| 1. To determine whether the incorporation of HA in a PMMA matrix would enhance the effect of mechanical as compared to PMMA and CPC.2.To determine the effect of endplate on the distribution structural properties with 10%HA/PMMA vertrbroplasty.3.To compare the biomechanical properties of isolated, fractured osteoporotic vertebral bodies treated by tamp vertebroplasty or injection vertebroplasty.4.To determine the strength and stiffness of cervical vertebral bodies subjected to compression fractures and subsequently stabilized via anterior injection of 10% HA/PMMA cement.5.PMMA has long been in the stabilization and reconstruction of traumatic and pathological fracture of the spine. And now 10%HA/PMMA, an osteoconductive, biocompatible cement, has use as an alternative to PMMA. In this study is to determine the stabilizing effects of 10%HA/PM MA in an experimental compression fraction of Lumbar.Methods.1. PMMA circular cylinder, diameter 10mm and height 9mm,with 0, 10 and 20 % HA, were compressed in a materials test machine to dermine strength and stiffness in one or 24 hour.2.The bony endplates of four intact human osteoporotic disintegrating vertebrae (T12-L5) were tested. Indentation tests were performed at-9-standardized test on the endplate of both contrast normal group and vertebriplasty with 10%HA/PMMA by using a 2.3-mm diameter, hemispherical indenter with a test rate of 0.2 mm/s to a depth of 3 mm. The failure load and stiffness at each site were determined from the load-displacement curves. Repeated measures analyses were used to analyze the resulting data for variation in the anterior-posterior and lateral directions, as well as to determine the effect of vertebroplasty.3.Compression fractures were experimentally created in 4 osteoporotic VBs assigned to either the tamp or vertebroplasty group. The tamp treatment consisted of inserting 6mm drill into pedicle of vertebral body. A diameter 5mm stick raised the endplate, and filling the void with 10%HA/PMMA cement bone .The vertebroplasty treatment consisted of directly injecting 10%HA/PMMA cement into the vertebral body. The repaired vertebral bodies were recompressed to determine post treatment strength and stiffness values.4.Three vertebral bodies (C4-C6) from three fresh spines harvested from adult male cadavers, were disarticulated, and compressed in a materials testing machine to determine initial strength and stiffness. The fractures then were repaired using an anterior injection of 10%HA/PMMA and recrushed to determine post treatment strength and stiffness values.5.Seven T11-L5 cadaveric spinal specimens were mounted individually on test fram. The cubes were placed on the vertebra by a pin. Motion was tracked by 3D digital microscopic laser in response to applied loads of 0 to 8 Nm. The compressive impact technique was used to induce a reproducible compression fracture of L-l after partially coring out the vertebra. Load testing was performed on the intact spine. Postfracture, after bipedicular transpedicular vertebroplasty with 8 ml of 10%HA/PMMA and after flexion-extension fatiguing to 3000 cycles at 5 Nm. Ranges of motion and neutral zones were measured.Results.1. The addition of 10% wt and 20 % HA caused a signigcant decrease in-10-strength about 9.14% and 40%, in stiffness 10.17% and 48.82%. There is no difference between 1 hour and 24 hour. CPC cement strength is only 6.92% of PMMA alone.2.For the contrast group endplates, both the failure load and stiffness varied significantly across the endplate surfaces, without the poster lateral regions being stronger and stiffer than other except the central regions. The central regions are lowest. On vertebroplatsty endplate, the mean failure load and stiffness increased significantly with the posterolateral regions being weaker and lower than others. The central regions are strongest.3.Both treatments resulted in significantly stronger vertebral bodies relative to their initial state. The vertebroplasty treatment restored vertebral body stiffness to initial values... |
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