This study was designed to determine the effect of backpack loading on the gait pattern and corresponding compensatory strategy, which is important to the balance control of biped robot and military training. Five healthy subjects were instructed to walk at their preferred speed on level pathway taking three different loads i.e. 6 kg, 12 kg and 25 kg, on their backs. The results showed that the gait pattern was apparently influenced, and the dominant effects were found to be the flexion of hip, knee joints and pitch angle of torso. The stride speed decreased apparently with loading on their backs, but the stride length showed less changes. Besides, the responses to taking loads might be influenced by the strength of body. An apparent multi-joints coordination motor mode was employed to compensate the influences of loading, however, their contributions are different; hip, knee joints and torso pitch made dominant contributions to the compensation while ankle joints made minor. The anterior pitch of upper torso could be employed to adjust the overall center of mass while loading on their backs, the larger the magnitude of loading on their backs, the larger the anterior pitch angle of torso. After the heel touched the ground, the flexion of hip and knee joints were effective for the shock absorption, which means that the stiffness of hip and knee joints can be used to absorb the shock and avoid the trauma of each joints.
Adult ; Ankle Joint ; physiology ; Back ; physiology ; Gait ; physiology ; Hip Joint ; physiology ; Humans ; Knee Joint ; physiology ; Male ; Weight-Bearing ; physiology

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

Based on the biomechanical simulation curve of OpenSim, an open source software of biomechanical model, a spherical exoskeleton parallel mechanism with two degrees of freedom for hip joint is proposed in this paper for the rehabilitation therapy of patients with impaired leg motor function or elderly people with walking dysfunction. Firstly, the parallel mechanism is modeled and the position inverse solution of the parallel mechanism is obtained using inverse kinematics analysis. The velocity analysis expression of the mechanism is derived by deriving the inverse kinematics solution. The model is imported into the mechanical system dynamics analysis software ADAMS and matrix processing analysis software MATLAB to carry out simulation experiments. The correctness of the velocity analysis is verified by comparing the velocity simulation results of the two methods. Then, three singular types of the mechanism are analyzed according to the obtained Jacobian matrix. According to the inverse solution of the mechanism, the reachable workspace of the mechanism is obtained by programming in MATLAB with given mechanism parameters and restriction conditions. Finally, the prototype platform is built. The experimental results show that the exoskeleton hip joint using this parallel mechanism can satisfy the requirement of rotation angle of human hip joint movement, but also can be good to assist patients with leg flexion-extension movement and adduction-abduction movement, and it is helpful to carry out corresponding rehabilitation training. It also has theoretical significance and application value for the research work of human hip exoskeleton parallel mechanism.
Biomechanical Phenomena ; Exoskeleton Device ; Hip Joint ; physiology ; Humans ; Models, Theoretical ; Movement ; Rehabilitation ; instrumentation ; Rotation ; Walking

BACKGROUNDA quantitative and accurate measurement of the range of hip joint flexion (RHF) is necessarily required in the evaluation of disordered or artificial hip joint function. This study aimed to assess a novel method to measure RHF more accurately and objectively.

METHODSLateral radiographs were taken of 31 supine men with hip joints extended or flexed. Relevant angles were measured directly from the radiographs. The change in the sacrofemoral angle (SFA) (the angle formed between the axis of the femur and the line tangent to the upper endplate of S1) from hip joint extension to hip joint flexion, was proposed as the RHF. The validity of this method was assessed via concomitant measurements of changes in the femur-horizontal angle (between the axis of the femur and the horizontal line) and the sacrum-horizontal angle (SHA) (between the line tangent to the upper endplate of S1 and the horizontal line), the difference of which should equal the change in the SFA.

RESULTSThe mean change in the SFA was 112.5 ± 7.4°, and was independent of participant age, height, weight, or body mass index. The mean changes in the femur-horizontal and SHAs were 123.0 ± 6.4° and 11.4 ± 3.0°, respectively. This confirmed that the change of SFA between hip joint extension and hip joint flexion was equal to the difference between the changes in the femur-horizontal and SHAs.

