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目的:通过比较不同椎弓根螺钉固定及骨水泥强化方法在骨质疏松骶骨上的锚定强度,探讨骶骨椎弓根螺钉松动后的理想补救技术。方法:应用11具成人新鲜骶骨标本,经骨密度测试确认为骨质疏松后,在同一骶骨标本上,依次建立5种骶骨螺钉固定模型,A组,单皮质椎弓根螺钉固定(左侧);B组,双皮质椎弓根螺钉固定(右侧);C组,PMMA钉道强化后单皮质椎弓根螺钉固定(建立于A组螺钉拔出后);D组,PMMA钉道强化后侧翼钉固定(右侧);E组,后凸成形技术支持下的PMMA强化后侧翼钉固定(左侧)。应用MTS材料测试机进行轴向拔出测试,记录各种骶骨螺钉固定技术的最大拔出力并进行比较。结果:11具标本的骨密度为0.55～0.79g/cm2,平均0.71±0.08g/cm2。A～E组最大拔出力分别为508±128N、685±126N、846±230N、543±121N和702±144N。A组与D组间无显著性差异(P>0.05),且均显著低于B、C和E组(P<0.05);B组与E组间无显著性差异(P>0.05),但两组的拔出力均显著低于C组(P<0.05)。结论:在骨质疏松患者的骶骨固定中,双皮质骶骨椎弓根钉较单皮质具有更高的锚定强度。骶骨椎弓根钉一旦发生松动,PMMA钉道强化和后凸成形技术支持下的PMMA强化后的侧翼钉固定均可成为理想的补救手段。
OBJECTIVE: To compare the anchoring strength of different pedicle screw fixation and cement augmentation on the sacrum in osteoporosis and to explore the ideal remedy after sacral pedicle screw loosening. METHODS: Eleven adult fresh sacral specimens were obtained. After osteoporosis was confirmed by bone mineral density test, five sacral screw fixation models were established on the same sacrum specimen in turn. Group A, single cortical pedicle screw fixation (left) (Group B), double cortical pedicle screw fixation (right); group C, PMMA pin fixation after monocorticoid pedicle screw fixation (based on group A screw extraction); group D, PMMA pinch enhancement Flank pin fixation (right); Group E, PMMA enhanced posterior wing pin fixation (left) supported by kyphoplasty technique. The MTS material testing machine was used for axial pull-out testing. The maximum pull-out force of various sacral screw fixation techniques was recorded and compared. Results: The BMD of 11 specimens was 0.55-0.79g / cm2 with an average of 0.71 ± 0.08g / cm2. The maximum pull-out forces in groups A to E were 508 ± 128 N, 685 ± 126 N, 846 ± 230 N, 543 ± 121 N and 702 ± 144 N, respectively. There was no significant difference between group A and group D (P> 0.05), and were significantly lower than those of group B, C and E (P <0.05). There was no significant difference between group B and group E (P> 0.05) The pull-out force in both groups was significantly lower than that in C group (P <0.05). CONCLUSION: In sacral fixation of patients with osteoporosis, bicortical sacral pedicle screws have a higher anchoring strength than monoclasts. Once the sacral pedicle screw is loosened, PMMA pinning and PMMA-enhanced side-flap fixation under the support of kyphoplasty may be the ideal remedy.