ABSTRACT
Spinal manipulation is a manual treatment technique that delivers a thrust, using specific biomechanical parameters to exert its therapeutic effects. These parameters have been shown to have a unique dose-response relationship with the physiological responses of the therapy. So far, however, there has not been a unified approach to standardize these biomechanical characteristics. In fact, it is still undetermined how they affect the observed clinical outcomes of spinal manipulation. This study, therefore, reviewed the current body of literature to explore these dosage parameters and evaluate their significance, with respect to physiological and clinical outcomes. From the experimental studies reviewed herein, it is evident that the modulation of manipulation's biomechanical parameters elicits transient physiological responses, including changes in neuronal activity, electromyographic responses, spinal stiffness, muscle spindle responses, paraspinal muscle activity, vertebral displacement, and segmental and intersegmental acceleration responses. However, to date, there have been few clinical trials that tested the therapeutic relevance of these changes. In addition, there were some inherent limitations in both human and animal models due to the use of mechanical devices to apply the thrust. Future studies evaluating the effects of varying biomechanical parameters of spinal manipulation should include clinicians to deliver the therapy in order to explore the true clinical significance of the dose-response relationship.
Subject(s)
Animals , Humans , Manipulation, SpinalABSTRACT
BACKGROUND: Foot strike patterns in adults during running have always been the focus of worldwide research, and the strike patterns of children are also something that cannot be ignored. OBJECTIVE: Using biomechanical methods to explore the differences in kinematics and kinetics of children in different strike patterns during the running process, and to provide a scientific basis for children’s correct way of running. METHODS: Seventy-four children were randomly selected from a public kindergarten in Haidian District, Beijing, and were divided into 3-year-old group, 4-year-old group and 5-year-old group. The kinematics and kinetics data of enrolled children in different strike patterns during running were acquired simultaneously using the BTS infrared motion capture system, the Kistler three-dimensional force table and the VIXTA video analysis system. The muscle strength index of the lower limbs was calculated using the Anybody 5.2 simulation modeling software. Before participation in the trial, children’s parents were fully informed of study protocol and signed the informed consent form. The trial protocol met the relevant ethical requirements of Beijing Normal University. RESULTS AND CONCLUSION: (1) In the 3-year-old group, the proportion of mid foot strike (MFS) was the highest, and the proportion of fore foot strike (FFS) was the lowest. In the 5-year-old group, the proportion of MFS was the lowest, and the proportion of FFS was the highest. The rear foot strike (RFS) extension time was longer than that of FFS (P < 0.01) and MFS (P < 0.05). (2) At the moment of landing, the flexion angle of FFS was greater than that of RFS (P < 0.01) and MFS (P < 0.05), and the flexion angle of MFS was greater than that of RFS (P < 0.05). The hip adduction-abduction angle of RFS was greater than that of FFS (P < 0.01) and MFS (P < 0.05). The maximum hip abduction angle of RFS was greater than that of FFS (P < 0.01) and MFS (P < 0.01). The amount of joint changes in the RFS hip adduction and abduction was greater than that of FFS (P < 0.01) and MFS (P < 0.05). The minimum flexion and extension of RFS was greater than that of FFS (P < 0.05). The maximal hip adduction-abduction angular velocity of RFS was greater than that of FFS (P < 0.05), and the maximal knee adduction-abduction angular velocity of RFS was greater than that of FFS (P < 0.01) and MFS (P < 0.05). (3) The muscle strength of the short bones of the tibia, the long tibia and the third metatarsal muscle of FFS and MFS was greater than that of RFS (P < 0.05). The bundle muscle strength of the medial femoral muscle, the lateral femoral muscle bundle, the lateral femoral muscle bundle, the medial femoral muscle bundle, the medial femoral muscle bundle, and the medial femoral muscle of RFS were greater than that of FFS (P < 0.01) and MFS (P < 0.05). (4) In the 3-6 years old, children often run in the heel or full-foot landing mode to meet their stability during the running process. As the age increases, the running pattern with the forefoot landing gradually appears. To keep the movement steady, RFS can trigger more hip and knee frontal motions, FFS and MFS can offer more muscle strength on the anterior and posterior sides of the calf, while RFS can offer more muscle strength on the anterior side of the thigh.
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Objective To evaluate the biomechanical characteristics of 4 fixation methods (single reconstruction plate,dual reconstruction plates,single cannulated screw and dual cannulated screws) in the treatment of pubic symphysis disruption.Methods Miniature spiral CT scans were performed on the complete pelvis in 5 healthy volunteers.The primary two-dimensional CT scan data at Dicom format were imported into software Mimics 15.0 for three-dimensional reconstruction of bilateral hips and sacrums.The finite element model of skeletal pelvis was obtained by grid partitioning and assignment using software Abqus 6.13.Models of pubic symphysis disruption were simulated by cutting off the unilateral sacroiliac ligament,sacral spine ligament,sacral tuberosity ligament,pubic ligament and pubic arch.Four implants(single reconstruction plate,dual reconstruction plates,single cannulated screw and dual cannulated screws) were simulated and emplaced onto the models according to standard surgical procedures.Compressive and rotational loads were implemented in all models for finite element analysis.The biomechanical properties were recorded and analyzed,including construct stiffness,micromotion of the pubic symphysis and yon Misses stress.Results Under vertical load,the space of pubic symphysis disruption ＞ 25 mm.The vertical stiffness and rotational construct stiffness of the pelvis decreased significantly from 442.738 ±29.946 N/mm and 10.118 ± 1.432 N · m/Deg in the normal group to 14.754 ±0.876 N/mm and 0.328 ±0.119 N · m/Deg,respectively.Dual reconstruction plates and dual cannulated screws displayed the best vertical tensile strength;their construct stiffness achieved 117.647 ±9.193 N/mm and 131.443 ±4.348 N/mm,respectively.Under anti-rotation load,dual cannulated screws displayed the best performance because they rebuilt 68.6％ of the whole structural stiffness.For the local stability of the pubic symphysis,dual reconstruction plates showed a strong local anti-rotation capability and dual cannulated screws a good local anti-tensile capability.The displacement in the dual cannulated screws group was only-0.240 ±0.119 mm under vertical load while the angular displacement in the dual reconstruction plates group only 0.218°±0.182°.Single reconstruction plate endured the maximum yon Misses stress which was obviously concentrated.Conclusion Dual cannulated screws may have biomechanical advantages for treatment of pubic symphysis disruption.
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OBJECTIVE: The aim of this study was to compare recycled and unused orthodontic miniscrews to determine the feasibility of reuse. The comparisons included both miniscrews with machined surfaces (MS), and those with etched surfaces (ES). METHODS: Retrieved MS and ES were further divided into three subgroups according to the assigned recycling procedure: group A, air-water spray; group B, mechanical cleaning; and group C, mechanical and chemical cleaning. Unused screws were used as controls. Scanning electron microscopy, energy-dispersive X-ray spectrometry, insertion time and maximum insertion torque measurements in artificial bone, and biological responses in the form of periotest values (PTV), bone–implant contact ratio (BIC), and bone volume ratio (BV) were assessed. RESULTS: Morphological changes after recycling mainly occurred at the screw tip, and the cortical bone penetration success rate of recycled screws was lower than that of unused screws. Retrieved ES needed more thorough cleaning than retrieved MS to produce a surface composition similar to that of unused screws. There were no significant differences in PTV or BIC between recycled and unused screws, while the BV of the former was significantly lower than that of the latter (p < 0.05). CONCLUSIONS: These results indicate that reuse of recycled orthodontic miniscrews may not be feasible from the biomechanical aspect.