ABSTRACT
Objective To investigate the influence from compressing manipulation by flexing hip and knee in supine position on stress distributions in the pelvis and strain distributions in the sacroiliac joints by 3D finite element method, and discuss the possibility of moving the whole sacroiliac joints under such manipulation. Methods A 3D finite element model of the normal pelvis was constructed based on CT images. According to the manipulation principle, the compressing force in flexing hip and knee was decomposed in two directions, and loaded on the 3D finite element model to calculate stress of the pelvis and strain of the sacroiliac joints. Results Under the loading of simulative manipulation, stress of the pelvis was mainly located at 1/3 part of the anterior inferior of the sacroiliac joints, the greater sciatic notch, and the middle 1/3 part of the inferior and anterior of gluteal lines. The maximum strain of the sacroiliac joints was mainly located in the posterior superior, posterior inferior and central 1/2 part of the sacroiliac joints. Conclusions The compressing manipulation by flexing hip and knee can only move 1/3 part of the interior of the sacroiliac joints, rather than the whole of the sacroiliac joints.
ABSTRACT
Objective To observe the effect of cervical rotatory manipulation on tensile mechanical properties of atherosclerotic carotid artery in rabbits, so as to provide safety references for such manipulation. Methods Twenty male New Zealand rabbits were randomly divided into control group (n=10) and experimental group (n=10), then all fed with high-cholesterol diet for 12 weeks. The rabbits in experimental group were then applied with cervical rotatory manipulation (rotating on each side once a day during a total of 4 weeks), while no manipulation for rabbits in control group. The bilateral carotid arteries were obtained after all the rabbits were executed, and measured for the maximum load, the maximum displacement, the average load, the elastic modulus, elongation at break and stress-strain by the material testing machine. Results The maximum tension, the maximum displacement, the average tension, the elastic modulus and elongation at break in experimental group were (1.36±0.35) N, (6.84±2.08) mm, (0.44±0.30) N, (4.30±2.66) MPa and (83.08±51.32)%, respectively, while the corresponding data in control group were (2.92±0.65) N, (9.23±2.62) mm, (1.17±0.63) N, (3.71±0.60) MPa and (154.19±34.32)%. The maximum load, the average load and elongation at break in experimental group were obviously smaller than those in control group (P0.05). Conclusions The tensile mechanical properties of atherosclerotic carotid artery after cervical rotatory manipulation were declined; thus, intensity and magnitude of cervical rotatory manipulation should be proper so as to avoid harm to carotid artery.