A novel structural dynamics test method and device were designed to test the biomechanical effects of dynamic axial loading on knee cartilage and meniscus. Firstly, the maximum acceleration signal-to-noise ratio of the experimental device was calculated by applying axial dynamic load to the experimental device under unloaded condition with different force hammers. Then the experimental samples were divided into non-specimen group (no specimen loaded), sham specimen group (loaded with polypropylene samples) and bovine knee joint specimen group (loaded with bovine knee joint samples) for testing. The test results show that the experimental device and method can provide stable axial dynamic load, and the experimental results have good repeatability. The final results confirm that the dynamic characteristics of experimental samples can be distinguished effectively by this device. The experimental method proposed in this study provides a new way to further study the biomechanical mechanism of knee joint structural response under axial dynamic load.
Animals ; Cattle ; Biomechanical Phenomena ; Knee Joint/physiology* ; Meniscus ; Mechanical Phenomena ; Weight-Bearing

In order to study the mechanical behavior of degeneration and nucleotomy of lumbar intervertebral disc, compression experiments with porcine lumbar intervertebral discs were carried out. The lumbar intervertebral discs with trypsin-treated and nucleus nucleotomy served as the experimental group and the normal discs as the control group. Considering the effects of load magnitude and loading rate, the relationship between stress and strain, instantaneous elastic modulus and creep property of intervertebral disc were obtained. The creep constitutive model was established. The results show that the strain and creep strain of the experimental group increase significantly with the increase of compression load and loading rate, whereas the instantaneous elastic modulus decreases obviously, compared with the control group. It indicates that the effect of load magnitude and loading rate on load-bearing capacity of intervertebral disc after nucleotomy is larger obviously than that of normal disc. The creep behavior of the experimental group can be still predicted by the Kelvin three-parameter solid model. The results will provide theoretical foundation for clinical treatment and postoperative rehabilitation of intervertebral disc disease.
Animals ; Biomechanical Phenomena ; Intervertebral Disc ; physiology ; surgery ; Lumbar Vertebrae ; Stress, Mechanical ; Swine ; Weight-Bearing

PURPOSE: To investigate the effect of intramuscular Botulinum toxin type A (BoNT-A) injection on gait and dynamic foot pressure distribution in children with spastic cerebral palsy (CP) with dynamic equinovarus foot. MATERIALS AND METHODS: Twenty-five legs of 25 children with CP were investigated in this study. BoNT-A was injected into the gastrocnemius (GCM) and tibialis posterior (TP) muscles under the guidance of ultrasonography. The effects of the toxin were clinically assessed using the modified Ashworth scale (MAS) and modified Tardieu scale (MTS), and a computerized gait analysis and dynamic foot pressure measurements using the F-scan system were also performed before injection and at 1 and 4 months after injection. RESULTS: Spasticity of the ankle plantar-flexor in both the MAS and MTS was significantly reduced at both 1 and 4 months after injection. On dynamic foot pressure measurements, the center of pressure index and coronal index, which represent the asymmetrical weight-bearing of the medial and lateral columns of the foot, significantly improved at both 1 and 4 months after injection. The dynamic foot pressure index, total contact area, contact length and hind foot contact width all increased at 1 month after injection, suggesting better heel contact. Ankle kinematic data were significantly improved at both 1 and 4 months after injection, and ankle power generation was significantly increased at 4 months after injection compared to baseline data. CONCLUSION: Using a computerized gait analysis and foot scan, this study revealed significant benefits of BoNT-A injection into the GCM and TP muscles for dynamic equinovarus foot in children with spastic CP.
Adolescent ; Ankle Joint ; Botulinum Toxins, Type A/administration & dosage/*pharmacology ; Cerebral Palsy/*complications/drug therapy ; Child ; Child, Preschool ; Clubfoot/*drug therapy/*etiology/physiopathology ; Female ; Foot ; Gait/*drug effects/physiology ; Humans ; Injections, Intramuscular ; Male ; Muscle Spasticity/drug therapy ; Muscle, Skeletal/diagnostic imaging ; Neuromuscular Agents/administration & dosage/*pharmacology ; Pressure ; Prospective Studies ; Treatment Outcome ; Weight-Bearing

