Ankle-Preserving Surgery for Ankle Instability After Triple Arthrodesis: A Case Report.

This report describes a case in which ankle-preserving surgery was performed for secondary ankle instability with good results in a patient with residual deformity after triple arthrodesis. A 42-year-old woman had undergone triple arthrodesis at the age of 16 years to correct a club foot deformity that had caused paralysis of the lower extremities. However, her left ankle instability worsened over time. Eventually, she visited our hospital, where she was found to have ankle instability and club foot. The ankle joint appeared to have a ball-and-socket shape, and plain radiographs showed a talus varus. The cause of the instability was varus deformity of the calcaneus in the standing position, which remained after the previous surgery. We performed a distal tibial oblique osteotomy and lateral displacement calcaneal osteotomy to improve ankle eversion. She could mobilize soon after surgery, reaching full load capacity at 12 weeks. After two years, her range of motion at the ankle and load-bearing stability were maintained, significantly improving her walking endurance. Triple arthrodesis is a common treatment for conditions associated with paralysis of the lower extremities. However, persistent malalignment can lead to prolonged ankle instability and deformity, prompting a need for additional procedures such as Dwyer surgery and ankle arthrodesis. In this case, although ankle joint instability was present, the range of motion was maintained without worsening arthropathy. Therefore, joint-preserving surgery was chosen. Notably, a literature search did not reveal any similar cases. Surgery to correct joint morphology in a patient with ankle instability improved ground contact and avoided varus deformity, resulting in positive outcomes.