Validity of Instrumented 360° Turn Test in Older Adults with Cognitive Impairment

Abstract

Aims: To examine concurrent and construct validity of inertial sensor 360° turn measures in relation with motion capture and mobility assessments in cognitively impaired older adults.

Methods: Data was collected in 31 participants, mean age 85.2 (SD 5.2), during clockwise (CW) and counter clockwise (CCW) 360° turns using (1) APDM body-worn inertial sensors and (2) Qualisys 8-camera laboratory-based motion capture.

Results: Absolute agreement between inertial sensor and motion capture measures was excellent for turn duration and turn peak velocity (ICC = 0.96–0.98). Strong to moderate correlations were present between inertial sensor turn measures and performance on the Timed Up and Go, Short Physical Performance Battery and 90-s Balance Test. ROC curve analysis of CCW 360° turn duration and turn peak velocity distinguished higher risk versus lower risk for mobility disability.

Conclusions: Inertial sensor 360° turn measures demonstrated concurrent and construct validity in relation to motion capture and mobility assessments.     

Progressive resistance training and dynamic alignment in osteoarthritis: A single-blind randomised controlled trial

Background

We hypothesised that high intensity progressive resistance training would improve lower limb dynamic alignment and function (lower knee adduction moment, increased muscle strength, and fewer knee osteoarthritis symptoms).

Methods

Women (n = 54) with osteoarthritis in at least one knee were randomised into a 6-month resistance training or a sham-exercise program. The primary outcomes were dynamic shank and knee adduction angles and knee adduction moment of the most symptomatic knee measured with quantitative gait analysis. Secondary outcomes were muscle strength, gait speed, and osteoarthritis symptoms.

Findings

Dynamic alignment and knee adduction moment did not change over time or between groups. Muscle strength improved in both groups over time, but significantly more in the resistance training group (P = 0.002). By contrast, gait velocity and pain improved over time (P ≤ 0.009) in both groups. Improvements in shank adduction angle were related to improvements in self-reported disability (r = 0.381, P = 0.015), but not to changes in muscle strength, gait velocity, or pain (all P > 0.05).

Interpretations

Although muscle strength improved significantly more in the PRT group, the hypothesised reduction in knee adduction moment, shank and knee adduction angles were not evident after either exercise modality. However, improvements in disability and shank adduction angle were significantly directly related. Initial alignment should be used to stratify this population into separate groups when designing future trials and alternative modes of training investigated to potentially enhance beneficial alterations in knee alignment.     

Muscular co-contraction is related to varus thrust in patients with knee osteoarthritis

BackgroundPatients with knee osteoarthritis often present with varus thrust and muscular co-contraction during gait. It is unclear if these adaptations are related. The objective was to examine the relationship between muscle co-contraction and varus thrust during gait in patients with knee osteoarthritis and to determine if these relationships are modulated by disease severity or history of knee ligament rupture.MethodsParticipants (n = 42, 23 women, mean age 58 years) with knee osteoarthritis completed gait trials at self-selected speeds. Varus thrust was measured with an eight camera motion capture system sampled at 100 Hz. Co-contraction ratios were measured with surface electromyography sampled at 2000 Hz over the quadriceps, hamstrings, and gastrocnemius. Disease severity was measured on radiographs and history of anterior cruciate ligament rupture was confirmed on magnetic resonance imaging. Linear regression analyses examined the relationship between varus thrust and co-contraction ratios after controlling for radiographic disease severity and history of anterior cruciate ligament rupture.FindingsHigher vastus lateralis–lateral hamstring (b = 0.081, P < 0.001; R² = 0.353) and vastus medialis–medial hamstring (b = 0.063, P = 0.028; R² = 0.168) co-contraction ratios were associated with greater varus thrust. Quadriceps-gastrocnemius co-contractions ratios were not related to varus thrust (P > 0.05). Radiographic disease severity or history of anterior cruciate ligament injury did not significantly contribute to regression models.InterpretationGreater quadriceps-hamstring co-contraction is associated with greater varus thrust in patients with knee osteoarthritis. Potential explanations include increased co-contraction may provide stability or there is a proprioceptive reflex that is independent of any stabilizing role. Research is needed to test these hypotheses.     

