Correction of Ankle Varus Deformity using Patient Specific Dome Shaped Osteotomy Guides Designed on Weight Bearing CT

Abstract

Category:Ankle Arthritis; HindfootIntroduction/Purpose:Dome shaped supramalleolar osteotomies are a well-established treatment option for correcting ankle deformity. However, the procedure remains technically demanding and is limited by a two-dimensional (2-D) radiographic planning of a three-dimensional (3-D) deformity. Therefore, we implemented a weight-bearing CT-scan (WBCT) to plan a 3-D deformity correction using patient specific guides.Methods:A 3-D guided dome shaped supramalleolar osteotomy was performed to correct ankle varus deformity in a cohort of 5 patients with a mean age of 53,8 years (range: 47-58). WBCT images were obtained to generate 3-D models, which enabled a deformity correction using patient specific guides. These technical steps are outlined and associated with a retrospective analysis of the clinical outcome using the EFAS score, Foot and Ankle Outcome Score (FAOS) and Visual Analog Pain scale (VAS).Radiographic assessment was performed using the tibial anterior surface angle (TAS), tibiotalar angle (TTS), talar-tilt angle (TTA), hindfoot angle (HA), tibial lateral surface angle (TLS) and tibial rotation angle (TRA).Results:The mean follow-up was 40,8 months (range 8-65) and all patients showed improvements in the EFAS score, FAOS and VAS (p < 0.05). A 3-month postoperative WBCT confirmed healing of the osteotomy site and radiographic improvement of the TAS, TTS and HA (p<0.05), but the TTA and TRA did not change significantly (p>0.05).Conclusion:Dome shaped supramalleolar osteotomies using 3-D printed guides designed on WBCT, are a valuable option in correcting ankle varus deformity and mitigates the technical drawbacks of free-hand osteotomies.