In a small number of children, two bones in the ankle are formed as one without the normal separation between them. The child is born this way but may not know it until later in life when the foot looks flat and ankle pain and deformity interfere with standing and walking.
This condition is referred to as a coalition. The two most common bony coalitions in the ankle are formed by the talus and calcaneus bones (talocalcaneal coalition) and the calcaneus and navicular bones (calcaneonavicular coalition). The condition has been treated in the past with conservative (nonoperative) care (e.g., leg cast) or with surgery to fuse the ankle.
But more modern surgical approaches are now available. And the surgeons who wrote this article offer their insights, expertise, and results performing one of the newer techniques. The specific approach they took was to treat a talocalcaneal coalition in 32 patients (49 total feet).
They describe the surgery designed to remove the bridge of bone between the talus and the calcaneus. Then a piece of fat (taken from the patient’s buttocks or abdomen) was placed in the space left by the resected bone. Fat implantation of this type is referred to as a fat graft interposition.
After the surgical procedure, the children were put immediately into a short leg cast for three weeks. They were allowed to walk on the foot right away as much as they could tolerate. When the cast came off, they used a supportive athletic shoe and began physical therapy right away. The therapist helped them regain motion, strength, and alignment.
Overall results were measured using a test called the American Orthopaedic Foot and Ankle Society Ankle-Hindfoot score (AOFAS). The AOFAS provides a way to measure three areas: pain, function, and alignment. Each child was followed for at least one full year. Before and after X-rays and CT scans were also compared.
Only one of the 49 feet was rated “poor” on the AOFAS. The majority (85 per cent) had good-to-excellent results. Ankle range-of-motion and mobility were much better for 92 per cent of the group. One fourth of the group did require additional surgery to further correct ankle alignment. In a small number of cases (two patients), the first surgery was considered a failure and a second (revision) surgery was needed to repeat the procedure.
Comparing these results to other studies where patients’ ankles were fused, the authors point out that this bone resection and fat graft implantation is just as successful (if not more so) than the fusion. The hope is that long-term studies will show less arthritis from this condition (a typical response to the ankle fusion). These patients will continue to be followed to see if results hold or if there is a gradual but steady decline in function and alignment over time.
The authors make note of one final consideration. They suggest that the group of patients who required additional surgery to further correct hindfoot deformities may have two separate conditions: the talocalcaneal coalition discussed and the hindfoot deformity referred to as hindfoot valgus.
Children and their families (as well as older patients who have this surgery later in life) should be advised that the bone resection and fat implantation may be just part one of a two-stage procedure. Further study is also needed to determine whether or not fat implantation is even necessary. At least one study has been done without this step and patients had equally good mid-term results after five years. Long-term studies are needed to compare this bone resection procedure with and without fat implantation.
In summary, current views on talocalcaneal coalitions suggest the need for early surgery to relieve pain, improve alignment, and restore full function of the foot and ankle. Surgical fusion may be replaced by this new technique of bone resection and fat graft implantation. With this approach, patients with talocalcaneal coalitions may be spared early arthritic changes in the ankle. More studies are needed in this area to provide surgeons with evidence-based guidelines for the condition of ankle bone coalition.