The relationship between muscle capacity utilization during gait and pain in people with symptomatic knee osteoarthritis

BackgroundMuscle capacity utilization reflects the percentage of maximal knee extensor strength required to complete physical activities.Research questionIs pain associated with muscle capacity utilization during walking in older adults with knee osteoarthritis? Secondarily, is muscle capacity utilization in older adults with knee osteoarthritis sex-specific?MethodsTwenty-three participants (15 females) with symptomatic knee OA completed this study [age 67 ( ± 8) years, body mass index 29.7 ( ± 3.9) kg/m², gait speed during the Six Minute Walk test 1.25 ( ± 0.25) m/s]. Pain was measured using the Knee injury and Osteoarthritis Outcome Score. Muscle capacity utilization was quantified as the peak external knee flexor moment during level walking normalized to knee extensor maximum voluntary isometric contraction. The knee flexor moment was calculated from kinematic and kinetic data during barefoot level walking at a self-selected speed and at 1.1 m/s. Knee extensor maximum voluntary isometric contraction was measured on a dynamometer. Multiple linear regressions were used to determine the relationship between pain and muscle capacity utilization after adjusting for age, sex, body mass index, and gait speed. Independent sample t-tests examined sex differences.ResultsPain was not associated with muscle capacity utilization during self-selected and standardized walking speeds (p = 0.38 and p = 0.36, respectively). Females did not require a greater muscle capacity utilization than males to complete gait at self-selected and standardized speeds (p = 0.28, and p = 0.40, respectively).SignificanceMuscle capacity utilization was not associated with pain during walking in people with knee osteoarthritis. Future work should explore more challenging activities of daily living in knee OA.     

Effects of functional power training on gait kinematics in children with cerebral palsy

BackgroundMuscle weakness is one of the most prevalent symptoms in children with cerebral palsy (CP). Although recent studies show that functional power training can improve strength and functional capacity in young children with CP, effects on specific gait parameters have not previously been reported.Research questionWhat are the effects of functional power training on gait in children with CP? Specifically, we investigated effects of training on gait kinematics and spatiotemporal parameters, and whether these were dependent on walking speed.MethodsTen children with CP (age 5–10 years, GMFCS I–II) participated in a functional power training program. At the start and end of the program, children underwent 3D gait analysis on a treadmill at a gradual range of walking speeds (70–175% of their comfortable walking speed). Multilevel (linear mixed model) analysis was used to evaluate effects pre-post training at different walking velocities.ResultsAlthough children’s self-chosen comfortable walking speed improved (0.71 ± 0.25 to 0.85 ± 0.25 m/s, p < .05), effects on gait kinematics at similar speed were limited and only exceeded statistical and clinically meaningful thresholds when children walked at higher walking speed. At fast speeds, improvements up to 5° were found in knee and hip extension during stance (p < .01).SignificanceThis study demonstrates that gait kinematics can improve after functional power training, but the magnitude of effects is dependent on walking speed. In this light, improvements are underestimated when evaluating gait at pre-training comfortable walking speed only.     

Knee extensor functional demand in individuals with knee osteoarthritis

BackgroundKnee extensor (KE) weakness is commonly exhibited in individuals with knee osteoarthritis (KOA) and may contribute to disability due an increased muscle functional demand and resulting compensatory gait strategies during locomotion. Muscle functional demand is defined as the percentage of maximal strength that is used during a task.Research question:The study aim was to quantify KE functional demand in KOA, the impact of walking speed and the relationships with the relative joint contribution to total limb work.Methods:Fourteen individuals with symptomatic KOA underwent gait analysis at preferred and faster speeds and isokinetic dynamometry for KE maximum voluntary isometric torque. The KE functional demand as well as the relative and peak joint work and powers were calculated. Paired samples t-test was used to compare functional demand and relative work between speeds and Pearson’s correlation was used to assess the relationship between relative work and functional demand values (α = 0.05).Results:The KE functional demand was 36.0 ± 15.7 % for the preferred speed and significantly higher at 49.8 ± 16.1 % for the faster speed, (t(13) = −5.45, p .05). Knee flexion moment was also significantly higher for the faster speed (t(13) = −5.54, p .001). There were significant relationships between fast speed functional demand and relative ankle negative power (r = −0.57) and relative ankle positive work (r = 0.66), (all p .05).Significance:The results suggest that as functional demand nears or exceeds 50 % of the muscle capacity individuals with KOA reduce the relative effort at the knee and use an ankle-based compensation strategy to meet task demands.     

