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Objective To design and implement a control algorithm in a 6 degree of freedom (DOF) robotic manipulator, so as to simulate the spinal motion and provide stable and efficient testing plan for biomechanical tests on spinal implants. Methods The recognition method of stiffness matrix for L2-5 spinal system was firstly studied for decoupling purpose. Secondly, the direct force control system under each axial motion was established by combining the 6-axis manipulator control system with the incremental proportion integration differentiation (PID) control algorithm. By using the 6-axis direct force control system, pure moment of 7.5 N·m was applied in the direction of main motion axis to simulate flexion-extension (FE), lateral bending (LB) and axial rotation (AR) motion of L2-5 spinal segment. Results The range of motion (ROM) of L2-5 segment in FE, LB and AR direction was 23.01°,27.92°,9.81°, respectively. A 7.5 N·m pure moment could be achieved in the main motion axis, while maintaining zero force/moment in the unconstrained axis with root mean square (RMS) errors being less than 3 N and 0.1 N·m, respectively. Conclusions The proposed algorithm of direct force control using PID controller with predetermined stiffness decoupling matrix was capable of applying pure moment to the spine under FE, LB, AR motion. The research findings have a relatively high value of engineering application for various biomechanical testing of lumbar vertebrae.
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Objective To design and implement a control algorithm in a 6 degree of freedom (DOF) robotic manipulator, so as to simulate the spinal motion and provide stable and efficient testing plan for biomechanical tests on spinal implants. Methods The recognition method of stiffness matrix for L2-5 spinal system was firstly studied for decoupling purpose. Secondly, the direct force control system under each axial motion was established by combining the 6-axis manipulator control system with the incremental proportion integration differentiation (PID) control algorithm. By using the 6-axis direct force control system, pure moment of 7.5 N·m was applied in the direction of main motion axis to simulate flexion-extension (FE), lateral bending (LB) and axial rotation (AR) motion of L2-5 spinal segment. Results The range of motion (ROM) of L2-5 segment in FE, LB and AR direction was 23.01°,27.92°,9.81°, respectively. A 7.5 N·m pure moment could be achieved in the main motion axis, while maintaining zero force/moment in the unconstrained axis with root mean square (RMS) errors being less than 3 N and 0.1 N·m, respectively. Conclusions The proposed algorithm of direct force control using PID controller with predetermined stiffness decoupling matrix was capable of applying pure moment to the spine under FE, LB, AR motion. The research findings have a relatively high value of engineering application for various biomechanical testing of lumbar vertebrae.
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Objective@#To evaluate and describe the changes of core muscle groups based on DAVID spine biomechanics training system in ankylosing spondylitis (AS) patients.@*Methods@#The clinical data of 100 patients of AS and 31 healthy controls were collected. Clinical symptoms, Bath ankylosing spondylitis disease activity index (BASDAI), Bath ankylosing spondylitis function index (BASFI), Bath ankylosing spondylitis measurement index (BASMI), ankylosing spondylitis disease activity (ASDAS), and simultaneous detection of DAVID spine biomechanics training system, simple core muscle fitness test: Eight-grade abdominal bridge, PLANK exercise (flat support), Abdominal static muscle endurance test, Back static muscle endurance test were compared using t-test analysis and spearman correlation analysis.@*Results@#① Between AS and healthy male control o group, there were significant differences of spinal mobility in forward flexion, right rotation, left rotation (42±13 vs 48±1, 52±14 vs 69±12, 52±13 vs 58±11; all P values <0.05); and significant differences of spinal muscle strength in forward bending force, right rotation force, left rotation force, right bending force (103±42 vs 146±17, 87±34 vs 104±13, 80±35 vs 101±13, 161±55 vs 186±19; all P values <0.05), and significant differences in the left/right rotational force (1.17±0.21 vs 1.02±0.111, P<0.05) of spine balance strength comparison.