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

Objective: To investigate the associations of obesity and physical activity with cognition in the elderly. Methods: A cross-sectional survey was conducted from October 2009 to June 2010 among people aged ≥50 years selected through multistage random cluster sampling in Shanghai. The subjects' body weight, body height, waist circumference and hip circumference were measured to calculate body mass index (BMI) and waist-hip ratio (WHR), and the data on self-reported physical activity level were collected through questionnaire survey. A comprehensive battery of cognitive tests was conducted to assess subjects' cognitive functions, including verbal recall, forward digit span (FDS), backward digit span (BDS), and verbal fluency (VF). General linear model was used to examine the associations of BMI, WHR and physical activity with cognition. Results: A total of 7 913 participants were included, with a median age of 60 years. Age, sex, education level, income level, BMI, WHR and physical activity level were significantly associated with cognitive scores in univariate analysis. After adjusted for age, sex, education level and income level, BMI was no longer significantly associated with cognitive scores in all cognitive functions (all P>0.01). WHR was significantly associated with VF score (P<0.01). Abdominally obese participants had lower VF score than non-abdominally obese participants (P<0.01). Physical activity level was significantly associated with all cognitive functions (P<0.01). Compared with participants with moderate physical activity level, participants with low physical activity level had lower scores in all cognitive functions (P<0.01). Conclusion: Abdominal obesity and low physical activity level were negatively associated with cognition level in the elderly, suggesting that waist circumference control and physical activity might help maintain cognition in the elderly.
Aged ; Body Height ; Body Mass Index ; Body Weight ; China ; Cognition/physiology* ; Cross-Sectional Studies ; Exercise ; Humans ; Middle Aged ; Obesity ; Surveys and Questionnaires ; Waist Circumference ; Waist-Hip Ratio

BACKGROUND: To augment cement-bone fixation, Dr. Hironobu Oonishi attempted additional physicochemical bonding through interposition of osteoconductive crystal hydroxyapatite (HA) granules at the cement-bone interface in 1982. He first used the interface bioactive bone cement (IBBC) technique in 12 selected patients (12 hips) in 1982 (first stage) and followed them for 2 years. In 1985, the technique was applied in 25 total hip arthroplasty (THA) patients (second stage) and the effects were investigated by comparing the side with the IBBC technique and the other side without the IBBC technique. He has employed this technique in all THA patients since 1987 (third stage). METHODS: In the IBBC technique, HA granules (2 to 3 g) were smeared on the bone surface just before the acetabular and femoral components were cemented. In the first stage, 12 hips were operated using the IBBC technique in 1982. In the second stage, THA was performed without the IBBC technique on one side and with the IBBC technique on the other side within 1 year in 25 patients. In the third stage, THA was performed with the IBBC technique in 285 hips in 1987. RESULTS: In the first stage patients, implant loosening was not detected at 30 years after operation. In the second stage patients, revision was required in 7 hips without the IBBC technique due to cup loosening (5 hips) and stem loosening (2 hips), whereas no hip was revised after THA with the IBBC technique at 26 years after operation. In the third stage patients, the incidence of radiolucent lines and osteolysis was very few at 25 years after operation. CONCLUSIONS: The long-term follow-up of THA performed around the inception of the IBBC technique has revealed low incidences of radiolucent lines, osteolysis, and revision surgery.
Adult ; Aged ; Aged, 80 and over ; *Arthroplasty, Replacement, Hip/adverse effects/instrumentation/methods ; *Bone Cements/adverse effects/therapeutic use ; Bone-Implant Interface/physiology ; Follow-Up Studies ; Hip/diagnostic imaging/surgery ; Humans ; Hydroxyapatites/therapeutic use ; Middle Aged ; Young Adult

OBJECTIVETo compare the difference of early postoperative hip abductor strength and function between improved Gibson anterolateral approach (group A) and conventional Gibson posterolateral approach (group B) in patients who had underwent total hip arthroplasty (THA).

