OBJECTIVE: To compare the biomechanical properties of personalized Y-shaped plates with horizontal plates, vertical plates, and traditional Y-shaped plates in the treatment of distal humeral intra-articular fractures through finite element analysis, and to evaluate their potential for clinical application. METHODS: The study selected a 38-year-old male volunteer and obtained a three-dimensional model of the humerus by scanning his upper limbs using a 64-slice spiral CT. Four types of fracture-internal fixation models were constructed using Mimics 19.0, Geomagic Wrap 2017, Creo 6.0, and other software: horizontal plates, vertical plates, traditional Y-shaped plate, and personalized Y-shaped plate. The models were then meshed using Hypermesh 14.0 software, and material properties and boundary conditions were defined in Abaqus 6.14 software. AnyBody 7.3 software was used to simulate elbow flexion and extension movements, calculate muscle strength, joint forces, and load torques, and compare the peak stress and maximum displacement of the four fixation methods at different motion angles (10°, 30°, 50°, 70°, 90°, 110°, 130°, 150°) during elbow flexion and extension. RESULTS: Under dynamic loading during elbow flexion and extension, the personalized Y-shaped plate exhibits significant biomechanical advantages. During elbow flexion, the peak internal fixation stress of the personalized Y-shaped plate was (28.8±0.9) MPa, which was significantly lower than that of the horizontal plates, vertical plates, and traditional Y-shaped plate ( P<0.05). During elbow extension, the peak internal fixation stress of the personalized Y-shaped plate was (18.1±1.6) MPa, which was lower than those of the other three models, with significant differences when compared with horizontal plates and vertical plates ( P<0.05). Regarding the peak humeral stress, the personalized Y-shaped plate model showed mean values of (10.9±0.8) and (13.1±1.4) MPa during elbow flexion and extension, respectively, which were significantly lower than those of the other three models ( P<0.05). Displacement analysis showed that the maximum displacement of the humerus with the personalized Y-shaped plate during elbow flexion was (2.03±0.08) mm, slightly higher than that of the horizontal plates, but significantly lower than that of the vertical plates, showing significant differences ( P<0.05). During elbow extension, the maximum displacement of the humerus with the personalized Y-shaped plate was (1.93±0.13) mm, which was lower than that of the other three models, with significant differences when compared with vertical plates and traditional Y-shaped plates ( P<0.05). Stress contour analysis showed that the stress of the personalized Y-shaped plate was primarily concentrated at the bifurcation of the Y-shaped structure. Displacement contour analysis showed that the personalized Y-shaped plate effectively controlled the displacement of the distal humerus during both flexion and extension, demonstrating excellent stability. CONCLUSION The personalized Y-shaped plate demonstrates excellent biomechanical performance in the treatment of distal humeral intra-articular fractures, with lower stress and displacement, providing more stable fixation effects.
Humans ; Male ; Adult ; Healthy Volunteers ; Finite Element Analysis ; Tomography, Spiral Computed ; Models, Anatomic ; Biomechanical Phenomena ; Humeral Fractures, Distal/surgery* ; Fracture Fixation, Internal/instrumentation* ; Bone Plates ; Computer Simulation ; Precision Medicine/methods* ; Elbow Joint/surgery* ; Elbow/surgery* ; Humerus/surgery* ; Torque ; Stress, Mechanical ; Intra-Articular Fractures/surgery* ; Prosthesis Design/methods* ; Imaging, Three-Dimensional ; Range of Motion, Articular

