Constrained Total Talonavicular Replacement with Subtalar Arthrodesis for Spontaneous Osteonecrosis of the Navicular and Talus

This case involves a 35-year-old female who underwent a custom talonavicular replacement with subtalar fusion for spontaneous osteonecrosis of the navicular and talus. Preoperatively, she had an American Orthopedic Foot and Ankle Society (AOFAS) score of 42, a talocalcaneal height of 64.6 mm, and a talar declination angle of 23.6°. Imaging showed severe erosive changes in the talonavicular and anterior subtalar joints, with marrow edema throughout the navicular and anterior talus. The procedure involved removing the talus and navicular and replacing them with a titanium, nitride-coated talonavicular implant, secured by two 5.5-mm screws. One year postoperatively, her AOFAS score improved to 65, with a talar declination of 15.9° and a talocalcaneal height of 63.8 mm. She had an ankle range of motion with 12° dorsiflexion and 40° plantarflexion. Radiographs showed proper implant seating and no radiolucency. The patient expressed satisfaction with the outcome. This article aims to contribute to the literature on custom implants for severe deformities and pathologies on patients who wish to maintain motion within vital joints. In conclusion, it appears a custom-made talonavicular implant may be a viable solution for spontaneous osteonecrosis of the talus and navicular.