Sagittal plane hip motion reversals during walking are associated with disease severity and poorer function in subjects with hip osteoarthritis

A midstance reversal of sagittal plane hip motion during walking, or motion discontinuity (MD), has previously been observed in subjects with endstage hip osteoarthritis (OA) and in patients with femoroacetabular impingement. The goal of the present study was to evaluate whether this gait pattern is a marker of OA presence or radiographic severity by analyzing a large IRB approved motion analysis data repository. We also hypothesized that subjects with the MD would show more substantial gait impairments than those with normal hip motion. We identified 150 subjects with symptomatic unilateral hip OA and Kellgren-Lawrence OA severity data on file, and a control group of 159 asymptomatic subjects whose ages fell within 2 standard deviations of the mean OA group age. From the gait data, the MD was defined as a reversal in the slope of the hip flexion angle curve during midstance. Logistic regressions and general linear models were used to test the association between the MD and OA presence, OA severity and, other gait variables. 53% of OA subjects compared to 7.5% of controls had the MD (p<0.001); occurrence of the MD was associated with OA severity (p=0.009). Within the OA subject group, subjects with the MD had reduced dynamic range of motion, peak, extension, and internal rotation moments compared to those who did not (MANCOVA p ≤ 0.042) after controlling for walking speed. We concluded that sagittal plane motion reversals are indeed associated with OA presence and severity, and with more severe gait abnormalities in subjects with hip OA.     

Feasibility of a gait retraining strategy for reducing knee joint loading: increased trunk lean guided by real-time biofeedback

The purpose of this feasibility study was to examine changes in frontal plane knee and hip walking biomechanics following a gait retraining strategy focused on increasing lateral trunk lean and to quantify reports of difficulty and joint discomfort when performing such a gait modification. After undergoing a baseline analysis of normal walking, 9 young, healthy participants were trained to modify their gait to exhibit small (4°), medium (8°), and large (12°) amounts of lateral trunk lean. Training was guided by the use of real-time biofeedback of the actual trunk lean angle. Peak frontal plane external knee and hip joint moments were compared across conditions. Participants were asked to report the degree of difficulty and the presence of any joint discomfort for each amount of trunk lean modification. Small (4°), medium (8°), and large (12°) amounts of lateral trunk lean reduced the peak external knee adduction moment (KAM) by 7%, 21%, and 25%, respectively, though the peak KAM was only significantly less in the medium and large conditions (p<0.001). Increased trunk lean also significantly reduced the peak external hip adduction moments (p<0.001). All participants reported at least some difficulty performing the exaggerated trunk lean pattern and three participants reported ipsilateral knee, hip, and/or lower spine discomfort. Results from this study indicate that a gait pattern with increased lateral trunk lean can effectively reduce frontal plane joint moments. Though these findings have implications for pathological populations, learning this gait pattern was associated with some difficulty and joint discomfort.     

Time course and extent of functional recovery during the first postoperative year after minimally invasive total hip arthroplasty with two different surgical approaches--a randomized controlled trial

While others have reported short-term comparisons between various minimally invasive surgical (MIS) approaches to total hip arthroplasty (THA) and their conventional analogues, longer-term data is lacking, as is information indicating whether MIS approaches to THA provide a biomechanically complete recovery. Furthermore, different MIS approaches have not been compared. Our approaches of interest were a one-incision modified Watson-Jones, and a two-incision approach. Hypotheses: (1) There are significant differences in gait recovery patterns between the two surgical groups and (2) THA subjects have significant differences in function one year after surgery compared to control subjects. To test these hypotheses, THA candidates (n=26) were randomized to receive one of these MIS approaches and evaluated preoperatively, and postoperatively at 3 weeks, and at 3, 6 and 12 months. Evaluations included three-dimensional gait analysis and 24-hour step-counts. The same data were obtained from 25 control subjects. Recovery time-course was assessed using repeated measures ANOVA. T-tests were used to compare controls with the pooled group of THA subjects. We found no differences between the two THA surgical groups regarding the time-course of recovery (p≥0.591). Although recovery was statistically complete by 3 months postoperatively for all variables, there were significant differences from controls at 12 months. Most notably, the external hip adduction moment, which reflects hip abductor function, was more than one standard deviation below normal (p<0.001). THA subject inactivity could not explain the gait differences, since one year after surgery daily step counts were not significantly different from controls (p=0.346). More work is necessary to determine ways to improve biomechanical outcomes for today's patients with high expectations for function and implant longevity.     

