The relevance of the number of distal locking planes and nail to canal ratio in bone healing after intramedullary nailing in tibial shaft fractures.

Introduction: The objective of this retrospective study was to assess the effect of the nail to canal ratio and the number and configuration of distal locking screws in bone healing in tibial shaft fractures.

Methods: We analyzed 223 consecutive tibial shaft fractures treated with reamed intramedullary nailing between January 2014 and December 2020. We recorded and evaluated the nail to canal ratio (NCR) and the number and configuration of distal locking screws. Median NCR was 0.87 (IQR 0.82-0.94). Ten (4.48%) fractures were treated with one distal locking screw, 173 (77.57%) with two, and 40 (17.93%) with three. Uniplanar fixation was used in 63 (28.25%), biplanar in 150 (67.26%), and triplanar in 10 (4.48%) cases. Uni-, bi-, and multivariate analyses were performed to compare patients who achieved bone union with those who did not.

Results: Bone union was achieved in 195 (87.44%) patients. Uni- and bivariate analyses showed that bone union increased significantly with larger NCR (p = 0.0001) and a greater number of locking planes (p = 0.001) and distal screws (p = 0.046). NCR > 0.78 (OR 48.77 CI 95% 15.39-154.56; p =  < 0.0001) and distal locking screw configuration (OR 2.91 CI 95% 1.12-9.91; p = 0.046) were identified as independent variables for union.

Conclusion: Our findings suggest that in tibial shaft fractures treated with intramedullary nailing, NCR should be equal to or greater than 0.79. Additionally, distal locking screws should be used with a biplanar or triplanar configuration.