Plantar structures in relation to a straight retrograde hind foot (RHF) nail inserted through a midline heel pad approach – a cadaveric study

S. Hussain, E.N. Cinar, M. Baid, A. Acharya

Background: RHF nail is an important tool for simultaneous ankle and subtalar joint stabilisation +/- fusion.  Straight and curved RHF nails are available to use, but both seem to endanger plantar structures, especially the lateral plantar artery and nerve and Baxter’s nerve. There is a paucity of literature on the structures at risk with a straight RHF nail inserted along a line bisecting the heel pad and the second toe (after Stephenson et al).  In this study, plantar structures ‘at risk’ were studied in relation to a straight nail inserted as above.

Methods: Re-creating real-life conditions and strictly following the recommended surgical technique with regards to the incision and guide-wire placement, we inserted an Orthosolutions Oxbridge nail into the tibia across the ankle and subtalar joints in 6 cadaveric specimens. Tissue flaps were then raised to expose the heel plantar structures and studied their relation to the inserted nail.

Results: The medial plantar artery and nerve were always more than 10mm away from the medial edge of the nail, while the Baxter nerve was a mean 14mm behind.  The lateral plantar nerve was a mean 7mm medial to the nail, while the artery was a mean 2.3mm away with macroscopic injury in one specimen.  The other structures ‘at risk’ were the plantar fascia and small foot muscles.

Conclusion: Lateral plantar artery and nerve are the most vulnerable structures during straight RHF nailing. The risk to heel plantar structures could be mitigated by making incisions longer, blunt dissection down to bone, meticulous retraction of soft tissues and placement of the protection sleeve down to bone to prevent the entrapment of plantar structures during guide-wire placement, reaming and nail insertion.