Imaging Studies
- Plain anteroposterior (AP) and lateral radiographs of the foot are usually not diagnostic but may be suggestive of tarsal coalitions. Classic secondary signs of tarsal coalition are mainly seen in the lateral view. These include talar beaking seen on the anterior talar side of the talonavicular junction, broadening and rounding or flattening of the lateral talar process, and narrowing of the posterior facet. The last 2 are signs of degenerative changes. Any rotation of the foot may result in the appearance of a tarsal pseudocoalition on the lateral view secondary to off-plane view of the subtalar joint facets.
- Some have suggested that the C-sign of Lateur, a C-shaped line composed of the dome of the talus and the inferior outline of the sustentaculum tali, is pathognomonic for subtalar coalition.[25] A study by Sakellariou et al examined lateral radiographs of 20 patients with clinical and radiographic diagnosis of talocalcaneal coalition and compared them to 22 asymptomatic volunteers.[26] CT scans were used as the diagnostic standard. They concluded that the C-sign was highly sensitive and specific for the diagnosis. However, in a retrospective review of 48 patients who had lateral ankle radiographs and CT scans for nontraumatic indications, Brown et al found that the C-sign was specific but not sensitive for a flatfoot deformity and was neither specific nor sensitive for talocalcaneal coalition.[27]
- Calcaneonavicular coalition may be suggested by the presence of the anteater-nose sign on the lateral view corresponding to an elongated anterior calcaneal process.[28] This radiographic sign may be found on the lateral radiograph of patients aged 9 years or older with tarsal coalition. Oblique 45º views of the foot demonstrate a calcaneonavicular coalition 90-100% of the time. Only approximately 10% of the cases demonstrate a frank osseous coalition, with the remainder demonstrating increased proximity of the 2 tarsals, indistinct juxtaposed cortices, hypoplasia of the head of the talus, and flattening or narrowing of the navicular as it approaches the anterior calcaneus process.
- A talocalcaneal coalition is best seen with the Harris-Beath axial or "ski-jump" view. This is taken with the patient standing on the cassette, bending 10º at the ankle. Harris and Beath recommended a 45º beam view originally, but they later expanded their views to beam angles of 30º, 35º, and 45º. Cowell recommended first taking the 45º beam view and then, if the middle and posterior facets are not well visualized, using a standing lateral view to measure the appropriate angle for the axial view.[29] In cases in which the middle and posterior facets are not parallel, 2 different angles would have to be measured and 2 corresponding axial views taken. If a middle facet coalition is present, the coalition is seen on the medial side. If the coalition is osseous, no joint is visualized. If it is fibrous or cartilaginous, the joint appears irregular and angled inferior medial. In normal feet, the middle facet is usually parallel to the posterior facet on axial views.
- In the past, tomograms have been necessary to demonstrate anterior facet coalitions and to confirm the presence of more difficult middle or posterior facet coalitions. Since the mid-1980s, however, coronal CT scans have become the criterion standard in the evaluation of tarsal coalitions.[4] In 1986, Herzenberg et al correlated the use of the coronal CT views to evaluate tarsal coalitions to cadaver specimens. In their study, the patient's feet were placed in a plantar position on the gantry with the CT ring in the neutral position.[12] Other studies have used a special apparatus to dorsiflex the foot and rotate the ring to maintain a coronal axis of the subtalar joint. The advent of high-speed spiral CT scanners and advanced image reconstruction software has prompted some to accept coronal reconstructions of noncoronal CT views, but no study has demonstrated equal diagnostic ability.
- MRIs have been advanced as another tool to evaluate cases of fibrous or cartilaginous coalitions that may not be well seen in CT scans, but no good study has been performed demonstrating significant diagnostic utility over CT scans. Although MRI has been found to be very good at detecting tarsal coalition, CT scanning is still considered to be the criterion standard and to be more cost-effective than MRI.[30]
- Bone scintigraphy has been advanced as a way to confirm suspected coalitions that are not well seen in plain radiographs or as a screening tool. However, the decreasing expense of CT scans and CT scans' ability to depict detail has reduced the utility of scintigraphs.
Histologic Findings
The tissue of a tarsal coalition may be osseous, cartilaginous, or fibrous. Histopathologic analysis of resected nonosseous coalitions has revealed no evidence of neural elements. This absence of nerve tissue argues against the abnormal coalition tissue acting as a primary pain generator. Microfractures and histologic signs of bone remodeling near a coalition's boundary with normal bone have been identified and are likely pain generators via periosteal nerve fibers.
Lemley F, Berlet G, Hill K, Philbin T, Isaac B, Lee T. Current concepts review: Tarsal coalition. Foot Ankle Int. Dec 2006;27(12):1163-9. [Medline].
