Study Guide

Tarsal Coaltion

Key Points:

Description:

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)

Epidemiology:

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)

Treatment:

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.

Complications:

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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References:

  1. Cowell HR. Talocalcaneal coalition and new causes of peroneal spastic flatfoot. Clin Orthop Relat Res. 1972; 85: 16-22.
  2. Emery KH, Bisset GS, Johnson ND, et al.  Tarsal coalition: a blinded comparison of MRI and CT.  Pediatr Radiol.  1998; 28(8): 612-6.
  3. Gonzalez P, Kumar SJ.  Calcaneonavicular coalition treated by resection and interposition of the extensor digitorum brevis muscle.  J Bone Joint Surg Am.  1990; 72(1): 71-7.
  4. Harris RI, Beath T.  Etiology of peroneal spastic flat foot.  J Bone Joint Surg Br.  1948; 30: 624-34.
  5. Khoshbin A, Law PW, Caspi L, Wright JG: Long-term functional outcomes of resected tarsal coalitions. Foot Ankle Int 2013;34(10):1370-1375.
  6. Leonard, MA.  The inheritance of tarsal coalition and its relationship to spastic flat foot.  J Bone Joint Surg Br.  1974; 56: 520-526.
  7. Luhmann SJ, Schonecker PL.  Symptomatic talocalcaneal coalition resection: indications and results.  J Pediatr Orthop.  1998; 18: 748-54.
  8. Mosca VS, Bevan WP.  Talocalcaneal tarsal coalitions and the calcaneal lengthening osteotomy: the role of deformity correction.  J Bone Joint Surg Am.  2012; 94(17):1584-94.
  9. Mitchell GP, Gibson JM.  Excision of calcaneo-navicular bar for painful spasmodic flat foot.  J Bone Joint Surg Br.  1967; 49(2): 281-7.
  10. Olney BW, Asher MA.  Excision of symptomatic coalition of the middle facet of the talocalcaneal joint.  J Bone Joint Surg Am.  1987; 69(4): 539-44.
  11. R?hli FJ, Solomon LB, Henneberg M.  High prevalence of tarsal coalitions in tarsal joint variants in a recent cadaver sample an its possible significance.  Clin Anat.  2003; 16: 411-5.
  12. Scranton PE.  Treatment of symptomatic talocalcaneal coalition.  J Bon Joint Surg Am. 1987; 69(4): 533-9.
  13. Smith RW, Staple TW.  Computerized tomography (CT) scanning technique for the hindfoot.  Clin Orthop.  1983; 177: 34-38.
  14. Swiontkowski MF, Scranton PE, Hansen S.  Tarsal coalitions: Long-term results of surgical treatment.  J Pediatr Orthop.  1983; 3(3): 287-92.  
  15. Vincent KA.  Tarsal coalition and painful flatfoot.  J Am Acad Orthop Surg.  1998; 6: 274-281.
  16. Warren MJ, et al.  Computed tomography in suspected tarsal coalition.  Examination of 26 cases.  Acta Orthop Scand.  1990; 61(6): 544-7.
  17. Wilde PH, Torode IP, Dickens DR, Cole WG.  Resection for symptomatic talocalcaneal coalition.  J Bone Joint Surg Br.  1994; 76(5): 797-801.

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Jennifer Bauer, MD
Jeff Martus, MD