Analysis of the stress-strain state of the spine model with posterior fusion in the treatment of scoliotic deformities in children

Background. Mathematical modeling of the correction of scoliotic deformities of the spine makes it possible to analyze the effectiveness of various methods of treatment without surgical intervention. In the study of traction, mainly experimental methods were used. The purpose was to investigate the stress-strain state of the spine models with varying degrees of scoliotic deformity during posterior spinal fusion. Materials and methods. Deformities of the spine of 40, 70 and 100° were modeled, with posterior spondylodesis of the Th1-Th12 vertebrae. A load of 300 N was used. Results. With a deformity of 40°, the most stressed are the areas of frontal plane curve. For the upper vertebrae Th1-Th4, a more even distribution of stress over the vertebral body is observed. For Th5-Th10 vertebrae, the concave side of the vertebral bodies is more stressed. In the thoracic spine, the more stressed vertebrae are Th2 and Th5. The main load is borne by the fixing structure, in which the level of stress is significantly higher than in the bone structures of the vertebrae. In the posterior supporting complex of the vertebrae, the stress concentration areas are located at the points where fixing screws enter the bone. An increase in the magnitude of the scoliotic deformity of the spine up to 70° causes an increase in the level of stresses in all elements of the model, with the exception of Th9-Th10 vertebrae. With a deformity of 100° in the posterior supporting complex of the vertebrae, the stress concentration areas are located at the points where fixing screws enter the bone. The stress level of 116.0 MPa exceeds the ultimate strength of the cortical layer of the bone tissue of the spine, which can lead to microdamage of the bone tissue and loosening of the screws. Conclusions. For all values of scoliotic deformity of the spine, the most stressed are Th4 and Th5 vertebrae. A decrease in the degree of deformity has a significant effect on the stress-strain state of the spinal column. In the Th4 vertebral body, the level of stresses with a deformity of 100° is more than twice as high as with a deformity of 70°, and more than 4 times higher than with a deformity of 40°. In the body of the Th5 vertebra, the stress level with a deformity of 70° is 1.5 times less than with a deformity of 100°, and with a deformity of 40°, it is 3 times less. The level of stress in the Th1-Th5 vertebral bodies is higher than that of Th6-Th12. In the posterior supporting complex, at the points where screws enter the bone, the maximum stress value at a deformity of 40° is 34.0 MPa, which is not critical for the bone tissue. With a deformity of 70°, the stresses are 85.0 MPa, which can exceed the ultimate strength for the cortical bone and lead to microdestruction of the bone tissue in the screw-bone contact area. With a deformity of 100°, the stresses are equal to 116.0 MPa, which exceeds the ultimate strength for the cortical bone and can lead to microfracture in the screw-bone contact area.

Spinal osteotomy for children with congenital scoliosis with unilateral unsegmented bar: Preliminary results

Introduction. Segmentation disorder of the lateral surfaces of the vertebral bodies leads to the development of progressive deformity of the spine. Surgical interventions in different variants are the only effective way of treatment. This study examines the use of corrective vertebrectomy in patients with congenital scoliosis with impaired segmentation of the lateral surfaces of the vertebral bodies. Objective of the study. To evaluate the results of surgical treatment of children with congenital scoliosis with impaired segmentation of the lateral surfaces of vertebral bodies. Materials and Methods. A single-center retrospective study on the basis of the Department of Spinal Pathology and Neurosurgery at the Turner Scientific and Research Center for Pediatric Traumatology and Orthopedics. G.I. Turner for the period from 2014 to 2020. Twenty-six patients were included in the study: 14 girls and 12 boys. The age range was 84 to 144 months. All patients underwent surgical intervention in the volume of a one-stage corrective wedge vertebrectomy. Statistical processing was performed by comparing the reliability of differences in distributions using Wilcoxon t-criterion. Results and discussion. The median Cobb preoperative scoliotic deformity was 31, interquartile interval (IQR) = 30.5. The median preoperative lordotic deformity was 29 Cobb, IQR = 29.5. The magnitude of correction of the scoliotic component of the deformity was 84%, (median value after intervention: 5 according to Cobb, IQR = 14.5). The magnitude of correction of pathological lordosis of the thoracic spine was 41%, (median value after intervention: 17 according to Cobb, IQR = 14.5). The obtained results were statistically significant (p 0.05). Conclusion. Corrective wedge vertebrectomy is an effective method for surgical treatment of children with congenital spinal deformity with impaired segmentation of the lateral surfaces of vertebral bodies. This method of treatment achieves an average of 84% correction of scoliotic deformity and 41% correction of pathological lordosis.

