9

Total ankle arthroplasty (TAA) implanted in cases of osteoarthritis with hindfoot varus is a significant challenge due to its relative frequency and the high rate of complications typically reported. There is currently controversy in the literature regarding the maximum degree of varus that can authorize TAA implantation, and the associated surgical procedures remain undetermined. The aim of this study was to evaluate the medium- and long-term survival rates of implants in cases of osteoarthritis with varus of the hindfoot, and to study the factors influencing failure, particularly associated procedures or the severity of the initial deformation. This monocentric retrospective study included all the TAAs implanted between 2000 and 2008 with a deformation of greater than 10° in the frontal plane between the mechanical axis of the tibia and the talar surface; 42 ankles (38 patients with a mean age of 61.1 ± 11.6 years) were included. The survival rate was calculated, and factors potentially responsible for failures were studied (etiology, radiological deformities, pre- and postoperative conditions, associated procedures, etc.). The AOFAS (American Orthopaedic Foot and Ankle Society) score was also evaluated before surgery and at follow-up. The mean follow-up period was 8.7 years. Four patients had died and 3 were lost to follow-up. The mean AOFAS score improved from 39.9 to 79.4 postoperatively. The mean preoperative deformation was 18.0 ± 7.3 (range 10–43) in varus, which was corrected to 2.6 ± 3.7° after surgery. There were 11 major failures in 42 TAAs. The mean survival rate was 81.4% ± 0.06 at 8 years. Major failures were statistically more frequent in cases of significant preoperative frontal deformity (but not in postoperative cases) and in cases of revision for minor causes. A medial ligament release was systematically performed, a lateral tightening carried out in 2 cases (resulting in 2 failures), fusion of the torsion couple in 4 cases (2 failures), and an osteotomy in 2 cases (1 failure). This study with a follow-up of more than 8 years confirms the feasibility of TAA in cases of significant varus osteoarthritis, but also highlights the necessity for careful indication and intervention, including associated procedures.