Table of Content

28 February 2024, Volume 28 Issue 6 Previous Issue   

For Selected:

Download Citations EndNote Reference Manager ProCite BibTeX RefWorks

Toggle Thumbnails

Select

Biomechanical changes of the cervical spine in internal fixation with different anterior cervical interbody fusion systems Wang Qiang, Li Shiyun, Xiong Ying, Li Tiantian 2024, 28 (6):  821-826.  doi: 10.12307/2023.787 Abstract ( 221 )   PDF (6369KB) ( 47 )   Save BACKGROUND: Due to the treatment of cervical spondylosis, the Zero-P system of the anterior cervical interbody fusion system will have problems such as screw loosening and fracture after operation, so a novel Low-P system has been developed. OBJECTIVE: To compare the effects of the novel Low-P and Zero-P anterior cervical intervertebral fusion systems on the biomechanical properties of adjacent segments of the cervical spine and to perform stress analysis on the internal fixation system, so as to provide a theoretical reference for clinical treatment. METHODS: A complete model of the C1-C7 segment of the cervical spine was established. Based on the effectiveness of the model, a finite element model of Low-P (type Z Low-P and type H Low-P) and Zero-P system implanted in C4-C5 segments was established. The stress distribution of implanted devices and adjacent vertebral nucleus pulposus, fibrous rings and end plates was analyzed under the conditions of forward flexion, posterior extension, lateral bending and rotation.   RESULTS AND CONCLUSION: (1) After implantation of Low-P and Zero-P internal fixation devices, the range of motion of the type H Low-P system was large; the maximum stress value of type Z Low-P system was small; the maximum stress of Zero-P on the nucleus pulposus of adjacent segments was large; the maximum stress of end plate was small. (2) The influence of three internal fixation systems on adjacent segment fiber rings was close. (3) The screw stress of the Zero-P internal fixation system was much greater than that of the Low-P system. (4) It is indicated that compared with Zero-P type internal fixation system, the novel Low-P system reduces the stress value of steel plate and screw, which can reduce screw loosening and internal fixation system failure. The Low-P system has less stress on the nucleus pulposus of adjacent discs and reduces disc degeneration in adjacent segments. This paper provides a theoretical basis for the clinical study of a Low-P type internal fixation system.  Figures and Tables | References | Related Articles | Metrics

Select

Finite element analysis of effects of sagittal cervical manipulation on intervertebral disc and facet joints Wei Yuanbiao, Lin Zhan, Chen Yanmei, Yang Tenghui, Zhao Xiao, Chen Yangsheng, Zhou Yanhui, Yang Minchao, Huang Feiqi 2024, 28 (6):  827-832.  doi: 10.12307/2024.006 Abstract ( 253 )   PDF (3219KB) ( 32 )   Save BACKGROUND: Among the pathogenic factors of cervical spondylosis, herniation of the intervertebral disc, dislocation of the facet joint and the stenosis of the intervertebral foramen are important factors leading to symptoms in patients. Moreover, inappropriate manipulation may aggravate the possibility of cervical disc rupture, leading to exacerbation of symptoms in patients.   OBJECTIVE: To compare the effect between sagittal cervical manipulation and traditional cervical rotation manipulation on the area of the intervertebral disc, facet joint and intervertebral foramen at the operative segment by the finite element analysis. METHODS: The neck CT data of a male volunteer with a normal neck were selected and imported into Mimics 17.0 three-dimensional reconstruction software. Geo-magic Studio 12.0, Solidworks 2017 and Ansys Workbench 17.0 software were used for the construction of the finite element model of cervical vertebrae (C3-6) including intervertebral disc and articular cartilage. The lower end plate of the C5 vertebral body was fixed. A uniformly distributed vertical downward 50 N load was applied on the upper surface of the upper vertebral body (C3). The stress, deformation and deformation direction of the C4-5 intervertebral disc, joint capsule stress, the displacement of facet joints and the area of bilateral intervertebral foramen were compared between sagittal cervical manipulation and traditional rotation reduction.   RESULTS AND CONCLUSION: (1) When using the rotation technique, the maximum normal equivalent stress (von Mises stress) of the C4-5 disc was 8.06 MPa; the total deformation was 1.05 mm, and the fiber ring expanded to the left and outside. When using the sagittal tip lifting technique, the maximum normal equivalent stress (von Mises stress) of the C4-5 disc was 2.60 MPa; the total deformation was 0.90 mm, and the fiber ring expanded to the left and back. Compared with the rotation technique, the pressure of the cervical manipulation technique on the disc was less (about 32.3% of the rotation technique), and the deformation degree of the disc was also light (about 85.7% of the rotation technique). (2) When the rotation technique was used, the maximum stresses of the left and right articular capsule ligaments were 0.37 MPa and 1.69 MPa, respectively. The overall displacement of the facet joint was 2.21 mm. The area of the right intervertebral foramen decreased by about 3.8% and the area of the left intervertebral foramen increased by about 0.9%. When the sagittal end lifting manipulation was performed, the maximum stresses of the left and right articular capsule ligaments were 0.27 MPa and 1.70 MPa, respectively; the overall displacement of the facet joint was 1.63 mm; the area of the right intervertebral foramen increased by about 2.6%, and the area of the left intervertebral foramen decreased by about 0.9%. Compared with rotation manipulation, sagittal end lifting manipulation had fewer changes in the displacement of facet joint, joint capsule stress and intervertebral foramen area, so it was safer to operate. (3) In conclusion, compared with cervical rotation manipulation, sagittal end lifting manipulation has fewer changes in facet joint displacement, intervertebral disc stress/deformation degree, joint capsule stress, and foraminal area. In clinical practice, more appropriate manipulation should be selected based on biomechanical results after an accurate assessment of patients’ conditions. Figures and Tables | References | Related Articles | Metrics

Select

Effects of endoscopic foraminoplasty and laminoplasty on biomechanical properties of intervertebral disc and isthmus Zhang Rui, Wang Kun, Shen Zicong, Mao Lu, Wu Xiaotao 2024, 28 (6):  833-839.  doi: 10.12307/2023.779 Abstract ( 251 )   PDF (4700KB) ( 61 )   Save BACKGROUND: Endoscopic treatment of lumbar disc herniation has obvious advantages over traditional open surgery. Endoscopic surgery involves the implantation of a working cannula, which requires only partial bone removal, and there are no studies on the effects of two types of intraoperative foraminoplasty and laminoplasty on the mechanical properties of the local structure of the lumbar spine.   OBJECTIVE: To compare the effect of foraminoplasty and laminoplasty on the biomechanical properties of disc and isthmus of the responsible segment. METHODS: The lumbosacral CT images of a healthy male volunteer were taken, and a finite element model M0 of the L3 to sacral vertebrae was established, on which the primary and secondary foraminoplasty models M1 and M2 of the L5/S1 and the laminoplasty model M3 were built. The same load was applied to compare the intervertebral motion range, disc Von Mises stress and equivalent stress characteristics of L5 vertebral isthmus with each model.   RESULTS AND CONCLUSION: (1) Compared with M0, M1 and M2 motion range in L5/S1 segment did not change significantly in all directions; M2 overall motion range increased by 8.60% in flexion; M3 increased by 8.23% and 8.26% in L5/S1 right bending and right torsion, and 5.39% and 5.67% in overall motion range in flexion and right bending, with no significant changes in motion range in the rest of working conditions. (2) Compared with M0, M1 showed no significant change in the extremes of Von Mises stress at L5/S1 disc; M2 increased 11.06%, 12.50%, 18.32%, and 15.48% in flexion, extension, left torsion, and right torsion; M3 increased 12.22%, 19.54%, 10.05%, and 9.97% in flexion, extension, left torsion, and right torsion, and the rest working conditions and L4/5 disc maximum Von Mises stress did not change significantly. (3) Compared to M0, the maximum Von Mises stress in the left isthmus of L5 of M1 increased by 12.43% in left bending, 18.38%, 13.29%, 13.62%, and 40.00% in the right isthmus in extension, right bending, left torsion, and right torsion. The maximum Von Mises stress in the left isthmus of L5 of M2 increased by 38.87%, 42.63%, 16.95%, and 19.35%, and that in the right isthmus increased by 12.58%, 33.70%, 12.92%, and 17.42% in flexion, extension, left bending, and left torsion. The maximum Von Mises stress in the left isthmus of L5 of M3 increased 67.07%, 78.14%, 32.33%, 62.94%, and 89.99% in flexion, extension, left and right bending, and right torsion. (4) The results suggest that foraminoplasty and laminoplasty have a small effect on spinal motion range; there is a mild increase in the extreme values of disc Von Mises stress in the segments operated by interbody laminoplasty and secondary foraminoplasty; there is no significant change in the extreme values of disc Von Mises stress in adjacent segments, and there is a significant increase in the Von Mises stress in the ipsilateral isthmus operated by the interbody laminoplasty model. Figures and Tables | References | Related Articles | Metrics

