SLR - December 2019 - Collin G. Messerly
Reference: Gun-Woo L, Keun-Bae Lee, Outcomes of Total Ankle Arthroplasty in Ankles with >20 degrees of Coronal plane Deformity. JBJS 2019 October (Epub ahead of print)Scientific Literature Review
Reviewed By: Collin G. Messerly, DPM
Residency Program: Regions Hospital/HealthPartners Institute – St. Paul, MN
Podiatric Relevance: Total ankle arthroplasty is becoming increasingly more popular today among foot and ankle surgeons. Preoperative selection is imperative for implant survivability and among contraindications for TAR it has been thought that a coronal plane deformity >20 degrees is a major contraindication. This present study aims to evaluate whether outcomes of TAR in ankles with severe coronal plane deformity (20 degrees to 35 degrees of varus or valgus) are comparable with those of moderate deformity (5 degrees-15 degrees of varus of valgus).
Methods: A retrospective review of 287 consecutive patients between January 2005 and December 2016, who received consecutive primary total ankle arthroplasties using cementless mobile-bearing Hintegra prosthesis. One hundred forty-two patients (148 ankles) met inclusion criteria and were divided into two groups according to pre-op coronal plane tibiotalar angle: the severe group (36 patients 41 ankles; >20 degrees to 35 degrees of varus or valgus) and the moderate group 9106 patients and 107 ankles; 5 degrees to <15 degrees of varus or valgus). Mean follow-up was 74 months (24 to 160)
Results: The clinical outcomes provided, AOS pain and disability, AOFAS, SF-36 PCS, VAS pain score and ROM had all improved at the time of final follow-up and there was no significant intergroup difference between the two groups. The mean preoperative tibiotalar angle and the mean talar tilt angle both improved in the two groups; however, a greater residual tibiotalar angle was observed in the severe group. Of note, there was no case of incongruent ankle with a talar tilt angle exceeding 5 degrees in the groups. Concomitant procedures were more prevalent in the severe group 66 procedures on 41 ankles and 79 procedures on 107 ankles in the moderate group. The overall number of complications was 10 (24 percent) of 41 cases in the severe group and 32 (30 percent) of 107 cases in the moderate group, however no statistical significance between the two groups. Kaplan-Meier survival curves for the 148 total ankle arthroplasties were done and showing overall survival probability of the implant was 92.3 percent in the severe and 90.7 percent in the moderate group at a mean follow-up of 74 months.
Conclusions: Preoperative severe coronal plane deformity has been described as a contraindication for total ankle arthroplasty. This study found similar survivability rates between severe and moderate coronal plane deformity groups as mentioned above. The study achieved satisfactory clinical outcomes and complications were comparable between the two groups. However, with the radiographic outcomes, a significant difference was observed in the number of outliers and the final tibiotalar angle which were greater in the severe group. These post-op residual deformities could lead to early edge-loading and early polyethylene liner wear which could lead to failure of further revision. Concomitant procedures were also more prevalent in the severe group including osteotomies to achieve a neutral and stable alignment. In conclusion, similar results were found between the two groups however greater coronal deformity was noted post-operatively in the severe group that could lead to revision and implant failure in the future.