② Between AS and healthy controls of female group, there were differences in forward bending force (49±23 vs 77±10, P<0.05) of spinal muscle strength; and significant differences in forward bending/backward extension strength, left and right rotation strength (0.32±0.11 vs 0.58±0.21, 1.29±0.21 vs1.03±0.11, all P values <0.05) of spine balance strength; ③ In AS group, the spinal mobility was correlated with age (Rear extension r=-0.28, right flexion r=-0.268, left flexion r=-0.404, right rotation r=-0.367, left rotation r=-0.235; all P values <0.05), course of disease (Rear extension r=-0.354, forward flexion r=-0.283, right flexion r=-0.204, left flexion r=-0.284, right rotation r=-0.339, left rotation r=-0.23; all P values <0.05), body mass index (BMI) (Rear extension r=-0.23, forward flexion r=-0.288, right flexion r=-0.22, left flexion r=-0.201, right rotation r=-0.26, left rotation r=-0.29; all P values <0.05), sacroiliac joint stage(Rear extension r=-0.375, forward flexion r=-0.446, right flexion r=-0.331, left flexion r=-0.367, right rotation r=-0.368, left rotation r=-0.314; all P values <0.05) and BASDAI (Rear extension r=-0.381, forward flexion r=-0.374; all P values <0.05). Spinal muscle strength was correlated with gender (Posterior extensor force r=0.344, flexor force r=0.507, right rotation force r=0.376, left rotation force r=0.399, right flexion force r=0.433, left flexion force r=0.445; all P values <0.05); the left/right spine rotation strength was correlated with gender (r=0.271, P<0.05). ④ In the simple core muscle fitness test, eight-grade abdominal bridge was correlated with spinal muscle strength (Rear extension force r=0.234, right rotation r=0.290, left rotation r=0.219, right flexion r=0.35, left flexion r=0.327; all P values <0.05); PLANK exercise was correlated with spinal muscle strength (Rear extension force r=0.234, right rotation r=0.290, left rotation r=0.219, right flexion r=0.35, left flexion r=0.327; all P values <0.05); abdominal static muscle endurance test was correlated with forward flexion strength (r=0.341, P<0.05); back static muscle endurance test was correlated with spinal mobility (Rear extension r=0.262, forward flexion r=0.23, right rotation r=0.455, left rotation r=0.426, right flexion r=0.387, left flexion r=0.46; all P values <0.05); correlated with spine strength (right flexion r=0.256, left flexion r=0.272; all P values <0.05).@*Conclusion@#Compared with healthy people, AS patients have decreased activity, strength and balance of spinal core muscle. There are significant decline in spinal mobility and muscle strength of male AS patients and muscle imbalance of female AS patients. Simple core muscle fitness test could be used in clinic to measure the changes of AS patients'core muscle group.
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Objective To evaluate and describe the changes of core muscle groups based on DAVID spine biomechanics training system in ankylosing spondylitis (AS) patients.Methods The clinical data of 100 patients of AS and 31 healthy controls were collected.Clinical symptoms,Bath ankylosing spondylitis disease activity index (BASDAI),Bath ankylosing spondylitis function index (BASFI),Bath ankylosing spondylitis measurement index (BASMI),ankylosing spondylitis disease activity (ASDAS),and simultaneous detection of DAVID spine biomechanics training system,simple core muscle fitness test:Eight-grade abdominal bridge,PLANK exercise (fiat support),Abdominal static muscle endurance test,Back static muscle endurance test were compared using t-test analysis and spearman correlation analysis.Results ① Between AS and healthy male control o group,there were significant differences of spinal mobility in forward flexion,right rotation,left rotation (42±13 vs 48±1,52±14 vs 69±12,52±13 vs 58±11;all P values ＜0.05);and significant differences of spinal muscle strength in forward bending force,right rotation force,left rotation force,fight bending force (103±42 vs 146±17,87±34 vs 104±13,80±35 vs 101±13,161±55 vs 186±19;all P values ＜0.05),and significant differences in the left/right rotational force (1.17±0.21 vs 1.02±0.111,P＜0.05) of spine balance strength comparison.