Hip extension power and abduction power asymmetry as independent predictors of walking speed in individuals with unilateral lower-limb amputation

BackgroundPreferred walking speed (PWS) is an indicator of walking ability, prosthetic walking potential, and function following a lower-limb amputation (LLA). There is a link between lower-limb muscle performance and PWS in individuals with LLA. However, the ability of select hip muscle performance parameters to determine PWS in these individuals still needs to be thoroughly investigated.Research questionWhich hip muscle and joint torque parameters best determine PWS in persons with LLA?MethodsSeventeen patients with LLA (6 transfemoral, 4 knee disarticulation, and 7 transtibial; 16 men, 1 woman; mean age ± standard deviation, 56 ± 15yr) participated in this cross-sectional study. Maximal joint torque and power were evaluated unilaterally, for both amputated and intact limbs, in isometric and isokinetic conditions during hip flexion/extension (60°/s and 180°/s) and abduction/adduction (30°/s and 90°/s). PWS was measured at habitual walking speed over a 10-m distance. Pearson's correlation coefficient was used to verify the degree of association between each torque parameter and PWS and multiple regression analysis was performed to identify the best predictors of PWS. The level of significance was p < 0.05.ResultsCorrelations between hip muscle performance parameters and PWS were found in most cases (r = 0.51–0.82; p ≤ 0.036–0.0005). The multiple regression model revealed that the best independent predictors of PWS were hip extension power at 180°/s on the amputated side (r² = 0.672; p < 0.0005) and the asymmetry of hip abduction power at 30°/s (r² = -0.147; p < 0.008), accounting together for 82% of the variance in PWS.SignificanceLesser hip extension power on the amputated side and greater hip abduction power asymmetry between limbs are detrimental to PWS in persons with LLA. These muscle groups and performance parameters should be considered during gait rehabilitation to assist individuals with LLA in achieving functional waking speed.     

Kinematic changes in patients with severe knee osteoarthritis are a result of reduced walking speed rather than disease severity

BackgroundKinematic changes in patients with knee osteoarthritis (OA) have been extensively studied. Concerns have been raised whether the measured spatiotemporal and kinematic alterations are associated with disease progression or merely a result of reduced walking speed.Research question: The purpose of this study was to investigate the effect of walking speed on kinematic parameters in patients with knee OA using statistical parametric mapping (SPM).MethodsTwenty-three patients with unilateral knee OA scheduled for a total knee replacement and 28 age matched control subjects were included in this study. Spatiotemporal parameters and sagittal plane kinematics were measured in the hip, knee, and ankle using the inertial sensors system RehaGait® while walking at a self-selected normal (patients and controls) and slow walking speed (controls) for a distance of 20 m. Gait parameters were compared between groups for self-selected walking speed and for matched walking speed using SPM with independent sample t tests.ResultsAt self-selected walking speed, patients had significantly lower knee flexion during stance (maximum difference, -6.8°) and during swing (-11.0°), as well as higher ankle dorsiflexion during stance phase (+12.5°) and lower peak hip extension at the end of stance compared to controls (+4.2°). At matched speed, there were no significant differences in joint kinematics between groups.SignificanceDifferences in sagittal plane gait kinematics between patients with knee OA and asymptomatic controls appear to be mainly a result of reduced walking speed. These results emphasize the importance of considering walking speed in research on gait kinematics in patients with knee OA and in clinical trials using gait parameters as outcome measures.     

