Bone strength of the proximal femur in healthy subjects with ossification of the posterior longitudinal ligament.

ABSTRACT

We compared the bone strength measured via quantitative computed tomography-based finite element method (QCT/FEM) between healthy adults with and without ossification of the posterior longitudinal ligament (OPLL). No statistically significant difference was observed in the bone strength between healthy adults with and without OPLL. Hyperostosis of the posterior longitudinal ligament in OPLL may not be associated with the systemic bone strength. INTRODUCTION: Although patients with OPLL have been reportedly associated with increased level of bone mineral density (BMD) using dual-energy X-ray absorptiometry (DXA), little is known about the bone strength in OPLL subjects. The aim of this study is to investigate the bone strength measured via QCT/FEM in healthy subjects with OPLL using the medical check-up data, including whole-body CT scans. METHODS: We examined 796 participants (529 men and 267 women) who underwent CT scans in a single health center between January 2008 and May 2009. We identified OPLL in whole spine and divided the subjects into two groups non-OPLL and OPLL groups. We calculated the predicted bone strength (PBS) of the proximal femur using QCT/FEM and examined the bone mineral status of the calcaneus using quantitative ultrasound (QUS). We compared the PBS and the QUS parameters between the non-OPLL and OPLL groups. RESULTS: Seventy-four subjects (9.3%; 57 men and 17 women) were diagnosed with OPLL in the whole spine. The OPLL group was significantly older than the non-OPLL group. No statistically significant difference was observed in the PBS and the QUS parameters between the non-OPLL and OPLL groups in both sexes. Furthermore, no statistically significant difference was noted in the PBS and the QUS parameters between two groups in age- and gender-matched analysis. CONCLUSIONS: Our results suggest that hyperostosis of the posterior longitudinal ligament in OPLL may not be associated with bone strength and bone mineral status at the extremities.