Changes in gait characteristics of women with early and established medial knee osteoarthritis: Results from a 2-years longitudinal study

BackgroundDespite the large number of cross-sectional studies on gait in subjects with knee osteoarthritis, there are scarcely any longitudinal studies on gait changes in knee osteoarthritis.MethodsGait analysis was performed on 25 women with early and 18 with established medial knee osteoarthritis, as well as a group of 23 healthy controls. Subjects were asked to walk at their comfortable speed. Kinematic and kinetic data were measured at baseline and after 2 years follow-up.FindingsResults indicated that the early osteoarthritis group, similar to established osteoarthritis group, showed significantly higher maximum knee adduction angles compared to the controls during the early stance phase of gait. None of the kinematic or kinetic measures, changed over two years in the early osteoarthritis group. In the established osteoarthritis group, at the time of entry, an increased first and second peak knee adduction moment, as well as higher mid-stance knee adduction moment and knee adduction moment impulse, were present compared to the control and the early osteoarthritis groups. Mid-stance knee adduction moment and knee adduction moment impulse, further increased over two years only in the established osteoarthritis group. For all three groups, the peak knee flexion angle during the stance phase decreased significantly over time.InterpretationIncreased maximum knee adduction angle during stance phase was the only alteration in the gait pattern of subjects with early knee osteoarthritis compared to the controls. This suggests that, unlike in the later stages of the disease, gait is rather stable over two years in early osteoarthritis.     

Sex-specific hip osteoarthritis-associated gait abnormalities: Alterations in dynamic hip abductor function differ in men and women

BackgroundHip osteoarthritis results in abnormal gait mechanics, but it is not known whether abnormalities are the same in men and women. The hypothesis tested was that gait abnormalities are different in men and women with hip osteoarthritis vs. sex-specific asymptomatic groups.Methods150 subjects with mild through severe radiographic hip osteoarthritis and 159 asymptomatic subjects were identified from an Institutional Review Board-approved motion analysis data repository. Sagittal plane hip range of motion and peak external moments about the hip, in all three planes, averaged from normal speed walking trials, were compared for men and women, with and without hip osteoarthritis using analysis of variance.FindingsThere were significant sex by group interactions for the external peak hip adduction and external rotation moments (P = 0.009–0.045). Although asymptomatic women had peak adduction and external rotation moments that were respectively 12% higher and 23% lower than asymptomatic men (P = 0.026–0.037), these variables did not differ between men and women with hip osteoarthritis (P ≥ 0.684). The osteoarthritis vs. asymptomatic group difference in the peak hip adduction moment was 45% larger in women than in men. The osteoarthritis vs. asymptomatic group difference in the peak hip external rotation moment was 55% larger for men than for women (P < 0.001). Sex did not influence the association between radiographic severity and gait variables.InterpretationNormal sex differences in gait were not seen in hip osteoarthritis. Sex-specific adaptations may reflect different aspects of hip abductor function. Men and women with hip osteoarthritis may require different interventions to improve function.     

Effect of real-time biofeedback on peak knee adduction moment in patients with medial knee osteoarthritis: Is direct feedback effective?

BackgroundGait modifications can reduce the knee adduction moment, a representation of knee loading. Reduced loading may help to slow progression of medial knee osteoarthritis. We aimed to investigate the response of patients with medial knee osteoarthritis to direct feedback on the knee adduction moment as a method for modifying the gait pattern, before and after training with specific gait modifications.MethodsForty patients with medial knee osteoarthritis underwent 3D gait analysis on an instrumented-treadmill, while receiving real-time feedback on the peak knee adduction moment. Patients were trained with three different modifications; toe-in, wider steps and medial thrust gait. The response to real-time feedback on the knee adduction moment was measured before and after training. To evaluate the short term retention effect, we measured the changes without feedback. We also evaluated the effects on the knee flexion moment and at the hip and ankle joints.FindingsWith direct feedback on the knee adduction moment, patients were initially unable to reduce the knee adduction moment. After training with specific modifications, peak knee adduction moment was reduced by 14% in response to direct feedback. Without feedback a 9% reduction in peak knee adduction moment was maintained. Hip moments were not increased with modified gait, but small increases in ankle adduction moment and knee flexion moment were observed.InterpretationReal-time biofeedback directly on the knee adduction moment is a promising option for encouraging gait modifications to reduce knee loading, however only when combined with specific instructions on how to modify the gait.     