The effect of walking speed on hamstrings length and lengthening velocity in children with spastic cerebral palsy

Children with cerebral palsy often walk with reduced knee extension in terminal swing, which can be associated with short length or slow lengthening velocity of hamstrings muscles during gait. This study investigated the role of two factors that may contribute to such short and slow hamstrings: walking speed and spasticity. 17 children with spastic cerebral palsy and 11 matched typically developing children walked at comfortable, slow, and fast walking speed. Semitendinosus muscle-tendon length and velocity during gait were calculated using musculoskeletal modeling. Spasticity of the hamstrings was tested in physical examination. Peak hamstrings length increased only slightly with walking speed, while peak hamstrings lengthening velocity increased strongly. After controlling for these effects of walking speed, spastic hamstrings acted at considerably shorter length and slower velocity during gait than normal, while non-spastic hamstrings did not (all P < 0.001). These data are important as a reference for valid interpretation of hamstrings length and velocity data in gait analyses at different walking speeds. The results indicate that the presence of spasticity is associated with reduced hamstrings length and lengthening velocity during gait, even at constant walking speed.     

Muscle fatigue during a short walking exercise in children with cerebral palsy who walk in a crouch gait

BackgroundA deterioration of crouch gait was found in a group of children with cerebral palsy (CP) after a short walking exercise. The increased knee flexion reported after a continuous walk could be related with muscle fatigue and muscle strength.AimDoes muscle fatigue appears at the end of a walking exercise in children with CP who walk in a crouch gait?MethodsEleven children with cerebral palsy (GMFCS I to III) who walk in a crouch gait were included. Isometric muscle strength was assessed using a handheld dynamometer. Children were asked to walk for 6 min at comfortable speed. Spatio-temporal, kinematic and electromyographic (EMG) measurements were recorded at the first and the last minute of the 6-minute walking exercise. Muscle fatigue was evaluated using the shift of EMG signals median frequency.ResultsThere was no significant difference in walking speed, cadence, and step length at the end of the 6mwe. Maximal and mean anterior pelvic tilt decreased and knee flexion increased (p < 0.05). Rectus femoris EMG median frequency decreased (p < 0.05). The median frequency in other muscles did not decrease significantly. Greater hip extensor strength was associated with lesser knee flexion at the end of the 6-minute walking exercise (p < 0.05).SignificanceThe increase in knee flexion at the end of the 6-minute walking exercise can be explained by muscle fatigue found in rectus femoris. Hip extensor strength can limit the deterioration of crouch gait after a 6-minute walking exercise representative of daily activities.     

Side to side kinematic gait differences within patients and spatiotemporal and kinematic gait differences between patients with severe knee osteoarthritis and controls measured with inertial sensors

BackgroundKinematic changes associated with knee osteoarthritis (OA) have been traditionally measured with camera-based gait analysis. Lately, inertial sensors have become popular for gait analysis with the advantage of being less time consuming and not requiring a dedicated laboratory.Research questionDo spatiotemporal and discrete kinematic gait parameters measured with the inertial sensor system RehaGait® differ between the affected and unaffected side in patients with unilateral knee OA and between patients with severe knee OA and asymptomatic control subjects? Do these differences have a similar magnitude as those reported in the literature?MethodsTwenty-two patients with unilateral knee OA scheduled for total knee replacement and 46 age matched control subjects were included in this study. Spatiotemporal parameters and sagittal kinematics at the hip, knee, and ankle joint were measured using the RehaGait® system while walking at a self-selected speed for a distance of 20 m and compared between groups.ResultsPatients with knee OA had slower walking speed, longer stride duration, shorter stride length and lower cadence (P < 0.001). Peak knee flexion during stance and swing was lower in the affected than the unaffected leg (-4.8° and -6.1°; P < 0.01). Peak knee flexion during stance and swing (-5.2° and -8.8°; P < 0.01) and knee range of motion during loading response and swing (-3.6° and -4.4°; P < 0.01) were lower than in the control group.SignificanceThese side to side differences within patients and differences between patients with knee OA and control subjects agree with known gait alterations measured with camera-based systems. The RehaGait® inertial sensor system can detect gait alterations in patients with knee OA and is suitable for gait analysis in a clinical environment.     

