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

PURPOSE: We designed this study to demonstrate recent trends in the proportion of adult hip research in orthopedics, to identify countries leading the adult hip research, and to evaluate the relationship between the economic power of the countries and their contributions. MATERIALS AND METHODS: Studies published in seven select orthopedic journals were retrieved from PubMed. Among them, we determined the number of adult hip studies. The countries-of-origin of adult hip studies, and the economic power of the countries were investigated. RESULTS: A total of 7218 orthopedic publications and 1993 (27.6%) addressed adult hip research were identified. Adult hip studies increased from 313 (23.7%) in 2000 to 555 (27.9%) in 2011. Twenty-five countries accounted for 97.6% of the total number of adult hip studies, and gross domestic product correlated with publication volume (Spearman's rho, 0.723; p=0.000). CONCLUSION: Researchers from a limited number of developed countries have published their studies in the adult hip discipline.
Adult ; Geography ; Hip/*physiology ; Humans ; PubMed ; Publications/*trends ; Research/*trends

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

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

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

PURPOSE: The purposes of this study was to develop a comprehensive community-based fall prevention program and to test the effects of the program on the muscle strength, postural balance and fall efficacy for elderly people. METHODS: The design of this study was a nonequivalent control group pretest-posttest design. There were 28 participants in the experimental group and 29 in the control group. The program consisted of balance exercises, elastic resistance exercises and prevention education. The program was provided five times a week for 8 weeks and each session lasted 90 minutes. Data were analyzed using chi2-test, independent t-test and paired t-test using the SPSS program. RESULTS: Muscle strength of the lower extremities, postural balance and fall efficacy scores significantly improved in the experimental group compared to the control group. CONCLUSION: These results suggest that this program can improve lower extremity muscle strength, postural balance and fall efficacy in elders. Therefore, this program is recommended for use in fall prevention programs for elders living in the community.
Accidental Falls/*prevention & control ; Aged ; Aged, 80 and over ; Ankle/physiology ; Exercise ; Female ; Health Knowledge, Attitudes, Practice ; Hip/physiology ; Humans ; Knee/physiology ; Male ; *Muscle Strength ; *Postural Balance ; *Program Evaluation

OBJECTIVETo analyze the extent of postoperative hip abductor insufficiency in primary total hip arthroplasty (THA) patients undergoing anterolateral minimally invasive (ALMI) approach, and to investigate whether the clinical outcomes are more favorable in femoral neck fracture (FNF) patients than in non-femoral neck fracture (nFNF) patients.

METHODSA total of 48 patients were enrolled in this study. Each patient underwent a clinical examination preoperatively and 6, 12, 24 and 48 weeks postoperatively. The abductor torque, Trendelenburg's sign, gait velocity, Harris hip score, Oxford hip score, Westren Ontario and McMaster Universities (WOMAC) score and visual analog scale pain score were recorded. Statistical evaluation was performed with SPSS software version 18.0. The significance level was set at P<0.05.

RESULTSThe abductor torque of the operated hip and the recovery ratio showed a gradual improving tendency from 6 weeks postoperatively until the last follow-up. Gait velocity, Harris hip score, Oxford hip score and WOMAC score improved significantly after the operation until 24 weeks postoperatively. In the FNF group, the abductor torque of the operated side and the recovery ratio were significantly higher than in nFNF group at 6 weeks postoperatively, however, as time passed, this trend tended to disappear.

CONCLUSIONThis study demonstrates that patients can obtain good abductor strength and function in the early postoperative period and the hip abductor function of patients who suffer from hip osteoarthritis, rheumatoid arthritis, avascular necrosis of the femoral head could be significantly improved following ALMI THA.

Aged ; Arthroplasty, Replacement, Hip ; Femoral Neck Fractures ; physiopathology ; surgery ; Hip ; Humans ; Middle Aged ; Minimally Invasive Surgical Procedures ; Muscle Strength ; Muscle, Skeletal ; physiology ; Prospective Studies ; Recovery of Function ; Torque

By integrating bone-remodeling theory with finite element (FEM) models, the behavior of femoral remodeling after implantation of artificial femoral head was simulated and the stress shield effect of artificial femoral head on the femur was analyzed quantitatively. Bone was calculated with finite element code of the FEM model. The normal loading condition of femur was used as Model One, and the stress condition that bone was fixed by the bone-cement of the artificial head with collar was used as Model Two. It has been shown that bone was stress-shielded by the artificial femoral head and femur resorbed. Bone resorption near the proximal artificial stem was very severe. Its cross-section resorbed the greatest. The ratio of cross-sectional resorption was psi = 31.3% and the ratio of loss of the anti-bend cross-sectional modulus was zeta = 54.58%.
Arthroplasty, Replacement, Hip ; Bone Remodeling ; Bone Resorption ; Computer Simulation ; Femur Head ; physiology ; Finite Element Analysis ; Hip Prosthesis ; Humans ; Postoperative Period ; Software ; Stress, Mechanical

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 evaluate the changes of periprosthetic bone mineral density in femur after hip resurfacing arthroplasty.

METHODSFrom July 2002 to June 2005, a comparative study was carried out on 52 hips in 52 patients. Twenty-six patients (26 hips) who underwent Birmingham hip resurfacing arthroplasty (group BHR), and 26 patients (26 hips) who performed cementless total hip arthroplasty with Versys System stem (group THA). The periprosthetic bone mineral density of the femur was measured through dual energy X-ray absorptiometry of the Gruen zones at pre-operation, post-operation 3, 6, 12 and 24 months in patients from both group BHR and group THA. The bone mineral density of femoral neck in group BHR was measured too. Changes of bone mineral density ratio in proximal femur between pre-operation and post-operation were compared and analyzed.

RESULTSThe mean ratio of bone mineral density of the proximal femur in group BHR reduced by 5.8%, 4.9%, 2.6% and 0.4%, in group THA reduced by 7.0%, 10.6%, 1.0% and 4.1% at 3, 6, 12 and 24 months respectively. In group BHR, the mean ratio of bone mineral density in range of interest 1 decreased to 89.7% at 6 months and increased to 103.8% at 24 months, in range of interest 7 decreased to 95.1% at 6 months and increased to 103.7% at 24 months. In group THA, the mean ratio of bone mineral density in range of interest 1 decreased to 90.8% at 6 months, 94.4% at 24 months and in range of interest 7 decreased to 94.2% at 3 months, 96.7% at 24 months. In group BHR, the bone mineral density of femoral neck was restored to the pre-operation level at 6 months. The bone mineral density in superior-lateral zone of femoral neck decreased to 97.1% at 3 months and increased to 107.4% at 24 months respectively. The bone mineral density in inferior-medial zone of femoral neck increased to 117.9% at 24 months.

CONCLUSIONThe bone stock of proximal femur can be well preserved and recovered quickly after hip resurfacing arthroplasty.

Adult ; Arthroplasty, Replacement, Hip ; methods ; Bone Density ; physiology ; Female ; Femur ; physiopathology ; Follow-Up Studies ; Humans ; Male ; Middle Aged ; Postoperative Period