Energy Metabolism ; Humans ; Oxygen Consumption ; Walking ; physiology ; Weight-Bearing ; physiology

BACKGROUNDThe time until weight-bearing after arthroscopic microfracture when treating osteochondral lesions of the talus (OLT) is very important to the clinical outcomes of the operation. However, there have been no consistent opinions regarding the optimal time to start weight-bearing postoperatively. Many opinions advocate that weight-bearing should begin not earlier than the sixth or eighth week postoperatively, whereas others point out that earlier weight-bearing could also obtain satisfactory outcomes. The purpose of our study was to evaluate the clinical outcomes of early weight-bearing after arthroscopic microfracture during the treatment of OLT.

METHODSFifty-eight ankles in 58 patients with a single OLT <2 cm(2) were retrospectively studied. All lesions were treated with arthroscopic debridement and microfracture under local anesthesia. After the operation, the patients were allowed to bear full weight under the protection of figure-8-shaped splints. The visual analog scale (VAS) for pain and the American Orthopaedic Foot and Ankle Society (AOFAS) ankle--hindfoot scale were evaluated preoperatively and at six postoperative timepoints (1st day, 1st month, 3rd month, 6th month, 12th month, and 24th month). Patients were followed up for 24-52 months (mean (34.97 ± 7.33) months).

RESULTSAll 58 patients achieved excellent recovery with significant relief of their symptoms. The VAS score decreased from 7.31 ± 1.0 preoperatively to 0.95 ± 0.76 at the 24th month follow-up (P = 0.000), whereas the AOFAS score improved from 53.53 ± 8.57 preoperatively to 87.62 ± 5.42 at the 24th month follow-up (P = 0.000).

CONCLUSIONThe successful clinical outcomes of this study demonstrated that early weight-bearing after the treatment of OLT with arthroscopic microfracture can be allowed.

Adolescent ; Adult ; Arthroscopy ; Female ; Fractures, Bone ; Humans ; Male ; Middle Aged ; Retrospective Studies ; Talus ; injuries ; surgery ; Weight-Bearing ; physiology ; Young Adult

This study investigated the effect of prolonged walking with load carriage on body posture, muscle fatigue, heart rate and blood pressure of the tested subjects. Ten healthy volunteers performed 30 min walking trials on treadmill (speed = 1.1 m/s) with different backpack loads [0% body weight (BW), 10% BW, 15% BW and 20% BW]. The change of body posture, muscle fatigue, heart rate and blood pressure before and after walking and the recovery of muscle fatigue during the rest time (0, 5, 10 and 15 min) were collected using the Bortec AMT-8 and the NDI Optotrak Certus. Results showed that the forward trunk and head angle, muscle fatigue, heart rate and blood pressure increased with the increasing backpack loads and bearing time. With the 20% BW load, the forward angle, muscle fatigue and systolic pressure were significantly higher than with lighter weights. No significantly increased heart rate and diastolic pressure were found. Decreased muscle fatigue was found after removing the backpack in each load trial. But the recovery of the person with 20% BW load was slower than that of 0% BW, 10% BW and 15% BW. These findings indicated that the upper limit of backpack loads for college-aged students should be between 15% BW and 20% BW according to muscle fatigue and forward angle. It is suggested that backpack loads should be restricted to no more than 15% BW for walks of up to 30 min duration to avoid irreversible muscle fatigue.
Blood Pressure ; Body Weight ; Exercise Test ; Healthy Volunteers ; Heart Rate ; Humans ; Muscle Fatigue ; Posture ; Walking ; physiology ; Weight-Bearing

In this research, a new set of training methods was created and put into practice to train the body's sit-to-stand balancing ability, and controlling ability of body's gravity centre of patients with cerebrovascular diseases. It contains a series of motion trainings, including sitting position training, standing position training, sit-to-stand training and game training, etc. There is also a series of trainings of feedback included in this set of methods, such as internal feedback, external feedback, bandwidth feedback, conclusive feedback, visual feedback, acoustical feedback and so on. The trainings resulted in better controlling ability of body's centre of gravity in the sit-to-stand process of patients after a period of training. It indicated that these targeted-designed trainings, especially the feedback trainings, could effectively help the under-trained patients to have a better knowledge of their current situation, and in turn to have a better knowledge of which aspects they should take more training to achieve a better therapeutic effect.
Equipment Design ; Exercise Therapy ; instrumentation ; methods ; Hemiplegia ; etiology ; physiopathology ; rehabilitation ; Humans ; Movement ; physiology ; Postural Balance ; physiology ; Self-Help Devices ; Stroke Rehabilitation ; Weight-Bearing

