Influence of cancellous bone quality on load-sharing in human lumbar spine. A finite element analysis.

Objective: Different parts of the human spine have to accomplish different functions. But little is known about the exact distribution of forces withi n the spine and whether this is influenced by bone quality. The purpose of this study was to predict fields and extent of greatest load in compression in a human lumbar spine motion segment using a finite element model. Metho ds: A three-dimensional isothrophic finite element model was generated: usi ng the software ANSYS 5.4. Spinal loading was performed in axial compressio n (600 N). The model was validated by biomechanical analysis using 12 human spinal segments that were loaded with the same forces. Prediction was done with different E-modulus for cancellous bone, representing a wide range of bone:quality between osteoporotic and strong bone quality. Results: Load-s haring was influenced by bone quality: the weaker bone quality is, the high er is the extent of load that is passed through the posterior part of the s pine. Conclusion: This finite element model predicts that load-sharing in a lumbar spine segment With decreased bone mineral density is different from that in healthy segments. A decrease of bone mineral density ii resulting in an increase of load that is passed through the posterior part of the lum bar spine. Keeping in mind the simplifications of this model, the results m ay influence surgical treatment of patients suffering from osteoporosis or osteolytic destructions of the lumbar spine.