Tarsal Bones
Seven tarsal bones form the posterior and middle portions of the foot. Unlike the carpal bones, they bear full body weight and are subject to very different stress patterns — stress fractures, coalition, and avascular necrosis are the key clinical concerns.
✦ The Mnemonic
"Careful Trekkers Navigate Cuboid Country — Meet, Intermediate, Lateral"
Calcaneus, Talus, Navicular, Cuboid, then three Cuneiforms (medial, intermediate, lateral)
Clinical Breakdown
The foot has three functional columns: medial (calcaneus→talus→navicular→cuneiforms→metatarsals 1–3), lateral (calcaneus→cuboid→metatarsals 4–5), and the transverse arch maintained by the cuneiforms and cuboid. The talus receives forces from the tibia and distributes them backward (calcaneus) and forward (navicular).
The talus is the only bone in the body with no muscle attachments. Its blood supply enters distally, making it vulnerable to avascular necrosis following displaced talar neck fractures (Hawkins classification). The sustentaculum tali of the calcaneus supports the body of the talus and is the origin of the spring (plantar calcaneonavicular) ligament.
Lisfranc injury involves disruption of the tarsometatarsal (Lisfranc) joint complex. The 'keystone' of this joint is the 2nd metatarsal base, which is recessed between the medial and lateral cuneiforms. Injury is often missed — a gap >2 mm between the 1st and 2nd metatarsal bases on weight-bearing X-ray, or an avulsion fracture of the 2nd metatarsal base, is diagnostic.
⭐ Clinical Pearl
Calcaneal fractures from axial loading (falls from height) are associated with lumbar spine fractures in 10% of cases and contralateral calcaneal fracture in 5–10%. Always examine and image the lumbar spine in any patient with bilateral heel pain after a fall. Böhler's angle (<20° = depressed fracture) is the key radiological measurement on lateral X-ray.