Select

Finite element model establishment and stress analysis of lumbar-sacral intervertebral disc in ankylosing spondylitis Kang Zhijie, Cao Zhenhua, Xu Yangyang, Zhang Yunfeng, Jin Feng, Su Baoke, Wang Lidong, Tong Ling, Liu Qinghua, Fang Yuan, Sha Lirong, Liang Liang, Li Mengmeng, Du Yifei, Lin Lin, Wang Haiyan, Li Xiaohe, Li Zhijun 2024, 28 (6):  840-846.  doi: 10.12307/2023.799 Abstract ( 262 )   PDF (2283KB) ( 51 )   Save BACKGROUND: Ankylosing spondylitis is a chronic inflammatory disease with chronic rheumatic immunity. Soft tissue ossification and fusion and spinal stiffness can cause biomechanical changes. OBJECTIVE: To reconstruct the lumbar-sacral intervertebral disc in ankylosing spondylitis patients with lumbar kyphosis by finite element analysis, and to study the range of motion of each segment of T11-S1 and the biomechanical characteristics of annulus fibrosus and nucleus pulposus. METHODS: The imaging data were obtained from an ankylosing spondylitis patient with lumbar kyphosis. The original CT image data of continuously scanned spine were imported into Mimics 21.0 in DICOM format, and T11-S1 was reconstructed respectively. The established model was imported into 3-Matic software in the format of “Stl” to reconstruct the intervertebral disc, and the fibrous intervertebral disc model was obtained. The improved model was further imported into Hypermesh software, and the vertebra, nucleus pulposus, annulus fibrosus and ligament were mesh-divided. After the material properties were given, the model was imported into ABAQUS software to observe the range of motion of each vertebral body in seven different working conditions of T11-S1, and analyze the biomechanical characteristics of each segment of annulus fibrosus and nucleus pulposus. RESULTS AND CONCLUSION: (1) The range of motion of L1 vertebrae was higher than that of other vertebrae under six different working conditions: extension, forward flexion, rotation (left and right), and lateral flexion (left and right). The maximum range of motion was 2.18° during L1 vertebral flexion, and the minimum range of motion was 0.12° during L5 vertebral extension. (2) The annular fiber flexion at L2-L3 segments was greater than the extension (P < 0.05), and the annular fiber flexion at L3-L4 and L4-L5 segments was less than the extension (P < 0.05). The left rotation of L1-L2 annular fibers was greater than the right rotation (P < 0.05). The left flexion of the annulus was greater than the right flexion in L1-L2, L2-L3, L3-L4, L4-L5 and L5-S1 segments (P < 0.05). (3) The nucleus pulposus stresses of T11-L12, L1-L2, L2-L3, L3-L4 and L4-L5 segments in forward flexion were greater than in extension (P < 0.05). The left rotation of T12-L1 and L3-L4 segments was smaller than the right rotation (P < 0.05), and that of T11-T12, L1-L2, and L2-L3 segments was larger than the right rotation (P < 0.05). The left flexion was larger than the right flexion in the T11-S1 segment. (4) It is concluded that in ankylosing spondylitis patients with lumbar kyphosis, the minimum range of motion of the vertebral body is located at the L5 vertebral body in extension. To prevent fractures, it is recommended to avoid exercise in the extension position. During the onset of lumbar kyphosis in patients with ankylosing spondylitis, the maximum stress of the annulus fibrosus and nucleus pulposus is located in the L1-L2 segment, which is fixed and will not alter with the change of body position. The late surgical treatment and correction of deformity should focus on releasing the pressure of the annulus fibrosus and nucleus pulposus in this segment to avoid the rupture of the annulus fibrosus and the injury of the nucleus pulposus.  Figures and Tables | References | Related Articles | Metrics

Select

Mechanical properties of L3/4 laminar decompression and intervertebral fusion in elderly osteoporosis patients analyzed by finite element method Zhang Min, Peng Jing, Zhang Qiang, Chen Dewang 2024, 28 (6):  847-851.  doi: 10.12307/2023.796 Abstract ( 309 )   PDF (2091KB) ( 68 )   Save BACKGROUND: The incidence of high lumbar disc herniation in elderly patients with osteoporosis is increasing. The changes in lumbar overall mechanical strength and biomechanical properties of adjacent vertebrae after conventional posterior approach decompression and interbody fusion have not been clarified. Finite element analysis has great value in the field of biomechanics because of its advantages of non-invasiveness, high repeatability and accuracy.   OBJECTIVE: To explore the establishment of a finite element model of senile osteoporotic L3/4 lamina decompression using finite element analysis and intervertebral fusion spine, and to evaluate the biomechanical status of the internal fixation complex of bones under bending motion in elderly patients with osteoporosis. METHODS: Mimics 21.0 was used to extract the DICOM data of the spine CT to establish the 3D bony structure of the lumbar spine (T12-L5), which was imported into Geomagic wrap 2017. The L3/4 full lamina decompression model was established after redrawing the mesh, deleting the nails, cutting the model, filling the cavity, detecting and editing the contour line, constructing curved surfaces and grids, fitting curved surfaces and other operations. Solidworks 2017 was used to construct pedicle screws, connecting rods, and intervertebral fusion cages, which were assembled into the L3/4 full lamina decompression model. Intervertebral discs and articular process cartilage and other structures were established through operations such as stretching, isometric surfaces, moving and copying entities. ANSYS Workbench 17.0 was utilized for material assignment, simulating spinal ligaments, meshing, applying force and limiting boundary conditions. A complete osteoporotic L3/4 laminar decompression and intervertebral fusion spine finite element model was established. The stress, strain and displacement cloud diagram of the L3/4 lamina decompression and intervertebral fusion full lumbar spine finite element model were observed under simulated bending conditions.   RESULTS AND CONCLUSION: (1) In terms of the stress cloud diagram: The T12-L1 vertebra had the highest average stress value; L2 dropped by 24%; L3 dropped by 55%, and L4-5 dropped by about 80%. The stress concentration in the L4/5 articular process area was the highest, followed by L2/3, and lighter in L1/2 and T12/L1. The stress concentration at the junction of the screw and the connecting rod was obvious, followed by the screw at the entrance and exit of the pedicle. (2) In terms of strain and displacement cloud map: The strain degree of L4/5 and L2/3 articular process was the highest; the strain degree of T12/L1 and L1/2 was the second, and the L3/4 segmental fusion cage, pedicle screw and connecting rod had no any visible deformation. The intervertebral discs of all segments showed great deformation. (3) It is concluded that the cooperative operation of multiple software can successfully construct a finite element model of the spine with L3/4 lamina decompression and intervertebral fusion in elderly patients with osteoporosis. Elderly patients after lumbar spine surgery can tolerate forward flexion, confirming that L3/4 laminar decompression and intervertebral fusion can maintain the shape of the spine and ensure the stability of the spine, but it is necessary to be alert to the occurrence of thoracolumbar stress fractures and adjacent spondylopathy. Figures and Tables | References | Related Articles | Metrics

Select

Correlation between coronal pressure variation and coronal imbalance in adolescent idiopathic scoliosis patients Wu Maodong, Su Qinglun, Huang Yiming, Shen Longying, Lu Yu, Zhao Qin 2024, 28 (6):  852-856.  doi: 10.12307/2023.731 Abstract ( 239 )   PDF (2387KB) ( 20 )   Save BACKGROUND: The distribution of horizontal pressure in adolescent idiopathic scoliosis can be used to evaluate the coronal imbalance. Currently, there are no reports on the characteristics of coronal pressure distribution and its correlation with coronal imbalance.   OBJECTIVE: To explore the correlation between coronal pressure variation and coronal imbalance in adolescent idiopathic scoliosis patients. METHODS: A total of 39 adolescent idiopathic scoliosis patients who met the inclusion and exclusion criteria in Lianyungang First People’s Hospital from March 2021 to June 2022 were selected as the adolescent idiopathic scoliosis group, and 30 matched healthy volunteers were recruited from the outpatient department as the control group. The horizontal position pressure, folding position pressure, coefficient of variation, and global and trunk pressure variation were measured by the TBED Postural Couch evaluation system. In the adolescent idiopathic scoliosis group, full-length spine radiographs were taken to measure Cobb angle, coronal balance, apical vertebral deviation and Nash-Moe rotation. The characteristics of coronal pressure variation and its correlation with coronal imbalance were analyzed.   RESULTS AND CONCLUSION: (1) Compared with the control group, there was no statistically significant difference in the horizontal position pressure and folding position pressure in the adolescent idiopathic scoliosis group (P > 0.05), but the global pressure variation and coefficient of variation were significantly increased (all P < 0.05). (2) There were differences in both sides of the trunk of the adolescent idiopathic scoliosis group and the control group (P < 0.05), and the convex side pressure variation in the adolescent idiopathic scoliosis group was higher than the concave side pressure variation in the left and right side pressure variation in the control group (all P < 0.05). (3) The variation of the convex side pressure of the trunk in adolescent idiopathic scoliosis patients was positively correlated with coronal balance intensity (r=0.692, P < 0.05), moderately positively correlated with Cobb angle and apical vertebral deviation (r=0.499, 0.595, all P < 0.05), and weakly correlated with Nash-Moe grade (r=0.377, P < 0.05). The variation of the concave side pressure of the trunk was moderately positively correlated with coronal balance (r=0.410, P < 0.05), and the rest was weakly correlated or not correlated (P > 0.05). (4) These findings indicate that pressure variation may be used as an adjoint assessment tool in patients with mild to moderate scoliosis. Figures and Tables | References | Related Articles | Metrics