Hip kinematics and kinetics in total hip replacement patients stratified by age and functional capacity

To examine functional differences in total hip replacement patients (THR) when stratified either by age or by functional ability as defined by self-selected walking speed. THR patients and a control group underwent three-dimensional motion analysis under self-selected normal and fast walking conditions. Patients were stratified into five age groups for comparison with existing literature. The THR cohort was also stratified into three functional groups determined by their self-selected gait speed (low function <1SD of total cohort’s mean walking speed; high function >1SD; normal function within 1SD). Hip kinematics, ground reaction forces, joint moments and joint powers in all three planes (x-y-z) were analysed. 137 THR and 27 healthy control patients participated. When stratified by age, during normal walking the youngest two age groups walked quicker than the oldest two groups (p < 0.0001) but between-group differences were not consistent across age strata. The differences were diminished under the fast walking condition. When stratified by function, under normal walking conditions, the low function and normal function THR groups had a reduced extension angle (mean = 1.75°, SD = ±7.75, 1.26° ± 7.42, respectively) compared to the control group (−6.07° ± 6.43; p < 0.0001). The low function group had a reduced sagittal plane hip power (0.75 W/kg ± 0.24), reduced flexor (0.60 Nm/kg ± 0.85) and extensor moment (0.51 Nm/kg ± 0.17) compared to controls (p < 0.0001). These differences persisted under the fast walking condition. There were systematic differences between patients when stratified by function, in both walking conditions. Age-related differences were less systematic. Stratifying by biomechanical factors such as gait speed, rather than age, might be more robust for investigating functional differences.     

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.     

Kinematic and kinetic changes in obese gait in bariatric surgery-induced weight loss

This study examines the effects of a radical bariatric surgery-induced weight loss on the gait of obese subjects. We performed a three-dimensional motion analysis of lower limbs, and collected force platform data in the gait laboratory to calculate knee and hip joint moments. Subjects (n=13) performed walking trials in the laboratory before and 8.8 months (SD 4.2) after the surgical procedure at two gait speeds (1.2m/s and 1.5m/s). The average weight loss was 26.7kg (SD 9.2kg), corresponding to 21.5% (SD 6.8%) of the initial weight. We observed a decrease in step width at both gait speeds, but no changes in relative double support or swing time or stride length. A significant decrease was noted in the absolute values of peak knee abductor, peak knee flexor and peak hip extensor moments. However, the moment values normalized by the body weight and height remained unchanged in most cases. Thus, we conclude that weight loss reduces hip and knee joint moments in proportion to the amount of weight lost.     

Sex-specific differences in gait patterns of healthy older adults: results from the Baltimore Longitudinal Study of Aging

The effects of normal aging and orthopedic conditions on gait patterns during customary walking have been extensively investigated. Empirical evidence supports the notion that sex differences exist in the gait patterns of young adults but it is unclear as to whether sex differences exist in older adults. The aim of this study was to investigate sex-specific differences in gait among older adults. Study participants were 336 adults (50-96 years; 162 women) enrolled in the Baltimore Longitudinal Study of Aging (BLSA) who completed walking tasks at self-selected speed without assistance. After adjusting for significant covariates, women walked with higher cadence (p=0.01) and shorter stride length (p=0.006) compared to men, while gait speed was not significantly related to sex. Women also had less hip range of motion (ROM; p=0.004) and greater ankle ROM (p<0.001) in the sagittal-plane, and greater hip ROM (p=0.004) in the frontal-plane. Hip absorptive mechanical work expenditure (MWE) of the women was greater in the sagittal-plane (p<0.001) and lower in the frontal-plane (p<0.001), compared to men. In summary, women's gait is characterized by greater ankle ROM than men while men tend to have greater hip ROM than women. Characterizing unique gait patterns of women and men with aging may be beneficial for detecting the early stages of gait abnormalities that may lead to pathology.     

