Overview of the Subtalar Joint

A Facet of the Ankle Central to Joint Stability

Run off your heels
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The subtalar joint, also known as the talocalcaneal joint, is a compound joint positioned directly below the ankle joint. It is comprised of the calcaneus (heel bone) and a column-shaped bone called the talus. The subtalar joint is vital to movement as it helps readjust the lateral (side-to-side) position of your foot as you navigate uneven or shifting terrain. Without the subtalar joint, you would be unable to run, jump, walk, or move with any precision.

Joint Structure

The subtalar joint is multi-articular, meaning that it is able to move in more than one direction. There are three articulated facets to the subtalar joint, which allow it to move forward (anterior articulation), backward (posterior articulation), and laterally.

The bones are held in placed by strong but flexible connective tissues called ligaments. The main ligament is called the interosseous talocalcaneal ligament, which runs along a groove between the bones called the tarsal channel. Four other weaker ligaments provide the joint added stability.

In between the calcaneus and talus is tissue called synovial membrane, which lubricants the joint space.

Function of the Subtalar Joint

Walking is a sophisticated function for which we give little thought. From the perspective of the ankle and foot, this requires three distinct actions:

  • We need to be able to roll the foot away from the midline of the body (supination) or toward the midline of the body (pronation).
  • We need to be able to flex the foot upward (dorsal flexion) and downward (plantar flexion).
  • We need to be able to rotate our foot laterally away from the midline (abduction) or toward the midline (adduction).

Doing so together not only provides us the means to walk, it allows us to adapt to shifting terrain and to absorb shock as the force of an impact is redistributed according to the position of the bones.

With regards to the subtalar joint, its articulated structure enables the inversion or eversion of your foot. While inversion and eversion are components of pronation and supination, respectively, they specifically involve the hindfoot rather than the entire foot. With inversion, you rotate your ankle inward. With eversion, you rotate it outward.

By contrast, pronation involves inversion in association with the collapse of the midfoot into the arch. Supination involves eversion as the arch is lifted and the midfoot rolls to the side.

The subtalar joint plays no role in either dorsal or plantar flexion.

Subtalar Joint Problems

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

Among some of the more common disorders involving or affecting the subtalar joint:

  • Osteoarthritis is the wear-and-tear form of arthritis that is often caused by a previous joint injury, such as a fracture.
  • Subtalar instability involves a lateral weakness in which the ankle can suddenly "give way." This can lead to the twisting of an ankle or chronic inflammation due to extreme pressure placed on the lateral ligament.
  • Subtalar dislocation, often described as "basketball foot," typically occurs if you land hard on the inside or outside of your foot.
  • Pes planus, also known as "flat feet," essentially is a collapsed arch. It usually develops during childhood due to the overpronation and can sometimes cause extreme pain if the foot is not structurally supported.
  • Pes cavus, also referred to as a high instep, is an exaggerated arch of the foot that is often caused by a neurological disorder that alters the structure of the foot. This can lead to a severe restriction of movement, pain, and disability.
  • Tarsal coalition is the fusion of bones of the hindfoot. It is characterized by a limited range of motion, pain, and a rigid, flat foot. It often occurs during embryogenesis (development of the embryo) in which the bones of the foot fail to fully differentiate.
  • Tarsal tunnel syndrome is a pinched nerve in the joint space that can cause shooting pains and an abnormal burning or tingling sensation.

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).

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View Article Sources
  • Krahenbuhl, N.; Horn-Lang, T.; and Hintermann, B. The subtalar joint: A complex mechanism. EFORT Open Rev. 2017;2(7):309-16. DOI:10.1302/2058-5241.2.160050.
  • Wheeless, C.; Nunley, J.; and Urbaniak, J. (2016) "Subtalar Joint." Wheeless' Textbook of Orthopaedics. Durham, North Carolina: Data Trace Internet Publishing, LLC.