follow-up ranged from 3 months to 5 years. Conclusions Management of severe open lower limb fractures guided by BOAST principles, using an orthoplastic approach from initial presentation to definitive fixation and soft tissue coverage, may mitigate FRI risk. FRI was uncommon but associated with increased mortality. Combined with access to a collaborative, multidisciplinary orthoplastic infection centre, this approach enables effective treatment of sequelae of these limb-threatening injuries, notably FRI.