Proximity and Risks of the Anterior Neurovascular and Tendinous Anatomy of the Distal Leg Relative to Anteriorly Applied Distal Locking Screws for Tibia Nailing: A Plea for Open Insertion.

PURPOSE: To determine the proximity and potential risks to distal leg anatomy from anterior to posterior (A-P) applied distal tibia locking screws for tibial nailing.

DESIGN

Retrospective.

SETTING

ACS level I trauma center.

PATIENTS/

PARTICIPANTS

Twenty consecutive adult patients undergoing computed tomograms with intravenous contrast (computed tomography angiograms) on uninjured legs.

MAIN OUTCOME MEASUREMENTS: Simulated 5-mm distal interlocking screws placed in the A-P axis of an ideally placed tibial nail at 10-mm increments from the tibial plafond (10-40 mm) were studied in relation to the distal leg's anterior anatomy.

RESULTS

All A-P screws (80/80, 100%) impacted the tibialis anterior tendon, extensor hallucis longus tendon, and/or anterior tibial neurovascular (NV) bundle between 10 and 40 mm cranial to the plafond. The NV bundle was impacted in 53% of cases. The medial extent of the tibialis anterior tendon was greatest 10 mm cranial to the plafond and averaged 27 degrees (95% confidence interval, 22-33 degrees) medial to the A-P line. The maximum lateral border of the foot's common extensors, found 40 mm cranial to the plafond, averaged 71 degrees (95% confidence interval, 62-80 degrees) lateral to the A-P line.

DISCUSSION: The anterior tibial NV bundle and foot and ankle extensor tendons are at high risk from A-P-directed distal locking screws. The tendinous anatomy of the distal leg is at risk between 33 degrees medial and 80 degrees lateral to the A-P axis of a tibial nail. Distal locking screws placed from the A-P direction should be thoughtfully applied and an open approach should be strongly considered.