Relationships between mediolateral trunk-pelvic motion,hip strength,and knee joint moments during gait among persons with lower limb amputation

BackgroundRepeated exposures to larger lateral trunk-pelvic motion and features of knee joint loading likely influence the onset of low back pain and knee osteoarthritis among persons with lower-limb amputation. Decreased hip abductor strength can also influence frontal plane trunk-pelvic motion and knee moments; however, it is unclear how these are inter-related post-amputation.MethodsTwenty-four participants with unilateral lower-limb amputation (14 transtibial; 10 transfemoral) and eight uninjured controls walked at 1.3 m/s while full-body biomechanical data were captured. Multiple linear regression and Cohen's f² predicted (P < 0.05) the influences of mediolateral trunk and pelvic ranges of motion and angular accelerations, and bilateral isometric hip abductor strength on peak (intact) knee adduction moment and loading rate.FindingsThere were no group differences in hip strength, peak knee adduction moment or pelvis acceleration (p > 0.06). The combination of hip strength, and mediolateral trunk and pelvic motion did not predict (F_(5,29) = 2.53, p = 0.06, adjusted R² = 0.27, f² = 0.08) peak knee adduction moment. However, the combination of hip strength and trunk and pelvis acceleration predicted knee adduction moment loading rate (F_(7,29) = 3.59, p = 0.008, adjusted R² = 0.45, f² = 0.25), with peak trunk acceleration (β = 0.72, p = 0.008) and intact hip strength (β = 0.78, p = 0.008) significantly contributing to the model.InterpretationThese data suggest increased hip abductor strength counteracts increased lateral trunk acceleration, concomitantly influencing the rate at which the ground reaction force vector loads the intact knee joint. Persons with lower-limb amputation perhaps compensate for increased intact limb loading by increasing trunk motion, thereby increasing demand on hip abductors to attenuate this preferential loading.     

The role of knee joint moments and knee impairments on self-reported knee pain during gait in patients with knee osteoarthritis

BackgroundThe association between high mechanical knee joint loading during gait with onset and progression of knee osteoarthritis has been extensively studied. However, less attention has been given to risk factors related to increased pain during gait. The purpose of this study was to evaluate knee joint moments and clinical characteristics that may be associated with gait-related knee pain in patients with knee osteoarthritis.MethodsSixty-seven participants with knee osteoarthritis were stratified into three groups of no pain (n = 18), mild pain (n = 27), or moderate/severe pain (n = 22) based on their self-reported symptoms during gait. All participants underwent three-dimensional gait analysis. Quadriceps strength, knee extension range of motion, radiographic knee alignment and self-reported measures of global pain and function were also quantified.FindingsThe moderate/severe pain group demonstrated worse global pain (P < 0.01) and physical function scores (P < 0.01) compared to the no pain and the mild pain groups. The moderate/severe pain group also walked with greater knee flexion moments during the midstance phase of gait compared to the no pain group (P = 0.02). Additionally, the moderate/severe pain group demonstrated greater varus knee malalignment (P = 0.009), which was associated with higher weight acceptance peak knee adduction moments (P = 0.003) and worse global pain (P = 0.003) and physical function scores (P = 0.006).InterpretationGreater knee flexion moment is present during the midstance phase of gait in patients with knee osteoarthritis and moderate/severe pain during gait. Additionally, greater varus malalignment may be a sign of increased global knee joint dysfunction that can influence many activities of daily living beyond gait.     

The use of a lateral wedge insole to reduce knee loading when ascending and descending stairs in medial knee osteoarthritis patients

Background

Stair climbing is a challenging task to the elderly being the task with the first complaint in patients with mild to moderate knee osteoarthritis. Stair climbing results in around six times more compressive load transmitted through the knee joint than walking on level ground. The purpose of this study was to assess whether lateral wedge insoles would reduce medial compartment knee loading when ascending and descending stairs in patients with medial knee osteoarthritis.

Methods

Eight patients with medial knee osteoarthritis were tested in random order with and without a pair of 5° off-the-shelf lateral wedge insoles for two separate activities (stair ascent and stair descent). Kinematic and kinetic data were collected for the lower extremity using a sixteen camera motion capture system and two force plates. Primary outcome measures were the external knee adduction moment and the knee adduction angular impulse.

