Wednesday, September 28, 2011

The Subtalar Joint


The subtalar joint sits below the ankle joint, and is composed of the articulation between the talus and the calcaneus.  It plays a crucial role in the normal function of the foot, and allows for motion along an axis that runs through three planes of the body; the frontal plane, the sagittal plane, and the transverse plane.  Motion along the subtalar joint axis is defined as pronation and supination.  The pronation and supination allows the foot to adapt to uneven surfaces, and functions as the connecting joint between the ankle and the rest of the foot. 

The articulation between the talus and the calcaneus is actually composed of three separate articular surfaces; the posterior articular facet, the middle articular facet, and the anterior articular facet.  Together, these three articulations create a joint between the two bones. 

The joint is stabilized by a number of ligaments that connect the talus to the calcaneus.  The ankle ligaments also help to stabilize the talus within the ankle joint, and keep it improper alignment with the calcaneus.

Pathology of the subtalar joint may include primary osteoarthritis, arthritis secondary to fractures of the ankle and/or calcaneus, tarsal coalition, inflammatory conditions, and a number of other problems that can affect bones and joints.  Subtalar joint arthritis is a very common etiology of subtalr joint pain.  When the subtalar joint becomes an area of pain, it is often confused for ankle pain.  Thus, when people come to the doctor with a complaint of ankle pain, they are often shocked to find out that it is not actually their ankle that hurts, but their subtalar joint. 

Subtalar joint pain, particularly when it is due to arthritis, can be differentiated from ankle pain with a careful clinical exam, as well as the use of diagnostic injections.  Diagnostic injections involve injecting a small amount of local anesthetic, a numbing agent, into the painful joint.  If all of the pain is relieved, than it can be deduced that the subtalar joint is the source of pain.  If some, but not all of the pain is relieved, than it is possible that the ankle or other surrounding joints, or the soft tissues around the joint may be the source of the problem. 

Treating subtalar joint arthritis begins with conservative therapy.  This may consist of various padding and strapping methods, orthotics, and the use of cortisone injections into the joint.  Oral anti-inflammatories, ice, physical therapy, and other modalities may be tried as well.

Occassionally, the arthritis is severe enough to warrant surgical intervention.  Most commonly, subtalar joint arthritis is treated surgically with a fusion of the joint, also known as an arthrodesis.  In subtalar joint arthrodesis, the talus is fused to the calcaneus.  This removes all motion available at the joint, thus eliminating the pain associated with its movement.  The joint will not move after it has been fused. 

Screws are used to hold the bones in place while they heal together, and a period of non-weight bearing is generally employed for a minimum of 6-8 weeks.  After this period of time, the patient may be transitioned to a partial weight-bearing status, for another period of 4-6 weeks.  After the bones have completely healed, normal activity may begin again.



Central Florida Foot & Ankle Center, LLC 101 6th Street N.W. Winter Haven, FL 33881 Phone: 863-299-4551 http://www.FLFootandAnkle.com