Many people complain of deep and aching pain in the midfoot. This pain is often near the level of the arch but in the center of the foot. It often occurs after a sprain but could very well be associated with no injury or trauma at all. Too often, this sort of pain is simply ascribed to ‘arthritis’ or ‘age’ and the patient is told to put up with it until they need a fusion. However, we believe that more can be done for this pain.
Occasionally, this type of pain is due to damage to the ligaments of the subtalar joint. The subtalar joint is the moving connection between the talus and the calcaneus. The calcaneus is the heel bone and the talus is the bone under the tibia that comprises the ankle joint. While the ankle joint allows the foot to bend up and down, the subtalar joint is important for inversion and eversion.
That is, the subtalar joint is necessary to navigate uneven surfaces and is integral to balance and position sense.
The subtalar joint has three separate cartilaginous surfaces (facets); this means that the joint is actually a three-part joint. There is a posterior facet that is the largest part of the joint. This is the primary load-bearing joint of that region. The middle facet is positioned more to the inside of the foot and is next to important tendons and nerves. The anterior facet sits a bit more forward in the foot and is near the anterior process of the calcaneus. The posterior facet has a wall between it and the anterior and middle facets that is made of the tarsal canal and sinus tarsi. This region contains arteries, ligaments and tissue that are important for the health of the joint and also for stability. When these structures are damaged, one can often have a deep-seated and aching pain in the middle of the foot that is unexplainable.
The outside portion of the subtalar joint is supported and balanced by the lateral and posterior talocalcaneal ligaments.
In addition, the lateral aspect of the inferior extensor retinaculum supports this joint as well. The extensor retinaculum is an oblique (diagonal) band of tissue that holds the tendons down against the ankle. The interosseous ligament is the largest soft-tissue structure within the subtalar joint and is very important for overall stability of the foot and ankle region. It sits more medially in the joint (closer to the center of the foot). Without the interosseous ligament, there is misalignment of the various joints in the foot and over time a subtle instability. This instability can often be a source of pain. Many times this ligament will tear with a severe ankle and foot sprain. However, it is difficult to diagnose and is often missed. When an interosseous ligament tear is undiagnosed, the patient is doomed to have chronic midfoot pain without treatment.
However, there is a great treatment for this problem. Once it is diagnosed, often a simple arthroscopic procedure can help with the pain. By inserting a small camera and shaver device into the subtalar joint, the surgeon can clean up the torn ligament. Many individuals diagnosed with so-called ‘sinus tarsi’ syndrome actually have an interosseous ligament tear. This tear can be managed with the arthroscopic surgery; it has been shown that surgery for this condition is successful up to 94% of the time. Around 85% or more patients have reported excellent outcomes from surgery to debride this torn ligament when that is found to be the source of the midfoot pain.
If you have deep pain in the arch region of the foot that is not being treated satisfactorily, you might consider a full work-up of the subtalar joint.
