To compare the relative risks of neurovascular injury from perforation during distal interlocking and the biomechanical stability of two approaches to distal interlocking of tibial nails.

In vitro anatomical and biomechanical study.

All mechanical testing was performed in a servohydraulic test frame with a customized motion transducer.

Tibial nails were interlocked distally with a medial-to-lateral (ML) or a lateral-to-medial (LM) approach.

The distances from the nearest end of each distal locking screw to four neurovascular structures were measured manually with calipers, and two-dimensional motion under simulated stance load across the fracture site was recorded.

There were greater distances from the posterior tibial neurovascular bundle and the superficial peroneal nerve with distal targeting from the LM direction compared with targeting from the ML direction. Biomechanically, the ML nail configuration demonstrated slightly greater resistance to bending than the LM configuration.

Distal tibial interlocking from the LM direction appears to be safer than interlocking from the ML direction with regard to relative distances from the neurovascular structures. This small anatomical advantage must be considered in light of slightly greater resistance to bending of the ML interlocking configuration compared with the LM interlocking configuration.