[Effect of spongiosa density on load bearing of the 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 within 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.


METHODS
A three dimensional isotrophic finite element model was generated using the software ANSYS 5.4. Spinal loading was performed in axial compression (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-sharing was influenced by bone quality: the weaker bone quality is, the higher is the extent of load that is passed through the posterior part of the spine.


CONCLUSIONS
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 is resulting in an increase of load that is passed through the posterior part of the lumbar spine. Keeping in mind the simplifications of this model, the results may influence surgical treatment of patients suffering from osteoporosis or osteolytic destructions of the lumbar spine.
Pitzen
T
T
Neurochirurgische Klinik, Universitätskliniken des Saarlandes, Homburg.
Matthis
D
D
Müller-Storz
H
H
Ritz
R
R
Caspar
W
W
Steudel
W I
WI
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D015519:Bone Density / Q000502:physiology*; D003198:Computer Simulation; D005260:Female; D020342:Finite Element Analysis; D006801:Humans; D008159:Lumbar Vertebrae / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D010024:Osteoporosis / Q000503:physiopathology; D012984:Software; D016474:Weight-Bearing / Q000502:physiology*