The subtalar joint is an articulation between two of the tarsal bones in the foot - the talus and calcaneus. The joint is classed structurally as a synovial joint, and functionally as a plane synovial joint. This article will look at the anatomy of the subtalar joint - its articulating surfaces, movements and neurovascular supply, as well as a common injury to the joint.
The subtalar joint is formed between two of the tarsal bones: the inferior surface of the body of the talus, which is known as the posterior talar articular surface; and the superior surface of the calcaneus, which is known as the posterior calcaneal articular facet. As is typical for a synovial joint, these surfaces are covered by articular cartilage.
It is important to note that some texts will refer to the talocalcaneal part of the talocalcaneonavicular joint as being part of the subtalar joint. Although this forms part of the functional joint, the true anatomical subtalar joint consists only of the surfaces mentioned above.
The subtalar joint is enclosed by a joint capsule, which is lined internally by synovial membrane and strengthened externally by a fibrous layer. The capsule is also supported by three ligaments- the posterior talocalcaneal ligament, medial talocalcaneal ligament, and lateral talocalcaneal ligament. An additional ligament – the interosseous talocalcaneal ligament – acts to bind the talus and calcaneus together. It lies within the sinus tarsi (a small cavity between the talus and calcaneus), and is particularly strong; providing the majority of the ligamentous stability to the joint.
The subtalar joint is formed on an oblique axis and is therefore the chief site within the foot for generation of eversion and inversion movements. This movement is produced by the muscles of the lateral compartment of the leg and tibialis anterior muscle respectively. The nature of the articulating surface means that the subtalar joint has no role in plantar or dorsiflexion of the foot.
The subtalar joint receives supply from two arteries and two nerves. Arterial supply comes from the posterior tibial and fibular arteries. Innervation to the plantar aspect of the joint is supplied by the medial or lateral plantar nerve, whereas the dorsal aspect of the joint is supplied by the deep fibular nerve.
The calcaneus is often fractured in a ‘crush' type injury. The most common mechanism of damage is falling onto the heel from a height – the talus is driven into the calcaneus. The bone can break into several pieces, known as a comminuted fracture. Upon x-ray imaging, the calcaneus will appear shorter and wider.
A calcaneal fracture can cause chronic problems, even after treatment. The subtalar joint is usually disrupted, causing the joint to become arthritic. The patient will experience pain upon inversion and eversion – which can make walking on uneven ground particularly painful. Surgery may be required to repair the joint and bones, followed by long-term physical therapy to restore mobility.
In some cases, the joint may never fully recover and may need to be supported with braces or crutches. Pain medications can also be prescribed to manage any discomfort. It is important for patients with calcaneal fractures to follow their doctor's advice and stick to their rehabilitation program to ensure the best outcome.
The subtalar joint is an intricate and important joint of the foot, and a disruption of its function can have serious consequences. Knowing the anatomy and structure of the joint can help us to identify and treat any injuries, and prevent long-term problems associated with its damage.
The calcaneus, also known as the heel bone, is a short, wide bone located at the back of the foot. Upon x-ray imaging, the calcaneus can be seen as a sharply defined bone with a distinct outline.
A calcaneal fracture is a disruption of the heel bone, and can cause chronic problems even after treatment. This is most commonly caused by extreme trauma, such as a car accident or a fall from a height onto the heels. The subtalar joint, located between the talus and the calcaneus, may become disrupted due to the fracture, leading to arthritis of that joint. This can lead to limited range of motion, and pain in the heel while walking on uneven ground.
Treatment for a calcaneal fracture typically involves immobilizing the foot with a short leg cast or a walking boot for several weeks. Physical therapy is often prescribed to help the patient gain strength in the affected foot, as well as to help improve mobility of the subtalar joint. In cases of severe displacement, surgery may be necessary to repair the bone and realign the joint. Follow-up care is important in order to monitor the healing process.
Follow-up care is vital to ensuring proper healing of a calcaneal fracture. X-rays should be taken at regular intervals to monitor the healing progress, and the patient should be evaluated for any ongoing pain or discomfort. The patient should also be evaluated for any changes in range of motion or flexibility in the subtalar joint. Regular visits to the physician are also important during the recovery period to ensure that the calcaneal fracture does not lead to the development of any chronic issues.
The best way to prevent calcaneal fractures is to practice proper safety measures when engaging in activities that can be particularly hazardous, such as skiing, running, and biking. Wearing protective footwear is also important, as it can provide additional cushioning for the heel and provide support to the foot. Strengthening the muscles in the foot through regular exercise can also help to stabilize the heel and reduce the risk of fractures.
Understanding the anatomy of the calcaneus is important for proper diagnosis and treatment of calcaneal fractures. It is vital to receive proper medical care and follow-up care for any fracture of the heel bone, as it can lead to long-term problems and mobility issues. Practicing proper safety measures and wearing protective footwear are essential for preventing calcaneal fractures and keeping the foot and ankle healthy.
