External Dynamic Apparatus Correction in Rigid Posttraumatic Spinal De-formations Engineering and Clinical Aspects

Abstract

Study design: The authors define most dangerous sections and calculate the stresses arising in the parts of the external fixation device. They configure external fixation devices taking into account the obtained results and use them in medical practice. Objective: the development of an apparatus correction technique for the treatment of spinal deformations. Summary of background data: standard methods of rigid deformation correction are technically complicated and high-costly; there are also possible formidable intraoperative complications. Authors consider a variant of apparatus external correction as an alternative to the known methods, which is devoid of the aforementioned disadvantages. Methods: The authors use theoretical and experimental research methods. The theoretical deductions are confirmed experimentally during clinical trials. Clinical studies were evaluated using ray-based diagnostic procedures, computed tomography, and patient interviewing using the Oswestry Disability Index and visual analogue scale. Results: The calculations showed that in case of one-sided point load, the stresses arising in the dangerous section of screws-rods from that load can reach 60 – 70% of the total stresses in the device nodes. During clinical testing it was established that external apparatus correction leads to normalization of anatomical relationships in the area of damaged segments, normalization of the spinal column axis, and reduction of pain; it does not preclude the use of dorsal internal puncture fixation. Conclusions: It is advisable to load the structural element of the external spinal fixation device in a skew-symmetric pattern, applying distraction and compression forces to the transverse plate on both sides along parallel straight lines in opposite directions. Apparatus external fixation makes it possible to perform a complete correction of rigid deformations without releasing the supporting structures, to control the level of neurological dis-orders, to simplify the technique of internal fixation operations, to use the minimally invasive procedure for the installation of the internal pedicle fixator.