• Volume 28,Issue 3,2013 Table of Contents
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      2013, 28(3).

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      2013, 28(3).

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    • Instructions for Authors by "Journal of Medical Biomechanics"

      2013, 28(3):245-254. DOI: 10.3871/j.1004-7220.2013.3.254.

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    • >Special Column
    • Several key issues in biomechanical study of spinal manipulation

      2013, 28(3):255-258. DOI: 10.3871/j.1004-7220.2013.3.258.

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      Abstract:The science of Tuina(Chinese therapeutic massage) with its long history plays an important role in traditional Chinese medicine. Due to its simple operating skill and unique curative effect, Tuina manipulation has a good reputation for treating traumatological diseases and pain syndromes. Although spinal manipulation is widely used in clinic, its basic research is still weak. In this paper, the relationship between manipulative forces and movements, cracking sounds, real-time measurement on intra-stress of lumbar disc during spinal manipulation, as well as deformation and displacement of lumbar canal and changes of vertebral structures in Cartesian coordinate system were discussed, so to provide a more solid experimental reference and theoretical basis for scientific explanation about mechanism of spinal manipulation.

    • >Invited Review
    • Biomechancial issues in traditional Chinese medcine research

      2013, 28(3):259-262. DOI: 10.3871/j.1004-7220.2013.3.262.

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      Abstract:Traditional Chinese medicine (TCM) has been formed and developed in medical practices over thousands of years, while biomechanics as a new research direction in TCM has been developing rapidly in recent years. Biomechanics in TCM encompasses abundant contents, such as hemodynamics in meridians, substance transport of Yin-Yang and the Five Elements, hemodynamics of pulse manifestation, heat conduction in tongue diagnosis, biomechanics of orthopaedics and traumatology, mechanics of acupuncture, massage and manipulation, TCM medical device, biomechnopharmacology and etc. Journal of Medical Biomechanics has published some papers about TCM biomechanics in the past years, and in this issue, a special column of TCM biomechanics in three research directions is organized, including massage and manipulation, fracture fixator by TCM treatment, and Tai Chi Quan, so as to arouse readers’ interest in TCM biomechanics.

    • >骨骼肌肉系统生物力学
    • EMG characteristics of lower extremities during movement of white crane spreads its wings in Tai Chi Quan

      2013, 28(3):263-268. DOI: 10.3871/j.1004-7220.2013.03.268.

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      Abstract:Objective To analyze how the athletes control postural balance through observing their joint angular motion change,center of pressure (COP) change and EMG activities of lower extremities for both athletes and beginners when performing the movement of white crane spreads its wings in Tai Chi Quan. Methods Twenty subjects were divided into 2 groups as 10 athletes and 10 beginners of Tai Chi Quan in each. When performing the movement of white crane spreads its wings, their EMG activities of 10 skeletal muscles, two-dimensional angular motion of 3 large joints in bilateral lower extremities, and COP displacements in lateral and anterior-posterior directions were recorded. Each performing trial took 8 seconds and repeated 5 times. All data were statistically processed for EMG, motion and balance analysis, and the EMG data were normalized to compare the differences between the athletes and beginners of Tai Chi Quan. Results The EMG activities of tibialis anterior(Ta), biceps femur(bF), gluteus medium(Gm) in support leg of athletes were significantly greater than those of the ipsilateral muscles in support leg of beginners, and the same was the EMG activities of gastrocnemius (G) and rectus femur(rF) in virtual leg of athletes compared with the beginners. The maximal average angular motion of 3 large joints and the coxa -joint motion of support leg in athletes were both significantly greater than that in beginners, but the anterior-posterior COP displacement in athletes was significantly smaller than that in beginners. Conclusions When performing the movement of white crane spreads its wings in Tai Chi Quan, athletes could oppose the COP change by enhancing muscle activities to maintain the postural balance, while beginners couldn’t make such active muscle activities against the uncontrolled anterior-posterior COP displacement. This may preliminarily explain the reason why Tai Chi Quan exercise can improve the muscle strength in lower extremities and enhance the ability of postural control.

    • Finite element analysis of Tuina manipulation on three-dimensional displacement of lumbar intervertebral disc protrusion

      2013, 28(3):269-274. DOI: 10.3871/j.1004-7220.2013.03.274.

