The Anatomy of the Subtalar Joint

A Facet of the Ankle Central to Joint Stability

Table of Contents
View All
Table of Contents

The subtalar joint, also known as the talocalcaneal joint, forms a bridge between the foot and ankle. Located in the hindfoot, it's the point at which the calcaneus (heel bone) and the talus (a bone at the lower part of the ankle joint) meet.

The subtalar joint allows you to move your foot side-to-side (laterally), pivot to change directions, and stay balanced as you move across uneven terrain. Without it, you would constantly roll your ankles when you run, jump, or walk.

This article covers the anatomy and functions of the subtalar joint. It also discusses several injuries and chronic conditions that can affect this joint, along with how they are treated.

Interior view of the hindfoot
Yuri_Arcurs / Getty Images

Anatomy

The subtalar joint works with other joints in your foot and ankle to control the movements involved in gait (walking pattern) and other motions.

This joint's unique structure enables your foot to rotate in several directions, keeping you stable and supported as you move.

Structure

The subtalar joint is multi-articular, meaning that it can move in more than one direction. It has three articulated facets, or flat areas that provide a surface for the joint to glide:

  • The anterior subtalar joint (ASTJ): Allows the joint to glide forward (anterior articulation)
  • The medial subtalar joint (MSLJ): Allows the joint to glide side-to-side
  • The posterior subtalar joint (PSTJ): Allows the joint to glide backward (posterior articulation)

The talus and calcaneous bones are held in place by strong but flexible connective tissues called ligaments. The main ligament that attaches these bones is called the interosseous talocalcaneal ligament, which runs along a groove between them. Four other weaker ligaments provide the joint with added stability.

In between the calcaneus and talus is the synovial membrane. This tissue secretes fluid to lubricate the joint space, protecting the cartilage and bones from damage.

Location

You have seven tarsal bones in each foot. (Tarsal is the latin word for ankle.) Together, these seven bones form the framework of the heel, ankle, and the rest of the hindfoot.

The talus and calcaneous bones are proximal tarsal bones. This means that they are closest to the part of the ankle that attaches to the rest of your body.

If you grab your heel, the big bone you are holding is the calcaneous bone. It is the largest and strongest bone in the foot, and attaches the Achilles tendon.

If you take two fingers and place them on the curve of your ankle between your shinbone (tibia) and your foot, you'll find the talus beneath your fingers. It is the most superior tarsal bone, meaning that it sits at the top of the tarsals, connecting the ankle to the tibia.

The talus is stacked directly above the front part of the calcaneous. The three subtalar facets are in the groove between the top of the calcaneous bone and the bottom of the talus bone.

In this same groove is the interosseous talocalcaneal ligament, linking the talus and calcaneous bones together.

Function

The subtalar joint is key to such motions as walking and running, as well as your posture while performing them. The mechanisms behind how the subtalar joint propels you are complex.

This joint's primary movements involve supination, in which the foot rolls toward the body's midline, and pronation, in which the foot rolls away from the midline. Both of these movements require a combination of distinct actions.

Pronation requires a combination of dorsiflexion, abduction, and eversion.

  • Dorsiflexion, in which the foot flexes upward
  • Abduction, in which the foot rotates laterally away from the midline
  • Eversion, in which the sole of the foot rotates outward

Supination requires a combination of:

  • Plantar flexion, in which the foot flexes downward
  • Adduction, in which the foot rotates laterally toward the midline
  • Inversion, in which the sole of the foot rotates inward

Each of these actions must occur together for you to have a normal gait. Furthermore, your foot and ankle's ability to glide and rotate in different directions is crucial to you being able to adapt your footing to shifting or uneven terrain.

While pronation and supination are the subtalar joint's primary responsibilities, the separate actions involved in pronation and supination also involve other parts of the foot and ankle.

For example, most of the eversion and inversion motions occur in the subtalar joint, but it doesn't work alone. The transverse tarsal joint, which connects the hindfoot to the midfoot, joins these efforts and the two work together as one functional unit.

The ankle joint, known as the talocrural joint, is primarily responsible for dorsiflexion and plantar flexion. But the subtalar joint also plays a small role in these motions.

Motor Function

The gait cycle is what happens to the foot and ankle from the time the heel first strikes the ground to the point at which the same heel strikes the ground again.

The gait cycle has two phases:

  • The stance phase: The foot is fixed against the ground, accounting for 60% of the gait cycle.
  • The swing phase: The foot is not in contact with the ground, accounting for 40% of the gait cycle.

When the heel first strikes the ground, the foot is supinated. The foot begins to pronate immediately after heel strike, as the outer portion of the heel and the rest of the foot makes contact with the ground.

In the middle of the stance phase (midstance), the foot is at its most pronated point. Here, the subtalar joint unlocks and the foot becomes fully flexible so that it can make full contact with the ground.

As your body weight shifts forward, the heel prepares to lift from the ground and the foot returns to neutral position. At the end of the stance phase, the heel lifts and the foot supinates.

Supination causes the subtalar joint to lock, creating a rigid lever that allows the toes to lift from the ground.

Associated Conditions

The subtalar joint is vital to mobility. As such, it can be especially prone to wear and tear, trauma, and joint-specific disorders. The damage can often be deeply felt and be difficult to pinpoint without imaging tests, such as an ultrasound.

Any damage done to the subtalar joint and any connective tissues that support it can trigger pain, lead to foot deformity (often permanent), and affect your gait and mobility. The damage may be broadly described as capsular or non-capsular.