Asymptomatic radiographic hip osteoarthritis is associated with gait differences,especially in women: A population-based study

BackgroundHip and knee osteoarthritis (OA) are debilitating diseases that impair gait at severe stages. Although associations between OA and gait are established for normal walking, little is known about its relation with turning and tandem (heel-to-toe) walking. Furthermore, it is unknown how asymptomatic OA associates with gait, and whether associations differ by sex. We investigated how symptomatic and asymptomatic hip and knee OA associate with gait in community-dwelling individuals.MethodsIn 2706 participants of a population-based cohort study, gait was assessed by electronic walkway and summarised into seven gait domains. Hip and knee radiographs were graded for radiographic OA (ROA) using the Kellgren and Lawrence (K&L) score. Linear regression was used to investigate associations between ROA and gait. Analyses were repeated including only participants with asymptomatic ROA, defined as a K&L-score of 2 without pain.ResultsIn total, 177 participants (6.5%) had hip ROA and 441 (16.3%) knee ROA. We found no associations of knee ROA with gait. Hip ROA associated with Rhythm, Tandem, and Turning. Furthermore, unilateral hip ROA associated with larger gait asymmetry and gait differences in osteoarthritic and non-osteoarthritic leg, when compared to people without hip ROA. Associations between hip ROA and gait were generally stronger for women than men. Associations for hip ROA remained after restricting to asymptomatic ROA.ConclusionHip ROA, but not knee ROA, associates with gait differences in normal walking, turning, and tandem walking in community-dwelling individuals. These associations differ between the sexes, and are already present for asymptomatic ROA.     

Gait outcomes following proximal tibial tumor resection and endoprosthetic reconstruction

BackgroundDespite the proximal tibia being a common site of primary malignant bone tumors, there is limited information about gait function following proximal tibial tumor resection and endoprosthetic reconstruction (PTR).Research questionWhat is the impact of PTR on gait and quality of life?MethodsThis was a cross-sectional study of patients ≥18 years old who were ≥2 years post-PTR compared to a control group of similar age and sex distribution. Eighteen participants (9 PTR, 9 Control) were recruited. Gait spatial-temporal data, joint kinematics and kinetics were collected at preferred and fast walking speeds. Community walking cadence, health-related quality of life (SF-36) and knee joint torque were assessed. Comparisons were performed using one-way ANOVAs with Bonferroni corrections for multiple comparisons. Nonparametric tests were used for data not normally distributed.ResultsMean age was 31 years for each group (PTR range = 18–42 yrs, Control range = 18–44 yrs). Compared to both control and nonsurgical limbs, the surgical limb exhibited significantly decreased % single limb support time, reduced heel rise during terminal stance and an absence of normally occurring knee flexion angles, extensor moments and power generation during initial double limb support. Additionally, a reduced peak plantar flexor moment was found for the surgical as compared to the control limb. The number of gait abnormalities increased during fast walking. Significantly reduced surgical knee extensor torque on isokinetic testing and weakness of the knee and ankle on clinical examination support gait findings. During community walking, the number of low frequency strides was an average of 5.3 % greater for the PTR group (p < 0.05). Norm-based PTR group SF-36 component scores were within normal values (53.4 physical, 56.5 mental).SignificanceGait abnormalities were consistent with ankle muscle resection and transposition and knee extensor mechanism disruption. Despite these deficits, walking speed and quality of life were relatively normal.     

Dynamic knee joint stiffness and contralateral knee joint loading during prolonged walking in patients with unilateral knee osteoarthritis

BackgroundLong duration walking, a commonly recommended treatment option for knee osteoarthritis (OA), may lead to increased knee joint loading.Research questionTo evaluate the effects of prolonged walking on dynamic knee joint stiffness and contralateral knee joint contact forces (KCFs) in individuals with unilateral symptomatic knee OA.MethodsTwenty-six older adults with knee OA completed a 45-minute bout of walking on a treadmill. Dynamic knee joint stiffness, estimated KCFs, measured ground reaction forces (GRFs), and simulated muscle forces were evaluated for both the symptomatic and asymptomatic limbs at 15-minute intervals using repeated measures, analysis of variance (ANOVA).ResultsDynamic knee joint stiffness during the early weight-acceptance phase of gait was significantly higher for the symptomatic limb throughout the 45-minute bout of walking. A significant increase in peak KCFs and simulated muscle forces were also observed during the weight-acceptance phase of gait for both limbs after 30 and 45 min of walking. Additionally, significantly elevated peak KCFs and muscle forces were observed during the late-stance phase of gait for the contralateral asymptomatic limb throughout the 45-minute bout of walking.SignificanceWalking durations of 30 min or greater lead to increased knee joint loading. Additionally, the elevated dynamic knee joint stiffness observed for the symptomatic knee during the weight acceptance phase of gait appears to be unrelated to the knee joint loading profile. Finally, the greater KCFs during the late-stance phase of gait observed for the asymptomatic limb are consistent with previously demonstrated risk factors for OA development and progression.     

