The bifurcate ligament is a Y-shaped structure at the Chopart joint level, arising from the anterior calcaneus and dividing into medial (calcaneonavicular) and lateral (calcaneocuboid) arms. Its avulsion from the calcaneus in inversion injuries produces the 'nutcracker fracture' pattern. In Chopart fracture-dislocations, the bifurcate ligament is always disrupted. It is the key ligament of the Chopart joint complex visible on dorsal midfoot dissection.
| Origin | Anterior calcaneus (dorsolateral surface) |
|---|---|
| Insertion | Two arms: calcaneonavicular (medial arm) and calcaneocuboid (lateral arm) |
| Actions | Stabilises the Chopart joint (talonavicular and calcaneocuboid) from the calcaneal side; the primary midfoot constraint at the calcaneocuboid-navicular level |
|---|
Bifurcate ligament avulsion from the anterior calcaneus produces the Crusell fracture — a small bony avulsion at the anterior calcaneus visible on plain X-ray that is commonly dismissed as a normal variant. Symptomatic avulsions require 4-6 weeks of immobilisation for bone healing.
Inversion ankle injury avulsion of the anterior calcaneal bifurcate ligament origin producing dorsolateral midfoot pain managed with immobilisation.
