• Anthony Lim, Garance Biosse-Duplan, Alastair Gregory, Krishnaa T Mahbubani, Fergus Riche, Cecilia Brassett, and John Scott.
• Human Anatomy Teaching Group, Department of Physiology, Development and Neuroscience, University of Cambridge, CB2 3EL, UK. Electronic address: ajcl3@cam.ac.uk.
• Injury. 2022 Apr 1; 53 (4): 1532-1538.

BackgroundTibial shaft fractures are the commonest long bone fracture, with early weight-bearing improving the rate of bony union. However, an intact fibula can act as a strut that splints the tibial segments and holds them apart. A fibular osteotomy, in which a 2.5 cm length of fibula is removed, has been used to treat delayed and hypertrophic non-union by increasing axial tibial loading. However, there is no consensus on the optimal site for the partial fibulectomy.MethodsNine leg specimens were obtained from formalin-embalmed cadavers. Transverse mid-shaft tibial fractures were created using an oscillating saw. A rig was designed to compress the legs with an adjustable axial load and measure the force within the fracture site in order to ascertain load transmission through the tibia over a range of weights. After 2.5cm-long fibulectomies were performed at one of three levels on each specimen, load transmission through the tibia was re-assessed. A beam structure model of the intact leg was designed to explain the findings.ResultsWith an intact fibula, mean tibial loading at 34 kg was 15.52 ± 3.26 kg, increasing to 17.42 ± 4.13 kg after fibular osteotomy. This increase was only significant where the osteotomy was performed proximal to or at the level of the tibial fracture. Modelling midshaft tibial loading using the Euler-Bernoulli beam theory showed that 80.5% of the original force was transmitted through the tibia with an intact fibula, rising to 81.1% after a distal fibulectomy, and 100% with a proximal fibulectomy.ConclusionThis study describes a novel method of measuring axial tibial forces. We demonstrated that a fibular osteotomy increases axial tibial loading regardless of location, with the greatest increase after proximal fibular osteotomy. A contributing factor for this can be explained by a simple beam model. We therefore recommend a proximal fibular osteotomy when it is performed in the treatment of delayed and non-union of tibial midshaft fractures.Copyright © 2022 Elsevier Ltd. All rights reserved.

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