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      Abstract:Objective To study the mechanisms of vertebrae semi-dislocation of Tuina manipulation for treating patients with lumbar intervertebral disc protrusion (LIDP) by observing the three-dimensional (3D) displacement of lumbar before and after Tuina manipulation. Methods Ten LIDP patients were selected and evenly divided into two groups: Group 1 as tendon-smoothing manipulation group (relaxing group), Group 2 as tendon-smoothing plus adjusting manipulation group (adjusting group). Besides, Group 3 as control group was established by 5 healthy volunteers treated with tendon-smoothing manipulation. Before and after manipulation intervention, all subjects were scanned from L1 to L5 segment by using Philips 64 spiral CT under equal conditions for accessing the volume data. ITK reconstruction software was used to reconstruct each lumbar skeleton for finite element analysis. The 3D displacements and angular displacements among three groups were compared. Results 3D displacement from L1 to L5 segment all changed in three groups. For adjusting group, the angular displacements at X-axis in L3 segment was (1.77±0.46)°, and that in L4 segment at X-axis and Y-axis was (1.78±0.53)° and (1.89±0.75)°, respectively, which was significantly larger than relaxing group and control group (P<0.05); the angular displacements at X-axis from L1 to L5 segment were (1.50±0.47)°, (1.55±0.57)°, (1.77±0.46)°, (1.78±0.53)°, (1.61±0.39)°, respectively, which were significantly larger than control group (P<0.05); displacement at Y-axis in L3 segment was (2.87±0.74) mm, and that at X-axis in L4 segment was (1.68±0.64) mm, which were significantly larger than relaxing group and control group (P<0.05); displacement at X-axis in L1, L4 and L5 segment was (1.28±0.21),(1.68±0.64), (1.30±0.51) mm, and that at Y-axis in L1 to L3 segment was (1.92±0.42), (2.25±0.61), (2.87±0.74) mm, which was significantly larger than control group (P<0.05). The angular displacements and displacements of L1 to L5 segment in relaxing group were larger than those in control group, but without any significant differences. Conclusions Compared with relaxing manipulation, adjusting manipulation played a more obvious adjusting role in instability and degenerative lumbar vertebra, especially for angular displacements in X-axis, and displacements in X-axis and Y-axis. Namely, the mechanisms of vertebrae semi-dislocation of adjusting manipulation were to make horizontal and rotational displacements at lumbar vertebra other than upper and lower displacement. The effect of relaxing manipulation was not so obvious on lumbar structure of LIDP patients.

    • Mechanical properties of cervical spine manipulation with fine adjustment

      2013, 28(3):275-278. DOI: 10.3871/j.1004-7220.2013.3.278.

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      Abstract:Objective To analyze mechanical properties of cervical spine manipulation with fine adjustment, so as to provide mechanical data for popularization of such manipulation in clinic. Methods The founder, a skilled practitioner and a beginner of fine-adjusting manipulation operated the spinal fine-adjusting manipulation on two cervical vertebral segments of healthy subjects, respectively. The force data of thumbs were collected by FingerTPS Wireless System to analyze force differences between two thumbs while the force of right thumb was in its peak value, as well as regular pattern of the thumb force in relation with time. Results Significant differences were found between the maximum force of two thumbs in each subject (P<0.001). The process of force application (from trough to peak, T1) was longer than that of force reduction (from peak to trough, T2) when all the subjects operated spinal fine-adjusting manipulation, showing significant differences (P<0.001). Conclusions There exists the main and auxiliary hand during cervical spine manipulation with fine adjustment, which is actually a process of slow force application and rapid force reduction.

    • Cervical spine motion segments and movement patterns in paraphysiologic zone by fixed-point cervical rotatory manipulation

      2013, 28(3):279-283. DOI: 10.3871/j.1004-7220.2013.03.283.

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      Abstract:Objective To measure movement patterns and size of cervical spine motion segments in paraphysiologic zone by fixed-point cervical rotatory manipulation. Methods The cervical spines from two fresh cadavers of young males with acute brain death were fixed on MTS testing machine. Fixed-point cervical rotatory manipulation was simulated and 3D coordinate of each cervical spine motion segment was collected to calculate physical movement pattern of each segment in paraphysiologic zone. Results The physiological rotation range of C1-C2 segments at left and right side was 22.65°and 17.68°, respectively, being the largest in passive activities under the effect of C4 fixed-point countertraction. The physiological activities of the remaining 3 segments were decreased in turn. The paraphysiologic zone of C4-C5 segments was the smallest, which was 0.55°and 0.84° at left and right side, respectively. The other segment would have a larger paraphysiologic zone if it was farther from fixed-point C4 segment. When the cervical spine rotated in paraphysiologic zone, each motion segment would have a coupling movement to the stretching and contralateral bending side. Moreover, except for C1-C2 segments, the remaining segments moved upward, while movement patterns of C2-C3 segments were opposite to the other segments in backward and forward movement and at horizontal side. Conclusions The size of paraphysiologic zone in each segment of the cervical spine is different. The farther from the fixed-point area of segment, the larger the paraphysiologic zone, and there are significant differences in segmental motion patterns of cervical spine in paraphysiologic zone.