Select

Correlation between acetabular development and spinopelvic parameters in patients with developmental dysplasia of the hip Lin Tianye, Zhang Wensheng, He Xiaoming, He Mincong, Li Ziqi, Chen Zhenqiu, Zhang Qingwen, He Wei, Wei Qiushi 2024, 28 (6):  857-861.  doi: 10.12307/2023.794 Abstract ( 207 )   PDF (5567KB) ( 24 )   Save BACKGROUND: The majority of studies on developmental dysplasia of the hip focus on hip malformations, but there are few reports on the effects of acetabular dysplasia on the spine.   OBJECTIVE: To investigate the compensation of spinopelvic parameters in coronal and sagittal views in patients with developmental dysplasia of the hip, and to explore the correlation between acetabular development and spinopelvic parameters. METHODS: A total of 101 patients with developmental dysplasia of the hip admitted to the Third Affiliated Hospital of Guangzhou University of Chinese Medicine from January 2018 to June 2022 were selected as the trial group, and 114 healthy subjects were selected as the control group during the same period. The spinopelvic parameters of the subjects were measured through the full-length X-ray films of the coronal and sagittal spines: lumbar lordosis, anterior pelvic tilt, thoracolumbar kyphosis, Cobb angle, and the distance between the C7 plumb line and the center sacral vertical line, sacral slope, pelvic incidence, and thoracic kyphosis. The differences in spinopelvic parameters were compared between the two groups. In addition, the differences in spinopelvic parameters in patients with unilateral, bilateral and different Crowe classifications of developmental dysplasia of the hip were compared. Pearson correlation analysis was used to explore the correlation between Sharp angle and spinopelvic parameters.   RESULTS AND CONCLUSION: (1) In the sagittal view, the lumbar lordosis in the trial group was significantly lower than that in the control group (P < 0.05). The pelvic tilt and kyphosis angle of the thoracolumbar segment in the trial group were significantly greater than those in the control group (P < 0.05). In the coronary position, the Cobb angle and the distance between the C7 plumb line and center sacral vertical line in the trial group were significantly greater than those in the control group (P < 0.05). There was no significant difference in the remaining spinopelvic parameters between the two groups (P > 0.05). (2) The lumbar lordosis of patients with bilateral developmental dysplasia of the hip was significantly lower than that of patients with unilateral developmental dysplasia of the hip (P < 0.05). The pelvic tilt, thoracolumbar kyphosis, Cobb angle and the distance between the C7 plumb line and center sacral vertical line in bilateral developmental dysplasia of the hip patients were significantly greater than those in unilateral developmental dysplasia of the hip patients (P < 0.05). (3) The lumbar lordosis decreased with the increase of Crowe classification severity (P < 0.05). The pelvic tilt increased with the severity of the Crowe classification (P < 0.05). (4) Pearson correlation analysis showed that Sharp angle was negatively correlated with lumbar lordosis (P < 0.05), while Sharp angle was positively correlated with anterior pelvic tilt, Cobb angle, C7 plumb line and center sacral vertical line (P < 0.05). (5) It is concluded that the pelvic tilt, thoracolumbar kyphosis, Cobb angle and the distance between the C7 plumb line and center sacral vertical line increase, while lumbar lordosis decreases in developmental dysplasia of the hip patients. The degree of acetabular dysplasia was significantly correlated with lumbar lordosis, pelvic tilt, Cobb angle, C7 plumb line and center sacral vertical line. Figures and Tables | References | Related Articles | Metrics

Select

Finite element analysis of osteoporosis in proximal femur after cannulated screw fixation for femoral neck fracture Xue Xiaofeng, Wei Yongkang, Qiao Xiaohong, Du Yuyong, Niu Jianjun, Ren Lixin, Yang Huifeng, Zhang Zhimin, Guo Yuan, Chen Weiyi 2024, 28 (6):  862-867.  doi: 10.12307/2023.909 Abstract ( 219 )   PDF (30658KB) ( 15 )   Save BACKGROUND: After the internal fixation of cannulated screws in femoral neck fractures, because the affected limb is often unable to bear weight in the short term and the implants with high stiffness have a stress shielding effect on the fracture end, it is easy to cause osteoporosis of the affected limb and changes in the biomechanical distribution of the proximal femur, the incidence of osteonecrosis of the femoral head is high after surgery. At present, few studies have been conducted on the biomechanical effects of osteoporosis at the proximal end of the femur occurring after femoral neck fracture surgery on femoral neck fracture treated with cannulated screws.   OBJECTIVE: Using finite element analysis, to investigate the biomechanical effects of osteoporosis occurring after femoral neck fracture surgery on femoral neck fracture treated with cannulated screws and explore the role of biomechanical factors in osteonecrosis of the femoral head. METHODS: Based on the obtained CT scan data of the femur in a patient with a femoral neck fracture, a proximal femoral model for internal fixation for femoral neck fracture was established by Mimics 19.0, 3-Matic, UG 11.0, Hypermesh 14.0, and Abaqus software. One finite element model of the proximal femur without osteoporosis and three finite element models of the proximal femur with osteoporosis were analyzed using Abaqus software. The stress, contact pressure, displacement peak and cloud map under different components of the four models were measured and analyzed, and the internal stress changes and distribution of the femoral head were compared and analyzed.   RESULTS AND CONCLUSION: The stresses and contact pressures of the femoral head and lower anterior cannulated screws varied more with the degree of osteoporosis. The peak displacement of the four models increased slowly with the degree of osteoporosis. By one-way analysis of variance, there was no significant effect of the degree of osteoporosis on the peak stress, contact pressure, and displacement of the different components. The internal stress distribution of the femoral head changed with the degree of osteoporosis. Changes in the biomechanical environment of the proximal femur have an important impact on osteonecrosis of the femoral head. Figures and Tables | References | Related Articles | Metrics

Select

Finite element analysis of anterograde and retrograde intramedullary nail for different areas of femoral shaft fractures Huang Peizhen, Dong Hang, Cai Qunbin, Lin Ziling, Huang Feng 2024, 28 (6):  868-872.  doi: 10.12307/2023.786 Abstract ( 225 )   PDF (2073KB) ( 61 )   Save BACKGROUND: Intramedullary nail has achieved a good clinical result in the treatment of femoral shaft fractures, but some patients still have aseptic nonunion due to mechanical instability. The femur is the longest and largest bone in the human body, but there are few studies on whether the fracture of the femur has different biomechanical results in different areas and the influence of different inserting methods on the stability of fracture fragments in different areas. OBJECTIVE: To analyze the biomechanical characteristics of anterograde and retrograde intramedullary nails in the treatment of different areas of femoral shaft fractures, and to evaluate the best way of insertion to reduce the incidence of nonunion. METHODS: CT data of a healthy volunteer were selected to import into the software of Mimics 19.0 and Geomagic studio 2017 to extract and optimize the three-dimensional model of the right femur. The anterograde and retrograde intramedullary nail models were built with Solidworks 2017 software and assembled with femoral shaft fracture models at different fracture areas according to standard surgical techniques. The models were imported into Abaqus 2017 software in STEP format to set material attribute parameters, boundary conditions, load and submit calculation, and the results were viewed in the visualization module. Among them, the antegrade and retrograde intramedullary nails of the upper femoral shaft fracture were A1 and A2 models, B1 and B2 models in the middle segment, and C1 and C2 models in the lower segment.  RESULTS AND CONCLUSION: (1) In models A1, B1 and C2, the overall stress distribution of the femur was more uniform, and the placement, the displacement and angle of the fracture site, and inversion angle of the proximal femoral bone fragment were smaller. (2) For the upper and middle femoral shaft fractures, the anterograde intramedullary nail has a better biomechanical effect. For lower femoral shaft fractures, a retrograde intramedullary nail is preferable. Figures and Tables | References | Related Articles | Metrics

Select

Finite element analysis of different fixation methods of partially threaded cannulated screws for treating vertical femoral neck fractures Tan Nengxian, Wu Wenzheng, Zheng Churong, Luo Lieliang, Gu Peng, Ouyang Chongzhi, Zheng Xiaohui 2024, 28 (6):  873-878.  doi: 10.12307/2024.011 Abstract ( 239 )   PDF (3576KB) ( 22 )   Save BACKGROUND: The more vertical the femoral neck fracture line, the more shear force the femoral neck fracture may bear, so it may be prone to internal fixation failure, nonunion, or necrosis of the femoral head. At present, there is controversy as to which hollow nail fixation mode is ideal.  OBJECTIVE: To evaluate different configurations and numbers of cannulated screw configurations to learn more about the biomechanical differences in vertical fractures of the femoral neck using finite element analysis.  METHODS: Femoral CT data were collected from a 24-year-old healthy male volunteer and imported into Mimics software to build a three-dimensional geometric model of the femur. Model refinement and surface fitting processing were carried out in Geomagic software and imported into SolidWorks software to establish a vertical fracture model of the femoral neck. Six cannulated screw models were established, including three triangle configuration, three inverted triangle configuration, three double-plane double-support configuration (F scheme), three transverse configuration, four diamond configuration and four Alpha configuration. The peak stress, strain and displacement of internal fixation and femoral fracture models under different loads (350, 700, 1 400, and 2 100 N) were compared among different configurations. RESULTS AND CONCLUSION: (1) Under four kinds of loads, screw stress conditions were as follows: biplanar double-supported configuration (F scheme) > transverse configuration > inverted triangle configuration > positive triangular configuration > Alpha configuration > rhombus configuration. The peak value of Von mises stress was concentrated in the screw close to the fracture line. (2) Under four kinds of loads, the screw displacement was Alpha configuration > inverted triangle configuration > positive triangular configuration > biplanar double-supported configuration (F scheme) > rhombus configuration > transverse configuration, and the peak displacement was mainly concentrated on the hollow screw head. (3) Under four kinds of loads, the stress conditions of the proximal femoral bone block were biplanar double-supported configuration (F scheme) > transverse configuration > inverted triangle configuration > Alpha configuration > positive triangular configuration > rhombus configuration, and the stress peak mainly concentrated in the lower neck of femur. (4) Under 350 N load, the displacement of the proximal femur bone block was transverse configuration > biplanar double-supported configuration (F scheme) > positive triangular configuration > Alpha configuration > inverted triangle configuration > rhombus configuration. In the other three loads, the peak displacement of the inverted triangle configuration was smaller than that of the rhombus configuration. The peak displacement was mainly concentrated in the head. (5) The rhombus configuration was the most dispersed in the stress distribution of the proximal femoral bone. The rhombus configuration was the smallest in the peak displacement of the femur. The stress, displacement and peak displacement of the fracture end of each internal fixed model increased gradually with the increase of load. (6) The biomechanical performance of the four diamond-shaped models in the internal fixation of vertical femoral neck fractures is better than that of other groups of models. The four rhomboid models have stable fixation, small displacement value of fracture end and dispersed stress, which can help resist shear force and prevent varus collapse and create a good mechanical environment for fracture healing. Figures and Tables | References | Related Articles | Metrics

