Analysis of the Effect of Tibial Stem Length on Coronal Plane Deformity of the Tibial Component in Total Ankle Arthroplasty.

Abstract

Coronal plane deformity is common in patients who undergo total ankle arthroplasty. The correction of this deformity is paramount to the long-term survival of the implant. Coronal plane correction is achieved with soft tissue balancing and, in some part, is maintained through articular geometry constraint. The purpose of this study was to assess the influence of tibial component stem length on the coronal plane stability. A consecutive case series of stemmed implants that met inclusion criteria were reviewed to determine the correction and maintenance of the correction of coronal plane deformity with special emphasis on the effect of modular tibial stem lengths of 2 and >2 segments. Twenty patients received a tibial component with 2 stem segments, and 23 patients received a tibial component with >2 stem segments. At an average patient age of 62.1 years at implantation, there was no significant difference between the 2 cohorts with respect to preoperative deformity or demographics. Our case series had a mean coronal deformity of 5.7 degrees, with valgus being more common than varus. At a mean final radiographic follow-up of 266.3 days after the first postoperative weightbearing radiography, coronal deformity increased by 0.4 degrees (P = .031). From the first postoperative measurement to the last postoperative measurement, there was no difference in mean coronal plane ankle deformity change between patients who received 2 stem segments and patients who received >2 stem segments (t = -1.14, df = 41, P = .259). Coronal plane deformity had a tendency to recur, albeit at a much smaller angle than preoperatively. This recurrence of deformity did not occur because of tibial component movement. Tibial stem lengths of >2 segments did not influence the maintenance of correction of coronal plane deformity or the stability of the tibial component in the coronal plane. Level III, retrospective comparative series.