Hypertrophy of the posterior longitudinal ligament in the thoracic spine

Study design: This is a case report of a patient with hypertrophy of the posterior longitudinal ligament (HPLL) in the thoracic spine. This patient was followed for 10 years after surgery. Objectives: The purpose of this study was to report the long-term outcome of HPLL in the thoracic spine. Setting: Department of orthopedic surgery, Hiroshima Red Cross and Atomic-bomb Survivors Hospital, Hiroshima, Japan. Methods: A 58-year-old-woman with thoracic HPLL was reported. Magnetic resonance image (MRI) and computed tomography (CT) showed the expanded spinal cord compression from Th4 to Th12 due to HPLL. Anterior decompression and fusion (Th10-12) was performed. Histological findings of the surgical specimens showed thickening of the posterior longitudinal ligament with proliferation of chondroid tissue. The clinical outcome and the radiological findings (CT and MRI) were evaluated 10 years after surgery. Results: The patient was asymptomatic postoperatively. However, the subsequent CT examination revealed ossification of the previously hypertrophied posterior longitudinal ligament. Conclusions: HPLL in the thoracic spine is a rare pathological condition causing myelopathy. The results of this study support the hypothesis that HPLL is one of the prodromal conditions of HPLL.