Evaluation of a novel semicircular locking external fixator for treating fractures of long bones: Biomechanical comparison with a circular external fixator

Purpose: This study aimed to investigate the biomechanical properties of a novel semicircular locking external fixator with locking screw mechanism, shape of trapezoidal corrugations, half- ring designed for greater stability. Materials and methods: The novel external fixator had a half-ring with the shape of trapezoidal corrugations and locking screws fixing the bone at different angles in all three planes (sagittal, axial, and coronal). The biomechanical properties of the semicircular locking external fixator (group 1) were compared with those of a standard Ilizarov-type circular external fixator (group 2) (TST, İstanbul, Turkey) in an experimental study design. Five frames were used in each group. Standard PE 1000 (polyethylene) rod models (n = 10) simulating the tibia bone model were used. Both systems were compared biomechanically by applying axial and torsional loads simultaneously. Result: Two samples in group 2 were damaged before the test ended during axial loading. All of the samples in group 1 completed the tests without damage after 150,000 cycles. The axial stiffness of the semicircular locking external fixator was found to be significantly higher than that of the Ilizarov-type circular external fixator (p < 0.05). No statistically significant difference was found between the two fixators in torsional loading. The application time of semicircular locking external fixator was significantly shorter than Ilizarov-type circular external fixator (p < 0.05). Conclusion: The novel semicircular locking external fixator was biomechanically stronger than the Ilizarov-type external fixator for treating fractures of long bones. It can be used as a permanent external fixator for the definitive treatment of long bone fractures with soft tissue damage in terms of stability and application time.