OBJECTIVE: To explore changes of humerus torque screw tip distance on stability of proximal humeral internal locking system (PHILOS) by finite element analysis, in order to provide reference for selection of intraoperative plant size. METHODS: The proximal humerus 3D model was constructed based on Synbone artificial bone model in 3D engineering drawing software, and the corresponding 3D model was constructed based on PHILOS bone plate contour. The model was modified to simulate comminuted proximal humerus fracture, and the operation model was simulated after fracture, and the fixed operation model was assembled, the apex distance of humerus moment screw was set as 4, 8, 12 and 16 mm respectively. The axial and torsional loads were applied under the conditions of vertical downward and 20° abduction respectively, and the maximum displacement of humeral head and the peak stress of cortical bone and cancellous bone of humeral head were calculated under the corresponding working conditions, respectively, to evaluate influence of screw tip distance change on the risk of humeral head varus after PHILOS plate fixation. RESULTS: The peak displacement of humerus head did not generally increase with the increase of torque screw tip distance. On the contrary, the peak displacement of humerus head decreased slightly in all working conditions with the gradual increase of torque screw tip distance. At 20° abduction, the maximum displacement of humerus head was significantly higher in all models than that under vertical loading. At the same time, the lengthening of tip distance of torque screw did not lead to significant stress concentration of the humerus head after operation. The peak stress of cancellous bone decreased gradually with the extension of the peak distance of humerus moment screw, while the peak stress of cortical bone increased first and then decreased. When the peak distance was 12 mm, the peak stress of cortical bone was the largest under all working conditions, and then decreased with the further extension of the peak distance. CONCLUSION In the case of a small humeral head interlocking screw tip distance(less than 4 mm), increasing the humeral torque screw tip distance does not lead to a significant loss of stability after PHILOS plate fixation and a significant increase in the risk of postoperative complications.
Humans ; Finite Element Analysis ; Fracture Fixation, Internal/instrumentation* ; Bone Plates ; Bone Screws ; Humerus/surgery* ; Shoulder Fractures/surgery* ; Torque ; Biomechanical Phenomena

Objective To evaluate the effects of knee flexor and extensor strength on the subjective function and motor performance of knees after anterior cruciate ligament reconstruction. Methods A total of 53 patients who underwent anterior cruciate ligament reconstruction in the National Institute of Sports Medicine,General Administration of Sport of China from June 2015 to June 2021 and met the inclusion criteria were enrolled in this study.The patients were followed up time for at least 2 years.An isometric muscle strength test system was used to measure the strength of bilateral quadriceps and hamstring muscles.The patients were grouped according to whether the limb symmetry index (LSI) of peak torque of quadriceps and hamstring muscle reached 85% at an angular velocity of 60°/s.Specifically,26 patients were classified into group A (LSI≥85%) and 27 patients were classified into group B (LSI<85%).The subjective function and motor performance of knees were compared between the two groups. Results In terms of subjective function of knees,the international knee documentation committee (IKDC) score (88.76±9.93 vs. 81.08±12.57,P=0.017) and knee injury and osteoarthritis outcome score (KOOS) (86.27±8.96 vs. 80.22±11.31,P=0.036) were different between groups A and B.There was no significant difference in Lysholm score [95.0 (79.8,100.00) vs. 86.00 (66.00,100.00),P=0.238],ACL return to sports after injury scale score (66.08±22.25 vs. 61.12±23.53,P=0.434),Marx score [6.00 (4.75,7.00) vs. 6.00 (4.00,7.00),P=0.805] or Tegner activity score [8.00 (4.00,12.00) vs. 4.00 (2.00,12.00),P=0.566] between the two groups.In terms of motor performance,the single-leg triple hop LSI (0.92±0.13 vs. 0.81±0.18,P=0.016) and single-leg crossover hop LSI (0.96±0.12 vs. 0.84±0.22,P=0.021) showed significant differences between groups A and B,while there was no significant difference in single-leg hop LSI (0.90±0.18 vs. 0.79±0.25,P=0.116) between the two groups.In addition,there was no statistical significance in proprioception [30°:8.83±4.66 vs. 10.73±4.63,P=0.143;45°:6.94±3.82 vs. 7.66±3.93,P=0.504;60°:4.10 (3.20,4.72) vs. 3.90 (2.30,5.20),P=0.493] or Y-balance test results [anterior LSI:0.98 (0.84,1.02) vs. 0.94 (0.86,0.98),P=0.328;posterolateral LSI:1.00±0.08 vs. 0.97±0.07,P=0.249;posteromedial LSI:1.00 (0.97,1.03) vs. 0.96 (0.93,1.03),P=0.179] between groups A and B. Conclusion The patients with good symmetry of quadriceps and hamstring muscle strength after anterior cruciate ligament reconstruction had better subjective function and movement performance of knees than the patients with poor symmetry,which was mainly reflected in the IKDC score,KOOS,single-leg triple hop,and single-leg crossover hop.
Humans ; Anterior Cruciate Ligament Reconstruction ; Muscle Strength/physiology* ; Male ; Quadriceps Muscle/physiology* ; Female ; Adult ; Anterior Cruciate Ligament Injuries/physiopathology* ; Hamstring Muscles/physiopathology* ; Knee Joint/physiopathology* ; Anterior Cruciate Ligament/physiopathology* ; Torque ; Knee/physiopathology*

