Tarsal Coaltion

Key Points:


Tarsal coalitions are a spectrum of fibrous, cartilaginous, and/or ossified anomalous connections between two bones of the foot, almost always between the anterior calcaneal process and the navicular (calcaneonavicular), or the talus and calcaneus (talocalcaneal).  While the condition has been referred to as a “peroneal spastic flatfoot” because of the commonly associated valgus hindfoot and lateral sided pain, symptoms are caused by the fixed structural deformity rather than spasticity. (Swiontkowski, 1983; Harris, 1948)


The reported prevalence of tarsal coalitions ranges from less than 1% - 12.9%. (Harris, 1948; Vincent, 1998; R?hli, 2003) The wide variation may be due in part to the fact that the majority of coalitions are asymptomatic - up to 76% in one study. (Leonard, 1974) The highest published rates are from cadaveric studies.  Up to 80% of coalitions are calcaneonavicular and 20% talocalcaneal. (R?hli, 2003)

Clinical Findings:

The average age of onset of symptoms from tarsal coalitions is between 8 and 13 years. (Swiontkowski, 1983; Harris, 1948; Mitchell, 1967) Children complain of lateral foot pain.  Exam reveals a valgus hindfoot often rigid with toe rise, decreased subtalar motion, and pain with inversion along the peroneal tendons, which may be tight. (Swiontkowski, 1983; Vincent, 1998) The reduced subtalar motion causes adjacent joints to bear abnormal stress which can lead to arthrosis, particularly in the posterior talocalcaneal facet. (Vincent, 1998) 

Imaging Studies:

For calcaneonavicular coalitions, a 45-degree oblique lateral radiograph is often diagnostic, revealing the direct osseous connection or an elongated calcaneal process suggestive of fibrous coalition also called an anteater sign. (Vincent, 1998) A lateral foot xray is helpful in identifying a subtalar coalition.  A “C” sign is often described at the hindfoot.  For all coalitions that will be undergoing operative intervention, the gold standard has been CT scan. (Vincent, 1998; Smith, 1983; Warren, 1990)  CT scans are used to quantify subtalar coalitions and evaluate the foot for other coalitions.  CT arthrograms and MRI have not demonstrated greater sensitivity. (Warren, 1990; Emery, 1998) Dorsal talar beaking is a classic radiographic finding associated with tarsal coalition.  This finding may be related to compensatory excessive talonavicular motion, which then elevates the adjacent talar neck periosteum. (Cowell, 1972)


Symptomatic coalitions are often first treated by a period of cast immobilization for 2-4 weeks, followed by use of an orthosis. Persistent symptoms despite non-operative measures may lead to operative treatment.  Calcaneonavicular coalitions are treated by resection with either fat graft and/or extensor digitorum brevis interposition. (Swiontkowski, 1983; Vincent, 1998; Mitchell, 1967; Gonzalez, 1990) 

Talocalcaneal coalition recommendations are based on the percent of involvement of the facet joint within the coalition, as judged on CT.  Traditionally, greater than 50% posterior facet involvement was an indication for arthrodesis rather than resection; (Vincent, 1998; Scranton, 1987; Luhmann, 1998) with additional criteria to recommend fusion over resection including hindfoot valgus >16-21 degrees, and posterior talocalcaneal facet degeneration. (Wilde, 1994; Luhmann, 1998) However, the long term outcomes in function and patient satisfaction have been reported to be similar for talocalcacaneal coalition resections even when greater than 50% of the posterior facet is involved and there is hindfoot valgus of more than 16 degrees. (Khoshbin, 2013) A third option for those talocalcaneal coalitions not meeting resection criteria is calcaneal lengthening osteotomy, with or without coalition resection; this has had positive results in at least one small series. (Mosca, 2012) Addressing the associated foot deformity may be one of the more critical interventions in the operative treatment of this condition.  For either type of coalition, the salvage procedure is a triple arthrodesis.


Calcaneonavicular coalition resection can fail by recurrence in up to one third of patients when EDB interposition is not used, (Vincent, 1998; Mitchell, 1967) and by pain if there is already degenerative change present on radiographs at time of surgery. (Swiontkowski, 1983; Gonzalez, 1990) However, up to 77% report good to excellent results. (Gonzalez, 1990) Calcaneonavicular surgery is most successful in cartilaginous coalitions and in those younger than 16 years. (Gonzalez, 1990) Failure rates in talocalcaneal treatment range anywhere from 0-20% depending on the procedure used and the corresponding amount of facet involvement, valgus, and posterior facet degeneration.  (Scranton, 1987; Luhmann, 1998; Wilde, 1994; Mosca, 2012; Olney, 1987)

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Jennifer Bauer, MD
Jeff Martus, MD