Gait features for discriminating between mobility-limiting musculoskeletal disorders: Lumbar spinal stenosis and knee osteoarthritis

BackgroundFunctional ambulation limitations are features of lumbar spinal stenosis (LSS) and knee osteoarthritis (OA). With numerous validated walking assessment protocols and a vast number of spatiotemporal gait parameters available from sensor-based assessment, there is a critical need for selection of appropriate test protocols and variables for research and clinical applications.Research questionIn patients with knee OA and LSS, what are the best sensor-derived gait parameters and the most suitable clinical walking test to discriminate between these patient populations and controls?MethodsWe collected foot-mounted inertial measurement unit (IMU) data during three walking tests (fast-paced walk test-FPWT, 6-min walk test– 6MWT, self-paced walk test – SPWT) for subjects with LSS, knee OA and matched controls (N = 10 for each group). Spatiotemporal gait characteristics were extracted and pairwise compared (Omega partial squared – ω_p²) between patients and controls.ResultsWe found that normal paced walking tests (6MWT, SPWT) are better suited for distinguishing gait characteristics between patients and controls. Among the sensor-based gait parameters, stance and double support phase timing were identified as the best gait characteristics for the OA population discrimination, whereas foot flat ratio, gait speed, stride length and cadence were identified as the best gait characteristics for the LSS population discrimination.SignificanceThese findings provide guidance on the selection of sensor-derived gait parameters and clinical walking tests to detect alterations in mobility for people with LSS and knee OA.     

Effect of muscle compensation on knee instability during ACL-deficient gait

PURPOSE: The purpose of this investigation was to determine whether an isolated change in either quadriceps or hamstrings muscle force (quadriceps avoidance and hamstrings facilitation, respectively) is sufficient to stabilize the ACL-deficient (ACLd) knee during gait. METHODS: A three-dimensional model of the lower limb was used to calculate anterior tibial translation in the intact and ACLd knee during gait. The model was then used to predict the amount of quadriceps and hamstrings force needed to restore anterior tibial translation (ATT) in the ACLd knee to an intact or maximum allowable level. RESULTS: It was possible to reduce ATT in the ACLd knee to the level calculated for the intact knee by increasing the magnitude of hamstrings force (a hamstrings facilitation pattern). Although this strategy decreased the knee extensor moment calculated for walking, the effect was much less than that obtained when quadriceps force was reduced. Reducing quadriceps force to restore normal ATT resulted in complete elimination of the knee extensor moment (a quadriceps avoidance pattern); however, this strategy was insufficient to restore ATT to the level calculated for the intact knee over portions of the gait cycle. CONCLUSION: The model simulations showed that increased hamstrings force was sufficient to stabilize the ACLd knee during gait. Reduced quadriceps force was insufficient to restore normal ATT for portions of the gait cycle.     

Asymmetry of the knee extension deficit in standing affects weight-bearing distribution in patients with bilateral end-stage knee osteoarthritis

Purpose

The aim of this study was to evaluate weight-bearing distribution in patients with bilateral end-stage knee osteoarthritis (OA) and to clarify the gait parameters affecting the weight-bearing distribution during both standing and walking using gait analysis.

Methods

Twenty-five patients (averaged 71 years) with symptomatic bilateral end-stage medial knee OA participated in this study. They performed relaxed standing, placing one foot on a force plate and thereafter, level walking. First, knee resultant force was calculated on bilateral knees during standing. The knees in each patient were divided into Higher and Lower force side for the definition of dominant side limb. Second, gait parameters in each subject were compared between both sides.

