Double Sesamoid Ossicles of the Nuchal Ligament


Generally, the sesamoid bones are ovoid or round bones found embedded within a tendon or joint capsule.
Sesamoid ossicles of the nuchal ligament (ONL) is a type of ossification in the soft tissue posterior to the spinous process of the cervical spine, asymptomatic in the majority of cases, which is usually asymptomatic and observed accidentally on lateral cervical X-ray[1-3].

The incidence of ONL varies geographically, which is higher in Asians, such as Japanese (10.2% – 27.6%) and Koreans (11.3%), whereas lower in Western populations, such as Americans (6.1%) and Germans (4.5%)[4,5].

Case report

A 70-year-old woman was seen due to chronic neck pain over the last two years. There was history of cervical trauma. On physical examination, there was no limitation on cervical range of motion, but there was mild pain on cervical extension.Lateral view X-ray imaging of the cervical spine showed an ossicle within the nuchal ligament at the level of C4-C6 vertebral spinous process.Both ossicles had smooth borders and had nearly ovoid shape.

The possibility of avulsion fractures of the spinal processes were excluded due to absence of any tenderness at the C5 and C6 cervical spine processes and lack of irregular circumference of the lesions.Due to the nature and location of the diffuse pain, the symptoms of chronic neck pain were attributed to cervical spondylosis symptoms


This type of ossifi cation develops after the third decade of life, with its peak at the age of 50-60 years. In 75-81% of cases it is found at the level of C4-C5 or C5-C6. This incidence is 2-3 times greater in males than females[6].

The exact pathogenesis of such ossicles is unknown but is believed that they are classic sesamoid ossicles formed within ligamentous or tendinous structures. The trait may be misdiagnosed as myositis ossificans circumscripta, nuchal fibrocartilaginous pseudotumor, calcinosis circumscripta, Clay-shoveler's fracture, neoplasms, and diseases with concomitant calcification deposition [7-11].




1. Paraskevas GK, Raikos A, Martoglou S, Ioannidis O. Sesamoid ossicles within the nuchal ligament: a report of two cases and review of the literature. J Radiol Case Rep, 2011

2. Gokce E, Beyhan M. Evaluating ossifications of the nuchal ligament with cervical computed tomography. Eurasian J Med, 2018

3. Tsai YL, Weng MC, Chen TW, Hsieh YL, Chen CH, Huang MH. Correlation between the ossification of nuchal ligament and clinical cervical disorders. Kaohsiung J Med Sci, 2012

4. Wang H, Zou F, Jiang J, et al. The correlation between ossification of the nuchal ligament and pathological changes of the cervical spine in patients with cervical spondylosis. Spine, 2014

5. Izawa K. Comparative roentgenographical study on the incidence of ossification of the posterior longitudinal ligament and other degenerative changes of the cervical spine among Japanese, Koreans, Americans and Germans (author’s transl). Nihon Seikeigeka Gakkai Zasshi, 1980

6. Takeshita K, Peterson ET, Bylski-Austrow D, et al. The nuchal ligament restrains cervical spine fl exion.Spine 2004

7. Barsony T, Winkler K. Calcinosis circumscripta ligament nuchaei. Fabella nuchae. Fortschr Rontgens. 1936

8. Kohler A. Grenzen des normalen und anfange des pathologischen im rontgenbilde des skelettes. Stuttgart, Thieme Verlag, 1931

9. Nicoletti GF, Platania N, Cicero S, Furnani M, Albanese V. Nuchal firbrocartilaginous pseudomotor. Case report and review of the literature. J Neurosurg Sci. 2003

10. Ross JS, Brant-Zawadzki M, Moore KR, Crim J, Chen MZ, Katzman GL. Diagnostic imaging-spine. Part II-IV. Salt Lake city, Amirsys ed, 2005.

11. Eisenberg RL. Clinical imaging: An atlas of differential diagnosis. 3rd ed. Philadelphia, Lippincott-Raven, 2000

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