Evaluation of the idiopathic scoliosis of varying severity treatment effectiveness with transpedicular systems

Introduction Significant success has been achieved in the development of new methods of treatment and rehabilitation of patients with idiopathic scoliosis, however, in many aspects of this problem there is no unambiguous approach to the choice of a correction method, assessment of treatment results.Objective To study the results of treatment of patients with idiopathic scoliosis according to X-ray and MSCT data, as well as according to the questionnaire – the SRS-30, depending on the degrees of the deformity, the type of scoliosis.Material and methods The study is retrospective, single center. Evidence level – IV. In 300 patients with idiopathic scoliosis of varying severity at the age from 10 to 50 years, the immediate and long-term results of elimination of spinal deformity by the method of internal transpedicular fixation were studied. In the study we used polypositional radiography, multislice computed tomography (MSCT) and questionnaire SRS-30.Results In patients with spinal deformity up to 60 ° a year after surgery, no loss of correction was found. After elimination of the deformity at 60–90 °, loss of correction up to 2 ° was observed in 3.6% of patients. In patients with deformity greater than 90 °, the average postoperative progression of scoliotic deformity was 3.5 ± 0.7 °. When examining patients after 2–5 years, there was no loss of correction in the group with initial spinal deformity up to 60 ° and in the group from 60–90 °. In patients with deformity greater than 90 °, the postoperative progression of scoliotic deformity in persons over 25 years old was 4.5 ± 0.6 °, which is associated with degenerative changes in the spine.Conclusion The study of immediate and long-term results showed that 1 year after treatment, 94% of patients rated the treatment result as excellent and good, in 6% – as satisfactory. All patients noted a positive effect of the cosmetic and functional results of treatment, while 56% believed that they looked “better” than before surgery (4 points), 44% rated the effect at 5 points and noted that they looked “much better”. Long-term results were studied in 50 patients 10 years after surgery.

Sclerostin and Its Involvement in the Pathogenesis of Idiopathic Scoliosis

Idiopathic scoliosis is a disorder of unknown etiology. Bone biopsies from idiopathic scoliosis patients revealed changes at cellular and molecular level. Osteocytic sclerostin is downregulated, and serum level of sclerostin is decreased. Osteocytes in idiopathic scoliosis appear to be less active with abnormal canaliculi network. Differentiation of osteoblasts to osteocytes is decelerated, while Wnt/β-catenin signaling pathway is overactivated and affects normal bone mineralization that leads to inferior mechanical properties of the bone, which becomes susceptible to asymmetrical forces and causes deformity of the spinal column. Targeting bone metabolism during growth by stimulating sclerostin secretion from osteocytes and restoring normal function of Wnt/β-catenin signaling pathway could, in theory, increase bone strength and prevent deterioration of the scoliotic deformity.

Halo-gravity traction in the treatment of complex spinal deformities in children with respiratory dysfunctions

