Introduction
Background
Tarsal coalition is the abnormal union of 2 or more bones in the hindfoot and midfoot. This union may be either complete or incomplete, and the condition may be congenital or acquired secondary to trauma, infection, surgery, or articular disorders. Coalitions can be bony (synostosis), cartilaginous (synchondrosis), or fibrous (syndesmosis).1,2,3,4,5,6
The classification of tarsal coalitions is based on the bones affected. The 2 most common types, calcaneonavicular and talocalcaneal, comprise the majority. Although calcaneocuboid, talonavicular, and cubonavicular tarsal fusions also occur, they are less common.7
See also the following related topics in eMedicine:
Acquired Flatfoot
Foot Infections
Pathophysiology
Congenital, or developmental, coalition appears to represent a failure of primitive mesenchymal differentiation. It is possible for some coalitions to resolve during childhood as a result of weight-bearing biomechanical activity.4
Multiple cases have involved a familial history of tarsal coalition. Results of genetic studies suggest that tarsal coalitions are inherited as an autosomal dominant trait with almost complete penetrance. Variability in the degree of expression definitely occurs, with varying symptoms and degrees of fusion in the relatives of examined patients. The familial historical link becomes more relevant in patients with more significant coalitions.4
Tarsal fusions can be associated with other musculoskeletal conditions such as hand-foot-uterus syndrome, carpal coalition, symphalangism, arthrogryposis, Apert syndrome (acrocephalosyndactyly), and Nievergelt-Pearlman syndrome.
See also the related topic in eMedicine:
Apert Syndrome
Frequency
United States
Most investigators report that tarsal coalition has an incidence of 1% or less. The rate may be higher because patients are commonly asymptomatic and tarsal coalition is incidentally discovered. Therefore, estimating the true incidence in the general population is difficult.8
Bilateral coalitions occur in approximately 50% of cases, and they are most often associated with calcaneonavicular coalition. Talocalcaneal and calcaneonavicular coalitions account for approximately 90% of the cases of tarsal coalition. Disagreement exists regarding the prevalence of the 2 coalitions. While some groups report an almost equal number of each, others report that either talocalcaneal or calcaneonavicular coalition is more common.8
Mortality/Morbidity
Tarsal coalitions are a common cause of spastic peroneal flatfoot. Peroneal muscles may spasm intermittently, causing shortening to adjust for the heel valgus deformity. This effect maintains the foot in the least painful position possible. Attempted inversion can cause a significant amount of discomfort.
Race
No racial predilection exists.
Sex
Most investigators note a slight male predominance.
Age
Patients usually experience symptoms during their second decade of life. Presentations in younger patients are not as common when coalitions are fibrous or cartilaginous. Once ossification of the coalition occurs, the patient may begin experiencing pain due to restrictions in motion.
Anatomy
A total of 7 tarsal bones form the hindfoot and midfoot: the talus and the calcaneus constitute the hindfoot bones; the bones of the midfoot are composed of 5 distal tarsals. The cuneiforms and cuboid align in a row transversely across the midfoot. The navicular bone articulates anteriorly with the 3 cuneiforms and laterally with the cuboid.
A functional subtalar articulation consists of anterior, middle, and posterior facets. The transverse tarsal joint consists of the calcaneocuboid and the talonavicular joints. Biomechanical activities of the subtalar, transverse talar, and ankle joints are linked in such a fashion that limitations of motion at one of the joints can transmit abnormal forces and stressors upon the other joints.
See also the following related topics in eMedicine:
Talus, Fractures
Calcaneus, Fractures
Presentation
Although some patients may be completely asymptomatic, pain is the most common presenting sign of tarsal coalition. Symptoms may begin after a bout of vigorous activity or strain. Limitations of subtalar motion and valgus deformity vary in severity, but talocalcaneal coalitions appear to restrict motion the most.
Physical examination can reveal pes planus, with heel valgus, flattening of the medial longitudinal arch, and pronation of the midfoot. Peroneal spasms are occasionally present. Although some patients respond well to conservative treatment, surgical intervention may be necessary in patients who are symptomatic or in those who have more severe tarsal coalition.