Results

Each patient had large weight-bearing asymmetry, though passive range of motion, subjective pain level, femorotibial angle and radiographic disease severities were not significantly different between both sides. In standing, knees on Higher force side were significantly extended (11.2 ± 6.5°) than on Lower force side (14.4 ± 7.3°, P = 0.0086). Similarly, knees on Higher force side were also significantly extended at heel strike during gait. Besides, peak values of extension moment, knee adduction moment, knee adduction moment impulse and vertical force during gait were significantly greater on Higher force side.

Conclusions

Ability to extend the knee in standing was considered to be an essential factor to decide loading condition. It is clinically important to examine the ability to extend the knee in standing when considering loading asymmetry during gait in patients with bilateral knee OA.

Level of evidence

III.     

Performance-based physical function correlates with walking speed and distance at 3 months post unilateral total knee arthroplasty

BackgroundAfter total knee arthroplasty (TKA), walking speed and distance are main concerns of patients.Research questionWhich physical functions affect walking speed and distance after TKA?MethodsCross-sectional data from 149 patients who underwent unilateral primary TKA and completed performance-based physical function tests. Instrumental gait evaluation for spatiotemporal parameters, isometric knee extensor and flexor strength of both knees, 6-minute walk test (6MWT), timed up-and-go (TUG) test, timed stair climbing test (SCT), and knee flexion and extension range of motion (ROM) of surgical knee were examined. Western Ontario McMaster Universities Osteoarthritis Index (WOMAC) and EuroQol five dimensions (EQ-5D) questionnaires were also performed.ResultsUnivariate analyses revealed that post-operative walking speed showed significant positive correlations with cadence, stride length, propulsion index of surgical and non-surgical knee, peak torque (PT) of the extensor of surgical and non-surgical knee and flexor of surgical and non-surgical knee, 6MWT, EQ-5D, and significant negative correlations with gait cycle duration, TUG, SCT-ascent and descent, and WOMAC-pain scores. Post-operative walking distance had significant positive correlations with walking speed, cadence, stride length, swing phase duration, propulsion index of surgical and non-surgical knee, PT of the extensor of surgical and non-surgical knee, EQ-5D, and significant negative correlation with gait cycle duration, double support duration, TUG, SCT-ascent and descent. In the multivariate linear regression analyses, TUG, cadence, stride length and propulsion index of non-surgical knee were factor correlated with post-operative walking speed. The SCT-ascent and descent, TUG and propulsion index of surgical knee were factor correlated with post-operative walking distance.SignificancePhysical performance factors correlated with walking speed and distance at 3 months after surgery. Based on these observations, rehabilitation of bilateral muscle strength and functional mobility would be important for functional recovery after unilateral TKA.     

Changes in lower limb biomechanics when following floor-projected foot placement visual cues for gait rehabilitation

BackgroundLately, the projection of foot placement visual cues onto the floor has been considered for use in gait rehabilitation. While promising, this approach needs further basic assessment to ensure proper uses.Research questionDoes following floor-projected foot placement visual cues of one’s natural walking pattern induce gait mechanics changes immediately or after a practice period?MethodsGait mechanics data from fifteen healthy individuals (7 female, 25.4 ± 5.0 years, 21.5 ± 1.68 kg/m²) was collected during normal walking without visual cues, and during two testing phases (immediate and after 45−60 min of practice) of walking with floor-projected visual cues depicting their normal spatial parameters. Magnitudes and variabilities of spatial gait parameters and sagittal plane lower limb kinematics and kinetics were compared between the three testing phases using repeated measures ANOVA and post-hoc paired t-tests.ResultsCompared to normal walking without foot placement visual cues, there was a statistically significant (p < 0.05) increase in stride length (maximum change of 0.01 ± 0.01 m), stance phase knee flexion (2.0 ± 2.5°), and swing phase hip flexion (1.2 ± 1.3°) in both immediate and post-practice testing phases, along with an increase in terminal stance hip (0.28 ± 0.38 %BW*Ht) and knee (0.25 ± 0.25 %BW*Ht) flexion moments in the immediate testing phase. All of these changes between testing phases were smaller than their corresponding normal gait smallest real differences (SRD). With the addition of visual cues, variability was statistically significantly decreased in spatial parameters and increased in knee flexion angle at heel strike and knee flexion moment in terminal stance.SignificanceWhile biomechanical changes were observed, their magnitudes were small enough to suggest that floor-projected visual cues can be used in gait retraining without introducing unintended gait changes. Furthermore, the results suggested that lengthy practice periods are not necessary. The validity of these observations will, however, need to be confirmed in cases of severe impairments.     