HGT is a safe technique as the world literature describes complications in the form of loosening of the pins or superficial infections of the skin around the pins, which are not significant and do not pose a threat to the patient’s life. Purpose – to improve the results of the ventilation function of the lungs in patients with complex spinal deformities through the preliminary use of halo gravity traction and to introduce an effective and safe method for the treatment of complex spinal deformities in children with respiratory dysfunctions. Materials and methods. 64 children with complex spinal deformities (>100°) were treated in the orthopedic and traumatology department of the Okhmatdet NSPU using halo gravity traction during the period from 2003 until 2018. Of these, 38 are boys and 26 are girls. The average age of the patients was 11.6 years. The average Risser score was 3.8 (P>0.01). Results. According to the data of spirography performed, 46% of patients had moderate ventilation disorders and 54% – severe ventilation disorders (FVC<60% – grade 3 and 4 of ventilation failure). Mixed type disorders were recorded in 83% of patients, and restrictive type disorders in 17% (8/48) of children. After HGT, there was an improvement in pulmonary function indicators: an increase in FVC from 63.19% to 71.77% and FEV1 from 54.71% to 65.46%, Tiffeneau-Pinelli index – from 74.59% to 85.33%. Compared with the initial level of indicators, the improvement in FVC was 13.6% after HGT and 14.6% in dynamics during the year, and FEV1 – 19.6% and 21.6%, respectively. The results obtained indicate a significant improvement in the ventilation function of the lungs, especially due to the degree of FEV1 increase, which correlates with the degree of improvement in performance, mortality and life prognosis. Conclusions. The use of HGT makes it possible to improve the results of the final correction of spinal deformity, which in turn significantly improves the ventilation function of the lungs, which in turn helps to reduce the risks of mortality due to pulmonary insufficiency in adulthood. The choice of the appropriate methods of surgical correction for complex deformity of the spine is a prerequisite for successful treatment and the achievement of three-dimensional correction of the spine to maximally approximate its parameters to the physiological norm. The indication for halo gravity traction is a rigid scoliotic deformity of the spine with a deformity angle (>100°). This study was conducted in accordance with the principles of the Helsinki Declaration. The research protocol was approved by the Local Ethics Committee of the institutions mentioned in the work. Informed parental agreement was obtained for the research. No conflict of interests was declared by the authors. Key words: spinal deformity, respiratory dysfunctions, halo-gravity traction.

Changes in Coxo-Vertebral Parameters in Scoliotic Deformity of the Spine

Considering the pathology of the spine and hip joint, it is necessary to take into account their biomechanical relationships under axial loading. Scoliotic deformity leads to the development of compensatory misalignment and inclination of the pelvis, resulting in a functional shortening of one of the lower extremities, which, in turn, leads to the formation of degenerative changes in the hip joint. The development of degenerative changes in the hip joint depends on the degree of scoliotic deformity, taking into account changes in the sagittal and frontal balance. However, research studies state that scoliotic spinal deformity 40 did not cause a pronounced degenerative process in the hip joint area. In our review we studied and analyzed clinical and radiological data of patients operated on for 4 years at the spine surgery department of the National Medical Research Center of Traumatology and Orthopedics named after R.R. Vreden for scoliotic deformity 3-4 degrees. All patients underwent a teleroentgenogram of the spine with the capture of the upper third of the thigh in two projections. According to X-ray data, the angles of the lumbar lordosis, the inclination of the sacrum, the inclination of the pelvis, the deviation of the pelvis from the vertical, the angles of misalignment of the pelvis, the determination of the angle of inclination of the acetabulum in the vertical plane (Sharpe's angle)), sagittal and frontal balance were assessed. The presence of concomitant diseases of the hip joints was separately registered. To assess the correlation, Kendall's coefficients and Student's t-test were used. The study involved 60 patients (47 women and 13 men), aged on average 29.7. When evaluating the correlation, it was found that the Sharpe angle on the left (S) correlates with the Sharpe angle on the right (R), the Sharpe angle (R) correlates with hip dysplasia, where Lumbar lordosis (GLL) correlates with Sacral slope (SS), Sacral slope (SS) correlates with the pelvic incidence (PI). Pelvic deviation from the vertical (PT) correlates with PI, PI before surgery most strongly correlates with PI after surgery (for all values p 0.01). In addition, PI in patients with unilateral lesions of the hip joint is higher than in patients with bilateral lesions, which proves that there is no relationship between PI and GLL in this category of patients. According to the results of our study, changes in coxo-vertebral parameters did not change significantly in the pre and postoperative period, with the exception of lumbar lordosis and sagittal balance.

Prediction of Scoliosis Curve Correction Using Apical Fulcrum Bending Radiographs in Adolescent Idiopathic Scoliosis (AIS)