Preferred Examination
Initial evaluation of a patient with suggested tarsal coalition begins with conventional radiography. The acquisition of 3 images includes oblique, anteroposterior (AP), and lateral weight-bearing views of the feet.9,10
Cross-sectional imaging with CT or MRI is advantageous for evaluation of complicated cases of tarsal coalition for preoperative surgical planning. MRI is particularly useful in depicting nonosseous fibrous and cartilaginous coalitions.11,12,13,14
Limitations of Techniques
Virtually all calcaneonavicular coalitions can be evaluated by using plain radiographs, although talocalcaneal coalitions can be difficult to identify on standard radiographs.
Imaging with CT or MRI allows a more precise determination of articular involvement, and these examinations may be necessary for diagnosis. MRI is especially essential in the detection of nonosseous fibrous and cartilaginous coalitions.11,12,13,14
Differential Diagnoses
[Osteoarthritis, Secondary]
Ankylosing Spondylitis
Gout
Osteoarthritis, Primary
Other Problems to Be Considered
Acromegaly
Bone cyst
Iatrogenic subtalar arthrodesis
Osteochondral fracture
Osteochondrodystrophies
Pes planus
Posttraumatic arthritis
Rheumatoid arthritis
Sustentaculum tali malformation
Ankle sprain
Hindfoot or midfoot pain, chronic
See also the following related topics in Medscape:
Arthritis
Gout
Rheumatoid Arthritis
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References
Blakemore LC, Cooperman DR, Thompson GH. The rigid flatfoot. Tarsal coalitions. Clin Podiatr Med Surg. Jul 2000;17(3):531-55. [Medline].
Bohne WH. Tarsal coalition. Curr Opin Pediatr. Feb 2001;13(1):29-35. [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].
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].
Thometz J. Tarsal coalition. Foot Ankle Clin. Mar 2000;5(1):103-18, vi. [Medline].
Teramoto A, Kura H, Uchiyama E, Suzuki D, Yamashita T. Three-Dimensional Analysis of Ankle Instability After Tibiofibular Syndesmosis Injuries: A Biomechanical Experimental Study. Am J Sports Med. Oct 16 2007;[Medline].
Barrett SE, Johnson JE. Progressive bilateral cavovarus deformity: an unusual presentation of calcaneonavicular tarsal coalition. Am J Orthop. May 2004;33(5):239-42. [Medline].
Stormont DM, Peterson HA. The relative incidence of tarsal coalition. Clin Orthop. Dec 1983;(181):28-36. [Medline].
Resnick D. Diagnosis of Bone and Joint Disorders. 3rd ed. Philadelphia: WB Saunders Co;1995:4294-301.
Resnick D. Talar ridges, osteophytes, and beaks: a radiologic commentary. Radiology. May 1984;151(2):329-32. [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].
Hochman M, Reed MH. Features of calcaneonavicular coalition on coronal computed tomography. Skeletal Radiol. Jul 2000;29(7):409-12. [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].
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].
Crim JR, Kjeldsberg KM. Radiographic diagnosis of tarsal coalition. AJR Am J Roentgenol. Feb 2004;182(2):323-8. [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].
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].
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].
Taniguchi A, Tanaka Y, Kadono K, Takakura Y, Kurumatani N. C sign for diagnosis of talocalcaneal coalition. Radiology. Aug 2003;228(2):501-5. [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].
Sijbrandij ES, van Gils AP, de Lange EE, Sijbrandij S. Bone marrow ill-defined hyperintensities with tarsal coalition: MR imaging findings. Eur J Radiol. Jul 2002;43(1):61-5. [Medline].
Goldman AB, Pavlov H, Schneider R. Radionuclide bone scanning in subtalar coalitions: differential considerations. AJR Am J Roentgenol. Mar 1982;138(3):427-32. [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].
Hetsroni I, Ayalon M, Mann G, Meyer G, Nyska M. Walking and running plantar pressure analysis before and after resection of tarsal coalition. Foot Ankle Int. May 2007;28(5):575-80. [Medline].
Lyon R, Liu XC, Cho SJ. Effects of tarsal coalition resection on dynamic plantar pressures and electromyography of lower extremity muscles. J Foot Ankle Surg. Jul-Aug 2005;44(4):252-8. [Medline].
Further Reading
Keywords
flat foot, flatfoot, calcaneonavicular coalition, talocalcaneal coalition, tarsal fusion, spastic peroneal flatfoot, hindfoot, midfoot, bony coalition, synostosis, cartilaginous coalition, synchondrosis, fibrous coalition, syndesmosis
