Ověření pevnosti transpedikulárních šroubů - experimentální práce
| Title in English | Comparison of the Pull-out Strength of Pedicular Screws – A Biomechanical Study |
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| Authors | |
| Year of publication | 2018 |
| Type | Conference abstract |
| MU Faculty or unit | |
| Citation | |
| Description | Purpose: Pedicular screw fixation is the most common method of spinal stabilization. However, the vertebrae with reduced bone quality (osteopenia, osteoporosis) offer poor support to the pedicular screws, which is associated with a greater risk of instrumentation instability or even failure. We aimed to compare various types of screws from the perspective of their construct stability, assessed as pull-out strength. Methods: We have compared four types of pedicular screws: 5x50mm, 6x50mm, cement-augmented 6.5x50mm and 6.5x50mm expandable screws, each in 5 replicates. Screws were transpedicularly inserted into the porcine vertebrae and, where applicable, cement augmented or expanded. The screw positions were verified by CT. Subsequently, pull-out tests were performed. The results were statistically evaluated by ANOVA and the correlation between the screw pull-out strength and the size of the pedicle was investigated. Results: No significant difference was found between screws with 5mm and 6mm diameter (Favg = 898±189,7 resp. 1073±176) The same was true about the difference between cement-augmented and expandable (Favg = 1610±192,7 resp. 1704±101,1). The difference between 6mm and expandable or augmented screws ( Favg= 1073±176, 1704±101,1 and 1610±192,7 respectively) as well as that between 5mm screws and both expandable and cement-augmented screws ( Favg = 898±189,7 , , 1704±101,1 and 1610±192,7 respectively) was however statistically significant at the level of P<0.05. Conclusion: In our experiment, expandable and cemented screws yielded the highest pull-out strength. The results suggest that their use should be considered as preferable in older patients with an inferior quality of the bone tissue as a prevention of repeated surgery. |