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Calcaneonavicular Coalition

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Written by: Dr Don Ponnamperuma ā€“ created: 24 September 2025; last modified: 24 September 2025

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Calcaneonavicular Coalition is an abnormal complete or incomplete union between the calcaneus and navicular.[1]

Epidemiology

Tarsal coalitions can be seen in up to 13% of the population and CNC accounts for approximately 53% of them, with the majority of cases being asymptomatic.[2][3] A significant proportion of coalitions may not be identified as they may not be seen on plain x-ray.[4]. Up to 50% of cases may be bilateral, however bilateral symptoms are uncommon.[5]

Pathology

Connections between the calcaneus and navicular may be fibrous (syndesmosis), cartilaginous (synchondrosis) or osseous (synostosis).[4] Normal articulations at the talocalcaneal joint may be distorted in some individuals, with the talar head articulating with the coalition, or with the talar head articulating only with the navicular.[6] Subtalar movement is hindered, altering the biomechanics of the foot, thereby abnormally loading coalition and/or other joints in the foot.[7] During the stance phase, the normal subtalar joint rotates to relative internal rotation, which is then able to accommodate external rotation of the tibia. However, in the presence of a coalition, this internal rotation is hindered, leading to compensation at calcaneocuboidal and talonavicular joints. This leads to a flat foot, with flattening of the longitudinal arch, and forefoot abduction. The peroneal tendons may adapt by shortening and going into spasm, thereby living rise to peroneal spastic flat foot. When a normal foot dorsiflexes, there is a gliding motion of the subtalar joint; with a tarsal coalition this is hindered, which causes the navicular to override the talar head at maximus dorsiflexion, which repeatedly elevates the dorsal joint capsule.[1]

Aetiology

Congenital CNC is by far more common and is thought to be due to a failure of segmentation during embryological development; this is thought to be an autosomal dominant trait with variable penetrance. Acquired CNC can be due to trauma, degenerative changes, surgery, infection and inflammatory arthritis.[8][5]

Presentation

Patients typically present with pain around age 8-12, as the calcaneonavicular joint ossifies; those younger than eight present with foot fatigue, as the coalition is still fibrocartilaginous at that age. The pain is typically diffuse and insidious in onset but may be precipitated by activity or an ankle sprain that is slow to resolve; the patient may also have a history of recurrent ankle sprains. In some patients, the pain can be localised to the sinus tarsi.[7][1] There can also be a valgus hindfoot and decreased subtalar motion, but this can subtle.[9] Examination may reinforce decreased subtalar motion; placing a supination force on the foot by elevating the medial border of the foot may demonstrate a failure to correct a hindfoot valgus, indicating that the hindfoot is no longer mobile; patients may also demonstrate difficulty in walking on the lateral borders of the foot.[1]

Management

The initial investigation is plain x-ray; an oblique view may directly visualise the calcaneonavicular bar, while an anterior-posterior view may demonstrate a broad proximal navicular and tapering of the lateral navicular in addition to the calcaneonavicular bar seen on oblique view.[10] Lateral views may demonstrate the anteater sign and reverse anteater sign; the former is an elongation of the superior portion of the anterior process of calcaneus, approaching or contacting the navicular. The reverse anteater sign is an elongation of the lateral navicular.[11] A talar beak may also be observed in the lateral view; this occurs due to repeated lifting of the periosteum at the talonavicular ligament, due to altered biomechanics, leading to healing by ossification, but this may also be seen in other tarsal coalitions disorders, occurring with greater frequency in talocalcaneal coalitions.[5][1] CT scanning is the modality of choice for complete imaging of synostoses, while MRI is suitable for synchondroses or syndesmoses.[5][4][12]. SPECT-CT can be used to delineate pain generators in the foot, in particular whether sites other the coalition may be a pain generator. As such, SPECT-CT may have greatest utility in planning treatment (van der Bruggen et al., 2022).

Initial management of a symptomatic patient is rest and NSAIDs, aiming to reduce inflammation in any affected subtalar joints. Orthoses may address altered biomechanics but can also alter subtalar joint movements necessary for normal gait. Additionally, orthoses may need to be worn for 36 months for effective pain relief. Immobilisation with short leg cast or a walking boot for 3-8 weeks may also improve pain and decrease the risk of progressing onto surgery.[5][13][14]. To date, here has been no significant studies examining the role of corticosteroids in treating CNC. Surgery is reserved for those who failed conservative management; first line surgery is resection of the coalition as a block, with or without interposition of the extensor digitorum brevis tendon, with case series reporting success rates of 77-83%. Arthrodesis is reserved for those who fail resection surgery of the CNC, and this may be arthrodesis of only the affected subtalar joints, or fusion of several subtalar joint.[15][16][1]

