Heel Bone
Calcaneus
location_on Posterior and inferior foot, forming the heel
The calcaneus is the largest and strongest tarsal bone, forming the prominence of the heel. It bears the entire weight of the body during the heel-strike phase of gait and provides the lever arm for the calf muscles through the Achilles tendon insertion. The calcaneus has a complex internal trabecular architecture optimized for weight bearing, and its superior surface forms the posterior subtalar joint with the talus.
Key Anatomical Features
- Calcaneal tuberosity on the posterior surface receives the Achilles tendon
- Sustentaculum tali is a medial shelf supporting the talus and the flexor hallucis longus tendon
- Posterior subtalar facet is a large concave surface articulating with the talus
- Bohler's angle (normally 25-40 degrees) is measured on lateral radiographs to assess fracture depression
- Peroneal tubercle on the lateral surface separates the peroneal tendons
- Sinus tarsi is the cone-shaped opening between the calcaneus and talus
Muscle Attachments
| Muscle | Attachment | Action |
|---|---|---|
| Gastrocnemius and Soleus (via Achilles tendon) | Calcaneal tuberosity | Plantarflexes the ankle (most powerful ankle movement) |
| Plantaris | Medial calcaneal tuberosity | Weakly plantarflexes the ankle |
| Abductor hallucis | Medial process of calcaneal tuberosity | Abducts the great toe |
| Abductor digiti minimi | Lateral process of calcaneal tuberosity | Abducts the little toe |
| Flexor digitorum brevis | Medial process of calcaneal tuberosity | Flexes the middle phalanges of the lateral four toes |
| Plantar fascia (aponeurosis) | Medial process of calcaneal tuberosity | Supports the longitudinal arch of the foot |
Joints and Articulations
| Joint | Type | Connects to |
|---|---|---|
| Subtalar (talocalcaneal) joint | Synovial plane (posterior facet) | Talus |
| Calcaneocuboid joint | Synovial saddle | Cuboid |
Common Pathologies
Calcaneal fracture
Most common tarsal fracture, usually from axial loading (falls from height). Intra-articular fractures involving the posterior subtalar facet are classified by the Sanders CT classification. Associated with lumbar spine fractures in 10% of cases.
Plantar fasciitis
Inflammation and microtearing of the plantar fascia at its calcaneal origin, the most common cause of heel pain. Characterized by sharp pain with the first steps in the morning.
Achilles tendinopathy
Degeneration of the Achilles tendon at or near its calcaneal insertion, causing posterior heel pain. Can progress to complete rupture.
Calcaneal stress fracture
Overuse fracture within the calcaneal body, common in military recruits and distance runners. Presents with diffuse heel pain and a positive squeeze test.
Haglund deformity
Prominent posterosuperior calcaneal bump causing irritation of the Achilles tendon and retrocalcaneal bursa, often from rigid shoe wear.
Clinical Relevance
After a calcaneal fracture from a fall, always assess for associated lumbar spine compression fractures (present in about 10% of cases). Bohler's angle on the lateral radiograph normally measures 25-40 degrees; a decreased angle indicates depression of the posterior facet. The calcaneal squeeze test (medial and lateral compression) is positive in calcaneal stress fractures. Calcaneal fractures have significant long-term morbidity due to subtalar joint incongruity, heel widening, and peroneal tendon impingement.
Development and Ossification
The calcaneus ossifies from one primary center appearing around the 3rd fetal month and one secondary center (calcaneal apophysis) at the posterior tuberosity appearing around ages 6-8, fusing between ages 14 and 16. Sever disease (calcaneal apophysitis) is the most common cause of heel pain in children ages 8-14.
Did You Know?
- The calcaneus is the largest bone in the foot and the first tarsal bone to ossify
- The Achilles tendon (attaching to the calcaneus) is the strongest tendon in the body, capable of withstanding forces of over 1,000 pounds
- Calcaneus comes from the Latin calx meaning heel
Scan this bone yourself
Download Osteo+ and identify the heel bone instantly with your camera. Get all the details above and more from a single photo.