Select

Finite element analysis of three different minimally invasive fixation methods for distal tibial fractures with soft tissue injury Wang Mingming, Zhang Zhong, Sun Jianhua, Zhao Gang, Song Hua, Yan Huadong, Lyu Bin 2024, 28 (6):  879-885.  doi: 10.12307/2023.797 Abstract ( 260 )   PDF (13390KB) ( 18 )   Save BACKGROUND: The treatment of distal tibial fractures with soft tissue injury has always been challenging, and the new retrograde tibial nailing is a new choice. Up to now, there were few reports on the biomechanical properties between the new retrograde tibial nailing, anterograde intramedullary nailing and supercutaneous locking plate.  OBJECTIVE: To explore the biomechanical stability of new retrograde tibial nailing, antegrade intramedullary nailing and supercutaneous locking plate in the treatment of distal tibial fractures with soft tissue injury using finite element analysis so as to offer a scientific foundation for clinical application. METHODS: The finite element model of transverse distal tibia fracture was established by relevant software utilizing the CT data of the tibia from a 42-year-old healthy male. Retrograde tibial nailing, antegrade intramedullary nailing and supercutaneous locking plate finite element models were assembled under the principle of fracture fixation. Finally, meshing, applying loads, and data processing were accomplished with the ANSYS 2019 software. Moreover, the stress distribution and displacement of the tibia and internal fixation of each model were compared.   RESULTS AND CONCLUSION: (1) The displacement of fracture end in the three groups increased with the increase of load. In all mode loads, the average displacement of the fracture end was the least in the retrograde tibial nailing group, followed by the supercutaneous locking plate group, and the highest in the antegrade intramedullary nailing group. At 800 N vertical load, the displacement difference of the fracture end was statistically significant (P < 0.05). There was no statistical significance in other load modes. (2) Under different loads, the tibial stress in the three groups was the highest in the middle of the tibia, and gradually decreased to the proximal and distal ends. The stress distribution of the tibial shaft was the highest in the retrograde tibial nailing group, followed by the supercutaneous locking plate group, and the least in the antegrade intramedullary nailing group. (3) Under different loads, the stress of the tibial stress raiser in the three groups was significantly higher in the supercutaneous locking plate group than in the other two groups, with statistical significance (P < 0.05). (4) Under different loads, the stress of the fixators in the three groups was the largest in the supercutaneous locking plate group, followed by the retrograde tibial nailing group, and the minimum in the antegrade intramedullary nailing group. There were significant differences in the stress of fixator stress raiser among the three groups under different loading modes (P < 0.05). (5) It is indicated that all three fixation methods have the good anti-rotation ability and axial stability. Retrograde tibial nail shows better biomechanical stability. Figures and Tables | References | Related Articles | Metrics

Select

Finite element analysis of the mechanism of dorsiflexion injury of wrist joint in elderly people after falls Hou Zexin, Xu Benke, Dai Yuan, He Chuan, Zhang Chaoju, Li Xiaolin 2024, 28 (6):  886-890.  doi: 10.12307/2023.918 Abstract ( 252 )   PDF (1882KB) ( 22 )   Save BACKGROUND: At present, wrist protection products designed in and outside China have not solved the contradiction between protecting the wrist joint from injury and maintaining the flexible movement of the wrist joint.  OBJECTIVE: To investigate the biomechanical mechanism of dorsiflexion injury of the wrist joint in elderly people after falls, and to provide a biomechanical basis for the prevention and treatment of wrist injury in elderly people after falls.  METHODS: A 65-year-old man was selected to obtain the original data by uninterrupted CT scan of the middle and lower 2/3 of his left forearm up to the end of the finger. A finite element model of wrist dorsiflexion was established using ANSYS 12.0 finite element software. The palm surface of the model was constrained, and the model at a velocity load of 2 m/s in the direction of vertical downward was given to simulate the injury state of the palm when the elderly fall. The stress distribution of the soft tissues and bones of the wrist joint and the change of the stress with time were observed after the load was applied. RESULTS AND CONCLUSION: (1) A realistic and effective finite element model of the dorsal extension position of the wrist joint of the elderly was established. The soft tissue stresses were mainly concentrated in the small fissure of the palm and the dorsal side of the wrist after loading. The skeletal stresses were mainly concentrated in the lower end of the ulnar radius dorsally. The stresses in the lower end of the radius were the greatest. The palmar stresses were mainly concentrated in the middle and lower 1/3 of the radius and the hook bone. The stress distribution of the ulnar radius was asymmetric, and the stresses in the radius were more concentrated. (2) The results of the study are consistent with the clinical situation of a fallen wrist injury in elderly people, and can be used to explain the mechanism of wrist dorsiflexion injury, which can provide the biomechanical basis for the design of wrist protection devices that can be used to prevent wrist injury induced by falling and the treatment of wrist injury in elderly people. Figures and Tables | References | Related Articles | Metrics

Select

Finite element analysis on correction effect of varus foot orthosis based on the three-point force principle Ning Tianliang, Wang Kun, Wang Lingbiao, Han Pengfei 2024, 28 (6):  891-899.  doi: 10.12307/2023.710 Abstract ( 405 )   PDF (6725KB) ( 100 )   Save BACKGROUND: Three-point mechanics is an effective method for ankle foot orthosis correction and prevention of various foot diseases. At present, the clinical application research on 3D printing ankle foot orthosis has been widespread; however, there are relatively few reports on numerical simulation and finite element analysis involving three-point mechanical correction. There is a lack of relevant biomechanical experimental verification.   OBJECTIVE: Three-point force was loaded to analyze the composite model of ankle foot orthosis and foot by finite element method, observing the effect of foot correction with ankle foot orthosis under three-point force intervention, verifying the effectiveness of three-point force and the reliability of ankle foot orthosis. METHODS: A three-dimensional foot and ankle model of a healthy volunteer was constructed based on the medical image processing software Mimics. Rodin 4D and Geomagic reverse engineering software were used to optimize the models and design personalized ankle foot orthosis models. Solidworks software was utilized to turn the ankle model inside for 10° to simulate the foot varus disease. Static loading was carried out on the foot force application area by ANSYS software combined with the three-point mechanics principle. The deformation and stress changes of the foot and ankle tissues were analyzed when the human foot pain threshold was met. The display dynamics was used to further verify the effectiveness of the three-point force applied by the ankle foot orthosis.   RESULTS AND CONCLUSION: (1) The personalized ankle foot orthosis designed in this paper had the effect of preventing and fixing foot and ankle varus. The ankle varus was 1.81 mm after being loaded with 1 N•m of varus when not wearing ankle foot orthosis, while it was only 0.44 mm after wearing ankle foot orthosis, the deformation rate was reduced by 75.7%, and the effect of preventing varus was significantly enhanced. (2) When only coronal correction was performed, the low calcaneal force would aggravate the varus angle of the front foot. After adjusting the correction force on the inside of the heel and above the medial malleolus, the varus angle of the front foot and the calcaneus position were improved; however, the medial phalangeal region of the foot still had different degrees of adduction and displacement, which would aggravate the adduction deformity of the patient’s front foot. (3) The correction effect of the coronal plane and horizontal plane was better than that of the single coronal plane. There was no adduction and displacement of the medial phalanges of the front foot and the varus angle of the front foot decreased under the force (25, 10, 10, 20 N) of the medial heel, the medial shaft of the first metatarsal, below the lateral malleolus and above the medial malleolus, and the valgus along the X-axis was corrected by 1.395 mm, the calcaneus valgus was corrected by 1.227 mm. The calcaneus varus angle was corrected from 10.21° to 7.25°, and the varus angle was improved by 28.9%. (4) The lateral plantar metatarsal load decreased, the medial plantar metatarsal load increased under the action of a two-plane three-point force, and the plantar bone stress was significantly improved after correction. Thus, the reliability of the three-point force principle was further verified. This study provides an important theoretical support for the implementation of ankle foot orthosis in the treatment of varus in clinical practice. Figures and Tables | References | Related Articles | Metrics

