Nature or nurture: a latent ossification of the posterior longitudinal ligament after atlantoaxial fusion. Illustrative case

BACKGROUND: The natural history of ossification of the posterior longitudinal ligament (OPLL) remains poorly understood and multiple etiologies have been reported. However, most have focused on the characteristics of the patient rather than alternation of mechanical stress after spinal fusion. OBSERVATIONS: This report describes, for the first time, a de novo OPLL found at the subaxial cervical spine 7 years after an atlantoaxial fusion surgery. A 57-year-old female initially required atlantoaxial arthrodesis for os odontoideum and stenosis that caused myelopathy. The posterior fusion surgery went smoothly without complications and the patient had good recovery of neurological functions. There was no associated instability, trauma, or reoperations during the follow-up. Seven years later, the patient presented with slight neck pain and a newly developed OPLL at C3–4 caudal to the C1–2 fusion construct. LESSONS: Conflicting with the conventional concept that OPLL is common in elderly men with genetic or hormonal factors, or associated spondyloarthropathies, OPLL could develop in women even after solid C1–2 fusion. The adjacent subaxial cervical spine is not free of risks for subsequent development of OPLL and cervical spondylotic myelopathy. This case illustration extends the scope of etiologies of OPLL within the present literature.