Cervical myelopathy resulting from combined ossification of the ligamentum flavum and posterior longitudinal ligament: report of two cases and literature review

Background contextIn the cervical spine, the combination of ossification of the ligamentum flavum (OLF) and ossification of the posterior longitudinal ligament (OPLL) is rarely seen. There have been only four cases reported in the English literature.PurposeWe describe two more cases that exhibited cervical myelopathy resulting from the combination of cervical OLF and OPLL and required surgery. A literature review with a comparative analysis between previous reports and present cases was also performed.Study designCase report and literature review.Patient sampleTwo patients with combined OLF and OPLL.Outcome measuresPreoperative computed tomography, magnetic resonance imaging, and pathological findings from operative specimens were used to confirm the diagnoses.MethodsA 76-year-old man (Case 1) presented with disturbance of gait and fine finger movement. Magnetic resonance imaging showed severe spinal canal stenosis and cord compression at the C3–C4 level. Computed tomography showed OPLL at the C2–C6 levels (segmental type) and OLF at the left C3–C4 level. The patient underwent posterior decompression and OLF resection. A 75-year-old man (Case 2) presented with sensory disturbance and muscle weakness in his bilateral upper extremities and disturbance in fine finger movements. Magnetic resonance imaging showed severe spinal canal stenosis and cord compression at the C2–C3 and C3 levels. Computed tomography showed OPLL at the C3–C7 levels (mixed type) and OLF at the left C2–C3 and C3 levels. The patient also underwent posterior decompression and OLF resection.ResultsIn both cases, histological examination of the surgical specimens showed osseous tissue and enchondral ossification within the ligamentum flavum, and the diagnosis in each case was OLF. After surgery, both patients' symptoms immediately improved, and no recurrence was observed at 2 years after surgery.ConclusionsWe experienced two cases of cervical myelopathy resulting from the combination of OLF and OPLL in the cervical spine. The symptoms of myelopathy were treated successfully by laminectomy and laminoplasty with OLF resection in both cases. The literature review including the present two cases revealed that cervical OLF tended to occur adjacent or close to the margin of cervical OPLL, suggesting that the increased mechanical stress at the junction of OPLL may be a causative factor.