    • Recovery effect of postural control by electrical stimulation acupoint massage after local muscle fatigue

      2013, 28(3):284-290. DOI: 10.3871/j.1004-7220.2013.03.290.

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      Abstract:Objective To evaluate the recovery effect of postural control by electrical stimulation acupoint massage after local muscle fatigue by investigating joint torque, surface electromyography (EMG) signal, balance ability and foot pressure distributions. Methods Six subjects (12 person-times) accepted isokinetic, SEMG and foot pressure test under the condition of normal rest or electrical stimulation acupoint massage after ankle fatigue. Results After electrical stimulation acupoint massage, ①the forward and backward displacement of COF (center of force) was significantly reduced and the contact area of T1, T2 and T4,5 was increased to (11.64±2.12), (6.57±0.97), (3.72±1.33) cm2, respectively. ② In ankle isokinetic test (90°/s), the total work of ankle plantar flexion and dorsiflexion was significantly increased to (56.71±13.26) and (19.75±3.79) J. ③ In right leg stance, RMS (root mean square) of the tibialis anterior and lateral gastrocnemius was decreased significantly; the ankle isokinetic test (90°/s) showed that the RMS of the medial and lateral gastrocnemius was increased from (48.95±13.50) and (33.67±6.41) μV to (59.87±11.46) and (43.73±4.65) μV, respectively. Conclusions Electrical stimulation acupoint massage can optimize the force strategy and improve the stability of the ankle, further improve the postural control ability, promote the recovery of sports ability and avoid sports injuries.

    • Movement pattern and sEMG characteristics of upper limb muscles during one-finger pushing manipulation operation with different forces

      2013, 28(3):291-296. DOI: 10.3871/j.1004-7220.2013.3.296.

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      Abstract:Objective To observe the surface electromyography (sEMG) characteristics of upper limbs during one-finger pushing manipulation under different operating forces, so as to find out the muscle coordination movement pattern for key operating technology. Methods sEMG data of performing one-finger pushing manipulation by the expert, skilled and novice groups were collected. The manipulation force was divided into three different types, namely mild, moderate and severe. The continuous, stable data were adopted for analysis on Myo-Research software. Results Significant differences were found in the upper limb muscle integrated electromyography (iEMG) values (P<0.05). Under the three different forces, there were no significant differences in iEMG ratio of muscles between the expert and skilled groups (P>0.05), with the flexor carpi ulnaris, deltoid, wrist flexors and extensors ranking the top three of iEMG ratio. The expert and skilled groups had the same core muscles in the same movement pattern during their manipulation operation, while the novice group had different core muscles under different forces. There were significant differences in co-contraction ratio among the expert, skilled and novice groups (P<0.01). The novice and expert groups had the highest and lowest co-contraction ratio, respectively, and the co-contraction ratio was gradually decreased with force increasing. During 6-minute manipulation operation, deltoid median frequency(MF) slope of the expert group was declined more slowly than that in the other two groups (P<0.05), which indicated that the expert group were better at resisting to fatigue. Conclusions The expert and skilled groups have the same sEMG characteristics during one-finger pushing manipulation operation with the same core muscles. The movement pattern of upper limb muscles is of regularity. The iEMG ratio, MF slope and co-contraction ratio can be used as reference standard for evaluating the durability, and homogeneity of the manipulation operation and normalization of force application.

    • Frequency and effective work/time ratio of pushing manipulation with one finger

      2013, 28(3):297-299. DOI: 10.3871/j.1004-7220.2013.03.299.