References

  1. ā†‘ 1.0 1.1 1.2 1.3 1.4 1.5 Zaw, Htwe; Calder, James D.F. (2010-06). "Tarsal Coalitions". Foot and Ankle Clinics. 15 (2): 349ā€“364. doi:10.1016/j.fcl.2010.02.003. ISSN 1083-7515. Check date values in: |date= (help)
  2. ā†‘ Knƶrr, J.; Accadbled, F.; Abid, A.; Darodes, P.; Torres, A.; Cahuzac, J.-P.; Sales de Gauzy, J. (2011-09). "Arthroscopic treatment of calcaneonavicular coalition in children". Orthopaedics & Traumatology: Surgery & Research. 97 (5): 565ā€“568. doi:10.1016/j.otsr.2011.03.017. ISSN 1877-0568. Check date values in: |date= (help)
  3. ā†‘ RĆ¼hli, F.J.; Solomon, L.B.; Henneberg, M. (2003-09). "High prevalence of tarsal coalitions and tarsal joint variants in a recent cadaver sample and its possible significance". Clinical Anatomy (in English). 16 (5): 411ā€“415. doi:10.1002/ca.10146. ISSN 0897-3806. Check date values in: |date= (help)
  4. ā†‘ 4.0 4.1 4.2 Nalaboff, Kenneth M.; Schweitzer, Mark E. (2008). "MRI of tarsal coalition: frequency, distribution, and innovative signs". Bulletin of the NYU hospital for joint diseases. 66 (1): 14ā€“21. ISSN 1936-9719. PMID 18333823.
  5. ā†‘ 5.0 5.1 5.2 5.3 5.4 Lawrence, David A.; Rolen, Michael F.; Haims, Andrew H.; Zayour, Zakaria; Moukaddam, Hicham A. (2014-07). "Tarsal Coalitions: Radiographic, CT, and MR Imaging Findings". HSS JournalĀ®: The Musculoskeletal Journal of Hospital for Special Surgery (in English). 10 (2): 153ā€“166. doi:10.1007/s11420-013-9379-z. ISSN 1556-3316. Check date values in: |date= (help)
  6. ā†‘ Cooperman, Daniel R.; Janke, Bruce E.; Gilmore, Allison; Latimer, Bruce M.; Brinker, Mark R.; Thompson, George H. (2001-09). "A Three-Dimensional Study of Calcaneonavicular Tarsal Coalitions". Journal of Pediatric Orthopaedics (in English). 21 (5): 648ā€“651. doi:10.1097/01241398-200109000-00018. ISSN 0271-6798. Check date values in: |date= (help)
  7. ā†‘ 7.0 7.1 Olney, B. (2009). Tarsal Coalition. In Drennanā€™s The Childā€™s Foot and Ankle (pp.160ā€“171). Lippincott, Williams & Wilkins.
  8. ā†‘ "Tarsal coalition : Current Opinion in Pediatrics". LWW (in English). Retrieved 2025-09-24.
  9. ā†‘ Stuecker, Ralf D.; Bennett, James T. (1993-11). "Tarsal Coalition Presenting As A Pes Cavo-Varus Deformity: Report Of Three Cases and Review Of the Literature". Foot & Ankle (in English). 14 (9): 540ā€“544. doi:10.1177/107110079301400911. ISSN 0198-0211. Check date values in: |date= (help)
  10. ā†‘ Crim, Julia R.; Kjeldsberg, Kristina M. (2004-02). "Radiographic Diagnosis of Tarsal Coalition". American Journal of Roentgenology (in English). 182 (2): 323ā€“328. doi:10.2214/ajr.182.2.1820323. ISSN 0361-803X. Check date values in: |date= (help)
  11. ā†‘ Ridley, Lloyd J; Han, Jason; Ridley, William E; Xiang, Hao (2018-10). "Anteater nose and reverse anteater signs: Calcaneoā€navicular coalition". Journal of Medical Imaging and Radiation Oncology (in English). 62 (S1): 118ā€“119. doi:10.1111/1754-9485.01_12786. ISSN 1754-9477. Check date values in: |date= (help)
  12. ā†‘ Newman, Joel S.; Newberg, Arthur H. (2000-03). "Congenital Tarsal Coalition: Multimodality Evaluation with Emphasis on CT and MR Imaging: (CME available in print version and on RSNA Link)". RadioGraphics (in English). 20 (2): 321ā€“332. doi:10.1148/radiographics.20.2.g00mc03321. ISSN 0271-5333. Check date values in: |date= (help)
  13. ā†‘ Shirley, E., Gheorghe, R., & Neal, K. M. (2018). Results of Nonoperative Treatment for Symptomatic Tarsal Coalitions. Cureus, 10(7). https://doi.org/10.7759/cureus.2944
  14. ā†‘ Kurman, Kathleen; Romanelli, Andrew (2021 Dec). "Calcaneonavicular coalition: a case study of non-operative management in an adult patient". The Journal of the Canadian Chiropractic Association (in English). 65 (3): 350. PMID 35197650. Check date values in: |date= (help)
  15. ā†‘ Cohen, Bruce E.; Davis, W. Hodges; Anderson, Robert B. (1996-09). "Success of Calcaneonavicular Coalition Resection in the Adult Population". Foot & Ankle International (in English). 17 (9): 569ā€“572. doi:10.1177/107110079601700912. ISSN 1071-1007. Check date values in: |date= (help)
  16. ā†‘ Gonzalez, P; Kumar, S J (1990-01). "Calcaneonavicular coalition treated by resection and interposition of the extensor digitorum brevis muscle". The Journal of Bone & Joint Surgery. 72 (1): 71ā€“77. doi:10.2106/00004623-199072010-00012. ISSN 0021-9355. Check date values in: |date= (help)
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