Sex- and osteoarthritis-related differences in muscle co-activation during weight-bearing tasks

BackgroundIndividuals with knee osteoarthritis (OA) demonstrate impairments in muscle function (i.e. muscle weakness, high muscle co-activation believed to have detrimental effects on joint integrity). Women with knee OA exhibit poorer health outcomes than men. Sex and muscle function are known risk factors for knee OA. It is unclear how these risk factors are associated with muscle function in knee OA and the implications for disease aetiology.Research questionHow does sex and knee osteoarthritis disease status relate to muscle function, specifically strength and muscle co-activation, during walking, stair negotiation and sit-to-walk activities.MethodsA cross-sectional study assessed muscle co-activation in 77 individuals with knee OA (mean[SD], 62.5[8.1] years; 48/29 women/men) and 18 age-matched controls (62.5[10.4] years; 9/9 women/men), during a series of walking, stair ascent and descent and sit-to-walk activities. Muscle strength of the knee extensors and flexors was assessed using maximal voluntary isometric contractions (MVIC). Electromyography was recorded from the vastus lateralis/medalis, rectus femoris, biceps femoris, semitendinosus, medial/lateral gastrocnemius normalised to MVIC. Multiple regression assessed the relationship between sex, disease status, and muscle strength on muscle co-activation.ResultsIndividuals with knee OA were weaker than controls, had higher hamstrings-quadriceps and medial-lateral co-activation for specific phases of gait. Women were weaker than men with higher muscle co-activation across all activities. Sex and muscle weakness, but not age or disease status predicted high muscle co-activation.SignificanceHigh muscle co-activation was associated with female sex and muscle weakness regardless of disease status and age. High muscle co-activation is believed to be a compensatory mechanism for muscle weakness to maintain a certain level of function. High muscle co-activation is also thought to have detrimental effects on cartilage and joint integrity this may explain high muscle co-activation in women with muscle weakness and contribute to increased risk of incidence and progression of knee OA in women.     

Correlation between lower limb isometric strength and muscle structure with normal and challenged gait performance in older adults

BackgroundMuscular parameters have been considered to influence gait of older adults, but it is still unclear which specific lower limb muscular parameters correlate with kinematics of overground and obstacle crossing in older adults.Research questionWhat lower limb muscular parameters correlate and explain kinematics of overground walking and obstacle crossing ability in the elderly?MethodsMuscle structure was evaluated in 15 older individuals (75.4 ± 5 years) through measures of architecture (muscle thickness, fascicle length, and pennation angle) and muscle quality (echo intensity) from lower limb muscles (vastus lateralis, biceps femoris, rectus femoris, tibialis anterior, and gastrocnemius medialis). Muscle function was assessed through isometric strength of hip, knee and ankle joint muscles. Gait kinematics (toe and heel clearances, step length and gait speed) was evaluated during walking with and without obstacle crossing at preferred and maximal gait speeds. Correlation and regression analyses were performed considering a significance level of 0.05.ResultsIsometric strength did not correlate with gait kinematics and gait speed. Tibialis anterior thickness correlated with lead limb toe clearance, and vastus lateralis thickness with gait speed and step length. Vastus lateralis echo intensity correlated with step length and gait speed.SignificanceTibialis anterior and vastus lateralis muscles deserve attention in physical training to improve gait of older adults. Specifically, tibialis anterior should receive more attention on exercise programs aiming at improvement of obstacle crossing, and knee extensors when aiming at improving gait speed and step length.     