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      Abstract:Objective To study the frequency and effective work/time ratio of pushing manipulation with one finger (PMOF). Methods One skilled expert and nine beginners of PMOF were chosen. The frequency, effective work time/ratio during different work periods were recorded and compared after the technique information of each subject operating PMOF was collected by Novel Pliance Mobile System software. Results The operation frequency of each subject was all below 110/min, while the frequency of skilled expert was about 78/min. The time ratio between secondary work period and primary work period for the skilled expert was smaller than that of beginners. Conclusions The operation frequency of PMOF is preferably at 78/min, and the preferred time ratio between secondary work period and primary work period should be slightly larger than 0.28.

    • Biomechanical test in vivo on reduction fixator for treating distal radius fractures

      2013, 28(3):300-303. DOI: 10.3871/j.1004-7220.2013.03.303.

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      Abstract:Objective To investigate the regular pattern of traction forces during the treatment of distal radius fracture by reduction fixator with pins. Methods A self-designed pin-lock style force transducer instead of two original pin locks in the distal of reduction fixator was adopted to conduct continuous testing on six cases of unstable distal radius fracture of forearms treated by reduction fixator in vivo. The value of static traction force and the added value of traction force in fist clenching at the postoperative 1st, 5th, 14th, 21st, 28th, 35th, 42nd, 49th day, was recorded respectively. Results The maximum and minimum static traction force was 9.93 kg and 2.26 kg, respectively, with mean value of (4.93±1.79) kg. The maximum and minimum traction force increment in fist clenching was 10.40 kg and 0.13 kg, respectively, with mean value of (3.17±2.42) kg. Conclusions Larger axial forces can be generated in muscles of the forearm, by both static tension and dynamic contraction, which might be a serious negative factor in healing unstable distal radius fractures.

    • Biomechanical study on oblique-pulling manipulation in traditional Chinese medicine for treating lumbar intervertebral disc protrusion

      2013, 28(3):304-309. DOI: 10.3871/j.1004-7220.2013.3.309.

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      Abstract:Objective To analyze and study the biomechanical model of oblique-pulling manipulation in traditional Chinese medicine for the treatment of lumbar disc disease such as intervertebral disc protrusion, and compare the mechanical properties of two different manipulations, i.e. traditional oblique-pulling manipulation under impulse excitation and improved oblique-pulling manipulation under harmonic excitation. Methods The vertebra was set as rigid body, while the intervertebral disk and surrounding ligaments as viscoelastic body. A vibration system with 5-degree freedom for simulating lumbar L1-L5 was established. The basic vibration equation was solved using analytical method. Results The effect of improved oblique-pulling manipulation was related to the frequency of harmonic excitation. If the frequency of harmonic excitation was not higher than 1, the maximum displacement of the diseased segment under harmonic excitation was larger than that of traditional oblique-pulling manipulation under impulse excitation. With the lesion location shifted downward, the damage ratio (DR) under harmonic excitation was gradually decreased as compare to that under impulse excitation, indicating the safety of the improved oblique-pulling manipulation increasing. Conclusions The curative effect of oblique-pulling manipulation under harmonic excitation at the frequency lower than 1 was better than that of traditional oblique-pulling manipulation under impulse excitation, especially in that the medical injury can be controlled by oblique-pulling manipulation under harmonic excitation at the frequency no higher than 1.

    • >力学生物学
    • Development and mechanical testing on TC hemi-arthroplasty prosthesis system for femoral intertrochanteric fractures

      2013, 28(3):310-315. DOI: 10.3871/j.1004-7220.2013.03.315.

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      Abstract:Objective To develop a new hemi-arthroplasty system-Trochanteric Prosthesis System (TC) for the treatment of unstable femoral intertrochanteric fractures in the elderly, so as to preserve bone mass and meet requirement of functional exercises at early stage. Methods A normal male adult volunteer was chosen to receive CT scanning at middle and upper regions of his both intact femur. The serial digitized image data of spiral CT in DICOM format were imported to finite element modeling software to establish a three-dimensional (3D) solid model of the proximal femur. The Pro/E software was used to conduct computer-aided design of the new hemi-arthroplasty prosthesis system and then its metal model was also made by rapid prototyping techniques. After repeated verification and improvement on cadaver femur, the femoral prosthesis was molded and assembled in the solid fracture mode for finite element analysis. The unstable femoral intertrochanteric fracture model obtained from the fresh cadaver of an elderly male was chosen to make A2.2 Type of such fracture model in AO classification system. The new hemi arthroplasty prosthesis system was implanted and assembled into the model and received mechanical testing, including material performance testing, prosthesis head/neck and stem fatigue testing, anti-compression and anti-torsion testing, according to the National Industrial Standard YY0117 and YY0118. Results The sample of new hemi-arthroplasty prosthesis sustained 5 million cycle (8 Hz) fatigue testing on the part of the head-neck and the stem body without any breakage and failure. With the sample implanted into the intertrochanteric fracture model, the maximum compressive strength and torsional strength of the sample reached over 2 kN and 15.5 N?m without failure, respectively. The contact stresses between the stem and the femur were mostly distributed at the region below the femoral trochanter, where the maximum average Von Mises stress values were 17.6~26.4 MPa. Stresses at the region of intertrochanteric fractures were at a low level. The maximum average Von Mises stress values at the greater and lesser trochanter region were 2.7 and 4.9 MPa, respectively. Conclusions The new developed hemi-arthroplasty prosthesis has the advantages of easy performance, reliable fixation, sufficient bone preservation and it is capable of fulfilling the demands of early weight bearing and functional exercises. It is suitable for the treatment of unstable femoral intertrochanteric fractures in the elderly.

