Cupid's bow contour of the vertebral body: Evaluation of pathogenesis with bone densitometry and imaging-histopathologic correlation

PURPOSE: To investigate the Cupid's bow contour by means of bone densitome try and imaging-histopathologic correlation. MATERIALS AND METHODS: Radiographs and histologic slices were obtained in 64 cadaveric thoracolumbar spines to assess the morphology, distribution, and histopathologic features of the Cupid's bow contour. Dual-energy x-ray absorptiometry and radiography were performed in the lumbar spine in 406 healthy subjects. Bone density and body height and weight were then related to the presence of the Cupid's bow contour. The Cupid's bow contour was compared with the fish vertebra of osteoporosis and Schmorl node. RESULTS: No clinically important relationship was found between lumbar bone density, body height and weight, and prevalence of the Cupid's bow contour. Histologic examination showed thickened bone in the Cupid's bow end plate with annular fibers inserting into this region. In cadavers, the Cupid's bow contour occurred at multiple lumbar and thoracic levels, with the highest frequency in the lower lumbar spine. Lateral radiographs enabled better detection of the contour change. CONCLUSION: The Cupid's bow deformity is a developmental phenomenon that is unrelated to osteopenia or mechanical stress on the spine.