Background: Scoliosis is defined as a three-dimensional deformity of spine. Surgical treatment is indicated for curves equal to/or more than 40 degrees in magnitude. Curve flexibility is determined preoperatively through bending films, which help in the selection of fusion levels. Surgical treatment for fully-grown spine is a spinal fusion use to inhibit the progress of deformity which further helps in balancing of both sagittal and coronal planes. Therefore, this study aimed to find out the association between predicted via bending films after correction and final surgical correction of skeletally mature patients with Adolescent Idiopathic Scoliosis (AIS). Methods: Thirty-three patients with Adolescent Idiopathic Scoliosis (AIS) were recruited for the study. Those patients were operated at Dr. Ziauddin University Hospital, Karachi from June 2016 to June 2020. Using Pre- and post-operative radiographs of the spine, Cobb values were used to calculate the percentage of correction achieved. Percentage correction (surgical) was then compared to correction possible (predicted) to find association via an independent t-test with p<0.05 considered as statistically significant. Results: Out of total 33 patients, 24 (72.7%) were females and 9 (27.2%) were males. The mean age of the patients was 17.2±3.0 years. Using bending films, correction of the scoliotic deformity was predicted through measured angles with 78±18°. The corrections’ difference was 84.5±11°. This difference was found to be statistically insignificant (p=0.0769) which showed no difference in predicted and actual correction achieved. Conclusion: In skeletally mature patients with AIS, bending films have been shown to accurately predict the amount of postoperative correction of Cobb’s angle which is possible. Keywords: Age Determination by Skeleton; Scoliosis; X-Ray Film; Spinal Curvatures.

Anterior lengthening in scoliosis occurs only in the disc and is similar in different types of scoliosis

Relative anterior spinal overgrowth (RASO) was proposed as a generalized growth disturbance and a potential initiator of adolescent idiopathic scoliosis (AIS). However, anterior lengthening was also observed in neuromuscular (NM) scoliosis, was shown to be restricted to the apical areas and to be located in the intervertebral discs, not in the bone. In this study the goal was to determine if other scoliotic curves of known origin exhibit the similar mechanism of anterior lengthening without changes in the vertebral body. Therefore CT-scans of 18 patients in whom a short segment congenital malformation had led to a long thoracic compensatory curve without bony abnormality were included. Of each vertebral body and intervertebral disc in the compensatory curve, the anterior and posterior length was measured on CT-scans in the exact mid-sagittal plane, corrected for deformity in all three planes. The total AP% of the compensatory curve in congenital scoliosis showed a lordosis (+1.8%) that differed from the kyphosis in non-scoliotic controls (-3.0%; p<0.001), and was comparable to AIS (+1.2%) and NM scoliosis (+0.5%). This anterior lengthening was not located in the bone; the vertebral body AP% showed a kyphosis (-3.2%), similar to non-scoliotic controls (-3.4%), as well as AIS (-2.5%) and NM scoliosis (-4.5%; p=1.000). However, the disc AP% showed a lordosis (+24.3%), which sharply contrasts to the kyphotic discs of controls (-1.5%; p<0.001), but was similar to AIS (+17.5%) and NM scoliosis (+20.5%). The results demonstrate that anterior lengthening is part of the three-dimensional deformity in different types of scoliosis and is exclusively located in the intervertebral discs. The bony vertebral bodies maintain their kyphotic shape, which indicates that there is no active bony overgrowth. Anterior lengthening appears to be a passive result of any scoliotic deformity, rather than being related to the specific cause of AIS.

Transpedicular fixation of the spine with two-level navigation templates for narrow pedicles

Objective. To assess the correctness of transpedicular screw insertion in thoracic and lumbar vertebrae using two-level navigation templates for narrow pedicles.Material and Methods. Two-level navigation templates were used in surgical treatment of four patients aged 14–17 years with scoliotic deformity and multiple pedicles of small width (less than 4.35 mm). In each patient, the least favorable zones were selected for implantation using navigation templates. The rest of planned pedicle screws were inserted using free-hand technique. All patients underwent CT scanning postoperatively. Screws inserted to pedicles less than 4.35 mm in width were classified as correctly placed if they did not extend beyond the medial cortical layer by more than 2 mm.Results. Out of 68 pedicles planned for screw placement, 42 were narrower than 4.35 mm. In the pedicles difficult for implantation, 29 screws were inserted using navigation templates and 13 by free-hand technique. Screws classified as correctly placed were 28 from those inserted with navigation templates and 9 from those implanted by free-hand technique. Difference in results of screw placement in narrow pedicles with navigation templates and by free-hand technique was statistically significant (exact Fisher test, p < 0.05).Conclusion. Transpedicular screw placement with two-level navigation templates in narrow pedicles is more correct than insertion by free hand technique.