    • PIV experiment on flow fields of the real human upper respiratory tract gauge model

      2013, 28(3):316-320. DOI: 10.3871/j.1004-7220.2013.03.320.

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      Abstract:Objective To investigate the airflow distribution mode in human upper respiratory tract model for understanding the characteristics of the airflow in human upper respiratory tract, and provide scientific basis for analyzing the diffusion, transition and deposition patterns of aerosol in human upper respiratory tract. Methods PIV(particle image velocimetry)technology was adopted to study flow fields of the real human upper respiratory tract model. The airflow state in oral cavity,pharynx and trachea was analyzed. Results The flow velocity was relatively high at the upper tongue coating and in the middle of the oral cavity; when the airflow reached the pharynx, the velocity was increased rapidly due to the reduction of sectional area; the maximum velocity (10.24 m/s) appeared in the glottis, and the velocity in the anterior wall was higher than that in the posterior wall of the trachea; as the airflow injected at the glottis, the velocity gradient was increased, and the vorticity was concentrated at the anterior and posterior wall of the glottis, resulting in a significantly higher vorticity value at anterior wall of the trachea than that at the posterior wall. Conclusions PIV technology is an effective way to investigate the airflow distribution mode in human upper respiratory tract, and it is of great importance for exploring the harm of toxic aerosol to human body and the therapeutic effect of inhalation drug aerosol, as well as for researching the pathogenesis of respiratory system.

    • Three-dimensional finite element modeling of whole lumbar spine and its biomechanical analysis

      2013, 28(3):321-325. DOI: 10.3871/j.1004-7220.2013.03.325.

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      Abstract:Objective To develop an accurate finite element (FE) model of human L1-S1 spine segment for investigating the pathology of annulus fibrosus rupture of L4-5. Methods Based on CT images of a healthy adult, three-dimensional (3D) model of vertebras and intervertebral discs of lumbar L15 and sacral S1 segment was reconstructed by Mimics 10.01 and Geomagic 10.0 software. The 3D model was then imported into Hypermesh for meshing. With adding various ligaments and assigning material properties of all components, the FE model of L1-S1 segment was established to investigate its biomechanical responses under various loading conditions including axial compression, flexion, lateral bending and extension. Results The global stiffness of the model under flexion, lateral bending, extension with 10 N?m load was 0.61, 0.7 and 0.75 N?m/(°), respectively, which was in good agreement with the experimental results. The strain of annulus fibrosus between L4 and L5 was higher under axial compressive force and bending moment;annulus fibrosus showed obviously stress concentration under any of the different loads. Conclusions The stress concentration and higher strain in annulus fibrosus between L4 and L5 could be one of the reasons leading to rupture. The developed 3D FE model of L1~S1 motion segment demonstrated to be effective in reflecting the biomechanical response of spine and could be used for further spine biomechanics study.

    • Effect of exercise bike cadence and loads on pedaling force and lower extremity EMG

      2013, 28(3):326-332. DOI: 10.3871/j.1004-7220.2013.03.332.