The Influence of Visual Feedback on the Mental Representation of Gait in Patients with THR: A New Approach for an Experimental Rehabilitation Strategy

Due to total hip replacement (THR), patients reveal abnormal gait patterns which post-operative do often not return to “normal”. The restoration towards normal gait reduces stress on the adjacent joints which consequently reduces risk of osteoarthrosis development. Motor-performance is related to the structure of the movement in long-term memory, thus it seems to be essential to imprint correct gait patterns in there. Mental representation structures can develop over the course of training and visual feedback presumably helps regaining a better representation of gait in long-term memory. The purpose of this study is to evaluate the effect of visual feedback on mental representation in patients with THR. In a randomized controlled trial, 20 women (57 ± 6 years) with THR have been enrolled. Subjects were randomly assigned to a control group (CG) or intervention group (IG). Additionally to inpatient treatment, all subjects participated in a standardized gait training including either an intervention based on verbal information from a physiotherapist (CG) or an intervention based on real-time visual feedback (IG). Mental representation was measured in pre-test and post-test using the structure-dimensional analysis. Results indicate significant improvements in mental representation of gait in the post-test only in IG, suggesting that beneficial effects were provoked by visual feedback.     

The effects of walking speed on obstacle crossing in healthy young and healthy older adults

The effects of walking speed and age on the peak external moments generated about the joints of the trailing limb during stance just prior to stepping over an obstacle and on the kinematics of the trailing limb when crossing the obstacle were investigated in 10 healthy young adults (YA) and 10 healthy older adults (OA). The peak hip and knee adduction moments in OA were 21-43% greater than those in YA (p相似文献   

Decreased frontal plane hip joint moments in runners with excessive varus excursion at the knee

Knee varus position and motion have been correlated with increased medial knee loading during gait. The purpose of this study is to determine whether runners with excessive varus excursion (EVE) at the knee demonstrate frontal plane knee and hip kinetics that are different from those of runners with normal varus excursion (NVE). Twelve runners with EVE were compared with 12 NVE subjects using three-dimensional kinematics and kinetics. Frontal plane angles and moments were compared at the knee and hip. Runners with EVE had significantly greater abductor moment of the knee (p = .004) and lower peak abductor moment of the hip (p = .047). Runners with EVE demonstrate knee and hip mechanics thought to be associated with increased medial tibiofemoral loading. Further understanding of how changing hip abductor moments may affect changes in knee abductor moments during running may potentially lead to interventions that augment long-term risk of injury.     

Normalization of joint moments during gait: a comparison of two techniques

Joint moments are commonly used to characterize gait. Factors like height and weight influence these moments. This study determined which of two commonly used normalization methods, body mass or body weight times height, most reduced the effects of height and weight on peak hip, knee, and ankle external moments during walking. The effectiveness of each normalization method in reducing gender differences was then tested. Gait data from 158 normal subjects were analyzed using unnormalized values, body mass normalized values, and body weight times height normalized values. Without normalization, height or weight accounted for 7-82% of the variance in all 10 peak components of the moments. With normalization, height and weight accounted for at most 6% of the variance with the exception of the hip adduction moment normalized by body weight times height and the ankle dorsiflexion moment normalized by body mass. For the hip adduction moment normalized by body weight times height, height still accounted for 13% of the variance (p<0.001) and for the ankle dorsiflexion moment normalized by body mass, 22% of the variance (p<0.001). After normalization, significant differences between males and females remained for only two out of 10 moments with the body weight times height method compared to six out of 10 moments with the body mass method. When compared to the unnormalized data, both normalization methods were highly effective in reducing height and weight differences. Even for the two cases where one normalization method was less effective than the other (hip adduction-body weight times height; ankle dorsiflexion-body mass) the normalization process reduced the variance ascribed to height or weight by 48% and 63%, respectively, as compared to the unnormalized data.     

