Biomechanical construction principles of the human hip joint in frontal plane

The prognosis of hip joint function is only to determine unsatisfactory on the base of the knowledges of anatomy by means of inspection or angles and distances from X-rays as well as on the base of models known for the biomechanic of hip. The term "normal anatomical" hip structure is analysed with respect to functional biomechanical influences on its macroscopic design in frontal plane. It is shown to interpret the macroscopic hip design as result of an effective arrangement of centre of rotation and muscle forces which a minimum on energy needing for its function. A mathematical equation describes the skeleton-muscle-system hip biomechanically. This new connection between angles and distances as well as first easy consequences are proofed on a-p-hip radiographs of 53 normal adults.     

The effect of the frontal plane tibiofemoral angle and varus knee moment on the contact stress and strain at the knee cartilage

Subject-specific models were developed and finite element analysis was performed to observe the effect of the frontal plane tibiofemoral angle on the normal stress, Tresca shear stress and normal strain at the surface of the knee cartilage. Finite element models were created for three subjects with different tibiofemoral angle and physiological loading conditions were defined from motion analysis and muscle force mathematical models to simulate static single-leg stance. The results showed that the greatest magnitude of the normal stress, Tresca shear stress and normal strain at the medial compartment was for the varus aligned individual. Considering the lateral knee compartment, the individual with valgus alignment had the largest stress and strain at the cartilage. The present investigation is the first known attempt to analyze the effects of tibiofemoral alignment during single-leg support on the contact variables of the cartilage at the knee joint. The method could be potentially used to help identify individuals most susceptible to osteoarthritis and to prescribe preventive measures.     

Contribution of mono- and biarticular muscles to extending knee joint moments in runners and cyclists.

Motor actions are governed by coordinated activation of mono- and biarticular muscles. This study considered differences in mono- and biarticular knee extensors between runners and cyclists in the context of adaptations to task-specific movement requirements. Two hypotheses were tested: 1) the length-at-use hypothesis, which is that muscle adapts to have it operate around optimal length; and 2) the contraction-mode hypothesis, which is that eccentrically active muscles prefer to operate on the ascending limb of the length-force curve. Ten runners and ten cyclists performed maximal, isometric knee extensions on a dynamometer at five knee and four hip joint angles. This approach allowed the separation of the contribution of mono- and biarticular extensors. Three major differences occurred: 1) compared with runners, monoarticular extensors of cyclists reach optimal length at larger muscle length; 2) in runners, optimal length of the biarticular extensor is shifted to larger lengths; and 3) the moment generated by monoarticular extensor was larger in cyclists. Mono- and biarticular extensors respond to different adaptation triggers in runners and cyclists. Monoarticular muscles seem to adapt to the length-at-use, whereas biarticular muscles were found to be sensitive to the contraction-mode hypothesis.     

Relationship between moments at the L5/S1 level, hip and knee joint when lifting

A study was performed to determine the influence of load magnitude on the self selected technique of lifting. Specifically, it was hypothesized that with heavier weights a tendency would occur to lift more with the back and less with the legs. Flexion-extension moments at the L5/S1 level, hip and knee joints were calculated for subjects when lifting boxes weighing from 50 to 250 N. Lifts were performed using a freestyle technique at normal speed. The moment profiles (moment plotted vs time) were analyzed kinematically and as a function of the weight lifted. The kinematics of the lift changed as the weight increased. The moment at the L5/S1 level increased with increasing weight, however, the corresponding knee moment decreased. Thus, an inverse relationship was found between the moment at the L5/S1 level and the knee joint moment. An increase in weight lifted was also associated with an increase in the angular velocity at the knee while lifting. Apparently with heavier weights there is a tendency to extend the knees earlier during the lift than with lighter weights, confirming our hypothesis. This explains the reduced knee moment. Our findings lead to the hypothesis that quadriceps muscle strength limits the subjects' ability to lift with their knees flexed.     