② Between AS and healthy controls of female group,there were differences in forward bending force (49±23 vs 77±10,P＜0.05) of spinal muscle strength;and significant differences in forward bending/backward extension strength,left and right rotation strength (0.32±0.11 vs 0.58±0.21,1.29±0.21 vs 1.03±0.11,all P values ＜0.05) of spine balance strength;③ In AS group,the spinal mobility was correlated with age (Rear extension r=-0.28,right flexion r=-0.268,left flexion r=-0.404,right rotation r=-0.367,left rotation r=-0.235;all P values ＜0.05),course of disease (Rear extension r=-0.354,forward flexion r=-0.283,right flexion r=-0.204,left flexion r=-0.284,right rotation r=-0.339,left rotation r=-0.23;all P values ＜0.05),body mass index (BMI) (Rear extension r=-0.23,forward flexion r=-0.288,right flexion r=-0.22,left flexion r=-0.201,right rotation r=-0.26,left rotation r=-0.29;all P values ＜0.05),sacroiliac joint stage(Rear extension r=-0.375,forward flexion r=-0.446,right flexion r=-0.331,left flexion r=-0.367,right rotation r=-0.368,left rotation r=-0.314;all P values ＜0.05) and BASDAI(Rear extension r=-0.381,forward flexion r=-0.374;all P values ＜0.05).Spinal muscle strength was correlated with gender (Posterior extensor force r=0.344,flexor force r=0.507,right rotation force r=0.376,left rotation force r=0.399,right flexion force r=0.433,left flexion force r=0.445;all P values ＜0.05);the left/right spine rotation strength was correlated with gender (r=0.271,P＜0.05).④ In the simple core muscle fitness test,eight-grade abdominal bridge was correlated with spinal muscle strength (Rear extension force r=0.234,right rotation r=0.290,left rotation r=0.219,right flexion r=0.35,left flexion r=0.327;all P values ＜0.05);PLANK exercise was correlated with spinal muscle strength (Rear extension force r=0.234,right rotation r=0.290,left rotation r=0.219,right flexion r=0.35,left flexion r=0.327;all P values ＜0.05);abdominal static muscle endurance test was correlated with forward flexion strength (r=0.341,P＜0.05);back static muscle endurance test was correlated with spinal mobility (Rear extension r=0.262,forward flexion r=0.23,right rotation r=0.455,left rotation r=0.426,right flexion r=0.387,left flexion r=0.46;all P values ＜0.05);correlated with spine strength (right flexion r=0.256,left flexion r=0.272;all P values ＜0.05).Conclusion Compared with healthy people,AS patients have decreased activity,strength and balance of spinal core muscle.There are significant decline in spinal mobility and muscle strength of male AS patients and muscle imbalance of female AS patients.Simple core muscle fitness test could be used in clinic to measure the changes of AS patients'core muscle group.
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[Objective]To provide the mechanical evidence of self manufactured metallic-rectangular frame on the reconstruction of the stability of occipitocervical junction.[Method]Seven of the adult cervical spinal specimens which were entire wet-cadavers(from occipitale to C_6) were made to simulate the C_(0～2) fracture dislocation.These of specimens dislocated were fixed by metallic-rectangular frame and Occipito-cervical plate respectively.The three dimensional movements of C_(0～2) were recorded through photogrametry with a pure moment of 1.53 Nm.The range of motion(ROM) of each specimens in two fixation was caculated.[Result]Loaded by 1.53Nm,In metallic-rectangular frame fixation,the ROM in flexion,extension,lateral bending and axial rotation were 5.9?、7.7?、5.6?、11.2? respectively,decreased by 157.6%、68.8%、58.9%、131.3%,compared with occipitocervical plate fixation group.[Conclusion]Metallic-retangular frame fixation can reconstruct the stability of Occipitocervical junction immediatey,and is a relativity effective internal fixation for occipitocervical fusion.
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Cervical regulating manipulation is based on the extrinsic active system and intrinsic support system. Only when the former system is relaxed, can the motive force of regulating manipulation reach the latter system to extend the vertebral discs and regulate the posterior joints. Frequent cervical regulating manipulation can stretch soft tissue around the joint and enlarge activity of joint and make it soft from subjective views, but it isn’t proved by experiment. From the aspect of spinal biomechanics, cervical regulating manipulation has advantages and disadvantages, so it should be used according to certain standard, or it will cut down the self-regulation activity of spinal biomechanics.