Medial soft-tissue release for a lateralizing calcaneal osteotomy - a cadaveric study

K.K. Dash, I. Stavrakakis, K. Shah

Introduction: A lateralizing calcaneal osteotomy (LCO) for pes cavus is generally regarded to be harder to shift than a medializing calcaneal osteotomy for pes planus. LCO can also cause a significant reduction of tarsal tunnel volume and some surgeons recommend releasing the tarsal tunnel routinely.

Aim: Determine all the structures which restrain a lateral shift in lateralising calcaneal osteotomies using a cadaveric study.

Method: Permissions were obtained to dissect 8 embalmed below-knee cadavers. LCO was performed on 4 cadavers using a standard lateral approach, and the lateral shift was measured before and after the release of tarsal tunnel. However, our approach changed due to our findings after the first 4 cadavers.

Results: We found no significant change in lateral shift before and after tarsal tunnel release. We performed further dissection around the osteotomy and found the Abductor hallucis muscle to be the main restraint to a lateral shift. We changed the method in the subsequent 4 cadavers to LCO with abductor hallucis fascia and plantar fascia release, instead of tarsal tunnel release. By releasing the fascia over Abductor hallucis muscle as well as the plantar fascia, it was possible to increase the lateral shift in LCO by at least another 5mm on average.

Discussion: Limitation of lateral shift with LCO is generally considered to be due to tight soft-tissues in pes cavus, and several variations of LCO are practiced to overcome this limitation. However, no attempt has been made so far to identify any particular structure contributing to the limitation of lateral shift.

Conclusion: Our study suggests that the Abductor hallucis muscle the main structure limiting lateral shift in LCO, and release of the fascia over the abductor hallucis as well as the plantar fascia should be an essential part of the lateralizing calcaneal osteotomy.