METHODSAmong 149 patients performing total hip arthroplasty,130 patients were followed up and were randomly divided into two groups (19 unqualified cases were excluded). Group A included 65 cases who underwent anterolateral approach, and the other group included 65 cases who underwent posterolateral approach. In the group A, male:female = 26:39,with an average age of (72.5 ± 8.3) years old, BMI of (24.7 ± 3.7) kg/m², and hip abductor strength of (1.08 ± 0.49) N · m/kg. In the group B, male:female = 30:35, with an average age of (71.6 ± 7.1) years old, BMI of (25.5 ± 3.9) kg/m², and hip abductor strength of (1.05 ± 0.51) N · m/kg. In the age-related control group, male:female = 33:32, with an average age of (73.1 ± 7.5) years old, BMI of (24.2 ± 3.8) kg/m², and hip abductor strength of (1.17 ± 0.53) N · m/kg. The age, BMI, hip abductor strength, anatomy of surgical approach, hip abduction angles and Harris score in all patients were evaluated at the day before surgery and at 1, 2, 3, 6, and 12 months after surgery. All preoperative clinical data (age, BMI and abductor strength of the uninjured side limb ) of these cases had no significant differences.

RESULTSAt 1, 2, 3, 6, and 12 months after surgery, the hip abductor strength in group A were (0.53 ± 0.13), (0.66 ± 0.21), (0.85 ± 0.15), (0.95 ± 0.19), (1.03 ± 0.13) N · m/kg respectively, while in group B were (0.46 ± 0.14), (0.57 ± 0.18), (0.78 ± 0.12), (0.85 ± 0.18), (0.98 ± 0.14) N · m/ kg respectively.The differences between the two groups at the 6th months after operation were significant; the hip abduction angles in group A were (25.35 ± 4.31)°, (36.53 ± 5.13)°, (48.07 ± 1.62)°, (61.53 ± 1.77)°, (68.62 ± 3.16)°,while in group B were (23.47 ± 2.41)°, (33.42 ± 4.23)°, (46.64 ± 2.51)°, (60.96 ± 1.75)°, (67.47 ± 4.36)°. The differences between the two groups at the 3rd month after operation were significant. Harris score in the group A were 72.23 ± 2.57, 79.36 ± 3.91, 84.75 ± 3.17, 88.63 ± 2.16, 95.21 ± 1.37 repectively ; while in the group B were 71.58 ± 3.62, 78.96 ± 2.21, 83.97 ± 3.57, 87.92 ± 2.94, 94.83 ± 1.62 respectively. There were no significant differences between them.

CONCLUSIONOwing to less muscles interrupted, the THA with improved Gibson anterolateral approach offers a better improvement in earlier hip abductor strength and abduction angle compared with the conventional surgery.

Aged ; Aged, 80 and over ; Arthroplasty, Replacement, Hip ; methods ; Case-Control Studies ; Female ; Humans ; Male ; Middle Aged ; Muscle Strength ; Muscle, Skeletal ; physiology ; Postoperative Period

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

BACKGROUND: Recently, various femoral head fixation devices (HFDs) for trochanteric fractures have become available. However, there are some cases in which femoral head rotation with excessive sliding of the HFD is observed and it is often followed by cutout. The purpose of this study is to compare the ability of the three types of HFDs to prevent femoral head rotation. METHODS: Between July 2005 and December 2009, 206 patients aged over 60 years with trochanteric fractures who had undergone surgical treatment using a short femoral nail in our institution were enrolled into the study. We used the gamma 3 nail (GMN) as the screw-type HFD in 66 cases, the gliding nail (GLN) as a non-cylindrical blade in 76 cases, and the proximal femoral nail antirotation (PFNA) as a cylindrical blade in 64 cases. The sliding length of HFDs and the occurrence of femoral head rotation were evaluated by assessing radiographs as the main outcome, and the results were compared among these devices. RESULTS: A comparison of the degree of sliding in the GMN group showed that femoral head rotation was observed significantly more frequently in cases with rotation. Further, it appeared that femoral head rotation occurred more frequently in comminuted fractures. However, no significant differences between the sliding lengths of the different HFDs were observed among three groups. Femoral head rotation was observed in 15 cases of GMN (22.7%), 0 case of GLN, and 5 case of PFNA (7.8%). Significant differences with regard to the occurrence of femoral head rotation were observed among the three groups. Furthermore, significant differences were also observed between GLN and PFNA with respect to the occurrence of femoral head rotation. CONCLUSIONS: The ability to stabilize femoral head appears to be greater with blade-type materials than with screw-type materials. Furthermore, we believe that a non-cylindrical blade is preferable to a cylindrical blade for the surgical treatment of comminuted, unstable trochanteric fractures in order to prevent femoral head rotation and cut-out.
Aged ; Aged, 80 and over ; Female ; Femur Head/*surgery ; Hip Fractures/*surgery ; Humans ; Internal Fixators/*statistics & numerical data ; Male ; Postoperative Complications/epidemiology ; Range of Motion, Articular/physiology ; Retrospective Studies

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

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

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