Should distal interlocking of tibial nails be performed from a medial or alateral direction? Anatomical and biomechanical considerations

Objective: To compare the relative risks of neurovascular injury from perfo ration during distal interlocking and the biomechanical stability of two ap proaches to distal interlocking of tibial nails, Design: In vitro anatomical and biomechanical study. Setting: All mechanical testing was performed in a servohydraulic test fram e with a customized motion transducer. Intervention: Tibial nails were interlocked distally with a medial-to-later al (ML) or a lateral-to-medial (LM) approach. Main Outcome Measure: The distances from the nearest end of each distal loc king screw to four neurovascular structures were measured manually with cal ipers, and two-dimensional motion under simulated stance load across the fr acture site was recorded. Results: There were greater distances from the posterior tibial neurovascul ar bundle and the superficial peroneal nerve with distal targeting from the LM direction compared with targeting from the ML direction. Biomechanicall y, the ML nail configuration demonstrated slightly greater resistance to be nding than the LM configuration. Conclusions: Distal tibial interlocking from the LM direction appears to be safer than interlocking from the ML direction with regard to relative dist ances from the neurovascular structures. This small anatomical advantage mu st be considered in light of slight ly greater resistance to bending of the ML interlocking configuration compared with the LM interlocking configurat ion.