To substantiate experimentally a method for preventing adjacent vertebra fractures during cement transpedicular fixation of vertebral fractures in osteoporotic patients. Material and Methods. An experimental study included the assessment of overall strength of 10 cadaver blocks of Th 10-L 4 vertebral segments with simulated Magerl's type A fracture at the L 1 level and transpedicular fixation at the Th 12-L 2 levels with four-screw system and cement augmentation. In five control blocks, only cement augmented transpedicular fixation was performed after the L 1 fracture simulation. In five blocks of the study group it was supplemented by vertebroplasty at Th 11 and L 3 levels cranial and caudal to the level of fixation. Load testing of the blocks was carried out by destruction under the influence of a vertically directed force. Results. Vertical loading of anatomical specimens in the control group (average of 0.84 kN) caused Th 11 vertebral body fractures. In the study group, the vertebrae augmented by vertebroplasty were resistant to loading. Fractures occurred in the Th10 vertebral bodies (over the vertebra with vertebroplasty) under the average load of 1.91 kN. Conclusion. Vertebroplasty of the vertebra overlying the level of transpedicular fixation is an effective way to prevent its fracture.

Low-temperature ceramics based on magnesium calcium phosphate cement are a promising resorbable material for bone tissue restoration with the possibility of functionalization. The replacement of the magnesium Mg2+ ion with a calcium Ca2+ ion at the stage of preparation of the precursor leads to the production of multiphase ceramics containing phases of brushite, monetite, and newberyite, with different dissolution rates. Multiphase ceramics leads to volumetric resorption with preservation of their geometric shape, which was confirmed by the results of an evaluation of the output of magnesium Mg2+ and calcium Ca2+ ions into the contact solution of the ceramics and the X-ray density of ceramic samples during subcutaneous implantation. The combined introduction of sodium pyrophosphate decahydrate and citric acid monohydrate as setting inhibitors neutralizes their insignificant negative effect on the physico-chemical properties of ceramics (strength, pH, porosity), determining the optimal composition. In vivo experiments with setting inhibitors in the composition of ceramics showed a different biological response, affecting the rate of resorption on par with magnesium ions. Preliminary data on biocompatibility and solubility determined magnesium-calcium phosphate ceramics containing additives that regulate setting to be a potential material for bone tissue restoration and a vector for further research, including in orthotopic implantation models.

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Objectives. To estimate macroscopically the strength, rigidity and limit of elasticity in the “spinal segments – transpedicular fixator” system. versus similar characteristics of the intact spine under dislocating rotational loads. Material and Methods. Еxperiments with anatomic specimens of Th12–L2 segments were performed. Unstable damages of L1 and transpedicular fixation with 4 screw transpedicular spinal system were imitated. All specimens were exposed to the testing rotational load in universal test machine Zwick 1464. Results. It is established that under rotational load general strength of the injured Th12–L1–L2 spinal segments fused with transpedicular fixator is 20 % lower than that in a corresponding intact spine segment. Rigidity parameters of fused segments are 17.5 % lower than those of intact segments. Destabilization of «spinal segments – transpedicular fixator» system under rotational loads is caused by the compression of a bone substance in Th12 and L2 bodies with screws and a turn of screws around longitudinal rods due to a rod slip in anchoring elements. Conclusion. The performed study may serve a basis for following data analysis from a viewpoint of metal resistance and for development of optimal rehabilitation loads to the injured spine during postoperative period.

The technology for producing demineralized bone allografts (DBA) with definable degree of demineralization and sterilization by high energy electron bean was developed in the tissue bank of Central Institute of Traumatology and Orthopaedics (CITO). The authors consider the technology to be one of the ways of producing demineralized bones. The results of the experiments show that time of demineralization process as well as the absorption dose of radioactive high energy electron beam change substantially mechanical toughness and osteoinductive properties of DBA. Mechanical properties of DBA were tested by the universal testing machine 'Zwick 1464'. Quantitative assessment of DBA osteoinductive properties resulted from the investigation of DBA samples in the culture of stromal precursor bone marrow cells and in the culture of human skin fibroblasts. Cloning efficiency of fibroblasts was considered as indecies of proliferative potential of stromal bone marrow cells, i.e. osteogenic precursor cells. The growth of the cell mass after definite time as well as the index of 3H-timidin marked cells within biological inductor were considered as indecies of proliferative potential of skin fibroblasts. The obtained results showed, that inductive properties of allografts improve when the degree of their demineralization increases whereas the dose of high energy electron radiation decreases. Mechanical toughness of DBA deteriorates when both degree of their demineralization and radiation doses increase. This emphasizes the importance of optimizing technological stages in DBA producing. Since 1998 DBA have been used in Russian clinics for bone plasty in traumatology and orthopaedics, maxilla-facial surgery, ophthalmology, and neurosurgery. The resulting analysis is based on case histories of 257 patients operated from March 1998 to July 2002. The majority of patients were children and teenagers of 3-18 years old with prime tumors, tumor-like and systemic inherited diseases of skeleton, post-traumatic complications. Observation periods were from 1.5 to 5 years and 10 months. Good and satisfactory results were obtained in 93.4% cases.