Capsular Disorders

Capsular disorders are those that primarily impair the subtalar joint and its ability to function properly. Capsular disorders include:

  • Gout: A type of arthritis that commonly affects the first metatarsophalangeal joint (the big toe), but can also cause inflammation and pain in the subtalar joint
  • Juvenile idiopathic arthritis: A type of pediatric arthritis with no known cause in which the subtalar joint is often the first joint affected
  • Osteoarthritis: The wear-and-tear form of arthritis often caused by a previous joint injury, such as a fracture
  • Rheumatoid arthritis: The autoimmune form of arthritis in which the body's immune system primarily attacks joint tissues, often the ankle and foot

Non-Capsular Disorders

Non-capsular disorders are those in which the subtalar joint is indirectly affected or affected as a result of another defect or injury to the foot or ankle. Examples include:

  • Subtalar instability: A lateral weakness in which the ankle can suddenly "give way." This can cause chronic inflammation in the ankle and repeated ankle twisting due to the extreme pressure placed on the ligament.
  • Subtalar dislocation: Often described as "basketball foot," this injury typically occurs if you land hard on the inside or outside of your foot.
  • Pes planus: Also known as "flat feet," pes planus refers to a collapsed arch. It usually develops in childhood due to overpronation, or the inward rolling of the foot with movement. It can sometimes cause extreme pain if the foot is not provided with extra support, such as custom arch supports.
  • Pes cavus: Also known as a high instep, this is an especially high arch of the foot. It is often caused by a neurological disorder that alters its structure. This can lead to severely restricted movement, pain, and disability.
  • Polyarthropathy: A condition in which pain and inflammation occur in multiple joints. While arthritis is a common cause, polyarthropathy may be secondary to conditions like lupus, scleroderma, a regional infection, and Lyme disease.
  • Tarsal coalition: A condition that occurs when the hindfoot bones fuse together. Symptoms include limited range of motion, pain, and a rigid, flat foot. It may occur during fetal development if the bones of the foot fail to differentiate, but can also be caused by arthritis, an infection, or a serious heel injury.

Treatment

Injuries or disorders of the ankle and foot can be diagnosed and treated by a podiatrist (foot doctor) or an orthopedist (bone, joint, and muscle specialist).

Diagnosis typically involves a physical examination, a review of your medical history, and imaging tests, such as an X-ray, ultrasound, computed tomography (CT) scan, or magnetic resonance imaging (MRI) scan. In some cases, multiple imaging tests may be needed to reveal hidden fractures known as occult fractures, which are frequently missed in the heel area.

Blood tests may be ordered to measure markers that would suggest infection or that are associated with rheumatoid arthritis, lupus, or other autoimmune disorders. If a specific infection is suspected, a bacterial culture or antibody-based viral blood test may be performed.

Tests can also be used to differentiate subtalar joint disorders from other conditions that cause pain or inflammation in the ankle and heel area. These include:

Treatment can vary by the disorder diagnosed and the underlying cause.

Subtalar instability is often treated with corrective orthotics and over-the-counter anti-inflammatory drugs.

Arthritis may be treated with oral or injected anti-inflammatory medications (including corticosteroids), while rheumatic causes may benefit from immune-suppressive therapies.

Acute injuries may be treated with ample rest and ice application. More severe injuries or deformities may require arthroscopic or open surgery.

Summary

The subtalar joint is a joint in your hindfoot where two tarsal (ankle bones) are joined by the interosseous talocalcaneal ligament. The two bones that make up this joint are the talus bone, located in the curve of your ankle, and the calcaneous bone, which forms your heel.

The subtalar joint's primary responsibility is to facilitate gait movements. Because of the constant, repeated stress placed on it, it can be prone to acute traumatic injuries, like subtalar dislocation, as well as chronic conditions resulting from wear-and-tear, like osteoarthritis.

A Word From Verywell

Studies show that range of motion in the subtalar joint is 20% to 30% lower in older adults compared to younger people. Decreased range of motion puts one at risk for foot pain, something that one in four older adults experience.

Given the importance of your subtalar joint and the likelihood of foot pain, it's wise to work on improving your foot joint's strength and movement as much as you can, even if you are young or don't have foot pain. Some great exercises for this include walking in sand or water, or even picking up marbles and other small objects with your toes.

A little bit of foot strengthening every day can help prevent future foot pain along with the negative affects it can have on your gait, balance, and overall quality of life.

Was this page helpful?
6 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Brockett C, Chapman G. Biomechanics of the ankle. Orthopaed and Trauma. 2016 Jun;30(3):232-238. doi:10.1016/j.mporth.2016.04.015

  2. Di Gregorio R, Vocenas L. Identification of gait-cycle phases for prosthesis control. Biomimetics (Basel). 2021 Jun;6(2):22. doi:10.3390/biomimetics6020022

  3. Sebastian D. The active supination dorsiflexion test guided therapeutic intervention for shin and calf pain: a case report. J Musculoskelet Disord Treat. 2020 Jun;6(2):1-9. doi:10.23937/2572-3243.1510078

  4. Arthritis Foundation. Osteoarthritis.

  5. American Academy of Orthopedic Surgeons. Bursitis.

  6. Menz HB. Biomechanics of the ageing foot and ankle: A mini-review. Gerontology. 2015;61(1):381-388. doi:10.1159/000368357

Additional Reading