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      Abstract:Objective To compare the pedaling force and lower extremity electromyography (EMG) with different cadences (60, 75, 90 r/min) and diverse cycling intensities (50%, 65%, 80% POV) and study the different influence on exerciser's pedaling force and lower extremity EMG. Methods Twelve healthy males participated in this study, and underwent two stages. In stage 1 the power output test at VO2max (POV) was got by cycle ergometer. In stage 2, nine conditions (3 kinds of intensities × 3 kinds of cadences) were completed respectively by using counter-balance design to record the changes for their pedaling force and lower extremity EMG. Results The negative pedaling work was significantly increased with the cadence increasing, and the appearing time of the peak pedaling force was significantly shifted forward in the cycle. When the crank angle was at 270°, the average increase of the pedaling force with the cadence increasing could obtain 1.84 times higher. In general, the firing rate of lower extremity muscular activation would be increased with the cadence increasing. Conclusions The cadence has greater effect on the pedaling force and lower extremity EMG. The tendency of pedaling force was shifted forward and the pattern of pedaling force became smoother with the cadence increasing. There are no significant differences among the diverse intensities. Based on the pedaling efficiency in this study, the optimal cadence for untrained people should be 60 r/min.

    • Setting property and compressive strength of nHA/α-CSH combined bone grafts

      2013, 28(3):333-337. DOI: 10.3871/j.1004-7220.2013.03.337.

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      Abstract:Objective To develop a new type of combined bone grafts mainly including nanometer hydroxyapatite (n-HA) and α-calcium sulphate hemihydrate (α-CSH), and investigate its setting property and compressive strength. Methods The setting time and compressive strength of nHA/α-CSH combined bone grafts with different liquid-to-solid (L/S) ratio or calcium sulphate dehydrate (CSD) amount were measured and observed by the X-ray diffraction (XRD) and the scanning electron microscope (SEM). Results The setting time of combined bone grafts was increased along with the increase of L/S ratio or nHA amount, and reduced with the increase of CSD amount. The setting time of the compound with 20% of nHA, 80% of α-CSH was (169±36) min, while that of the compound with 5% of nHA, 20% of CSD, 75% of α-CSH was (6±1.1) min. The compressive strength of combined bone grafts reduced along with the increase of nHA amount. The average compressive strength of pure α-CSH was (12.3±2.4) MPa, while that of the compound with 20% of nHA, 80% of CSH was (4.8±0.6) MPa. The XRD results showed that no other materials were produced except that α-CSH was transformed to CSD during the setting process. The SEM results indicated that nHA was filled in the crystal structure of the CSD, presenting two-phase structure. Conclusions The setting time and compressive strength of nHA/α-CSH combined bone grafts can be adjusted by the different proportion of nHA, CSD amount and L/S ratio, which provides an appropriate condition for clinical application.

    • Biomechanical advantages of medial support screws in locking plate for treating proximal humerus fractures

      2013, 28(3):338-343. DOI: 10.3871/j.1004-7220.2013.03.343.

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      Abstract:Objective To evaluate the biomechanical advantages of medial support screws (MSSs) in locking proximal humeral plate for treating proximal humerus fractures. Methods Thirty synthetic left humeri were randomly divided into 3 groups to establish the fracture models. Group A was fixed with a locking proximal humerus plate with medial cortical support, but without MSSs; group B was fixed with 3 MSSs, but without medial cortical support; group C was fixed with neither medial cortical support nor MSSs. Axial compression, torsion, shear stiffness and failure tests were applied on the specimens of the three groups. Results For axial compression tests, the maximum load of group A, B, C was (240.88±19.13), (169.04±19.26), (128.58±17.53) N, respectively; the axial stiffness of group A, B, C was (424.4±101.2), (230.7±40.54), (147.0±29.2) N/mm, respectively, showing significant differences (P<0.05). For torsion tests, the maximum torque of group C was (7.57±0.53) N?m, which was statistically different from both group A((8.92±0.25) N?m) and group B((9.09±0.31) N?m, P<0.05), and the torsional stiffness of group C((1.53±0.10) N?m/(°)) was statistically different from both group A((1.80±0.07) N?m/(°)) and group B((1.86±0.07) N?m/(°), P<0.05), but no significant differences were found between groups A and groups B in the maximum torque and torsional stiffness(P>0.05). For shear stiffness tests, the maximum load of group A, B, C was (444.71±20.87), (228.79±28.95), (188.73±26.15) N, respectively; the shear stiffness of group A, B, C was (70.0± 54.4), (183.89±29.64), (140.2±32.1) N/mm, respectively, showing significant differences (P<0.05). For failure tests, the failure load of group A ((2 949.76±355.08) N) was statistically different from both group B ((2 448.13±402.39)N) and group C ((2 222.55±336.41) N) (P<0.05), but no statistical differences were found between group B and group C (P>0.05). Conclusions Using three MSSs in locking plate for proximal humerus fractures shows optimal biomechanical properties, as compared to the situation without restoration of the medial column support. The reconstruction of the medial cortical support or MSSs for proximal humerus fractures helps to enhance the mechanical stability of the humeral head and prevent failure after internal fixation.

