Stability difference of varied doses of polymethylmethacrylate reinforced anchor in osteoporotic bone module
DONG Yilong1, QIAN Yuenan2, ZHANG Xia2, LI Yimin1, CAI Chunyuan1, LIU Liangle1
1.Department of Orthopaedics, the Third Affiliated Hospital of Wenzhou Medical University, Wenzhou 325200,China; 2.Department of Ultrasonography, the Third Affiliated Hospital of Wenzhou Medical University, Wenzhou 325200, China
DONG Yilong,QIAN Yuenan,ZHANG Xia, et al. Stability difference of varied doses of polymethylmethacrylate reinforced anchor in osteoporotic bone module[J]. JOURNAL OF WEZHOU MEDICAL UNIVERSITY, 2021, 51(11): 912-916.
Abstract：Objective: To compare the anchor stability strengthened by polymethylmethacrylate (PMMA) with varied doses in osteoporotic bone modules and analyze the correlation between anchor stability and PMMA dose, and then, to find the optimal PMMA cement injection dose. Methods: Thirty-six osteoporotic bone modules were randomly divided into 6 experimental groups (A-F, n=6): group A (blank group), which was directly screwed into the anchor; group B-F, through injector push rod, were injected respectively with an accurate dose of 0.5, 1.0, 1.5, 2.0, and 2.5 mL PMMA bone cement into the screw channel. Then, X-ray examination was performed after the cement was hardened, followed by the observation of the bone cement distribution around the screw. Mechanical experiments were performed to measure the maximum axial pullout force (Fmax) and the destruction of the module observed. Results: The Fmax of group A-F was (145.50±23.82)N, (188.67±34.90)N,(234.00±21.14)N, (296.80±18.55)N, (445.00±33.72)N and (458.60±25.54)N, respectively, with significant statistical difference between the groups (F=143.020, P<0.001). There was positive correlation between Fmax and PMMA dose (0-2 mL, Pearson correlation coefficient (r=0.948, P<0.05). The modules in all groups were damaged to varying degrees after anchor pullout. The damage degree of the module from group A to group E was gradually aggravated, while the module’s damage for E and F was nearly the same. Conclusion: PMMA can significantly improve the anchor stability in osteoporotic bone modules, and the stability of anchors increases with the increase of PMMA dose among 0-2 mL. The recommended dose of PMMA in clinical practice is 2.0 mL.