Experimentally reduced hip abductor function during walking: Implications for knee joint loads

Hip and knee functions are intimately connected and reduced hip abductor function might play a role in development of knee osteoarthritis (OA) by increasing the external knee adduction moment during walking. The purpose of this study was to test the hypothesis that reduced function of the gluteus medius (GM) muscle would lead to increased external knee adduction moment during level walking in healthy subjects. Reduced GM muscle function was induced experimentally, by means of intramuscular injections of hypertonic saline that produced an intense short-term muscle pain and reduced muscle function. Isotonic saline injections were used as non-painful control. Fifteen healthy subjects performed walking trials at their self-selected walking speed before and immediately after injections, and again after 20 min of rest, to ensure pain recovery. Standard gait analyses were used to calculate three-dimensional trunk and lower extremity joint kinematics and kinetics. Surface electromyography (EMG) of the glutei, quadriceps, and hamstring muscles were also measured. The peak GM EMG activity had temporal concurrence with peaks in frontal plane moments at both hip and knee joints. The EMG activity in the GM muscle was significantly reduced by pain (?39.6%). All other muscles were unaffected. Peaks in the frontal plane hip and knee joint moments were significantly reduced during pain (?6.4% and ?4.2%, respectively). Lateral trunk lean angles and midstance hip joint adduction and knee joint extension angles were reduced by ?1°. Thus, the gait changes were primarily caused by reduced GM function. Walking with impaired GM muscle function due to pain significantly reduced the external knee adduction moment. This study challenge the notion that reduced GM function due to pain would lead to increased loads at the knee joint during level walking.     

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.     

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.     

Jogging gait kinetics following fatiguing lumbar paraspinal exercise

A relationship exists between lumbar paraspinal muscle fatigue and quadriceps muscle activation. The objective of this study was to determine whether hip and knee joint moments during jogging changed following paraspinal fatiguing exercise. Fifty total subjects (25 with self-reported history of low back pain) performed fatiguing, isometric lumbar extension exercise until a shift in EMG median frequency corresponding to a mild level of muscle fatigue was observed. We compared 3-dimensional external joint moments of the hip and knee during jogging before and after lumbar paraspinal fatigue using a 10-camera motion analysis system. Reduced external knee flexion, knee adduction, knee internal rotation and hip external rotation moments and increased external knee extension moments resulted from repetitive lumbar paraspinal fatiguing exercise. Persons with a self-reported history of LBP had larger knee flexion moments than controls during jogging. Neuromuscular changes in the lower extremity occur while resisting knee and hip joint moments following isolated lumbar paraspinal exercise. Persons with a history of LBP seem to rely more heavily on quadriceps activity while jogging.     

Kinematic and kinetic factors that correlate with improved knee flexion following treatment for stiff-knee gait

Stiff-knee gait is a movement abnormality in which knee flexion during swing phase is significantly diminished. This study investigates the relationships between knee flexion velocity at toe-off, joint moments during swing phase and double support, and improvements in stiff-knee gait following rectus femoris transfer surgery in subjects with cerebral palsy. Forty subjects who underwent a rectus femoris transfer were categorized as "stiff" or "not-stiff" preoperatively based on kinematic measures of knee motion during walking. Subjects classified as stiff were further categorized as having "good" or "poor" outcomes based on whether their swing-phase knee flexion improved substantially after surgery. We hypothesized that subjects with stiff-knee gait would exhibit abnormal joint moments in swing phase and/or diminished knee flexion velocity at toe-off, and that subjects with diminished knee flexion velocity at toe-off would exhibit abnormal joint moments during double support. We further hypothesized that subjects classified as having a good outcome would exhibit postoperative improvements in these factors. Subjects classified as stiff tended to exhibit abnormally low knee flexion velocities at toe-off (p<0.001) and excessive knee extension moments during double support (p=0.001). Subjects in the good outcome group on average showed substantial improvement in these factors postoperatively. All eight subjects in this group walked with normal knee flexion velocity at toe-off postoperatively and only two walked with excessive knee extension moments in double support. By contrast, all 10 of the poor outcome subjects walked with low knee flexion velocity at toe-off postoperatively and seven walked with excessive knee extension moments in double support. Our analyses suggest that improvements in stiff-knee gait are associated with sufficient increases in knee flexion velocity at toe-off and corresponding decreases in excessive knee extension moments during double support. Therefore, while stiff-knee gait manifests during the swing phase of the gait cycle, it may be caused by abnormal muscle activity during stance.     

