Neurovascular and tendinous damage with placement of anteroposterior distal locking bolts in the tibia

Objective: To determine the proximity of anteroposterior locking bolts inserted into the distal metaphyseal tibia to nearby neural, vascular, and tendinous structures. Design: A cadaver study. Setting: University trauma center. Methods: Sixteen legs (8 matched pairs) were nailed in either neutral (Group 1) or 10° of internal rotation (Group 2) and locked using one anteroposterior bolt. The anterior tibial and extensor hallucis longus tendons and neurovascular bundle were identified, and their respective locations in relation to the bolt head were measured. Average distances were calculated for each structure in each group and statistically compared. Damage to any structure was noted at final dissection. Results: Average distances from the bolt head to the neurovascular bundle, extensor hallucis longus, and anterior tibial tendons were 0.6, 0.5, and 1.6 mm, respectively, for Group 1 and 1.0, 1.5, and 1.8 mm, respectively, for Group 2 legs. Statistical comparison of distances for each anatomic entity for the two groups revealed no detectable significant differences (P = 0.7, 0.4, 0.7, respectively). For all specimens, the rate of nerve, artery, extensor hallucis longus, and anterior tibial tendon injury was 25%, 19%, 0%, and 6%, respectively. However, the incidence of at least one structure damage in Group 1 legs was 63% versus 12% in Group 2 specimens (P = 0.2). Conclusion: Anteroposterior distal tibial locking bolts lie in close proximity to the neurovascular bundle. With standard percutaneous techniques, these structures can be damaged. Although 10° of internal rotation does not statistically affect the measured distance of the locking bolt to the neurovascular bundle, it appears to decrease the incidence of neurovascular injury. This difference may best be explained by the necessary path the drill bit must take through the soft tissues to reach the underlying bone. Regardless of nail orientation, larger incisions with careful dissection and clear visualization of the anatomy are recommended to help prevent this complication.