Select

Effect of visual feedback on landing biomechanics in chronic ankle instability patients Zhang Lili, Zhang Xinglai, Zhang Jie, Zheng Jiejiao 2024, 28 (6):  900-904.  doi: 10.12307/2023.784 Abstract ( 319 )   PDF (1478KB) ( 73 )   Save BACKGROUND: The landing test can effectively observe the biomechanical indexes of the lower limbs of patients with chronic ankle instability, analyze the balance adjustment strategies that affect the stability of chronic ankle instability posture, and provide a valuable reference for chronic ankle instability patients to avoid re-injury and clinical rehabilitation after injury.   OBJECTIVE: To analyze the effects of vision on the balance of chronic ankle instability and the changes in balance adjustment strategies by observing the kinematics and kinetics of chronic ankle instability patients during landing with and without vision. METHODS: Totally 31 patients with chronic ankle instability landed on a single leg from a 40 cm platform with their eyes open and closed. The dynamic and kinematic data during the landing process were collected using a three-dimensional motion capture system. The difference in landing between the healthy and the ill side legs under the two conditions was compared by paired t-test.   RESULTS AND CONCLUSION: (1) Dynamic indexes: The relative value of the peak ground reaction force in the front, rear and vertical directions of the affected ankle joint when eyes were closed was greater than that when eyes were open, and the peak ground reaction force in the vertical direction appeared later than that when eyes were open (P < 0.05). (2) Kinematics indexes: The flexion angle of the knee of the healthy and affected sides when touching the ground was greater under the condition of closed eyes than under the condition of open eyes (P < 0.05). The maximum flexion angle and feedforward angle of the affected knee and ankle were greater than those of the affected side with eyes open (P < 0.05). The time of landing stability was longer than that of eye opening (P < 0.05). (3) It is indicated that under the condition of removing visual input, the peak of ground reaction force increases, the contact angle joint increases, and the time to stabilization of chronic ankle instability is prolonged during landing in patients with chronic ankle instability, which increases the probability of landing injury. Visual maintenance of the balance of chronic ankle instability patients cannot compensate for the vestibular sense and proprioception. Figures and Tables | References | Related Articles | Metrics

Select

Application of three-dimensional simulated osteotomy of the distal femur in total knee arthroplasty Wang Tihui, Wang Xu, Wu Jinqing, Chen Jiliang, Wang Xiaolu, Miao Juan 2024, 28 (6):  905-910.  doi: 10.12307/2023.764 Abstract ( 212 )   PDF (1833KB) ( 30 )   Save BACKGROUND: Studies have shown that there are significant differences in the geometric morphology of the distal femur of different races and genders, and there are more short female patients in southern China, so the phenomenon of overhanging or insufficient coverage of imported knee prostheses often occurs during surgery.   OBJECTIVE: To investigate the characteristics of distal femur bones in southern Chinese women and compare them with imported joint prostheses by simulating the three-dimensional reconstruction of the distal femur bone and matching the femoral side after osteotomy with common imported joint prostheses. METHODS: From January to December 2021, 120 female volunteers underwent a CT scan of knee joints. The images were imported into Mimics 20.0 software in Dicom format for three-dimensional reconstruction and then imported into Magic 22.0 software to simulate osteotomy by posterior cruciate ligament preserved total knee arthroplasty and to conduct a matching study with a normal imported joint prosthesis.   RESULTS AND CONCLUSION: (1) The functional anteroposterior dimension (fAP) of the distal femur and Persona matched prosthesis had a total overhang rate of 25%(30/120). The fAP≤47 mm group had an overhang than the other groups (P < 0.05). The poor coverage rate of Triathlon prosthesis was 12.5%(15/120), and poor coverage was more likely in fAP>53 mm group than in fAP≤53 mm group (P < 0.05). (2) The total poor coverage rate of femoral intercondylar width matching with Triathlon prosthesis was 27.5%(33/120). Therefore, the poor coverage rate of bone surface in the central region of the distal femur was more likely in the fAP≤47 mm group than in other groups (P < 0.05). The overhang rate of Journey II was 21.6%(26/120), and the overhang rate was higher in the fAP>53 mm group than in the fAP≤53 mm group (P < 0.05). (3) Journey II CR prosthesis had the largest difference with the length of the anterior mediolateral diameter of the femur, which was easy to hang out on the anterolateral side of the femoral prosthesis. The Persona CR prosthesis has the largest difference with the length of the posterior mediolateral diameter of the femur, which is easy to be poorly covered in the posterior medial part of the prosthesis. It is recommended to increase the femoral prosthesis with reduced mediolateral diameter in the fAP≤47 mm group and add wider and narrower sizes than the conventional size of intercondylar width, and optimize the anterolateral angular arc design of the femoral prosthesis to improve the matching of posterior cruciate ligament reserved knee prosthesis. Figures and Tables | References | Related Articles | Metrics

Select

Proximal femoral nail antirotation for femoral intertrochanteric fractures with lateral wall integrity and lateral wall risk Wu Zhonghan, Wang Jingkun, Li Tao, Xu Xinzhong, Yu Shuisheng, Cheng Li, Tian Dasheng, Tang Jian, Jing Juehua 2024, 28 (6):  911-916.  doi: 10.12307/2023.903 Abstract ( 223 )   PDF (1807KB) ( 136 )   Save BACKGROUND: For elderly patients with traumatic hip fractures, the related factors of prognosis are very complex, and the integrity of the lateral wall is one of the influencing factors. It is of important clinical value to understand the effect of lateral wall injury on the prognosis of femoral intertrochanteric fracture. OBJECTIVE: To evaluate the relationship between the integrity of the lateral wall and hip functional recovery and other outcomes in patients with femoral intertrochanteric fractures. METHODS: Totally 82 patients with femoral intertrochanteric fractures were screened and all patients received proximal femoral nail antirotation fixation. According to the thickness of the lateral wall, the patients were divided into the lateral wall intact group (n=31) and lateral wall risk group (n=51). The perioperative indexes, weight-bearing time, fracture healing time, hip joint function and range of motion, postoperative pain and complications were compared between the two groups. RESULTS AND CONCLUSION: (1) The time of hospitalization and the number of fluoroscopies during operation in the lateral wall intact group were significantly lower than those in the lateral wall risk group (P < 0.05), but there was no significant difference in other perioperative indexes. (2) Both groups were able to get down to the ground early after surgery and finally complete weight-bearing, but in the lateral wall risk group, the time of fracture healing was longer; the time of complete weight-bearing was significantly delayed; the Harris score of the last follow-up was lower; the range of motion of hip extension and flexion and neck trunk angle on the affected side were smaller (P < 0.05). (3) There was no significant difference in the incidence of postoperative complications between the two groups, but the overall incidence of complications in the lateral wall intact group was significantly lower (P < 0.05). (4) In summary, after internal fixation of proximal femoral nail antirotation, patients with the intact lateral wall had a relatively better prognosis than those with risk lateral wall.  Figures and Tables | References | Related Articles | Metrics

Select

Effect of different locations of necrotic focus on the natural course of non-traumatic osteonecrosis of the femoral head Zhao Rushun, Hao Yangquan, Xu Peng, Zheng Xin, Jiang Yonghong, Zhang Yuting, Wang Mengfei, Lu Chao 2024, 28 (6):  917-921.  doi: 10.12307/2024.010 Abstract ( 199 )   PDF (1522KB) ( 20 )   Save BACKGROUND: For non-traumatic osteonecrosis of the femoral head, if the femoral head collapses, it will have a great impact on the normal life of the patients. Thus, it is necessary to use an appropriate way to evaluate the risk of femoral head collapse and then to take targeted measures to delay the process of femoral head collapse.   OBJECTIVE: To analyze the natural course of early osteonecrosis of the femoral head (without collapse) under different locations of necrotic lesions. METHODS: 121 patients (191 hips) with early non-traumatic osteonecrosis of the femoral head who were treated in the Outpatient Department of Honghui Hospital Affiliated to Xi’an Jiaotong University from October 2016 to October 2017 were enrolled in this study. The clinical data of all patients were followed up for 5 years to observe the collapse of osteonecrosis of the femoral head and the risk coefficient of femoral head collapse among different JIC types. The collapse rate of osteonecrosis of the femoral head was calculated during the follow-up.   RESULTS AND CONCLUSION: (1) A total of 191 hips were included in this study. The femoral head collapsed in 86 hips during follow-up, with a total collapse rate of 45.0%. Among the influencing factors, age, ARCO stage and JIC classification were the main influencing factors of femoral head collapse (P < 0.05), but body mass index, sex, incidence side and pathogenic factors were not the main influencing factors (P > 0.05). (2) Among 191 hips, in JIC classification, the total collapse rates of type A, type B, type C1 and type C2 were 11.1%(2/18), 30.2%(16/53), 52.4%(43/82), and 65.8%(25/38), respectively. There were significant differences in the total collapse rate of the femoral head among all types (P < 0.05). The collapse risk results showed that the collapse risk of type B, type C1 and type C2 was 2.41, 5.22 and 7.89 times higher than that of type A, respectively. (3) Both JIC classification and ARCO stage were correlated with femoral head collapse (P < 0.01). There was no significant difference in the collapse rate of the femoral head among all JIC types in ARCO I stage hips (P > 0.05). In the hips with ARCO II stage, the collapse rates of the femoral head of JIC types A, B, C1 and C2 were 1.2%, 19.5%, 50.0% and 29.3%, respectively, and there were significant differences in the collapse rates among different types (P < 0.05). (4) During follow-up, the collapse rates of the femoral head in the first to fifth years were 29.3%, 7.9%, 4.7%, 2.6% and 0.5%, respectively. (5) Results showed that for early non-traumatic osteonecrosis of the femoral head, the risk of collapse of osteonecrosis of the femoral head is high within one year, and the location of the focus of osteonecrosis affects the risk of collapse of the femoral head. The effect of the location of the focus on the prognosis of the disease should be considered in clinical treatment. Figures and Tables | References | Related Articles | Metrics