Sit-stand movement is one of the most common movement behaviors of the human body. The knee joint is the main bearing joint of this movement. Thus, the dynamic analysis of knee joint during this movement has deeply positive influences. According to the principle of moment balance, the dynamics of the knee joint during the movement were analyzed. Furthermore, combined with the data obtained from optical motion capture and six-dimensional ground reaction force test, the curve of knee joint torque was calculated. To verify the accuracy of the analysis of dynamic, the human body model was established, the polynomial equations of angle and angular velocity were fitted according to the experimental data, and the knee joint simulation of the movement was carried out. The result revealed that in terms of range and trend, the theoretical data and simulation data were consistent. The relationship between knee joint torque and ground reaction force was revealed based on the variation law of knee joint torque. During the sit-stand movement, the knee joint torque and the ground reaction force were directly proportional to each other, and the ratio was 5 to 6. In the standing process, the acceleration first increased and then decreased and finally increased in reverse, and the maximum knee torque occurred at an angle of about 140°. In the sitting process, the torque was maximized in the initial stage. The results of the dynamics analysis of knee joint during sit-stand movement are beneficial to the optimal design and force feedback control of seated rehabilitation aids, and can provide theoretical guidance for knee rehabilitation training.
Humans ; Hip Joint ; Biomechanical Phenomena ; Movement ; Knee Joint ; Torque

The series of YY/T 0987 standards converted from the corresponding ASTM (American Society for Testing and Materials) standards regulate the marking medical devices and testing methods for passive implants in the magnetic resonance environment. Along with the advancement of scientific cognition and the development of technology, the ASTM continuously amends and updates standards. This article studies the new version of ASTM standards and analyzes the advancing parts newly added as compared to the current YY/T 0987-2016 standard and eventually pinpoints some problems that remained to be solved. Except for the standard for image artifacts, this study found out that other standards had also been constantly updated, such as the standard of ASTM F2503 for marking medical devices extends its referenced documents and adds some ISO standards in, meanwhile, the test method on magnetically induced displacement force, radio frequency induced heating and magnetically induced torque also had been significantly adjusted and improved accordingly. This article recommends that domestic standards need to keep pace with the latest edition of ASTM F standards and to supplement new research achievements timely, just in order to provide a better normalization, guidance and support to the development of Chinese passive implants industry.
Magnetic Resonance Imaging ; Magnetic Resonance Spectroscopy ; Prostheses and Implants ; Radio Waves ; Torque ; United States

OBJECTIVE: Develop an intelligent equipment that can perform multiple modes of functional exercise on the knee joint, and can accurately measure and control strength, angle, angular velocity, time, frequency and so on. METHODS: Using geared motors, magnetic powder brakes and synchronous belt wheel sets and other mechanical structure and transmission technology combined with sophisticated mechanical design methods, the knee joint multiple functional exercise methods are cleverly integrated; a highly reliable PLC is used as the control core; the resistance torque out-put by the equipment is accurately controlled by adjusting the size of the exciting current; the angle sensor is used to accurately measure the rotation angle around the axis; and the error of each parameter index and the actual measured value is controlled within 5%. RESULTS: The developed prototype has a compact structure and a simple and convenient method of use. Based on the control of joint parameters such as resistance, the expected goal is achieved. CONCLUSIONS The equipment can carry out diversified, accurate and automatic rehabilitation treatment for knee joint diseases, and has certain social and economic benefits.
Biomechanical Phenomena ; Knee Joint ; Powders ; Rotation ; Torque