Petrover D, Schweitzer ME, Laredo JD. Anterior process calcaneal fractures: a systematic evaluation of associated conditions. Skeletal Radiol. Jul 2007;36(7):627-32. [Medline].
Skwara A, Zounta V, Tibesku CO, Fuchs-Winkelmann S, Rosenbaum D. Plantar contact stress and gait analysis after resection of tarsal coalition. Acta Orthop Belg. Oct 2009;75(5):654-60. [Medline].
Upasani VV, Chambers RC, Mubarak SJ. Analysis of calcaneonavicular coalitions using multi-planar three-dimensional computed tomography. J Child Orthop. Aug 2008;2(4):301-7. [Medline]. [Full Text].
Heiple KG, Lovejoy CO. The antiquity of tarsal coalition. Bilateral deformity in a Pre- Columbian Indian skeleton. J Bone Joint Surg Am. Jul 1969;51(5):979-83. [Medline].
Cruveilhier J. Anatomie Pathologique du Corps Humain, tome 1, Paris, J.B. Balliere. 1829.
Badgley CE. Coalition of the calcaneus and the navicular. Arch Surg. 1927;15:75-88.
Harris RI, Beath T. Etiology of peroneal spastic flatfoot. J Bone Joint Surg Br. 1948;30:624-34.
Kirmission E. Double pied bot varus par malformation osseuse primitive associe a des ankyloses congenitales des doigts et des arteils chez quatre membres di' une meme Famille. Rev Orthop. 1998;9:392-8.
Conway JJ, Cowell HR. Tarsal coalition: clinical significance and roentgenographic demonstration. Radiology. Mar 1969;92(4):799-811. [Medline].
Deutsch AL, Resnick D, Campbell G. Computed tomography and bone scintigraphy in the evaluation of tarsal coalition. Radiology. Jul 1982;144(1):137-40. [Medline].
Herzenberg JE, Goldner JL, Martinez S, Silverman PM. Computerized tomography of talocalcaneal tarsal coalition: a clinical and anatomic study. Foot Ankle. Jun 1986;6(6):273-88. [Medline].
Wechsler RJ, Schweitzer ME, Deely DM, et al. Tarsal coalition: depiction and characterization with CT and MR imaging. Radiology. Nov 1994;193(2):447-52. [Medline].
Rankin EA, Baker GI. Rigid flatfoot in the young adult. Clin Orthop. Oct 1974;0(104):244-8. [Medline].
Vaughan WH, Segal G. Tarsal coalitions, special reference to roentogenographic interpretation. Radiology. 1953;60:855-63.
Shands AR, Wentz IJ. Congenital anomalies, accessory bones, and osteochondritis in the feet of 850 children. Surg Clin North Am. 1953;33:1643-66.
Leonard MA. The inheritance of tarsal coalition and its relationship to spastic flat foot. J Bone Joint Surg Br. Aug 1974;56B(3):520-6. [Medline].
Snyder RB, Lipscomb AB, Johnston RK. The relationship of tarsal coalitions to ankle sprains in athletes. Am J Sports Med. Sep-Oct 1981;9(5):313-7. [Medline].
Cooperman DR, Janke BE, Gilmore A, et al. A three-dimensional study of calcaneonavicular tarsal coalitions. J Pediatr Orthop. Sep-Oct 2001;21(5):648-51. [Medline].
Stormont DM, Peterson HA. The relative incidence of tarsal coalition. Clin Orthop. Dec 1983;(181):28-36. [Medline].
Jack EA. Bone anomalies of the tarsus in relation to "peroneal spastic flatfoot". J Bone Joint Surg Br. 1954;36:530-42.
Bettin D, Karbowski A, Schwering L. Congenital ball-and-socket anomaly of the ankle. J Pediatr Orthop. Jul-Aug 1996;16(4):492-6. [Medline].
Pistoia F, Ozonoff MB, Wintz P. Ball-and-socket ankle joint. Skeletal Radiol. 1987;16(6):447-51. [Medline].
Takakura Y, Tamai S, Masuhara K. Genesis of the ball-and-socket ankle. J Bone Joint Surg Br. Nov 1986;68(5):834-7. [Medline].
Lateur LM, Van Hoe LR, Van Ghillewe KV, et al. Subtalar coalition: diagnosis with the C sign on lateral radiographs of the ankle. Radiology. Dec 1994;193(3):847-51. [Medline].
Sakellariou A, Sallomi D, Janzen DL, et al. Talocalcaneal coalition. Diagnosis with the C-sign on lateral radiographs of the ankle. J Bone Joint Surg Br. May 2000;82(4):574-8. [Medline].
Brown RR, Rosenberg ZS, Thornhill BA. The C sign: more specific for flatfoot deformity than subtalar coalition. Skeletal Radiol. Feb 2001;30(2):84-7. [Medline].