    • Influence of fluid shear stress on anti-platelet aggregation of salvianolic acid B

      2013, 28(3):344-349. DOI: 10.3871/j.1004-7220.2013.3.349.

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      Abstract:Objective To study effects of flow shear stress combined with salvianolic acid B (Sla B) on anti-platelet aggregation and its possible mechanism under the theoretical framework of biomechanopharmacology. Methods 2×4 factor experimental design was employed. By using Bioflux 1000 microfluidic system, shear stresses of 0.02 Pa and 1.5 Pa were applied together with four levels of Sla B concentration treatment on human vascular endothelial cells (HUVECs) for 20 hours. Then the cell supernatant was collected to detect concentration of 6-keto-PGF1α and vWF by ELISA and their effects on ADP-induced platelet aggregation were tested. Immunofluorescence method was used to detect vWF in endothelial cell cytoplasm. Results Physical shear stress of 1.5 Pa combined with Sla B of 100 μg/mL could significantly promote the endothelial secretion of 6-keto-PGF1α as compared to low shear stress condition (P<0.05). The endothelial cell supernatant under shear stress of 1.5 Pa showed an obvious anti-platelet aggregation effect. As the single factor, shear stresses significantly influenced vWF secretion (P<0.01), but Sla B had no obvious effects on vWF secretion. Conclusions Sla B inhibited ADP-induced platelet aggregation by increasing endothelial secretion of PGI2 under physical shear stresses. From the view of biomechaopharmacology (interaction between blood flow, blood vessel and blood), the physical flow shear stress is beneficial for the anti-thrombosis effect of Sla B.

    • Cyclic stretch-induced apoptosis in human osteoarthritic chondrocytes is mediated by reactive oxygen species generation

      2013, 28(3):350-356. DOI: 10.3871/j.1004-7220.2013.3.356.

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      Abstract:Objective To explore the mechanism of reactive oxygen species (ROS) generation on apoptosis of human osteoarthritic chondrocytes induced by cyclic stretch in vitro. Methods The human osteoarthritic chondrocytes were subjected to cyclic stretch at the frequency of 0.5 Hz with 20% elongation. The chondrocytes without cyclic stretch were used as a control. ROS generation in chondrocytes was inhibited by the antioxidant, N-acetyl-L-cysteine (NAC) and potentiated by the glutathione depleter, DL-buthionine-[S,R]-sulfoximine (BSO). Apoptosis was detected by flow cytometry. Intracellular ROS was detected using DCFH-DA and caspase-9 activity was measured using spectrophotometry. Results The cyclic stretch at the frequency of 0.5 Hz with 20% elongation induced ROS generation, and activation of caspase-9 and apoptosis in human osteoarthritic chondrocytes were significantly increased (P<0.05). The inhibition or potentiation of intracellular ROS by NAC or BSO could obviously inhibit or improve caspase-9 activity and apoptosis in chondrocytes under cyclic stretch (P<0.05). Conclusions Cyclic stretch-induced apoptosis in human osteoarthritic chondrocytes is mediated by ROS generation and activation of caspase-9. Suppression of ROS can prevent chondrocytes from apoptosis induced by cyclic stretch.

    • >感觉系统生物力学
    • The role and mechanism of estrogen receptor in bone growth, metabolism and mechano-responsiveness

      2013, 28(3):357-362. DOI: 10.3871/j.1004-7220.2013.3.362.

      Abstract (2595) HTML (0) PDF 961.34 K (2991) Comment (0) Favorites

      Abstract:Mechanical signaling plays a critical role in bone growth, remodeling and healing. Recent studies discover that estrogen can modulate proliferation, apoptosis and functional activity of bone cell tissues via estrogen receptor (ER) and affect bone formation and absorption. Thus ER plays an important role in bone growth and remodeling. ER also involves in the adaptive response to mechanical stimulation, which is affected by ER numbers and activity. These findings suggest that mechanical stimulation and estrogen can act together to regulate functions of bone cells via common signaling pathways. In this review, the role and mechanism of ER in bone tissues and its respons to mechanical stimulation are discussed.

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