Select

3D printed guide template technique combined with multiple derotation for severe rigid scoliosis Zhang Zhidong, Qi Jialong, Pei Shaobao, Ma Li, Wang Shansong, Liu Yiming 2024, 28 (6):  922-926.  doi: 10.12307/2023.763 Abstract ( 195 )   PDF (2606KB) ( 14 )   Save BACKGROUND: In recent years, with the development of 3D printing, surgical surgery has become personalized and accurate. 3D printed guide template technique can realize preoperative planning and intraoperative navigation, making surgery more accurate. In clinical orthopedic surgery for moderate and severe stiff scoliosis, there is still a problem that the accuracy of screw placement is not high, resulting in screw loosening and even nerve complications. There are few studies on 3D printed guide template technique to guide screw placement in surgery for severe stiff scoliosis.   OBJECTIVE: To evaluate the clinical effect of the 3D printed guide template technique combined with multiple posterior derotation in the treatment of severe rigid scoliosis. METHODS: The clinical data of six patients with severe scoliosis undergoing 3D printed guide template technique of pedicle screw combined with multiple posterior derotation were retrospectively analyzed. There were 3 males and 3 females, with a mean age of (18.17±3.49) years (range, 15-23 years). The changes of parameters related to lateral bending were analyzed at postoperative 2 weeks and 18 months, and the results were obtained by statistical analysis.   RESULTS AND CONCLUSION: (1) The operation time was 280-540 minutes (mean 340.83±102.20 minutes). The intraoperative blood loss was 1 000-4 000 mL (mean 2 000.00±1 073.70 mL). The fixed segments were 9-14 vertebral bodies (mean 11.83±1.72), and no screw loosening occurred during the operation. (2) All patients were followed up. At postoperative 2 weeks, the anteroposterior and lateral radiography of the whole spine showed that the cobb angle, the distance between the vertical line of C7 on the coronal plane and the median line of S1, the distance between the vertical line of C7 in the sagittal plane and the posterior edge of S1, apical vertebral translation, thoracic kyphosis, and lumbar lordosis were significantly corrected. The average correction rate of the cobb angle in the main curve was 62.22%. After 18 months of follow-up, there was no significant change in all parameters compared with 2 weeks after operation; the orthopedic effect was satisfactory, and there was no infection or internal fixation fracture. (3) There was one case of delayed wound healing; scar healing appeared after dressing change treatment; no neurological complications occurred. (4) The results show that the 3D print-guide template combined with multiple posterior rod derotation technique is safe and effective in the treatment of severe rigid scoliosis, and the correction effect is satisfactory. Figures and Tables | References | Related Articles | Metrics

Select

Relationship between drainage time and early efficacy after short-segment lumbar fusion Chen Zan, Lei Fei, Ye Fei, Zhou Qingzhong, Yuan Hao, Zheng Lipeng, Zha Xian, Feng Daxiong 2024, 28 (6):  927-933.  doi: 10.12307/2023.777 Abstract ( 190 )   PDF (4013KB) ( 78 )   Save BACKGROUND: As a routine method after lumbar spine surgery, a drainage tube is convenient for postoperative bleeding drainage and management, and there is still no consensus on the choice of postoperative removal time for short-segment lumbar spine surgery with less risk. OBJECTIVE: To explore the effect of different drainage times on early clinical efficacy after short-segment lumbar fusion.   METHODS: A prospective randomized controlled study was performed on 220 patients in the Affiliated Hospital of Southwest Medical University who underwent posterior lumbar interbody fusion for lumbar degenerative diseases from March 2017 to April 2021. According to the different drainage times, the patients were randomly divided into removal on the second day after operation (group A), removal on the third day after operation (group B), and removal after the observation method 24-hour drainage volume < 30 mL (group C). The perioperative indicators and follow-up results of the three groups of patients were observed and compared.  RESULTS AND CONCLUSION: (1) Because 7 patients were lost to follow-up, 2 patients were excluded, and 211 patients were finally included (72 patients in group A, 71 patients in group B, and 68 patients in group C). (2) The average drainage time of group C was 2.91 days. The postoperative drainage volume in group A was significantly less than that in groups B and C, and the difference was statistically significant (P < 0.05). On day 3 after operation, the hematocrit value of group C was lower than that of group A and group B, and the difference was statistically significant (P < 0.05). Postoperative activity time and hospital stay in group A were shorter than those in groups B and C, and the difference was statistically significant (P < 0.05). (3) Four patients in group A, two patients in group B and three patients in group C received an allogeneic blood transfusion. There was no significant difference among the groups (P > 0.05). (4) In terms of postoperative complications, there were no statistical differences in postoperative wound leakage and surgical site infection in all three groups (P > 0.05). (5) All patients were followed up for more than 12 months. Visual analog scale score and Oswestry dysfunction index of the three groups of patients before discharge and at the last follow-up were significantly improved compared with those before surgery (P < 0.05). There was no statistical significance among the groups (P > 0.05). (6) It is indicated that the removal of the drainage tube on the second day after a posterior lumbar fusion can effectively reduce the time to get out of bed and hospital stay, without increasing the postoperative blood loss and the risk of complications.  Figures and Tables | References | Related Articles | Metrics

Select

Open reduction and internal fixation via the para-Achilles tendon approach for the treatment of posterior malleolus sandwich fractures Zheng Jiafa, Song Xiufeng, Li Hongzhi, Zhou Jinming, Guan Shengyi, Yu He 2024, 28 (6):  934-938.  doi: 10.12307/2023.783 Abstract ( 243 )   PDF (2488KB) ( 11 )   Save BACKGROUND: Accurate reduction of ankle fractures under direct vision has become a common understanding among foot and ankle surgeons. How to fully expose free or compressed fragments of the posterior ankle remains one of the most challenging problems. OBJECTIVE: To explore the clinical efficiency of the para-Achilles tendon approach in exposing and repositioning the posterior malleolus sandwich fracture. METHODS: A retrospective study was made for 26 patients with posterior malleolus sandwich fracture treated with open reduction and internal fixation via para-Achilles tendon approach from January to December 2020 in The Second People’s Hospital of Dalian. 21 of 26 cases were managed with the lateral approach of Achilles tendon and 5 cases were managed with the medial approach of Achilles tendon. There were 19 males and 7 females, with the age of 24-69 years, averagely 38.6 years. The operation time and postoperative complications were recorded. The fracture reduction condition was evaluated by Burwell-Charnley imaging standard. Before operation, 3 months after operation and last follow-up, visual analog scale score, ankle plantar flexion and dorsiflexion and American Orthopedic Foot & Ankle Society Ankle Hind Score were used to evaluate the treatment effect.   RESULTS AND CONCLUSION: (1) All 26 patients were followed up for an average of 14.6 months (range 13-18 months). The operation time was 52-85 minutes (average 64.2 minutes). (2) Part of the skin edge of the lateral malleolus incision was necrotic in one patient and healed completely after a dressing change. Incision healing of the other patients was in one stage. (3) Through Burwell-Charnley imaging standard, anatomical reductions were obtained in 24 of 26, and good reductions were in 2 of 26, with an excellent and good rate of 100%. (4) At the last follow-up, the visual analog scale score (1.19±0.40) was significantly lower than the preoperative score (6.81±0.80) (P < 0.01). Ankle plantar flexion (33.5±5.02)° and ankle plantar back stretch (17.23±0.99)° were significantly increased compared with preoperative data (14.58±2.50)° and (5.81±1.02)° (P < 0.01). American Orthopedic Foot & Ankle Society Ankle Hind Score was improved to (89.31±3.62) points compared to preoperative (46.00±5.45) points (P < 0.01). The results were excellent in 23 patients and good in 3 patients, with an excellent and good rate of 100%. (5) It is concluded that the open reduction and internal fixation via the para-Achilles tendon approach for the treatment of posterior malleolus sandwich fracture were efficient with decreased operation time, satisfying fracture reduction, fewer complications, satisfactory motion range, and functional recovery.   Figures and Tables | References | Related Articles | Metrics

Select

Imaging landmarks of one-hole split endoscope in the treatment of upper lumbar intervertebral disc herniation under the guidance of three-dimensional reconstruction Liu Changzhen, Liu Xin, Li Yuefei, Wang Jianye, Feng Zhimeng, Sun Zhaozhong 2024, 28 (6):  939-944.  doi: 10.12307/2023.736 Abstract ( 200 )   PDF (8200KB) ( 15 )   Save BACKGROUND: One-hole split endoscope technique has been widely used in the treatment of lumbar degenerative diseases, but there is no relevant literature on the safety analysis of this technique in the treatment of upper lumbar disc herniation. OBJECTIVE: To observe the position relationship of nerve roots, intervertebral space and bone landmarks in the upper lumbar spine by three-dimensional lumbar CT reconstruction technology, and to provide a basis for the clinical operation of one-hole split endoscope surgery. METHODS: Twenty-six patients with upper lumbar disc herniation underwent a lumbar CT scan. Mimics 17.0 software was imported to measure the related imaging parameters of L1/2 to L3/4 segments: (1) Measurement of vertical distance: In coronal view, the distance (a) from the intersection point of the medial facet of the superior articular process and the superior endplate (N) to the apex of the articular process (S); in the coronal view, the distance (b) from the sagittal intersection (M) of N and the inferior endplate to the apex of the inferior articular process (X). (2) Measured horizontal distance: the distance (c) between the cross-section of N and the lower edge of the outlet nerve root (N2); distance (d) between the cross-section of N and the intersection point of neural tissue (N1); N1 to N2 distance (e); distance (f) between the cross-section of M and the lateral edge of the nerve tissue (M1); M to M cross-section and exit nerve root intersection (M2) distance (g); distance (h) from M1 to M2; distance (i) from M2 to N1; distance (j) from the posterior edge of the articular surface (R) to M2 in sagittal view of the superior articular process.  RESULTS AND CONCLUSION: (1) With the decrease of the segment, the distances a and b gradually increased, and the distance j gradually decreased. There was no significant difference between L1/2 and L2/3 segments (P > 0.05). (2) With the decrease of the segment, distance d first decreased and then increased; distance f gradually decreased; distances c, e, g, h and i gradually increased; and there was no significant difference between L2/3 and L3/4 segments (P > 0.05). (3) Distance i was the shortest distance without pulling nerve roots in the natural state, and the area of the safety zone was between four points M1, M2, N1, and N2. The bone was removed to the upper and lower endplates by biting the bone downward and upward through S and X, respectively, to expose the intervertebral space, and the window of distance g to M2 could be opened outward to avoid injury of the outlet nerve roots. (4) In conclusion, the upper lumbar vertebrae have unique anatomical characteristics. Based on the relevant measurements of nerve roots, spinal dura and intervertebral space, the parameters of the one-hole split endoscope technique are more accurate and safe during operation.  Figures and Tables | References | Related Articles | Metrics

