Subtalar fusion

Subtalar fusion can help alleviate foot pain in cases of subtalar arthritis or certain tarsal coalitions. The goal of the subtalar fusion is to join the separate calcaneus and talus bones into a single bone. Another name for this operation is subtalar arthrodesis.

Case study: a talocalcaneal coalition

A talocalcaneal coalition is an abnormal connection between the talus above, and the calcaneus below. The middle facet of the joint is usually affected.

It is estimated that approximately 1 in 100 humans has some type and some degree of coalition of the foot bones.

The problem is congenital, the person who has a coalition was born with it. However, the diagnosis is usually made during teenage years because that's when the coalition becomes stiffer, and as a consequence painful. The typical scenario is that of a teenager with many ankle "sprains" that do not seem to get better.

The following xrays are from a 15 year old female who had had several "sprains." Typically these patients get diagnosed with a sprain because it is difficult or impossible to see the coalition in plain xrays.

For instance here is the lateral foot xray of this patient.

She was treated with a walking boot for 4 weeks, which is pretty typical treatment for an "ankle sprain." Subsequently, she continued to have significant pain with running and walking. At that point I ordered an MRI study, looking for a possible OCD or a coalition.

A coalition of 50% of the middle facet was discovered.

In order to encourage full fusion, a cast was applied for another 6 weeks.

After the cast was removed, patient continued to have pain with walking.

A follow up CT scan showed an "arthritic" middle facet of the subtalar joint with lack of fusion.

Several months into treatment with rest, casting, and bracing, surgical treatment was requested by family.

I presented two options:

  1. Resection (removal) of the middle facet. The advantage of this would be more flexibility of the foot and heel. The disadvantage of resection is that it may fail to resolve the pain. A second surgery would then be necessary: arthrodesis of the joint.
  2. Arthrodesis implies complete fusion of 2 separate bones so that they do not move relative to each other. Flexibility of the joint is lost, but hopefully the pain generated by that joint is gone too.

This patient's family elected subtalar arthrodesis, which solved the patient's problem.