Soft Tissue Structures at Risk With a Percutaneous Focal Dome Osteotomy: A Cadaver Study

The focal dome osteotomy allows deformity correction through frontal plane rotation, and if needed, anterior or posterior translation. This percutaneous technique allows extracapsular ankle realignment with minimal soft tissue dissection. While circumventing a standard anterior incision, this technique encounters soft tissue structures that must be considered. Focal dome osteotomies were simulated on 10 fresh-frozen below the knee cadavers. Centered proximal to the tibial plafond at the physeal scar, a radial arm using a 4-hole Rancho cube was used to map the dome. Medial, lateral, and central incisions were made to allow access for drilling and measured to nearby anatomic structures. Among 10 cadavers, the age and weight were 70 ± 7.96 years and 134.7 ± 30.8 pounds, respectively. In all cadavers, the hole below the most proximal posthole provided the ideal position for the creation of the osteotomy. The medial and central incisions were closest to the tibialis anterior tendon measuring 3.37 ± 2.48 mm and 0.43 ± 0.9 mm, respectively. The lateral incision and half-pin used to create the distal axis of rotation were closest to the extensor hallucis longus tendon, measuring 1.97 ± 1.92 mm and 1.27 ± 1.5 mm, respectively. Drilling the second hole from the top on a 4-hole Rancho cube, forming a 2.50 cm radial arm, created the ideal osteotomy arc. Though neurovascular structures were further away from respective incision and half-pin sites compared to tendons, in several specimens, anatomic variations held them closer, warranting preoperative handheld Doppler and mapping. Care should be taken to protect anterior ankle anatomy during dissection, drilling, and completing the osteotomy.