Clin Orthop Surg.  2014 Mar;6(1):96-100. 10.4055/cios.2014.6.1.96.

Congenital Anomaly of the Atlas Misdiagnosed as Posterior Arch Fracture of the Atlas and Atlantoaxial Subluxation

• Park Y
• Kim SM
• Lee YT
• Yoo JH
• Oh HC
• Ha JW
• Sung SY
• Yoon HK
• Chang JH
• Jung JY

• KMID: 1737637
• DOI: http://doi.org/10.4055/cios.2014.6.1.96

Abstract

Partial or complete absence of the posterior arch of the atlas is a well-documented anomaly but a relatively rare condition. This condition is usually asymptomatic so most are diagnosed incidentally. There have been a few documented cases of congenital defects of the posterior arch of the atlas combined with atlantoaxial subluxation. We report a very rare case of congenital anomaly of the atlas combined with atlantoaxial subluxation, that can be misdiagnosed as posterior arch fracture.

Keyword

Congenital anomaly of the atlas; Posterior arch fracture; Atlantoaxial subluxation

MeSH Terms

Adult
Cervical Atlas/*abnormalities
Diagnosis, Differential
Female
Humans
Spinal Diseases/*diagnosis

Figure

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  Fig. 1 Lateral radiograph of the cervical spine suggested a posterior arch fracture.

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  Fig. 2 Trans-oral anterior-posterior radiograph showing atlantoaxial subluxation (arrow).

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  Fig. 3 Axial computed tomography at the level of C1 showing absent posterior arch of the atlas and atlantoaxial subluxation.

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  Fig. 4 Three-dimensional computed tomography reconstruction showing a defect of the atlas.

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  Fig. 5 T2-weighted magnetic resonance images showing no definite evidence of rupture of alar or transverse ligament and soft tissue swelling.

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  Fig. 6 Whole body bone scans showing normal findings.

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  Fig. 7 Flexion and extension radiographs showing absence of the posterior arch of the atlas without evidence of atlatoaxial instability (arrow).

Reference

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