Rotational flexibility of the human knee due to varus/valgus and axial moments in vivo

Knee ligamentous injuries persist in the sport of Alpine skiing. To better understand the load mechanisms which lead to injury, pure varus/valgus and pure axial moments were applied both singly and in combination to the right knees of six human test subjects. The corresponding relative knee rotations in three degrees of freedom were measured. Knee flexion angles for each test subject were 15 and 60 degrees for the individual moments and 60 degrees for the combination moments. For both knee flexion angles the hip flexion angle was 0 degrees. Leg muscles were quiescent and axial force was minimal during all tests. Tables of data include sample statistics for each of four flexibility parameters in each loading direction. Data were analyzed statistically to test for significant differences in flexibility parameters between the test conditions. In flexing the knee from 15 to 60 degrees, the resulting knee rotations under single moments depended upon flexion angle with varus, valgus, and internal rotations increasing significantly. Also, rotations were different depending on load direction; varus rotation was significantly different and greater than valgus rotation at both flexion angles. Also external rotation was significantly different and greater than internal at 15 degrees flexion, but not at 60 degrees flexion. Coupled rotations under single moments were also observed. Applying pure varus/valgus moments resulted in coupled external/internal rotations which were inconsistent and hence not significant. Applying pure axial moments resulted in consistent and hence significant varus/valgus rotations; an external axial moment induced varus rotation and an internal axial moment induced valgus rotation. For combination moments, varus/valgus rotations decreased significantly from those rotations at similar load levels in the single moment studies. Also, a varus moment significantly increased external rotation and a valgus moment significantly decreased internal rotation. These differences indicate significant interaction between corresponding load combinations. These results suggest that load interaction is a potentially important phenomenon in knee injury mechanics.     

Gender differences exist in the hip joint moments of healthy older walkers

Gender differences in the incidence of symptomatic hip osteoarthritis (OA), changes in hip cartilage volume and hip joint space and rates hip arthroplasty of older people are reported in the literature. As the rate of progression of OA is in part mechanically modulated it is possible that this gender bias may be related to inherent differences (if they exist) in walking mechanics between older males and females. The purpose of this study was to examine potential mechanisms for gender differences in hip joint mechanics during walking by testing the hypotheses that females would exhibit higher hip flexion, adduction and internal rotation moments but not significantly greater normalized ground reaction forces (GRFs). Forty-two healthy subjects (21 male, 21 female), ages 50–79 yr were recruited for gait analysis. In support of the hypotheses, greater external hip adduction and internal rotation along with hip extension moments were found for females compared to males after normalizing for body size for all self-selected walking speeds. Differences in walking style (kinematics) were the main determinants in the joint kinetic differences as no differences in the normalized GRFs were found. As external joint moments are surrogate measures of the joint contact forces, the results of this study suggest the hip joint stress for the female population is higher compared to male population. This is in favor of a hypothesis that the increased joint contact stress in a female population could contribute to a greater joint degeneration at the hip in females as compared with males.     

Hip joint moments in symptomatic vs. asymptomatic people with mild radiographic hip osteoarthritis

Our primary objective was to examine external hip joint moments during walking in people with mild radiographic hip osteoarthritis (OA) with and without symptoms and disease-free controls. Three groups were compared (symptomatic with mild radiographic hip OA, n = 12; asymptomatic with mild radiographic hip OA, n = 13; OA-free controls, n = 20). Measures of the external moment (peak and impulse) in the sagittal, frontal and transverse plane during walking were determined. Variables were compared according to group allocation using mixed linear regression models that included individual gait trials, with group allocation as fixed effect and walking speed as a random effect. Participants with evidence of radiographic disease irrespective of symptoms walked 14–16% slower compared to disease-free controls (p = 0.002). Radiographic disease without symptoms was not associated with any altered measures of hip joint moment compared to asymptomatic OA-free controls once speed was taken into account (p ≥ 0.099). People with both mild radiographic disease and symptoms had lower external peak hip adduction moment (p = 0.005) and lower external peak internal rotation moment (p < 0.001) accounting for walking speed. Among angular impulses, only the presence of symptoms was associated with a reduced hip internal rotation impulse (p = 0.002) in the symptomatic group. Collectively, our observations suggest that symptoms have additional mechanical associations from radiographic disease alone, and provide insight into potential early markers of hip OA. Future research is required to understand the implications of modifying walking speed and/or the external hip adduction and internal rotation moment in people with mild hip OA.     

