足と足首の臨床研究

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Total Ankle Replacement with a Staged Correction of a 20 Degree Post Traumatic Ankle Valgus and Medial Ankle Instability

Lawrence A DiDomenico and Danielle N Butto

Total ankle replacement can be a challenging surgery especially when pre-operative deformity exists. Most authors advocate the indication for total ankle replacement should be narrowed to patients with less than 10 to 15 degrees of pre-operative varus or valgus. When greater than 10-15 degrees of coronal plane malalignment is found, ancillary procedures must be performed. We report a case of a 56 year old male with 20 degrees of pre-operative ankle valgus after a pronation-external rotation injury that was malreduced at an outside institution. In addition to the valgus, the patient presented with medial ankle instability, distal lateral tibial osteonecrosis and a shortened, posteriorly rotated fibula. Staged procedures were employed to successfully realign the patient’s ankle joint. The patient was first brought to the operating room and stressed under c-arm fluoroscopy. He was found to have instability of the deltoid complex. He subsequently underwent an ankle arthrotomy, synevectomy and deltoid imbrication to re-establish medial ankle stability. Second, the patient underwent a fibular lengthening and derotation, syndesmotic fusion and medial opening wedge tibial osteotomy. Once consolidation was confirmed by CAT scan, the patient had a gastrocnemius lengthening total ankle arthroplasty with a Zimmer trabecular metal implant (Zimmer Inc®, Warsaw, IN) and debridement and grafting of the distal lateral tibial osteonecrosis. The patient is now greater than 24 months post operatively and able to ambulate pain free without assistive devices.