Based on the biomechanical mechanism of human upper limb, the disadvantages of traditional rehabilitation training and the current status of upper limb rehabilitation robot, a six degree of freedom, flexible adjustment, wearable upper limb rehabilitation exoskeleton design scheme is proposed. Firstly, the mechanics of each joint of the upper limb is analyzed, and the virtual prototype design of the whole mechanical structure of the upper limb rehabilitation wearable exoskeleton is carried out by using CATIA three-dimensional software. The tooth transmission of the forearm and the upper arm single row four point contact ball bearing with internal/external rotation and the shoulder flexible passive adjustment mechanism (viscoelastic damper) are innovatively designed. Then, the joints of the upper limb rehabilitation exoskeleton are analyzed, theoretical analysis and calculation of the driving torque, the selection of the motor and gearbox of each driving joint are carried out. Finally, the whole finite element analysis of the upper limb exoskeleton is carried out. The research and experimental results showed that the design scheme of the upper limb exoskeleton assist structure is highly feasible, which can help the patients with upper limb paralysis and motor dysfunction self-rehabilitation.
Biomechanical Phenomena ; Exoskeleton Device ; Humans ; Robotics ; Stroke Rehabilitation ; Torque ; Upper Extremity ; Wearable Electronic Devices

This study designed an isokinetic muscle strength rehabilitation training equipment, based on oil resistance. The equipment detected joint angles during movement through displacement sensors to measure the angular velocity in real-time. Then it can achieve flow resistance adjustment and constant velocity movement, based on the flow area of the proportional valve calculated by PID algorithm and the deviation between the set speed and the measured speed. The equipment can also collect muscle strength during exercise through force-sensitive sensors to achieve real-time and accurate assessment of muscle strength. Moreover, the study preliminarily certificated the isokinetic motion the results showed that the mean error of peak torque test is less than 5%, and the correlation is between 0.89 and 0.92 (
Exercise Therapy ; Humans ; Movement ; Muscle Strength ; Muscle, Skeletal ; Torque

PURPOSE: The purpose of this finite element analysis study is to introduce the novel Lock screw system and analyze its mechanical property to see if it can prevent abutment screw loosening. MATERIALS AND METHODS: The Lock screw is a component tightened on the inside of the implant abutment which applies compressive force to the abutment screw head. To investigate the effect, modeling was done using CAD program and it was analyzed by finite element analysis under various load conditions. First, the preload was measured according to the tightening torque of the abutment screw then it was compared with the theoretical value to verify the analytical model. The validated analytical model was then divided into those with no external load and those with 178 N, and the tightening torque of the lock screw was changed to 10, 20, 30 Ncm respectively to examine the property of stress distribution on the implant components. RESULTS: Using Lock screw under various loading conditions did not produce equivalent stresses beyond the yield strength of the implant components. In addition, the axial load was increased at the abutment-abutment screw interface. CONCLUSION: The use of Lock screw does not exert excessive stress on the implant components and may increase the frictional force between the abutment-abutment screw interface, thus it is considered to prevent loosening of the abutment screw.
Finite Element Analysis ; Friction ; Head ; Torque

The aim of this study was to examine the bioactivity and osseointegration of Ti-6Al-4V alloy implant which was modified by an anodic oxidation and a cyclic precalcification treatments. After blasting treatment using HAp (Hydroxyapatitie; HAp) powder which is resorbable blasting media (RBM) on the surface of Ti-6Al-4V alloy implants, the anodic oxidation treatment and the cyclic precalcification treatment were conducted to form nanotube TiO2 layer and HAp precipitation respectively. The surface morphology of the surface-treated Ti-6Al-4V alloy implant was investigated after immersion in the simulated body fluid(SBF) for 3 days to investigate the bioactivity. To investigate the effect of surface treatment on bonding between the implant and bone, RBM treated implant and RBM-anodization-cyclic precalcification(RACP) treated implant were placed on the distal side of both tibia diaphysis of rats, and then the removal torque of the implant was measured after 4 weeks. On the surface of RACP treated group, bone-like apatite precipitation was observed after immersion in SBF for 3 days. The removal torque was significantly higher in the RACP treated group than in the RBM treated group. The interfacial fracture between the implant and the new bone was observed in the RBM treated group, but both the cohesive fracture at the new bone and the interfacial fractures between the implant and the new bone were observed in the RACP treated group.
Alloys ; Animals ; Diaphyses ; Immersion ; Nanotubes ; Osseointegration ; Rats ; Tibia ; Torque