Select

Effect of lumbar CT values in the diagnosis of osteoporosis in women patients with lumbar degenerative diseases Kaiyisaier•Abudukelimu, Maimaitimin•Abulimiti, Li Lei, Yang Xiaokai, Zhang Yukun, Liu Shuai 2024, 28 (6):  945-949.  doi: 10.12307/2023.907 Abstract ( 302 )   PDF (3282KB) ( 59 )   Save BACKGROUND: Patients with severe lumbar degenerative disease may have their bone mineral density incorrectly raised by dual-energy X-ray absorptiometry. While lumbar cancellous bone Hounsfield unit value can assist dual-energy X-ray absorptiometry in reducing osteoporosis misdiagnosis.   OBJECTIVE: To identify osteoporosis in woman patients with lumbar degenerative diseases using lumbar CT scans. METHODS: Bone mineral density test results and lumbar CT data of 192 women patients who were treated at the Department of Spine Surgery, Sixth Affiliated Hospital of Xinjiang Medical University were retrospectively reviewed. All patients were divided into a degeneration group (n=107) and a control group (n=85) according to the criteria of severity of vertebral degeneration as assessed on CT of the lumbar spine. The CT value of axial cancellous bone of L1 vertebral body was measured in the two groups. The T score and bone mineral density of the hip and L2-L4 were recorded. According to previously published studies, osteoporosis was diagnosed at L1 vertebral CT values ≤110. The prevalence of osteoporosis diagnosed by dual-energy X-ray absorptiometry and CT values was compared between the two groups.   RESULTS AND CONCLUSION:  (1) CT values were significantly and positively correlated with T scores and mean bone mineral density of the L2-L4 vertebrae in both groups (P < 0.001), while the correlation was higher in the control group. (2) Lumbar T scores and bone mineral density values were significantly higher in the degeneration group than those in the control group (P < 0.05) and CT values were significantly lower in the degeneration group than that in the control group (P = 0.001). Hip T scores and bone mineral density were not significantly different in the two groups. (3) The prevalence of osteoporosis diagnosed by CT thresholds was higher in all patients than that diagnosed by T values (51.0% and 42.7%). (4) The prevalence of osteoporosis diagnosed by CT values was as high as 23.6% in the 110 patients diagnosed with non-osteoporosis by dual energy X-ray absorptiometry in both groups, and was higher in the degeneration group than that in the control group (31.7% and 14.0%, respectively). (5) The prevalence of missed osteoporosis was as high as 38.6% (27/70) of non-osteoporosis patients diagnosed by dual-energy X-ray absorptiometry of the lumbar spine in the degeneration group compared to 19.6% (11/56) in the control group. (6) It is concluded that osteoporosis is common in female patients with lumbar degenerative diseases aged ≥50 years. Measurement of lumbar cancellous bone CT values may be a useful complementary method for diagnosing osteoporosis in patients with lumbar degenerative diseases, especially in patients with severe degenerative lumbar degenerative diseases where more missed osteoporosis patients can be identified. Figures and Tables | References | Related Articles | Metrics

Select

HU value of chest CT vertebral body in the opportunistic screening of type 2 diabetes mellitus osteoporosis Wang Liping, Lian Tianxing, Hu Yongrong, Yang Hongsheng, Zeng Zhimou, Liu Hao, Qu Bo 2024, 28 (6):  950-954.  doi: 10.12307/2023.795 Abstract ( 328 )   PDF (1675KB) ( 38 )   Save BACKGROUND: Some studies have shown that the hounsfield units (HU) value based on lumbar CT can be used to screen osteoporosis. At present, the number of patients with pulmonary infection has increased; the number of patients with pulmonary infection and type 2 diabetes is also increasing, which increases the utilization rate of chest CT.  OBJECTIVE: To investigate the role of lumbar 1 vertebral body HU value based on chest CT in the screening of type 2 diabetes mellitus osteoporosis. METHODS: The clinical data of 244 patients with type 2 diabetes mellitus treated in the First Affiliated Hospital of Chengdu Medical College from June 2020 to June 2022 were analyzed retrospectively. The bone mineral density was obtained by dual-energy X-ray absorptiometry. According to WHO’s diagnostic criteria for osteoporosis, the subjects were divided into the non-osteoporosis group (n=120) and the osteoporosis group (n=124). The general condition, T value and HU value of lumbar 1 vertebra in chest CT were compared, and the relationship between the HU value and T value of each position was analyzed and the accuracy of type 2 diabetes mellitus osteoporosis was evaluated.  RESULTS AND CONCLUSION: (1) There was no significant difference in sex, age, body mass index, glycosylated hemoglobin, mean blood glucose, calcium (Ca), phosphorus (P), time of type 2 diabetes mellitus, history of hypertension and history of hyperlipidemia between the two groups (P > 0.05). (2) The HU value was positively correlated with the lowest T value of the hip (r=0.619, P < 0.01); the HU value was positively correlated with the hip T value (r=0.584, P < 0.01), and the HU value was positively correlated with the femoral neck T value (r=0.641, P < 0.01). When the HU value was 98, the prediction of type 2 diabetes mellitus osteoporosis had good accuracy, and the sensitivity was 70.8%. (3) It is concluded that the HU value of the lumbar 1 vertebra based on chest CT examination is of good value for osteoporosis screening in patients with type 2 diabetes mellitus, and may be an opportunistic and cost-free supplementary screening method for type 2 diabetes mellitus osteoporosis.  Figures and Tables | References | Related Articles | Metrics

Select

Ischemia-reperfusion injury in total knee arthroplasty Yang Yifeng, Huang Jian, Ye Nan, Wang Lin 2024, 28 (6):  955-960.  doi: 10.12307/2023.788 Abstract ( 379 )   PDF (1568KB) ( 35 )   Save BACKGROUND: The mechanism, manifestation, prevention and treatment of ischemia-reperfusion injury have been reported in the past. However, there are few studies on the ischemia-reperfusion injury of lower limb skeletal muscle caused by total knee arthroplasty. This article focuses on the pathogenesis, clinical impact, prevention and treatment of the ischemia-reperfusion injury of lower limb caused by total knee arthroplasty. OBJECTIVE: To summarize the related literature of lower limb ischemia-reperfusion injury caused by total knee arthroplasty, analyze the mechanism and significance, and give hints for further research on skeletal muscle ischemia-reperfusion injury. METHODS: The relevant articles on PubMed, CNKI, WanFang and VIP databases published from January 1, 2000 to April 30, 2022 were searched by computer with the Chinese and English search terms of “ischemia-reperfusion injury, total knee arthroplasty, tourniquet, mechanism, pathophysiology, skeletal muscle, treatment”. After excluding repetitive research and some basic articles with low correlation, 68 articles were finally selected for review.  RESULTS AND CONCLUSION: (1) The pathogenesis of ischemia-reperfusion injury is related to oxygen free radicals, intracellular calcium overload, neutrophil activation, as well as high concentration of nitric oxide, no reflow phenomenon, apoptosis and other mechanisms. More detailed mechanism research can provide basis for future prevention and treatment. (2) Ischemia-reperfusion injury of lower limbs will cause local skeletal muscle injury, which may be caused by the trauma of the operation itself or the role of ischemia-reperfusion injury. More targeted research is needed to distinguish the relationship between the two. (3) Ischemia-reperfusion injury of lower limbs may even affect the distal organs, causing kidney and lung damage. It also affects local and systemic circulation. (4) To clarify the effect of ischemia-reperfusion injury can point out the direction for future prevention and treatment. The current prevention and treatment measures mainly include ischemic preconditioning, anesthetic, antioxidant and other drug prevention. (5) The detailed review of ischemia-reperfusion injury of lower limb skeletal muscle caused by total knee arthroplasty can provide basis for future diagnosis and treatment decisions. Figures and Tables | References | Related Articles | Metrics

