Treatment of Varus Ankle Osteoarthritis and Instability With a Novel Mortise-Plasty Osteotomy Procedure.

Although joint-preserving surgery for intermediate ankle osteoarthritis has been reported to be effective, failures of supramalleolar osteotomy and plafond-plasty can occur because of persistent malalignment of the distal tibia and incongruent ankle mortise. We introduce a novel opening wedge distal tibial osteotomy procedure (mortise-plasty) with rigid plate fixation combined with synthetic bone wedges. We performed 27 mortise-plasties in 25 patients with varus ankle osteoarthritis and instability. Six males (24%) and 19 females (76%), with a mean age of 63 (range 28 to 79) years, were followed up for a mean of 27.3 (range 14 to 45) months. The mean preoperative visual analog scale score, American Orthopaedic Foot and Ankle Society score, and Takakura ankle scale score were 7.4 (range 5.4 to 10), 58.7 (range 18 to 84), and 55.9 (range 29 to 88), respectively. These scores improved significantly to 2.1 (range 0 to 6.5), 89.3 (range 67 to 100), and 84.7 (range 55 to 100) postoperatively (p < .001). The mean preoperative tibial-anterior surface angle and talar tilt angle were 84.9° (range 78° to 90°) and 8.3° (range 3° to 21°), respectively. At the most recent follow-up visit, the corresponding values were 95.0° (range 82° to 99°) and 1.8° (range 0° to 8°), respectively (p < .001). Computed tomography scans indicated that the ankle mortise narrowed by approximately 1.8 mm and the tibial plafond was lowered after osteotomy. No patients underwent lateral ligament reconstruction, ankle joint replacement, or arthrodesis. Mortise-plasty osteotomy corrects the intra-articular and extra-articular deformities simultaneously and provides good clinical and radiographic outcomes for patients with varus ankle osteoarthritis and instability.