Variation in Lumbar Vertebral Pedicle Structure with Bone Mineral Density

Introduction: Despite widespread use of pedicles in lumbar spine fixation, relatively little is known regarding variations in pedicle structure particularly in osteoporosis. It is valuable to understand this relationship because pedicles provide an important area for screw fixation and a point of complication when screws penetrate through weak pedicle walls into adjacent structures. Hirano et al. compared DEXA measurements of bone mineral density (BMD) between cadaveric lumbar spines to define groups of normal and osteoporotic spines. The proportion of pedicle cortical to cancellous bone was determined using peripheral quantitative CT. In the osteoporotic group the pedicle cortex represented a smaller proportion of the pedicle on cross-section. Inceoglu et al. used microCT to evaluate lumbar pedicle cancellous structure and suggested that the trabecular thickness may decrease with osteoporosis while the trabecular number remains constant. However, in this study there were no pedicles from osteoporotic lumbar spines. The objective of the present study is to characterize the variation in lumbar pedicle structure and to clarify how pedicle structure is related to lumbar spine and pedicle BMD.