The purpose of this study was to investigate the effect of different backpack load on the plantar pressure of people during walking. By using three-dimensional force platform system, we collected the ground reaction force data from 20 college students, who were carrying different loads on their backs, and then we transformed the data into a characteristic two-peak curve. Seven characteristic parameters on the curve were selected and analyzed by using statistical methods. The results indicated that the peak ground reaction forces increased as the loads increased. Furthermore, in consideration of different genders, the amount increased was different. For the male subjects, when backpack load reached 17% body weight, changes in ground reaction force began to take place until the backloads reached 20% body weight changes in ground reaction force induced a significant difference. Por the female subjects, changes in ground reaction force began to take place with loads up to 14% body weight and while it reached 15% body weight it induced a significant difference.
Back ; physiology ; Biomechanical Phenomena ; physiology ; Female ; Foot ; physiology ; Humans ; Male ; Pressure ; Stress, Mechanical ; Walking ; physiology ; Weight-Bearing ; physiology ; Young Adult

DLUT4060 piezoelectric multi-component force platforms and DVM8820 three-dimensional infrared image capture system were used to test the sit-to-walk (STW) movements of 11 healthy elderly (72. 6 +/- 12. 2 years old) and 11 healthy young (19. 7 +/-1. 3 years old) individuals. Firstly, we studied the effects of seat-heights on the ground reaction forces, the velocity of the center of mass, and action time duration. Then we discussed the movement strategies and falling risks of the persons in the two age groups respectively. Finally, we decided the best seat height for the two age groups. It was found that the best seat heights for both the two age groups were 100% popliteal height. This height may make the subject get the greatest biomechanical advantages and the lowest falling risks. The popliteal height must be concerned when designing and fixing up the public activity area facilities and daily life of the elderly. To some extent, it can reduce the falling risk of the elderly.
Accidental Falls ; prevention & control ; Aged ; Aged, 80 and over ; Ankle Joint ; physiology ; Buttocks ; physiology ; Hip Joint ; physiology ; Humans ; Interior Design and Furnishings ; Knee Joint ; physiology ; Leg ; anatomy & histology ; physiology ; Male ; Middle Aged ; Movement ; physiology ; Posture ; Weight-Bearing ; physiology ; Young Adult

This study describes the details of how to construct a three-dimensional (3D) finite element model of a maxillary first premolar tooth based on micro-CT data acquisition technique, MIMICS software and ANSYS software. The tooth was scanned by micro-CT, in which 1295 slices were obtained and then 648 slices were selected for modeling. The 3D surface mesh models of enamel and dentin were created by MIMICS (STL file). The solid mesh model was constructed by ANSYS. After the material properties and boundary conditions were set, a loading analysis was performed to demonstrate the applicableness of the resulting model. The first and third principal stresses were then evaluated. The results showed that the number of nodes and elements of the finite element model were 56 618 and 311801, respectively. The geometric form of the model was highly consistent with that of the true tooth, and the deviation between them was -0.28%. The loading analysis revealed the typical stress patterns in the contour map. The maximum compressive stress existed in the contact points and the maximum tensile stress existed in the deep fissure between the two cusps. It is concluded that by using the micro-CT and highly integrated software, construction of the 3D finite element model with high quality will not be difficult for clinical researchers.
Bicuspid ; diagnostic imaging ; physiology ; Biomechanical Phenomena ; Finite Element Analysis ; Humans ; Image Processing, Computer-Assisted ; Imaging, Three-Dimensional ; methods ; Maxilla ; Models, Anatomic ; Software ; Stress, Mechanical ; Weight-Bearing ; physiology ; X-Ray Microtomography ; methods