Sustentaculum Tali Tunnel Placement for Tibiospring Ligament Reconstruction Augmented With Graft Material: Cadaveric Study

Progressive collapsing flatfoot deformities (PCFD) are commonly the result of the impairment of medial hindfoot soft tissue structures including the posterior tibial tendon, deltoid, and spring ligament. These deformities have been treated surgically via calcaneal osteotomies and tendon transfers; only recently has soft tissue reconstruction gained momentum. Advancements have now made available graft materials to help augment and stabilize ligament repairs to further improve results. Medial hindfoot ligament reconstruction procedures require surgeon familiarity with soft tissue and osseocartilaginous structures. We assessed 20 cadaveric specimens after a simulated medial hindfoot ligament reconstruction procedure focusing on the sustentaculum bone tunnel. Post-procedure anatomic and radiographic observations carefully detailed any damage to anatomic structures. The sustentaculum tunnel guidewire at the lateral calcaneal cortex was documented, including angular position in relation to the subtalar joint. We determined that the posterior-inferior aspect of the lateral calcaneal surface serves as the ideal target region for the placement of the guidewire and subsequent tunnel drilling. Complications increased when drilling tunnels at 7 mm in diameter. The results provide insight for medial-to-lateral drilling of the calcaneus when performing tunneling techniques and can be used to help optimize surgical results when for deltoid/spring ligament repair augmented with graft materials.<b>Level of Evidence:</b> Level V.