Contribution of passive tissues to the intersegmental moments at the hip

Many anatomic structures around the hip contribute either actively (i.e., muscle contractile elements) or passively (i.e., capsule, ligaments, non-contractile portions of muscles) to the intersegmental resultant forces and moments. Investigators have often assumed that the passive elements contribute negligibly to those moments, but without substantial supporting data. We explored this assumption by measuring the 'passive moments' in 15 normal subjects from near full extension to 60 degrees of hip flexion at speeds used in slow and normal walking. The data suggest that throughout most of the gait cycle and normal stair climbing, the passive structures contribute a small portion of the total moment, usually well less than 10%. Thus, for this limited range of activities, the assumption of negligible contribution of passive structures is reasonable.     

Associations among knee adduction moment, frontal plane ground reaction force, and lever arm during walking in patients with knee osteoarthritis

The adduction moment about the knee during walking gait has been proposed as an indirect measure of dynamic knee joint load. However, the relative contributions of the variables primarily used to calculate the knee adduction moment have not been investigated. The objectives of this paper were to: (1) describe and compare the magnitude and temporal characteristics of the knee adduction moment, frontal plane lever arm, and frontal plane ground reaction force (GRF) during gait in patients with knee osteoarthritis (OA) and, (2) examine the associations among these variables. Results indicated that both the knee adduction moment and the frontal plane GRF varied considerably throughout stance and exhibited the characteristic "double-hump" pattern, while the frontal plane lever arm magnitude varied only slightly during stance. Knees with OA had significantly greater peak knee adduction moments and frontal plane lever arms, but significantly less peak frontal plane GRF than knees without OA. Pearson product moment correlations indicated a higher association between peak knee adduction moment and peak frontal plane lever arm than between peak knee adduction moment and peak frontal plane GRF, particularly in knees with OA. These results suggest that the frontal plane lever arm assessed during walking is an important variable in the examination of knee OA, and warrants further investigation.     

Differences between measured and resultant joint moments during isometric contractions at the ankle joint

The purpose of this study was to examine two hypotheses: (a) during voluntary and electrically induced isometric contractions the moments measured at the dynamometer are different from the resultant moments in the same plane around the ankle joint and (b) at a given resultant moment during electrically induced isometric contractions the ankle angle while loading is different from the ankle angle while unloading. Twenty-seven long distance runners participated in the study. All subjects performed isometric maximal voluntary contractions (MVC) and contractions induced by electrostimulation at four different ankle-knee angle combinations on a Biodex-dynamometer. The kinematics of the leg were recorded using the vicon 624 system with eight cameras operating at 120 Hz. The main findings were: (a) the resultant moment at the ankle joint and the moment measured by the Biodex-dynamometer during isometric contractions are different, (b) during a plantar flexion effort the ankle angle changes significantly, whereas the knee angle shows only small and in most cases not significant changes, and (c) at identical resultant ankle joint moments the ankle angles are different between the loading and the unloading phases. The observed differences may lead to erroneous conclusions concerning the following: (a) diagnostic of muscle architecture, (b) estimation of the moment-ankle angle relationship and (c) estimation of the strain and hysteresis of tendons and aponeuroses.     

Comparison of the angles and corresponding moments in the knee and hip during restricted and unrestricted squats

ABSTRACT: Lorenzetti, S, Gülay, T, Stoop, M, List, R, Gerber, H, Schellenberg, F, and Stüssi, E. Comparison of the angles and corresponding moments in the knee and hip during restricted and unrestricted squats. J Strength Cond Res 26(10): 2829-2836, 2012-The aim of this study was to compare the angles and corresponding moments in the knee and hip during squats. Twenty subjects performed restricted and unrestricted squats with barbell loads that were 0, ?, and ? their body weight. The experimental setup consisted of a motion capture system and 2 force plates. The moments were calculated using inverse dynamics. During the unrestricted squats, the maximum moments in the knee were significantly higher, and those in the hip were significantly lower than during restricted squats. At the lowest position, the maximum knee flexion angles were approximately 86° for the restricted and approximately 106° for the unrestricted techniques, whereas the maximum hip flexion angle was between 95° and 100°. The higher moments in the hip during restricted squats suggest a higher load of the lower back. Athletes who aim to strengthen their quadriceps should consider unrestricted squats because of the larger knee load and smaller back load.     

