Can the Contralateral Ankle be used for Preoperative Planning in Total Ankle Arthroplasty in the Posttraumatic Patient? A Prospective Study

Abstract

Category: Ankle Arthritis; Ankle Introduction/Purpose: Total ankle arthroplasty (TAA) for posttraumatic osteoarthritis (OA) is becoming an increasingly popular treatment option. Clinical results and prosthesis longevity correlate directly with the hind foot and components' postoperative alignment. Therefore, a preoperative plan (PROP) that can accurately predict postoperative alignment of TAA could be valuable. Most PROPs use the diseased ankle as a reference despite the arthritic deformation. PROPs of the contralateral, unaffected limb have been tested in other fields, but not in TAA. In most cases of posttraumatic OA, the contralateral ankle is relatively preserved and therefore could serve as a valuable tool for preoperative planning. This prospective study aims to assess the accuracy of preoperative planning using a WBCT of the contralateral healthy ankle for TAA in the treatment of posttraumatic OA. Methods: A total of 44 patients were included. For each case, a preoperative WBCT scan of the contralateral foot was acquired. Individual PROPs consisted of virtual realignment and osteotomies prior to each surgery. After surgery, postoperative WBCT scan of the affected foot was performed. Six angles were used to assess the accuracy of the coronal and sagittal alignment of the prosthesis. Results: Forty-four ankles across 44 patients were operated on. Three angles had a statistically significant difference between the pre and postoperative measurements: (1) α angle was -3±4 degrees (p-value < 0.0001), (2) TTS 2.884±4 degrees (p-value < 0.00001), (3) TTR -7±14 mm (p-value < 0.001). Only 49% and 34% of the coronal and sagittal angles could be found within 3 degrees from the PROPs. Conclusion: In conclusion, the contralateral ankle cannot be used accurately as a preoperative planning tool for TAA. It should be used only in cases where the diseased ankle cannot be a referenced in the setting of deformation.