| Objective:1） To develop the percutaneous minimally invasive novel perfusional pediclescrew(PMI-NPPS),which can percutaneously inject the bone cement via the Ushaped hollow pedicle screw, and the matching apparatus of perfusion.2）To prove that PMI–NPPS, infusing the bone cement, can markedly strength thestability of pedicle screw under the condition of osteoporosis through thebiomechanical experiment, and to provide enough theoretical basis for wideapplication of PMI–NPPS in clinic.Methods:1) The simulation experiment of LU-SHPS combined with bone cement: weworked the preliminary inquiry of strengthening by the bone cement, using the longtail folded U-shaped hollow pedicle screw(LU-SHPS),which my supervisor haddeveloped in his early experimental research and clinical applications. It hadachieved the national patent. We placed LU-SHPS and infused bone cement in thedried human lumbar spinal specimens and fresh pig vertebral specimens. And then wetook them to do the X–ray and CT examination to check the distribution of bonecement.2) The development of a new pedicle screw: We designed PMI-NPPS on the basisof the LU-SHPS and improved the perfusion supporting devices, and then sent tomake the mechanical properties test. 3) The biomechanical test of PMI-NPPS: We prepared the screw channel of eachgroup by the same method on osteoporosis biomechanical test block (BTB). Controlgroup: directly screwed the LU-SHPS; Experimental group1: directly screwed thePMI-NPPS; Experimental group2: screwed the PMI-NPPS and perfused the bonecement by the side holes.15minutes after insertion of the pedicle screws, X-ray andCT examination and axial pullout tests were performed to all the BTB’S.Results:1）Infusing the bone cement through LU-SHPS were feasible, but the cement wereless and thin; X-ray and CT examination showed: Bone cement were found in themodel of dried human lumbar spinal specimens, but less in the fresh pig vertebralbone specimen models because of the hard bone.2) The new PMI-NPPS and perfusion supporting equipment were designed, and therequirements of human biomechanics in mechanical performance test of the screwwere achieved; The ultimate strength of PMI-NPPS were3258±22N, and the yieldstrength were2262±15N, the weight of the upper body could been met.3) The imaging studies of the BTB models showed: The position of all group ofscrews were better, and the bone cement shadow were visible seen.4) The results of the axial withdrawal of the experiment: The maximum axial pulloutforce of the experimental group2was127.0±15.1N.The energy absorption value ofthem was0.426±0.124J.The pullout stiffness of it was36.2±4.0N/mm.They weresignificantly higher than the control group and the experimental group1; There are nostatistically significant difference between the control group and the experimentalgroup1.Conclusion:1)Perfusing bone cement through the PMI-NPPS is an effective method of fixing,which can significantly enhance the stability of the pedicle screw, reduce the screwpullout and cutting under the condition of osteoporosis. 2) Our self-developed PMI-NPPS and the perfusion matching devices with bonecement augmentation are safe, simple and feasible to cure the thoracolumbarfractures using the minimally invasive pedicle internal fixation. |
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