CONCLUSIONSUsing the SFA, to evaluate RHF could prevent compromised measurements due to the movements of pelvis and lumbar spine during hip flexion, and is, therefore, a more accurate and objective method with reasonable reliability and validity.

Adult ; Hip Joint ; diagnostic imaging ; surgery ; Humans ; Male ; Radiography ; Range of Motion, Articular ; physiology ; Sacrum ; diagnostic imaging ; surgery ; Young Adult

OBJECTIVETo explore the factors effecting restoring femoral offset and the relation between femoral offset and hip abductor strength during total hip arthroplasty (THA).

METHODSNinety-nine THA for 81 patients were performed from March 1998 to January 2002. And follow-up was finished. There were 53 women and 28 men and the average age was 57 years (29 to 80). The right hip had been replaced in 28 cases, the left in 35 cases and the bilateral in 18 cases. The mean duration of clinical and roentgenographic follow-up was 36.8 months (range, 19 approximately 66 months). A posterolateral approach was used in all THA. The femoral offset and the abductor lever arm were measured from each radiograph. The measurement of the hip abduction strength was made for some THA by the Cybex machine. Statistical data analysis was performed by SPSS10.0 software.

RESULTSFemoral offset correlated positively with the length of the abductor lever arm (r = 0.613; P < 0.001). Simple regression analysis showed that femoral offset was significantly and positively related to the length of femoral neck and neck-shaft angle (r = 0.451, P = 0.001; r = 0.567, P < 0.001). There was a highly significant and positive correlation between femoral offset (and consequently abductor lever arm) and hip abductor strength (r = 0.500, P = 0.009; r = 0.477, P = 0.014).

CONCLUSIONSIt is very important to template both sides of hip preoperatively for restoring femoral offset in THA. Femoral component with more anatomical neck-shaft angle will be used with the increase in the femoral neck length.

Adult ; Aged ; Aged, 80 and over ; Arthroplasty, Replacement, Hip ; methods ; Female ; Femur ; physiology ; Follow-Up Studies ; Hip Joint ; physiology ; Hip Prosthesis ; Humans ; Male ; Middle Aged ; Range of Motion, Articular ; Treatment Outcome

OBJECTIVE: To develop a novel three dimensional finite element(FE) model of the human pelvis and investigate the biomechanics of the pelvic injury and explore the applications of FE approach in forensic medicine. METHODS: The FE model of pelvis including bilateral iliac bones, sacrum, bilateral femurs, joint cartilages and ligaments was developed with Mimics 13.1 based on the CT images. The CT value of material properties were assigned. A static pressure of 600 N was applied at the upper surface of the sacrum endplate downwards along the vertical axis of sacral bone to validate the model. To simulate the side impacts, the lateral forces of 1, 2, 3, 4 and 5 kN were applied to the trochanter surface of right femur, respectively. The von Mises stress contours, displacement contours and stress distribution curves were subsequently calculated. RESULTS: An integrated FE model of pelvis including the joint cartilages and ligaments was successfully established. The model geometry coincided well with the CT images. The stress distributions of pelvis in erect position mainly located near the sacroiliac joints and the greater sciatic notches. Stress concentration was found on the superior and inferior pubis ramus, hip and sacroiliac joints on both sides under side impacts. CONCLUSION The established FE model has accurate and reliable biomechanical features. The FE model can be used to simulate injury and provide intuitive and accurate evidence for medicolegal expertise.
Biomechanical Phenomena ; Cadaver ; Computer Simulation ; Finite Element Analysis ; Hip Joint/physiology* ; Humans ; Image Processing, Computer-Assisted ; Imaging, Three-Dimensional/methods* ; Ligaments/physiology* ; Male ; Models, Anatomic ; Models, Biological ; Pelvis/physiology* ; Pressure ; Software ; Stress, Mechanical ; Tomography, Spiral Computed/methods* ; Weight-Bearing/physiology*