Healthy older adults have insufficient hip range of motion and plantar flexor strength to walk like healthy young adults

Limited plantar flexor strength and hip extension range of motion (ROM) in older adults are believed to underlie common age-related differences in gait. However, no studies of age-related differences in gait have quantified the percentage of strength and ROM used during gait. We examined peak hip angles, hip torques and plantar flexor torques, and corresponding estimates of functional capacity utilized (FCU), which we define as the percentage of available strength or joint ROM used, in 10 young and 10 older healthy adults walking under self-selected and controlled (slow and fast) conditions. Older adults walked with about 30% smaller hip extension angle, 28% larger hip flexion angle, 34% more hip extensor torque in the slow condition, and 12% less plantar flexor torque in the fast condition than young adults. Older adults had higher FCU than young adults for hip flexion angle (47% vs. 34%) and hip extensor torque (48% vs. 27%). FCUs for plantar flexor torque (both age groups) and hip extension angle (older adults in all conditions; young adults in self-selected gait) were not significantly <100%, and were higher than for other measures examined. Older adults lacked sufficient hip extension ROM to walk with a hip extension angle as large as that of young adults. Similarly, in the fast gait condition older adults lacked the strength to match the plantar flexor torque produced by young adults. This supports the hypothesis that hip extension ROM and plantar flexor strength are limiting factors in gait and contribute to age-related differences in gait.     

Walking with increased ankle pushoff decreases hip muscle moments

In a simple bipedal walking model, an impulsive push along the trailing limb (similar to ankle plantar flexion) or a torque at the hip can power level walking. This suggests a tradeoff between ankle and hip muscle requirements during human gait. People with anterior hip pain may benefit from walking with increased ankle pushoff if it reduces hip muscle forces. The purpose of our study was to determine if simple instructions to alter ankle pushoff can modify gait dynamics and if resulting changes in ankle pushoff have an effect on hip muscle requirements during gait. We hypothesized that changes in ankle kinetics would be inversely related to hip muscle kinetics. Ten healthy subjects walked on a custom split-belt force-measuring treadmill at 1.25m/s. We recorded ground reaction forces and lower extremity kinematic data to calculate joint angles and internal muscle moments, powers and angular impulses. Subjects walked under three conditions: natural pushoff, decreased pushoff and increased pushoff. For the decreased pushoff condition, subjects were instructed to push less with their feet as they walked. Conversely, for the increased pushoff condition, subjects were instructed to push more with their feet. As predicted, walking with increased ankle pushoff resulted in lower peak hip flexion moment, power and angular impulse as well as lower peak hip extension moment and angular impulse (p<0.05). Our results emphasize the interchange between hip and ankle kinetics in human walking and suggest that increased ankle pushoff during gait may help to compensate for hip muscle weakness or injury and reduce hip joint forces.     

A new parametric approach for modeling hip forces during gait

An analytical parametric model was developed to estimate the natural biological variations in muscle forces and their effect on the hip forces subject only to physiological constraints and not predefined optimization criterion. Force predictions are based on the joint kinematics and kinetics of each subject, a previously published muscle model, and physiological constraints on the muscle force distributions. The model was used to determine the hip contact forces throughout the stance phase of gait of a subject with a total hip replacement (THR). The parametrically modeled peak hip force without antagonistic muscle activity varied from 2.7 to 3.2 Body Weights (mean 2.9 Body Weights), which agreed well with published in vivo measurements from instrumented THRs in other subjects. For every 10% increase in antagonistic activity, the mean peak hip force increased by 0.2 Body Weights. The parametric model allows one to examine the effect of specific muscle weaknesses or increased antagonistic muscle activity on the hip forces. The model also provides a tool for studying the effect of gait adaptations on hip forces, as predictions are based on each individual's gait data. Differences in peak forces between subjects can then be evaluated relative to the uncertainty in not knowing the precise muscle force distributions.