Oestreich AE, Mize WA, Crawford AH, Morgan RC Jr. The "anteater nose": a direct sign of calcaneonavicular coalition on the lateral radiograph. J Pediatr Orthop. Nov-Dec 1987;7(6):709-11. [Medline].
Cowell HR. Tarsal coalition--review and update. Instr Course Lect. 1982;31:264-71. [Medline].
Nalaboff KM, Schweitzer ME. MRI of tarsal coalition: frequency, distribution, and innovative signs. Bull NYU Hosp Jt Dis. 2008;66(1):14-21. [Medline].
Mubarak SJ, Patel PN, Upasani VV, Moor MA, Wenger DR. Calcaneonavicular coalition: treatment by excision and fat graft. J Pediatr Orthop. Jul-Aug 2009;29(5):418-26. [Medline].
Philbin TM, Homan B, Hill K, Berlet G. Results of resection for middle facet tarsal coalitions in adults. Foot Ankle Spec. Dec 2008;1(6):344-9. [Medline].
Migues A, Slullitel GA, Suárez E, Galán HL. Case reports: symptomatic bilateral talonavicular coalition. Clin Orthop Relat Res. Jan 2009;467(1):288-92. [Medline]. [Full Text].
Comfort TK, Johnson LO. Resection for symptomatic talocalcaneal coalition. J Pediatr Orthop. May-Jun 1998;18(3):283-8. [Medline].
Wilde PH, Torode IP, Dickens DR, Cole WG. Resection for symptomatic talocalcaneal coalition. J Bone Joint Surg Br. Sep 1994;76(5):797-801. [Medline].
Luhmann SJ, Schoenecker PL. Symptomatic talocalcaneal coalition resection: indications and results. J Pediatr Orthop. Nov-Dec 1998;18(6):748-54. [Medline].
Mann RA, Baumgarten M. Subtalar fusion for isolated subtalar disorders. Preliminary report. Clin Orthop. Jan 1988;(226):260-5. [Medline].
Asher MA, Mosher K. Coalition of the talocalcaneal middle facet: treatment by surgical excision and fat graft interposition. Orthop Trans. 1983;7:149-150.
Berman AT, Finn CA, Van Horne J, Fye MA. Answer please. Tarsal coalition. Orthopedics. Aug 1990;13(8):910-1, 915-7. [Medline].
Cowell HR. Diagnosis and management of peroneal spastic flatfoot. Instr Course Lect. 1975;24:94-103.
Cowell HR. Talocalcaneal coalition and new causes of peroneal spastic flatfoot. Clin Orthop. 1972;85:16-22. [Medline].
Cowell HR, Elener V. Rigid painful flatfoot secondary to tarsal coalition. Clin Orthop. Jul-Aug 1983;(177):54-60. [Medline].
Crim JR, Cracchiolo A, Bassett LW, et al. Magnetic resonance imaging of the hindfoot. Foot Ankle. Aug 1989;10(1):1-7. [Medline].
Danielsson LG. Talo-calcaneal coalition treated with resection. J Pediatr Orthop. Sep-Oct 1987;7(5):513-7. [Medline].
Elkus RA. Tarsal coalition in the young athlete. Am J Sports Med. Nov-Dec 1986;14(6):477-80. [Medline].
Emery KH, Bisset GS 3rd, Johnson ND, Nunan PJ. Tarsal coalition: a blinded comparison of MRI and CT. Pediatr Radiol. Aug 1998;28(8):612-6. [Medline].
Gonzalez P, Kumar SJ. Calcaneonavicular coalition treated by resection and interposition of the extensor digitorum brevis muscle. J Bone Joint Surg Am. Jan 1990;72(1):71-7. [Medline].
Graham JM Jr, Braddock SR, Mortier GR, et al. Syndrome of coronal craniosynostosis with brachydactyly and carpal/tarsal coalition due to Pro250Arg mutation in FGFR3 gene. Am J Med Genet. May 26 1998;77(4):322-9. [Medline].
Hark FW. Congenital anomalies of the tarsal bones. Clin Orthop. 1960;16:21-5.
Haygood TM. Magnetic resonance imaging of the musculoskeletal system: part 7. The ankle. Clin Orthop. Mar 1997;(336):318-36. [Medline].
Jacobs AM, Sollecito V, Oloff L, Klein N. Tarsal coalitions: an instructional review. J Foot Surg. Winter 1981;20(4):214-21. [Medline].
Jayakumar S, Cowell HR. Rigid flatfoot. Clin Orthop. Jan-Feb 1977;(122):77-84. [Medline].
Kitaoka HB, Wikenheiser MA, Shaughnessy WJ, An KN. Gait abnormalities following resection of talocalcaneal coalition. J Bone Joint Surg Am. Mar 1997;79(3):369-74. [Medline].
