Biomechanical Evaluation of Occipital Fixation
| Autor: | James J. Stone, Panayiotis J. Papagelopoulos, Dean R. Fisher, Kai Nan An, John J. Grabowski, Dirk R. Larson, Bradford L. Currier |
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| Rok vydání: | 2000 |
| Předmět: |
Adult
Male musculoskeletal diseases Bone density Bone Screws Absorptiometry Photon Bone Density Bone plate Cadaver Humans Medicine Aged Fixation (histology) Bone mineral Osteosynthesis business.industry Occipital bone Occiput Equipment Design Anatomy Middle Aged musculoskeletal system Biomechanical Phenomena medicine.anatomical_structure Equipment and Supplies Occipital Bone Female Surgery Neurology (clinical) business Cadaveric spasm Bone Plates |
| Zdroj: | Journal of Spinal Disorders. 13:336-344 |
| ISSN: | 0895-0385 |
| DOI: | 10.1097/00002517-200008000-00011 |
| Popis: | Many studies have shown a positive correlation among screw pullout strength, screw insertional torque, bone thickness, and areal bone mineral density (BMD) measured by dual-energy X-ray absorptiometry. Variations are significant in the anatomy of the occipital bone. But no studies have correlated these variables with respect to the two locations commonly used for plate fixation to the occiput. The purpose of this study was to determine the thickness and quality of the occipital bone and to correlate these variables with the insertional torque of screws and the pullout strength of plates secured into two different locations on the occiput. The occiputs of 12 adult human fresh frozen cadaveric specimens were used. The specimens were analyzed by dual-energy X-ray absorptiometry. Direct thickness measurements of the occiput were performed. Areal and volumetric BMD were measured. A simple pelvic reconstruction plate (3.2 mm) was fixed to the occiput either laterally or at the midline with bicortical 4-mm cancellous screws. Torque was recorded at the time of insertion of each screw. Axial pullout tests were performed on all specimens. The peak load, failure load, stiffness, and energy to failure were recorded for each construct. Statistical analysis showed that the average thickness of occipital bone is greater in the midline than laterally. Occipital bone is thicker and screw torque is greater close to the inion. There is a positive correlation between bone thickness, areal BMD as measured by dual-energy X-ray absorptiometry, screw insertional torque, and strength of fixation. A plate fixed in the midline region of the occiput provides more rigid fixation than a plate fixed laterally. Areal BMD correlates better than volumetric BMD with bone thickness and is a reliable predictor of the strength of occipital fixation. |
| Databáze: | OpenAIRE |
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