Surgical treatment of the lumbar disc herniation complicated by lumbar spinal stenosis

Degenerative disc diseases of the lumbar spine are a relevant medical and social problem. Annually, about 8 % of the population lose their ability to work because of spinal pain, and of the total number of disability cases, 40 % are associated with pain in the lumbar region. Common causes of lumbar spine pain are disc herniation and spinal canal stenosis. There are rare cases of their combination (15–45 %). The lumbosacral spine has a tendency to develop intervertebral disc herniation due to the peculiarities of biomechanics and is, therefore, the main cause of spinal surgery among adults. The clinical picture depends on several factors: the location of the herniated disc, the size and direction of the hernia, the diameter of the spinal canal at this level, the presence of concomitant stenosis and its variant. The purpose of surgical treatment of degenerative disc diseases in the lumbar spine is to carry out complete decompression of the roots of the cauda equina with minimal anatomical destruction of the structures of the spine. An adequate understanding of anatomical ratios and optimal volume of bone resection make it possible to minimize access, reduce traction and surgical traumatization of nerve structures, which ensures effective postoperative rehabilitation of patients.The paper covers the issues of etiology, pathophysiology and surgical treatment of disc herniation complicated by concomitant spinal canal stenosis. The reviews the literature and recent researches of the most optimal methods of surgical treatment of this pathology. The lack of uniform approaches to the surgical treatment of discs herniation complicated by spinal canal stenosis indicates the urgency of the problem and requires further scientific research

Differentiated tactics of surgical treatment of intervertebral disc herniation complicated by spinal canal stenosis

Objective: to conduct a retrospective analysis and evaluate the results of various methods of surgical treatment of patients with intervertebral disc herniation (IDH), which is complicated by spinal canal stenosis (SCS) of the lumbar spine.Materials and methods: 80 patients (36 (45%) men and 44 (55%) women) with a diagnosis of IDH complicated by SCS took part in the study. The average age of patients is under 50 years. All patients were operated on in the neurosurgery department of Zaporizhzhya Regional Clinical Hospital between 2016 and 2020. Patients were divided into two groups depending on the area of ​​the spinal canal and the method of surgical treatment. Group A (n=20) – relative SCS, area of the spinal canal – 75‒100 mm2, the presence of IDH >6 mm (according to magnetic resonance imaging). These patients underwent a standard microdiscectomy. Group B (n=60) ‒ absolute SCS, spinal canal area 0.05). In both groups, a significant decrease in the Oswestry index was registered immediately after surgery and its further decrease until the end of the follow-up period. When comparing the groups at the end of the first day after the operation, after 3 and 6 months, no statistically significant differences were found (p>0.05), but preoperative Oswestry index was significantly higher in group B, (р=0.04 according to the Mann‒Whitney test).Conclusions. In group A, the treatment effectiveness of patients reached 80‒85%, in the observation period on the 3 and 6 months. In group B, the treatment effectiveness of patients was also high and amounted to 75‒80%, in the observation period on the 3 and 6 months. Thus, taking into account the high variability of clinical and morphological changes in patients with IDH complicated by SCS, it is optimal to use differentiated surgical treatment tactics

The Model of Accuracy of a Local Radio Navigation System Considering Unstable Performance of Individual Elements

A mathematical model of the accuracy of the local radio navigation system was considered, built on the base of a network of pseudo satellites. It was determined that the key factor influencing the accuracy of determining the vector of status of the consumer is the geometry of the structure.However, for certain categories of consumers there is a necessity of taking into account a possibility of degradation of the structure because of malfunctioning and possible intentional damage. Existing mathematical models of accuracy do not consider a capacity of change in the topology structure.It was defined that for the assessment of the accuracy of navigation of specific consumers it is expedient to use a geometric factor that determines the degree of deterioration of finding the location relative to the accuracy of defining the pseudo remoteness from the consumer to the radio-navigation points.To consider the possibility of failure (destruction) of individual elements of the structure of a local radio navigation system, we introduce a probabilistic model that, on the base of registering the combinations of usable/faulty pseudo satellites and their relative geometric position, makes it possible to define the process of changing the accuracy of the system. As the main indicator of the accuracy, we use a root mean square deviation of the location definition (the state vector) of the consumer.As a result of the research we identified and confirmed by simulation that the maximum accuracy (minimum values of geometric factor) can be achieved in the case when a consumer is located in the centre of a regular tetrahedron.Given the sphericity of the Earth, a minimum value for a ground consumer is achieved when one pseudo satellite is in the zenith and the other three are evenly located in the horizontal plane.The combination of the base model of accuracy with a stochastic model of reliability/survivability will allow designing spatial structure of local radio navigation systems by the criterion of stable performance