Odontoid fracture with missed diagnosis of Transverse Atlantal Ligament (TAL) injury resulting in late-onset instability

Abstract

Background: Concurrent injuries to both the odontoid and transverse atlantal ligament are rare and can be easily missed. Failure to diagnose both lesions potentially leads to the late onset of sagittal plane instability and acute myelopathy. Here, we present a patient with an odontoid fracture whose transverse atlantal ligament (TAL) injury was originally missed on magnetic resonance imaging (MRI) and computed tomography (CT) scans. He later developed atlantoaxial instability requiring surgery.

Case description: A 17-year-old male presented with neck pain, restricted cervical range of motion, but a normal neurological exam following a motor vehicle accident. The original X-rays showed a moderately displaced type-3 odontoid fracture. Additional MRI and CT scans excluded ligamentous injury, and he was initially treated with 13 weeks of halo vest immobilization. Radiographs 5 months later showed an enlarged atlanto-dens interval (e.g., >3 mm); the diagnosis of an odontoid fracture with an accompanying TAL injury was established, following which the patient successfully underwent a posterior C1-C2 fusion.

Conclusion: Odontoid fractures require strict clinical and radiographic (X-ray, MRI, CT) surveillance to help rule out accompanying TAL injuries that may warrant surgical intervention.

Keywords: Atlantoaxial instability; odontoid; transverse atlantal ligament injury.

Figure 1

(a) Lateral radiograph showing moderately displaced odontoid fracture. (b and c) T2-weighted sagittal and axial MRI scans with no evidence of TAL injury

Figure 2

Preoperative CT scan showing fracture pattern

Figure 3

(a) Acceptable fracture reduction achieved after closed reduction in halo vest. (b) 4 weeks follow-up with well-aligned fracture

Figure 4

(a) Follow-up at 10 weeks. (b) Follow-up at 13 weeks

Figure 5

(a) At 17 weeks, slightly increased ADI (3.18 mm) with C2–C6 cervical kyphosis of 33°. (b) At 5 months, large ADI of 9.18 mm showing frank instability

Figure 6

(a) Postoperative AP and lateral radiographs after posterior fusion with sublaminar wiring and iliac crest bone graft. (b) 6 months follow-up AP and lateral radiographs showing fusion and C2–C6 cervical kyphosis of 41°. (c) 2 years follow-up showing resolution of some of kyphosis