Rate of fibular non-union in patients with tibial shaft fractures: a retrospective cohort study

PURPOSE: Fibular non-union occurs at an unknown rate in patients with tibial shaft fractures. The purpose of this study was to assess the rate of fibular non-union in patients with tibial shaft fractures. We also assessed if any factors are associated with the rate of fibular non-union. METHODS: This was an Institutional Review Board (IRB) approved retrospective cohort study performed at a level one trauma center. We reviewed the collected data on 400 patients that had fibular fractures with associated tibial shaft fractures from June 2012 to June 2021. To meet the inclusion criteria for this study, patients 16 years and older needed a minimum of three months of follow-up and sustained fibular fractures with associated tibial shaft fractures fix with an intramedullary rod. The standard and modified radiographic union scale in tibia (RUST and mRUST) fractures score of 8 was used as the parameter to determine fibular union. RESULTS: The rate of fibular non-union was 21% (84/400). Distal 1/3 fibular fractures had a higher non-union rate (25%, 46/179) than proximal and middle 1/3 fractures (12%, 10/83; 20%, 28/138 respectively) (p = 0.036). Patients that had fibular fixation went on to form a non-union at a rate of 25% (31/121) and patients that did not have fibular fixation went on to form non-union at a rate of 19% (52/279) (p = 0.114). Of the patients that did have fibular fixation, those fixed with intramedullary flexible nail (IMFN) or screw are less likely to form a non-union than those fixed with plates (p = 0.049). CONCLUSION: This study identified the rate of fibular non-union in patients with associated tibial shaft fractures treated with an intramedullary rod. We also identified that there is an increased risk of non-union when there is fibular fixation with plates and screws versus IMFN. We do not know the clinical implications of this, but it may be a source of pain in patients with healed tibia shaft fractures therefore we believe a prospective randomized controlled study may be warranted.