The two most common tarsal coalitions are the calcaneonavicular bar and the middle facet talocalcaneal bridge.1 Surgeons have managed both with surgical resection and fusion approaches. Slomann first described the resection of the calcaneonavicular coalition in 1921 and Badgley further elucidated the procedure in 1927.12,13 Authors have referred to the traditional approach as an extensor digitorum brevis arthroplasty. This involves excision of the calcaneonavicular bar through a dorsolateral midfoot Ollier’s incision with interposition of the extensor digitorum muscle belly into the defect. Over the years, the procedure has remained essentially unchanged with suggested modifications centering primarily on the interpositional material.
The procedure has worked quite well for the calcaneonavicular coalition with reported success rates averaging about 80 percent.1 Recently, Lui reported using arthroscopy to resect a calcaneonavicular coalition.14 He described his technique of using a 2.7 mm, 30-degree arthroscope and two arthroscopic portals to shave the coalition. However, Lui did not report any results.
Although somewhat more controversial, surgeons have also successfully resected the middle facet talocalcaneal coalition. A medial longitudinal incision approach over the sustentaculum tali allows direct exposure of the middle facet talocalcaneal coalition. Intraoperative fluoroscopy and passing guide pins from the sinus tarsi medial wards help to localize the coalition and confirm its dimensions. Typically, one retracts the tibialis posterior and flexor digitorum longus tendons dorsally, and retracts the neurovascular bundle and flexor hallucis longus tendons inferiorly. After exposing the coalition, gently resect it.
Debate continues as to whether interpositional material is necessary and what the best material would be. Bone wax, fat grafts, combinations of bone wax and fat grafts and split tendons (e.g., split flexor hallucis longus tendon) are suggested interpositional options. Authors have reported good results with no interpositional material at all or with the insertion of a subtalar arthroereisis implant.15 The goal of the implant approach is to keep the resected space open by holding the foot in a more supinated position. There is no current evidence to suggest that failure of talocalcaneal coalition resection is related to the interpositional material used or lack thereof.
On the other hand, several authors have suggested that failure of talocalcaneal coalition resection is due to the degree of hindfoot valgus present. Wilde and associates found that more than 16 degrees of heel valgus correlated with a poor outcome after resection.10 Luhmann and Schoenecker found no problems with 16 degrees of heel valgus but did find poorer outcomes with resection of talocalcaneal coalitions in patients with more than 21 degrees of heel valgus.16 These authors suggested either a medializing calcaneal osteotomy or a lateral column lengthening along with resection of a talocalcaneal coalition associated with severe hindfoot valgus.
More recently, Kernbach and colleagues advocated a single stage approach with resection of the talocalcaneal coalition and flatfoot reconstruction.17 They reported good results in six cases in three patients.
When a tarsal coalition is associated with severe hindfoot valgus, one must address the valgus either conservatively or surgically if the coalition is going to undergoing resection. Whether this should occur in one stage or in two stages is still open to debate. Overall, the success rates for resection of talocalcaneal coalitions reportedly average about 80 percent.1 Although the success rate of talocalcaneal coalition resection seems to parallel the success rate of calcaneonavicular coalition resection, it is generally considered to be less successful. As with talocalcaneal coalition resection, the primary improvement is a noted reduction in pain.