Calcaneus (Heel Bone)
The calcaneus is the bone that contacts the floor when the foot collapses medially (inward) under the ankle bone, a condition known as pes planus or flatfoot deformity. 1
Anatomical Context
The calcaneus is the largest tarsal bone in the foot and forms the heel. When the foot collapses on its interior (medial) aspect, this represents a valgus and pronation deformity where the heel bone shifts into an abnormal position relative to the ankle mortise. 1
Key Anatomical Relationships
- The calcaneus sits directly below the talus (ankle bone) and articulates with it at the subtalar joint 2
- In medial foot collapse, the calcaneus assumes a valgus position, meaning it tilts outward while the medial longitudinal arch flattens 1
- The sustentaculum tali, a medial shelf of the calcaneus, normally supports the talus from below 3
- When the foot collapses medially, the calcaneus becomes the primary weight-bearing bone contacting the ground surface 1
Clinical Significance
- Medial ankle instability with foot collapse creates a characteristic valgus and pronation deformity where pain localizes to the medial gutter of the ankle 1
- This deformity typically can be corrected by activation of the posterior tibial muscle, which helps maintain the medial longitudinal arch 1
- The calcaneus is a common site for osteonecrosis and fractures that may complicate chronic foot collapse 2, 4
- Axial Harris-Beath radiographic views are specifically used to evaluate calcaneal pathology and subtalar joint involvement 2, 5