Kulik SA Jr, Clanton TO. Tarsal coalition. Foot Ankle Int. May 1996;17(5):286-96. [Medline].
Kumai T, Takakura Y, Akiyama K, et al. Histopathological study of nonosseous tarsal coalition. Foot Ankle Int. Aug 1998;19(8):525-31. [Medline].
Kumar SJ, Guille JT, Lee MS, Couto JC. Osseous and non-osseous coalition of the middle facet of the talocalcaneal joint. J Bone Joint Surg Am. Apr 1992;74(4):529-35. [Medline].
McCormack TJ, Olney B, Asher M. Talocalcaneal coalition resection: a 10-year follow-up. J Pediatr Orthop. Jan-Feb 1997;17(1):13-5. [Medline].
Morgan RC Jr, Crawford AH. Surgical management of tarsal coalition in adolescent athletes. Foot Ankle. Dec 1986;7(3):183-93. [Medline].
Mosier KM, Asher M. Tarsal coalitions and peroneal spastic flat foot. A review. J Bone Joint Surg Am. Sep 1984;66(7):976-84. [Medline].
Newman JS, Newberg AH. Congenital tarsal coalition: multimodality evaluation with emphasis on CT and MR imaging. Radiographics. Mar-Apr 2000;20(2):321-32; quiz 526-7, 532. [Medline].
Pachuda NM, Lasday SD, Jay RM. Tarsal coalition: etiology, diagnosis, and treatment. J Foot Surg. Sep-Oct 1990;29(5):474-88. [Medline].
Percy EC, Mann DL. Tarsal coalition: a review of the literature and presentation of 13 cases. Foot Ankle. Aug 1988;9(1):40-4. [Medline].
Pineda C, Resnick D, Greenway G. Diagnosis of tarsal coalition with computed tomography. Clin Orthop. Jul 1986;(208):282-8. [Medline].
Plotkin S. Case presentation of calcaneonavicular coalition in monozygotic twins. J Am Podiatr Med Assoc. Sep 1996;86(9):433-8. [Medline].
Resnik CS, Aiken MW, Kenzora JE. Case report 780. Fracture of talar beaks in tarsal coalition. Skeletal Radiol. 1993;22(3):214-7. [Medline].
Sakellariou A, Claridge RJ. Tarsal coalition. Orthopedics. Nov 1999;22(11):1066-73; discussion 1073-4; quiz 10. [Medline].
Smith RW, Staple TW. Computerized tomography (CT) scanning technique for the hindfoot. Clin Orthop. Jul-Aug 1983;(177):34-8. [Medline].
Spero CR, Simon GS, Tornetta P 3rd. Clubfeet and tarsal coalition. J Pediatr Orthop. May-Jun 1994;14(3):372-6. [Medline].
Stoskopf CA, Hernandez RJ, Kelikian A, et al. Evaluation of tarsal coalition by computed tomography. J Pediatr Orthop. May 1984;4(3):365-9. [Medline].
Stuecker RD, Bennett JT. Tarsal coalition presenting as a pes cavo-varus deformity: report of three cases and review of the literature. Foot Ankle. Nov-Dec 1993;14(9):540-4. [Medline].
Sullivan JA. Pediatric flatfoot: evaluation and management. J Am Acad Orthop Surg. Jan 1999;7(1):44-53. [Medline].
Takakura Y, Tanaka Y, Kumai T, Sugimoto K. Development of the ball-and-socket ankle as assessed by radiography and arthrography. A long-term follow-up report. J Bone Joint Surg Br. Nov 1999;81(6):1001-4. [Medline].
Tanaka Y, Takakura Y, Sugimoto K, Kumai T. Non-osseous coalition of the medial cuneiform-first metatarsal joint: a case report. Foot Ankle Int. Dec 2000;21(12):1043-6. [Medline].
Thometz J. Tarsal coalition. Foot Ankle Clin. Mar 2000;5(1):103-18, vi. [Medline].
Varner KE, Michelson JD. Tarsal coalition in adults. Foot Ankle Int. Aug 2000;21(8):669-72. [Medline].
Vincent KA. Tarsal coalition and painful flatfoot. J Am Acad Orthop Surg. Sep-Oct 1998;6(5):274-81. [Medline].
Warren MJ, Jeffree MA, Wilson DJ, MacLarnon JC. Computed tomography in suspected tarsal coalition. Examination of 26 cases. Acta Orthop Scand. Dec 1990;61(6):554-7. [Medline].
Wheeler R, Guevera A, Bleck EE. Tarsal coalitions: review of the literature and case report of bilateral dual calcaneonavicular and talocalcaneal coalitions. Clin Orthop. May 1981;(156):175-7. [Medline].
Wright DG, Desai SM, Henderson WH. Action of the subtalar and ankle-joint complex during the stance phase of walking. J Bone Joint Surg Am. 1964;46:361-82.