The objective of this study was to investigate the influence of the hip flexion upon parameters that are indicators of spinal mobility. These parameters include intervertebral disc angle and lumbar curvature by measurement of the radiography in twenty eight healthy men. The state of knowledge of how these parameters relate to lumbar mobility have resolved. The results of the parameters showed negligible changes in relation to the mobility of lumbar spine according to angle of hip flexion except at L4-L5 intervertebral disc angle and lumbar curvature (p< 0.05). This results of study confirms that hip joint movement therapy can be applied to these norms in patient management in supine position of for the stable spinal injuries in the upper lumbar region during early phase.
Adult ; Aged ; Hip Joint/*physiology/radiography ; Human ; Intervertebral Disk/radiography ; Lumbar Vertebrae/physiology/*radiography ; Male ; Middle Age ; Movement ; Pelvis/physiology/*radiography ; Range of Motion, Articular ; Supine Position ; Support, Non-U.S. Gov't

OBJECTIVETo investigate the results and indication of differently internal fixation for intertrochanteric fracture and prevent for complication.

METHODSOne hundred and two patients of intertrochanteric fracture of femur from January 1997 to December 2007 were reviewed and analysed. There were 46 males and 56 females, with an average age of 76.5 years ranging from 60 to 93 years. There were 34 cases of stability fractures and 68 of instability fractures. The methods of internal fixation included dynamic hip screw in 82 cases, proximal interlocking nail in 5, multi-screw fixation in 9, dynamic codylar screw in 6.

RESULTSThese patients were followed up for 6 to 72 months (36 months in average). The time of fracture healing was from 8 to 12 weeks. According to evaluation criterion of effect, the results were excellent in 72 cases, good in 20, fair in 10. After operation, there were 3 cases of coax vara, 2 cases of lag screws cutting out, 1 case of breakage of screw, 2 cases of avascular necrosis of the femoral head, 1 case of postoperative infection, 1 case of delayed union.

CONCLUSIONSuitable implant selection according the type of fracture, health condition is an important factor to reduce the incidence of complication for unstable fracture in aged patients. DHS is a main treatment of intertrochanteric fracture. PFN is recommended for serious osteoporosis or unstable intertrochanteric fracture. Compression screws is a choice for the fixation of type I and type II fracture of bad health condition.

Aged ; Aged, 80 and over ; Bone Screws ; Female ; Fracture Fixation, Internal ; methods ; Fracture Fixation, Intramedullary ; methods ; Fracture Healing ; physiology ; Hip Fractures ; complications ; surgery ; Humans ; Joint Instability ; physiopathology ; Male ; Middle Aged ; Postoperative Complications ; prevention & control

OBJECTIVETo evaluate the correlation of venous return disturbance (VRD), bone marrow edema (BME) and the amount of joint fluid with clinical symptoms in osteonecrosis of the femoral head (ONFH).

METHODSTwenty patients (25 hips) with ONFH proved by pathology were parallelly examined by 1.5 T MR and medullograph.

RESULTIn total 25 hips VRD was observed in 16 hips with medullograph and 13 hips with the clinical symptoms (P <0.05). BME was found in 17 with MRI (P <0.01), and the was found in 15 hips with MRI (Spearman=0.949). VRD were found in 16 hydrarthrus.

CONCLUSIONONFH patients with clinical symptoms have VRD, BME and the hydrarthrus. The medullograph is of value in monitoring the development of ONFH.

Adult ; Bone Marrow ; pathology ; physiopathology ; Edema ; pathology ; Female ; Femur Head ; blood supply ; Femur Head Necrosis ; pathology ; physiopathology ; Hip Joint ; pathology ; Humans ; Magnetic Resonance Imaging ; Male ; Middle Aged ; Regional Blood Flow ; physiology ; Veins ; physiopathology