Regional variations in the intra- and intervertebral trabecular microarchitecture of the osteoporotic axial skeleton.

Trabecular structures in vertebral bodies are unequally distributed in the cervical, thoracic and lumbar spine, and also within individual vertebrae. Knowledge of the microstructure of these entities could influence our comprehension and treatment of osteoporotic fractures, and even surgical procedures. Appropriate investigations may clarify the pathomechanisms of various osteoporotic fractures (fish, wedge-shaped, and flat vertebrae). We obtained three cancellous bone cylinders from the centers and margins of cervical vertebra 3 to lumbar vertebra 5, and investigated these in regard of bone volume fraction, trabecular thickness, separation, trabecular number, trabecular bone pattern factor, connectivity density, and degree of anisotropy. Using a Jamshidi needle®, we obtained samples from three quadrants (QI: right-sided edge, QII: central, QIII: left-sided edge) of 242 prepared vertebrae, and investigated these on a micro-CT device. In all, 726 bone samples were taken from eleven body donors. Bone volume fraction, trabecular thickness, and the degree of anisotropy were significantly lower in QII than in QI and QIII. Trabecular pattern factor, however, was significantly higher in QII than in QI and QIII. The results helped to explain fish vertebrae. Wedge fractures and flat vertebrae are most likely caused by the complex destruction of trabecular and cortical structures. The higher bone volume fraction in the cervical spine compared to the thoracic and lumbar spine accounts for the small number of fractures in the cervical spine. The marked trabecular pattern factor in the center of thoracic and lumbar vertebrae could be a reason for the surgeon to use different screw designs for individual vertebrae.

Why Insufficiency Fractures are Rarely Found in the Cervical Spine, Even with Osteoporosis. / Warum sich in der Halswirbelsäule auch bei Osteoporose nur selten Insuffizienzfrakturen finden.

INTRODUCTION: The human bone structure changes with an increase in age. Both material and structural properties affect bone strength. Despite the ageing of society, however, hardly any data are available on these parameters for elderly individuals. Therefore, in the present study, cancellous bone cylinders were taken from the center of each vertebral body (C3 to L5) and examined with regard to bone volume fraction, trabecular thickness, separation, number of trabeculae, cross-linking, connectivity density and degree of anisotropy. MATERIAL AND METHODS: Samples were obtained from 440 body donors using a Jamshidi needle and analysed using microcomputed tomography. Existing deformities, fractures and bone mineral density of each vertebra were recorded by quantitative computed tomography. RESULTS: With regard to the microcomputed tomography parameters, statistically significant differences were found between the different sections of the vertebrae: the trabeculae of the cervical vertebrae were significantly thicker and more closely spaced than in the thoracic and lumbar vertebrae. The bone volume fraction was significantly higher in this spinal segment, as was the connection density and the number of trabeculae and cross-links. In addition, the degree of anisotropy was significantly lower in the cervical vertebrae than in the other spinal segments. With regard to quantitative computed tomography, there was a significantly higher bone mineral density in the cervical vertebrae. CONCLUSION: Even with osteoporosis, cervical vertebrae fracture significantly later than thoracic and lumbar vertebrae due to their unique microarchitecture and higher density. Thus, the cervical vertebrae has specific properties.