Lateral and medial plantar pressures after split versus whole anterior tibialis tendon transfer

If whole and split transfer of the anterior tibialis tendon (SPLATT) do not differ in balancing the forefoot, whole tendon transfer would provide a simpler alternative as part of treatment of an equinovarus deformity. We hypothesized that no significant differences in percent plantar lateral forefoot pressures would be observed between split and whole tendon transfer. We used a spastic model to test the hypothesis that overcorrection would not occur with whole tendon transfer.

In ten specimens from five lower extremity matched pairs, a SPLATT was anchored to the cuboid. After loading, simulated whole tendon transfer to the lateral cuneiform was done. Normal loading was Achilles, 250 N, tibialis anterior, 200 N, peroneals/tibialis posterior, 142 N; and spastic loading was Achilles, 500 N, tibialis anterior, 400 N, peroneals/tibialis posterior, 142 N. Pressure data were collected for both normal and spastic conditions. Percent of forefoot pressure was calculated for the lateral and medial sector.

Percent lateral pressure was slightly lower after whole tendon transfer (normal, p < 0.01; spastic, p < 0.01). This difference was not clinically important. Medial pressure did not differ in the spastic versus the normal model after split or whole tendon transfer.

Whole and split anterior tibialis tendon transfer both resulted in a balanced forefoot. Neither whole tendon nor split tendon transfer resulted in overcorrection in a simulated spastic model.

Whole tendon transfer may be an effective and simpler alternative to SPLATT for unloading the lateral forefoot in both a normal and a spastic foot.