Is the stability of a tibial fracture influenced by the type of unilateral external fixator?

OBJECTIVE: To examine whether the type of unilateral external fixator significantly influences the stability of a tibial fracture. DESIGN: Inter-fragmentary displacements were measured during walking while the fractures were stabilized, first with one type of fixator then with another. BACKGROUND: It is commonly claimed that one type of fixator exerts a different influence on mechanical stability at a fracture in comparison with another. METHODS: This study compares inter-fragmentary displacement, fixator displacement and weight bearing during walking, in four patients stabilized with an Orthofix DAF, which was replaced by a Howmedica International Monotube. RESULTS: The null hypothesis of no difference in fixator performance was unproved (P < 0.05) through insufficient data. Interpatient variability in inter-fragmentary displacement implies that anthropometry, gait and fracture type may influence fracture stability more than the type of fixator. CONCLUSIONS: Since weight-bearing and displacements were not substantially different, no basis was found for the claim that one fixator provides a mechanical environment substantially different to another. Sample size was not large enough to prove that a small but statistically significant difference exists. RELEVANCE: The influence on fracture stability of one type of unilateral fixator in comparison with another appears to be less than the influence of anthropometry, gait and the type of fracture.