Gait kinematic alterations in subjects with adult spinal deformity and their radiological determinants

BackgroundAdults with spinal deformity (ASD) are known to have postural malalignment affecting their quality of life. Classical evaluation and follow-up are usually based on full-body static radiographs and health related quality of life questionnaires. Despite being an essential daily life activity, formal gait assessment lacks in clinical practice.Research QuestionWhat are the main alterations in gait kinematics of ASD and their radiological determinants?Methods52 ASD and 63 control subjects underwent full-body 3D gait analysis with calculation of joint kinematics and full-body biplanar X-rays with calculation of 3D postural parameters. Kinematics and postural parameters were compared between groups. Determinants of gait alterations among postural radiographic parameters were explored.ResultsASD had increased sagittal vertical axis (SVA:34 ± 59 vs −5 ± 20 mm), pelvic tilt (PT:19 ± 13 vs 11 ± 6°) and frontal Cobb (25 ± 21 vs 4 ± 6°) compared to controls (all p < 0.001). ASD displayed decrease walking speed (0.9 ± 0.3 vs 1.2 ± 0.2 m/s), step length (0.58 ± 0.11 vs 0.64 ± 0.07 m) and increased single support (0.45 ± 0.05 vs 0.42 ± 0.04 s). ASD walked with decreased hip extension in stance (−3 ± 10 vs −7 ± 8°), increased knee flexion at initial contact and in stance (10 ± 11 vs 5 ± 10° and 19 ± 7 vs 16 ± 8° respectively), and decreased knee flexion/extension ROM (55 ± 9 vs 59 ± 7°). ASD had increased trunk flexion (12 ± 12 vs 6 ± 11°) and reduced dynamic lumbar lordosis (−11 ± 12 vs −15 ± 7°, all p < 0.001). Sagittal knee ROM, walking speed and step length were negatively determined by SVA; lack of lumbar lordosis during gait was negatively determined by radiological lumbar lordosis.SignificanceStatic compensations in ASD persist during gait, where they exhibit a flexed attitude at the trunk, hips and knees, reduced hip and knee mobility and loss of dynamic lordosis. ASD walked at a slower pace with increased single and double support times that might contribute to their gait stability. These dynamic discrepancies were strongly related to static sagittal malalignment.     

The 6DOF knee kinematics of healthy subjects during sloped walking compared to level walking

BackgroundLevel Walking is a frequent functional movement during daily life. However, sloped walking is also common. Exploring 6DOF knee kinematics during sloped walking is important. It provides a reference for the rehabilitation, safety, and knee health of patients with knee diseases walking on sloped surfaces.Research questionThe study aimed to explore 6DOF knee kinematics characteristics during sloped walking compared to level walking. We hypothesized that tibial anteroposterior translation and flexion angle (the sagittal plane) were significantly different from those of level walking.MethodsOne hundred young, healthy adults (50 males and 50 females) were recruited for this study. A three-dimensional gait analysis system was used to collect 6DOF knee kinematics during level and sloped walking. The slope was set to ± 15% when the sloped walking was performed.ResultsSloped walking mainly increased knee flexion angle (upslope, 2.5–26.2°, 1–100% gait cycle (GC), p < 0.05; downslope, 1.7–11.9°, 15–95% GC, p < 0.05) and anterior tibial translation (upslope, 0.7–4.1 mm, 3–54% GC & 0.6–2.1 mm, 80–94% GC; downslope, 1.0–2.2 mm, 21–69% GC) in the participants’ knees. However, participants' other 4DOF knee kinematics during sloped walking were significantly different from those during level walking (p < 0.05). Participants had ‘drastically changeable’ knee kinematic alterations in the transverse and coronal plane (the other 4DOF knee kinematics) during sloped walking compared to level walking.SignificanceOur results confirmed the hypothesis. Sloped walking significantly increased anterior tibial translation (in most GC) and flexion angle. These kinematic changes in healthy subjects should be evaluated and further explored for patients with knee diseases, such as anterior cruciate ligament deficiency. Our findings are meaningful for their rehabilitation or safety or knee health while walking on sloped surfaces. Our study may provide a pilot reference for the 6DOF knee kinematic exploration of sloped walking.