Abstract
Purpose
Coronal plane malalignment at the level of the tibiotalar joint is not uncommon in advanced ankle joint arthritis. It has been stated that preoperative varus or valgus deformity beyond 15 degrees is a relative contraindication and deformity beyond 20 degrees is an absolute contraindication to ankle joint replacement. There is limited evidence in the current literature to support these figures. The current study is a prospective clinical and radiographic comparative study between patients who underwent total ankle arthroplasty with coronal plane varus tibiotalar deformities greater than 10 degrees and patients with neutral alignment, less than 10 degrees of deformity.
Method
Thirty-six ankles with greater than 10 degrees of varus alignment were compared to thirty-six ankles which were matched for implant type, age, gender, and year of surgery. Patients completed preoperative and yearly postoperative functional outcome scores including the American Orthopaedic Foot and Ankle Society (AOFAS) Ankle-Hindfoot scores, the Ankle Osteoarthritis Scale (AOS) and the Short Form-36 Standard Version 2.0 Health Survey. Weightbearing preoperative and postoperative radiographs were obtained and reviewed by four examiners (AC, AQ, TD, TT) and measurements were taken of the degree of coronal plane deformity.
Results
After a mean follow-up of 27 months (9–54), the varus ankles improved significantly on the AOFAS (P<0.0001), AOS-Pain Score (P<0.0001), AOS-Disability Score (P<0.0001), and SF-36 Physical Component Score (P<0.0001). There was no improvement in SF-36-Mental Component Score. (P=0.722). There was no statistically significant differences between the two groups when comparing AOFAS (P=0.155), AOS-Pain Score (P=0.854), AOSDisability Score (P=0.593), SF-36-Physical Component Score (P=0.433), SF-36 Mental Component Score (P=0.633). Sixteen of Thirty-Six ankles in the varus group needed a secondary procedure (implant failure, infection, malalignment) which was approaching significance in comparison to eight ankles in the neutral group. (P = 0.079). Secondary procedures in the varus group included: tendon transfers, calcaneal / metatarsal / malleolar ostoetomies and ligament reconstructions.
Radiographically, the pre-operative coronal plane varus tibiotalar deformity averaged 19.4 6.4 and postoperatively 1.44 2.6 (P< 0.0001). There was no statistical difference in post operative tibiotalar alignment between the varus and neutral groups (P<0.05).
Conclusion
The clinical outcome of TAR performed in ankles with pre-operative varus alignment >10 degrees is comparable with that of neutrally aligned ankles. The increased number of secondary procedures in the varus group was attributed to the complexity of the deformity and the steep learning curve. Outcomes as measured radiographically and through validate scores were similar to patients without deformity suggesting that varus coronal plane deformity of the talus is not a contraindication to total ankle replacement.