An EMG-driven musculoskeletal model to estimate muscle forces and knee joint moments in vivo

This paper examined if an electromyography (EMG) driven musculoskeletal model of the human knee could be used to predict knee moments, calculated using inverse dynamics, across a varied range of dynamic contractile conditions. Muscle-tendon lengths and moment arms of 13 muscles crossing the knee joint were determined from joint kinematics using a three-dimensional anatomical model of the lower limb. Muscle activation was determined using a second-order discrete non-linear model using rectified and low-pass filtered EMG as input. A modified Hill-type muscle model was used to calculate individual muscle forces using activation and muscle tendon lengths as inputs. The model was calibrated to six individuals by altering a set of physiologically based parameters using mathematical optimisation to match the net flexion/extension (FE) muscle moment with those measured by inverse dynamics. The model was calibrated for each subject using 5 different tasks, including passive and active FE in an isokinetic dynamometer, running, and cutting manoeuvres recorded using three-dimensional motion analysis. Once calibrated, the model was used to predict the FE moments, estimated via inverse dynamics, from over 200 isokinetic dynamometer, running and sidestepping tasks. The inverse dynamics joint moments were predicted with an average R(2) of 0.91 and mean residual error of approximately 12 Nm. A re-calibration of only the EMG-to-activation parameters revealed FE moments prediction across weeks of similar accuracy. Changing the muscle model to one that is more physiologically correct produced better predictions. The modelling method presented represents a good way to estimate in vivo muscle forces during movement tasks.     

Discrepancies in knee joint moments using common anatomical frames defined by different palpable landmarks

The aim was to investigate the effects of three anatomical frames using palpable anatomical landmarks of the knee on the net knee joint moments. The femoral epicondyles, femoral condyles, and tibial ridges were used to define the different anatomical frames and the segment end points of the distal femur and proximal tibia, which represent the origin of the tibial coordinate system. Gait data were then collected using the calibrated anatomical system technique (CAST), and the external net knee joint moments in the sagittal, coronal, and transverse planes were calculated based upon the three anatomical frames. Peak knee moments were found to be significantly different in the sagittal plane by approximately 25% (p 相似文献   

The relation between the resultant moments at a joint and the moments measured by an isokinetic dynamometer

Isokinetic dynamometers have frequently been used to determine in vivo properties of human skeletal muscles. In these investigations the moments recorded by the dynamometer were often (implicitly) assumed to be the same as the joint moments produced by muscles. This assumption may have contributed to the conflicting results about in vivo muscle properties of human skeletal muscles that are reported in the literature. The purpose of this paper is to present a method for calculating the resultant joint moments from the moments recorded using a Cybex II dynamometer and to determine the differences between these two moments for some typical exercise conditions. The differences between these these moments are shown to be due to (a) gravitational effects, (b) inertial effects, and (c) non-rigidity of the Cybex arm/shank-foot system. The results obtained suggest that the moments recorded using the dynamometer should not be used to derive muscle properties without taking into account the relationship between the resultant joint moments and the moments measured using an isokinetic dynamometer.     

Influence of additional load on the moments of the agonist and antagonist muscle groups at the knee joint during closed chain exercise

The present study investigated the influence of additional loads on the knee net joint moment, flexor and extensor muscle group moments, and cocontraction index during a closed chain exercise. Loads of 8, 28, or 48 kg (i.e., respectively, 11.1 ± 1.5%, 38.8 ± 5.3%, and 66.4 ± 9.0% of body mass) were added to subjects during dynamic half squats. The flexor and extensor muscular moments and the amount of cocontraction were estimated at the knee joint using an EMG-and-optimization model that includes kinematics, ground reaction, and EMG measurements as inputs. In general, our results showed a significant influence of the Load factor on the net knee joint moment, the extensor muscular moment, and the flexor muscle group moment (all Anova p < .05). Hence we confirmed an increase in muscle moments with increasing load and moreover, we also showed an original “more than proportional” evolution of the flexor and extensor muscle group moments relative to the knee net joint moment. An influence of the Phase (i.e., descent vs. ascent) factor was also seen, revealing different activation strategies from the central nervous system depending on the mode of contraction of the agonist muscle group. The results of the present work could find applications in clinical fields, especially for rehabilitation protocols.     