Select

Research status and application prospect of cytokine therapy for osteoarthritis Zhang Kefan, Shi Hui 2024, 28 (6):  961-967.  doi: 10.12307/2023.793 Abstract ( 261 )   PDF (2399KB) ( 32 )   Save BACKGROUND: In cartilage degeneration in osteoarthritis, cytokines and signaling pathways that target chondrocytes play an important role.  OBJECTIVE: To review the latest research progress of osteoarthritis related cytokines and signaling pathways in recent years, such as the mechanism of action and treatment modalities, in order to provide a basis for future exploration of new therapeutic targets and modalities. METHODS: Literature search was conducted on CNKI, WanFang, VIP, PubMed, Web of Science, and Medline databases. Chinese search terms were “osteoarthritis, cytokines, signal pathway, chondrocyte, inflammation, treatment”. Finally, 60 papers were included for review.  RESULTS AND CONCLUSION: (1) In current studies, it is believed that the specific mechanism of osteoarthritis is not clear, and a large number of studies have shown that osteoarthritis is strongly associated with cytokines and signaling pathways, which is a complex process of action. Relevant studies taking cytokines and signaling pathways as therapeutic breakthroughs are also the current hot spot. (2) The receptor antagonists of pro-inflammatory factors such as interleukin 1 are not effective in the treatment of osteoarthritis, and more studies turn to gene therapy. (3) The therapeutic methods of transforming growth factor β, recombinant factors of Wnt signaling pathway, gene therapy and mesenchymal stem cells have obtained positive research results. However, basic and clinical studies on safety and efficacy are likely to be conducted in future studies. (4) At present, relevant therapeutic methods such as platelet-rich plasma have been widely used in clinical practice, while recombinant factor, gene therapy and mesenchymal stem cell therapy are all in the research stage, among which mesenchymal stem cell therapy and gene therapy are expected to make breakthroughs in the field of cartilage repair and regeneration, and are worthy of expectation in the future. However, more clinical and basic studies are needed to verify its effectiveness and safety, explore its mechanism of action and scope of application, and set standards for its clinical use.  Figures and Tables | References | Related Articles | Metrics

Select

Effect of foot progression angle on lower extremity kinetics of knee osteoarthritis patients of different ages: a systematic review and meta-analysis Zhang Zeyi, Yang Yimin, Li Wenyan, Zhang Meizhen 2024, 28 (6):  968-975.  doi: 10.12307/2023.782 Abstract ( 290 )   PDF (9852KB) ( 121 )   Save OBJECTIVE: Knee adduction moment and knee adduction angular impulse enlargement is the main biomechanical risk factor of knee osteoarthritis. According to the survey, a change in the foot progression angle could effectively change the motion mode of patients with knee osteoarthritis. However, the impact of toe-in and toe-out on knee adduction moment and knee adduction angular impulse in young and elderly patients did not reach a consensus. Therefore, this study comprehensively discussed the effect of foot progression angle on knee adduction moment and knee adduction angular impulse in different populations through meta-analysis and provided a reference for the treatment of knee osteoarthritis.  METHODS: By June 2022, searches were conducted on Web of Science, Ebsco, PubMed and CNKI databases using “foot progression angle, knee adduction moment, knee adduction angular impulse, gait” as Chinese and English search terms. Self-controlled randomized controlled studies analyzing the effects of toe-in and toe-out on knee adduction moment bimodality and knee adduction angular impulse were included. The cochrane bias risk assessment tool was utilized to make a quality evaluation of the literature. Stata 15.1 software was used for subgroup analysis to determine the effect of foot progression angle on knee adduction moment and knee adduction angular impulse. Meta-regression analysis was used to further determine characteristics of outcome indicators (knee adduction moment, knee adduction angular impulse) changing with foot progression angle. RESULTS: (1) A total of 15 self-control trials and 2 randomized controlled trials (455 subjects) were included in the meta-analysis. All of the included articles were of medium to high quality. (2) The meta-analysis results showed that the toe-in gait could reduce the first peak of knee adduction moment (SMD=-0.380, 95%CI:-0.710 to -0.060, P=0.022) and knee adduction angular impulse (SMD=-1.470, 95%CI:-2.160 to -0.770, P < 0.001) in young patients. The toe-out gait reduced the second peak of knee adduction moment (SMD=-0.720, 95%CI:-1.010 to -1.440, P < 0.001) in young patients. In addition, toe-in gait could reduce the first peak of knee adduction moment in elder patients (SMD=-0.550, 95%CI:-0.800 to -0.300, P < 0.001), but increase the second peak knee adduction moment of elderly (SMD=0.280, 95%CI:-0.010 to 0.560, P=0.047). The toe-out gait could decrease the second peak knee adduction moment in this population (SMD=-0.510, 95%CI:-0.830 to -0.190, P=0.002). (3) Meta-regression showed that the greater the toe-out in elderly patients, the lower the second peak knee adduction moment.  CONCLUSION: (1) Toe-in reduced the first peak knee adduction moment and knee adduction angular impulse in young knee osteoarthritis patients aged 18 to 34 years. Since knee adduction moment and knee adduction angular impulse were associated with medial knee loading and knee osteoarthritis incidence, toe-in gait intervention may be a suitable rehabilitation strategy for young patients. (2) Toe-in increased the second peak of knee adduction moment in older knee osteoarthritis patients over 60 years of age, which may exacerbate knee osteoarthritis in this population. However, the second peak of knee adduction moment during walking in this population decreases as the toe-out increases, contributing to a reduction in medial knee loading, suggesting that older patients may consider using toe-out gait during walking. Figures and Tables | References | Related Articles | Metrics

Select

Network meta-analysis of the modeling effects of different factors on rabbit models of steroid-induced osteonecrosis of femoral head Hu Zhixing, Li Qun, Yang Chao, Wang Xiaoxiao, Fang Luochangting, Hou Wuqiong, Lin Na, Chen Weiheng, Liu Chunfang, Lin Ya 2024, 28 (6):  976-984.  doi: 10.12307/2023.913 Abstract ( 221 )   PDF (1925KB) ( 26 )   Save OBJECTIVE: The rabbit model of steroid-induced osteonecrosis of femoral head is the most commonly used animal model of femoral head necrosis. The pathological changes of the femoral head are close to clinical practice, however, the conditions, methods and evaluation standards of animal models reported in and outside China are not uniform, which leads to the low scientific value of animal models and is difficult to popularize. This study aimed to clarify the influence of different mold-making conditions on the establishment of steroid-induced osteonecrosis of femoral head rabbit model and analyze the appropriate conditions for the successful model establishment. METHODS: We searched the CNKI, WanFang, VIP, CBM, WoS, PubMed and EMbsae databases for the literature on the modeling of steroid-induced osteonecrosis of femoral head rabbits up to April 1, 2022, completed the screening of the literature according to the inclusion and exclusion criteria and literature quality evaluation, and extracted the outcome index data in the literature. RevMan Stata and ADDIS statistical software were used to conduct a meta-analysis of the included data. RESULTS: (1) A total of 82 articles with 1 366 rabbits were included in the study. The steroid-induced osteonecrosis of femoral head modeling methods were divided into three types: steroid-alone method, steroid combined lipopolysaccharide method and steroid combined serum method. Among these, 33 articles used steroid-alone method; 20 articles used steroid combined lipopolysaccharide method; 29 articles used steroid combined serum method. (2) Meta-analysis results showed that the three modeling methods significantly increased the rate of empty bone lacunae in the femoral head of steroid-induced osteonecrosis of femoral head rabbits (P < 0.001), and significantly decreased the ratio of the trabecular bone area in the femoral head of steroid-induced osteonecrosis of femoral head rabbits (P < 0.001). The order of empty bone lacunae rate of each modeling method was: steroid combined with lipopolysaccharide method > steroid-alone method > steroid combined with serum method > normal group, and the order of trabecular bone area rate of each modeling method was: normal group > steroid combined with serum method > steroid-alone method > steroid combined with lipopolysaccharide method. (3) The results of subgroup analysis suggested that the rate of empty bone lacunae in the rabbit model induced by steroid alone might be related to the rabbit variety and the type of steroid used for modeling (difference between groups P < 0.05), in which the combined effect amount of New Zealand white rabbits was higher than that of Chinese white rabbits (P < 0.05) and Japanese white rabbits, and the combined effect amount of dexamethasone was higher than that of other steroids. The rate of empty bone lacunae induced by steroid combined with lipopolysaccharide was related to the administration mode of lipopolysaccharide and the type of steroid (P < 0.05), among which the combined effect of methylprednisolone sodium succinate was significantly higher than that of other steroids (P < 0.05), and the combined effect of prednisolone was significantly lower than that of other steroids (P < 0.05). The combined effect of lipopolysaccharide 100 μg/kg × twice was significantly lower than 10 μg/kg × twice and 50 μg/kg × twice (P < 0.05). The rate of empty bone lacunae in the model induced by steroid combined with serum was related to serum dose and steroid type (P < 0.05), among which the combined effect amount of dexamethasone sodium phosphate was significantly higher than other steroid types (P < 0.05), and the combined effect amount of dexamethasone was significantly lower than other steroid types (P < 0.05); the combined effect amount of serum “10 mL/kg+6  mL/kg” combined dose was lower than other serum doses (P < 0.05).  CONCLUSION: (1) With the rate of empty bone lacunae and the ratio of trabecular bone area as the judgment standard for the successful establishment of the model, the three modeling methods can successfully construct the rabbit steroid-induced osteonecrosis of femoral head model, of which the steroid combined with lipopolysaccharide method is the best. (2) New Zealand white rabbits and dexamethasone are recommended when selecting the steroid-alone method. Methylprednisolone sodium succinate and low-dose lipopolysaccharide are recommended when selecting the steroid combined with lipopolysaccharide method. Dexamethasone sodium phosphate is recommended when selecting the steroid combined with serum modeling method. Figures and Tables | References | Related Articles | Metrics