Significance of bone formation markers in patients with ossification of the posterior longitudinal ligament of the spine.

STUDY DESIGN: Serum concentrations of bone formation markers were correlated with the type, location, and progression of ossification of the posterior longitudinal ligament. OBJECTIVE: To determine the relation between bone formation markers and ossification of the posterior longitudinal ligament. SUMMARY OF BACKGROUND DATA: Few reports have correlated bone formation markers with ossification of the posterior longitudinal ligament. METHODS: In this study, 43 patients with cervical ossification of the posterior longitudinal ligament and myelopathy underwent laminoplasty. The patients were observed for more than 10 years, after which plain radiographs and tomograms of the cervical region were taken. The radiographs were selectively performed to address thoracic and lumbar ossification of the posterior longitudinal ligament. Serum concentrations of bone formation markers (intact osteocalcin, osteocalcin, carboxyterminal propeptide of human type 1 procollagen, and bone-specific alkaline phosphatase) were measured and correlated with these radiographic studies. RESULTS: A positive correlation was observed between intact osteocalcin, osteocalcin, and carboxyterminal propeptide of human type 1 procollagen in patients with combinations of cervical, thoracic, or lumbar ossification of the posterior longitudinal ligament. CONCLUSIONS: Serum concentrations of intact osteocalcin, osteocalcin, and carboxyterminal propeptide of human type 1 procollagen may reflect the activity of general ectopic bone formation in patients with ossification of the posterior longitudinal ligament.