Strategies of muscular support of varus and valgus isometric loads at the human knee

In this paper we studied how subjects activate their muscles in response to static varus and valgus loads at the knee. The muscles' contributions to the external moments were estimated using an EMG driven biomechanical model of the knee. The individual muscle activation and loading patterns were examined to identify the strategies that the nervous system uses to support varus and valgus knee moments. It was found that the (1) co-contraction of the hamstrings and quadriceps, and (2) activation of the gracilis and tensor fascia lata increased with the increasing magnitude of the varus and valgus moments. These 2 activation patterns provided positive support of valgus and varus loads at the knee The sartorius appears to be activated to provide positive support of valgus loads at the knee, whereas during varus moments this muscle increases the varus load on the knee, i.e. provides negative support. Generally, the hamstrings and quadriceps co-contraction contributed to most of the muscular support of the varus and valgus moments. In addition, co-contraction supported 11-14% of the external moment in pure varus and pure valgus respectively. It appears that there are activation strategies with the specific purpose to support varus and valgus moments, albeit small, which suggest dual goals of the neuromotor system during the support of varus and valgus moments.     

Differences in lower limb transverse plane joint moments during gait when expressed in two alternative reference frames

When comparing previous studies that have measured the three-dimensional moments acting about the lower limb joints (either external moments or opposing internal joint moments) during able-bodied adult gait, significant variation is apparent in the profiles of the reported transverse plane moments. This variation cannot be explained on the basis of adopted convention (i.e. external versus internal joint moment) or inherent variability in gait strategies. The aim of the current study was to determine whether in fact the frame in which moments are expressed has a dominant effect upon transverse plane moments and thus provides a valid explanation for the observed inconsistency in the literature. Kinematic and ground reaction force data were acquired from nine able-bodied adult subjects walking at a self-selected speed. Three-dimensional hip, knee and ankle joint moments during gait were calculated using a standard inverse dynamics approach. In addition to calculating internal joint moments, the components of the external moment occurring in the transverse plane at each of the lower limb joints were calculated to determine their independent effects. All moments were expressed in both the laboratory frame (LF) as well as the anatomical frame (AF) of the distal segment. With the exception of the ankle rotation moment in the foot AF, lower limb transverse plane joint moments during gait were found to display characteristic profiles that were consistent across subjects. Furthermore, lower limb transverse plane joint moments during gait differed when expressed in the distal segment AF compared to the LF. At the hip, the two alternative reference frames produced near reciprocal joint moment profiles. The components of the external moment revealed that the external ground reaction force moment was primarily responsible for this result. Lower limb transverse plane joint moments during gait were therefore found to be highly sensitive to a change in reference frame. These findings indicate that the different transverse plane joint moment profiles during able-bodied adult gait reported in the literature are likely to be explained on this basis.     

On the relation between joint moments and pedalling rates at constant power in bicycling

Joint moments are of interest because they bear some relation to muscular effort and hence rider performance. The general objective of this study is to explore the relation between joint moments and pedalling rate (i.e. cadence). Joint moments are computed by modelling the leg-bicycle system as a five-bar linkage constrained to plane motion. Using dynamometer pedal force data and potentiometer crank and pedal position data, system equations are solved on a computer to produce moments at the ankle, knee and hip joints. Cadence and pedal forces are varied inversely to maintain constant power. Results indicate that average joint moments vary considerably with changes in cadence. Both hip and knee joints show an average moment which is minimum near 105 rotations min-1 for cruising cycling. It appears that an optimum rotations min-1 can be determined from a mechanical approach for any given power level and bicycle-rider geometry.