Ligament Balancing for Total Ankle Arthroplasty: An in vitro Evaluation of the Elongation of the Hind- and Midfoot Ligaments

Abstract

The changes in length of the hindfoot ligaments in response to alterations in ankle and subtalar joint orientation under physiologic load in eight fresh-frozen cadaver limbs were documented. In eversion, the tibiocalcaneal (11% ± 4%, mean ± SD], calcaneofibular (6% ± 4%), posterior talofibular (7% ± 4%), posterolateral talocalcaneal (21% ± 9%), posteromedial talocalcaneal (33% ± 45%) and calcaneonavicular (bifurcate) (8% ± 7%) ligaments were elongated relative to their lengths in inversion. In inversion, the anterior capsular (talocalcaneal) (5% ± 3%) and the plantar cuboidnavicular (5% ± 6%) ligaments were elongated relative to their everted lengths. In dorsiflexion, the superficial (26% ± 8%) and deep posterior tibiotalar (30% ± 13%), calcaneofibular (8% ± 4%), tibiocalcaneal (4% ± 2%) and lateral talocalcaneal (cervical) (2% ± 1%) ligaments were elongated. In plantarflexion, the tibionavicular (26% ± 5%) and the anterior talofibular (7% ± 4%) ligaments were lengthened. No statistically significant elongation was documented in any ankle position for the anterior tibiotalar, talocalcaneal interosseous, plantar calcaneocuboid, calcaneocuboid (bifurcate), all components of the spring ligament, and the dorsal cuboidnavicular ligaments. Components of the deltoid ligament complex elongated largest at the ankle joint with any hindfoot movement but inversion. Therefore, selective release of components of the deltoid ligament complex may provide a means for achieving optimal ligament balancing in total ankle arthroplasty. Specifically, release of the superficial and deep posterior tibiotalar ligament may improve range of motion in total ankle arthroplasties, whereas the release of the tibiocalcaneal ligament may correct a varus talar tilt.