Effect of one versus two distal locking bolts on the biomechanics of tibial interlocking nail: a comparative study using a new model.

OBJECTIVE: To investigate the impact of one versus two distal locking bolts on the mechanical properties of tibial interlocking intramedullary nails. METHODS: Twenty 9-mm titanium alloy locking nails were divided into two equal groups in which the nails were fixed with only one and two distal locking bolts, respectively. Each group was further divided into two sub-groups for compression and torsion tests separately using a universal material-testing machine. RESULTS: In the compression tests, the average maximum strength of double bolts was greater than that of the single bolt (P<0.05), but the number of the bolts did not significantly affect the results of the torsion tests in terms of the either the maximum torsion moment or angle (P>0.05). CONCLUSION: One distal bolt is sufficient for fixing stable fractures and double bolts are recommended for management of serious fractures. The model we used is convenient and economic for examining the biomechanics of the tibial nails, especially for comparative purposes.