Effect of the Degree of Osteoporosis on the Biomechanical Anchoring Strength of the Sacral Pedicle Screws

• DOI: 10.1097/brs.0b013e3181c5fb21
• Publication Date: 2010-03-25T06:29:21Z
• Authors: Xin-Ming Zhuang; Bin-Sheng Yu; Zhao-Min Zheng; Jia-Fang Zhang; William W. Lu
• Keywords: Lumbosacral joint; Biomechanics

In Brief Study Design. An in vitro laboratory study. Objective. (i) To evaluate the effect of osteoporotic degree determining strength sacral screw fixation and (ii) to compare unaugmented bicortical pedicle polymethylmethacrylate (PMMA) augmented unicortical fixation. Summary Background Data. Screw loosening is a clinical problem lumbosacral fusions, especially patients. improve anchoring sacrum, PMMA techniques are widely used practice. However, biomechanical fixations remains undetermined different degrees osteoporosis. Methods. Twenty-five fresh cadavers were this According value lumbar bone mineral density (BMD) assessed by DEXA, specimens divided into 3 groups: group A (N = 9): BMD 0.7 0.8 g/cm2, B 8): 0.6 C < g/cm2. each specimen, S1 was inserted bicortically on left side, with augmentation unicortically right side sacrum. Following dynamic cyclic loading from 30 250 N head for 2000 cycles, subsidence displacement axial pull-out measured. Results. No failure (defined as exceeding 2 mm within cycles) occurred B. C, 6 cases (75%) 5 (63%) failed during loading. A, no significant difference between detected terms maximal strength. B, significantly less higher demonstrated technique than that Both exhibited lower The maximum statistical not Conclusion. For more 0.70 could obtain sufficient comparable technique. When would be beneficial improving values early may occur both fixations. This study evaluates compares screws screws. results show that, patients provide stronger anchorage