The Role of Subtalar Motion and Ankle Contact Pressure Changes from Angular Deformities of the Tibia

Abstract

It is a well known entity that fractures of the tibia heal with some component of angular deformity. Ankle and subtalar joints may compensate for small degrees of angular deformities, but the exact amount of malunion that can be accepted without development of late sequalae has yet to be determined. Two recent studies from this institution have concluded that contact changes at the tibiotalar joint tend to be greater with distal third tibial fracture deformities compared to proximal and middle with the ankle in neutral, 5 degrees dorsiflexion, and 20 degrees of plantar flexion. Anterior and posterior bow deformities produced a greater change in contact area of the tibiotalar joint than with valgus or varus deformities. This phenomena may be possibly explained by the subtalar motion in the horizontal plane which averages 23 degrees. Thus, it was the primary purpose of this paper to determine the exact role, if any, in subtalar motion on tibiotalar contact in angular deformities of the tibia. To achieve this objective the subtalar joint was transfixed thereby eliminating its perceived compensatory movement. Six cadaveric lower extremities were disarticulated at the knee joint and stripped of soft tissue preserving capsular and ligamentous structures. A custom universal joint was used to create various angulatory deformities at proximal, middle, and distal third levels of the tibia.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of medial and lateral displacement calcaneal osteotomies on tibiotalar joint contact stresses

“…Subtalar arthrodesis, however, results in reduced, displaced joint contact area in the ankle (3). After subtalar arthrodcsis, any varus or valgus angulatory malalignment of the tibia will cause a sizable decrease in the tibiotalar contact area (32). The modest spatial changes observed in the present study underscore the natural ability of the ankle and hindfoot to counterbalance substantial alterations in axial alignment.…”

Articular contact at the tibiotalar joint in passive flexion

“…For the contact at the tibiotalar joint, many experimental studies have been reported in the literature (Beaudoin et al, 1991;Bertsch et al, 2001;Calhoun et al, 1994;Clarke et al, 1991;Curtis et al, 1992;Driscoll et al, 1994;Earll et al, 1996;Friedman et al, 2001;Hartford et al, 1995;Kimizuka et al, 1980;Macko et al, 1991;Michelson et al, 2001;Pereira et al, 1996;Ramsey and Hamilton, 1976;Steffensmeier et al, 1996;Tarr et al, 1985;Thordarson et al, 1997;Ting et al, 1987), particularly looking at the effect of joint flexion position, joint loading, and integrity of the ligaments. Most of these are limited by the invasive measuring devices, i.e.…”

Comprehensive Treatment of Late-Onset Tibia Vara

“…Wagner et al 52 found decreased tibiotalar contact areas at the ankle in patients with distal tibial deformities of ≥10°. Ting et al 53 found that this effect was exacerbated in patients with decreased subtalar motion who were unable to compensate for the valgus. This has led us to correct deformities of >5° at the distal part of the tibia.…”