Was Mark Reiley Right? A Outcome Analysis of Intramedullary Versus Extramedullaryalignment Referencing for Total Ankle Replacement

CATEGORY: Ankle Arthritis; Ankle INTRODUCTION/PURPOSE: The purpose of this study was to report on the radiographic outcomes, clinical outcomes, and implant survivorship following extramedullary-referenced (EMr) versus intramedullary-referenced (IMr) total ankle replacement (TAR). METHODS: From May 2007 to February 2018, a consecutive series of patients with end-stage tibiotalar osteoarthritis undergoing TAR for primary arthritis, post-traumatic arthritis, and inflammatory arthritis was enrolled in this study. Analyses were performed comparing IMr versus EMr components for patient-reported outcomes data, pre and postoperative radiographic ankle alignment, concomitant procedures, and complications. Kaplan-Meier survivorship analyses served to determine implant reoperation and revision surgery. Data was prospectively collected and retrospectively analyzed. A p-value of < 0.05 was considered significant for all statistical analyses. RESULTS: A total of 340 TARs were included with 105 IMr TAR and 235 EMr TAR. The mean follow-up was 5.3 years ( +- 2.5, range 2-12). The absolute value for preoperative coronal alignment was significantly greater for IMr compared to EMr TAR (13.0 vs 6.4 degrees; p < 0.0001), but both groups achieved near neutral alignment postoperatively (1.4 vs 1.5 degrees; p=0.6655). The odds of having a concomitant procedure was 2.7 times higher in patients with an IMr TAR (OR 2.7, CI 1.7-4.4; p-value <0.0001). There were similar improvements in patient-reported outcome scores at one year and final follow up (all p > 0.05). The 5-year implant survivorship was 98.6.% for IMr versus 97.5% for EMr at final follow-up. CONCLUSION: Despite the IMr TAR group having more severe preoperative coronal and sagittal malalignment, both IMr and EMr TAR components had comparable postoperative alignment, patient-reported outcome scores, and complications. Among the patients with preoperative varus, valgus, or anterior distal tibial slope, the IMr patients achieved greater correction than the EMr patients. Although the 5-year implant survivorship was similar between the two cohorts with 98.6% survival for IMr TAR and 97.5% for EMr TAR, impending failures were greater for the mobile-bearing EMr TAR.