Findings

During stair ascent and descent, lateral wedge insoles significantly (P < 0.05) reduced the 1st peak external knee adduction moment in early stance (ascent 6.8%, descent 8.4%), the trough in mid stance (ascent 13%, descent 10.7%), 2nd peak in the late stance (ascent 15%, descent 8.3%) and the knee adduction angular impulse compared to the control (standard shoe) with large effect sizes (0.75–0.95).

Interpretation

In this first study on stairs, lateral wedge insoles consistently reduced the overall magnitude of medial compartment loading during stair ascent and descent. Further research is needed to determine the relationship of this with clinical results when ascending and descending stairs with lateral wedge insoles.     

Biomechanical mechanisms of toe-out gait performance in people with and without knee osteoarthritis

Background

Toe-out gait modification (increased toe-out angle) has been proposed to decrease medial knee joint loading and slow disease progression in patients with knee osteoarthritis. However, the manner in which toe-out gait modification is performed is unknown. The purposes of this study were to assess the biomechanical strategies of achieving a toe-out gait, and to compare these strategies between older individuals with knee osteoarthritis and young, healthy individuals.

Methods

Lower limb biomechanics were evaluated for ten patients with knee osteoarthritis and for ten young, healthy individuals during treadmill walking. Two trials, consisting of natural gait followed by a ten degree increase in toe-out angle were performed. Transverse plane rotations of the thigh, shank and foot segments were calculated and compared between walking conditions and groups.

Findings

External rotation changes with toe-out were significantly different between the thigh and shank, and thigh and foot (P < 0.001), but not between the shank and foot (P = 0.48). External rotation at each segment was not significantly different (P > 0.05) between groups, with the exception of thigh rotation during natural gait (P = 0.04).

Interpretation

Current findings suggest that increased toe-out gait is primarily achieved through rotation of the shank and foot, with less contribution from the thigh, and those individuals with knee osteoarthritis perform a toe-out gait biomechanically similar to young, healthy individuals. Gait modification programs should address individuals' limitations, such as joint stiffness, to ensure functional performance of toe-out gait modification.     

Lower limb muscle strengthening does not change frontal plane moments in women with knee osteoarthritis: A randomized controlled trial

Background

Osteoarthritis is a common musculo-skeletal problem accompanied with muscle weakness. Muscle weakness may be readily improved by resistance training. Greater muscle strength has been associated with a lower knee joint loading rate.

Methods

We conducted a single-blind randomized controlled trial of 54 female patients with osteoarthritis in at least one knee, according to the American College of Rheumatology clinical criteria. Patients were randomized into a 6-month high intensity progressive resistance training or a sham-exercise program. The primary outcomes were first peak knee and hip adduction moment measured using three-dimensional gait analysis at self-selected habitual and maximal speeds. Secondary outcomes were sagittal plane knee and hip moments, peak muscle strength, gait speed, and self-reported knee osteoarthritis symptoms measured by the Western Ontario and McMaster Osteoarthritis Index (WOMAC).

Findings

Six months of high intensity resistance training did not change the first peak knee or hip adduction moment at either habitual or maximum walking speeds (P > 0.413) compared to the sham-exercise. However, the second peak hip adduction moment (P = 0.025) and WOMAC pain score (P < 0.001) were reduced significantly in both groups over time, but there was no group effect. The changes in the second peak hip adduction moment were inversely related to the changes in the WOMAC pain score (r = − 0.394, P = 0.009).

Interpretations

Muscle strength training in women with osteoarthritis, while effective for reducing osteoarthritis symptoms, appeared to operate through mechanisms other than improved knee or hip joint loading, as paradoxically, improved symptoms were related to decreases of hip adduction moment in late stance.     

Effects of hip and trunk muscle strengthening on hip function and lower limb kinematics during step-down task

BackgroundStrengthening of the hip and trunk muscles has the potential to change lower limb kinematic patterns, such as excessive hip medial rotation and adduction during weight-bearing tasks. This study aimed to investigate the effect of hip and trunk muscles strengthening on hip muscle performance, hip passive properties, and lower limb kinematics during step-down task in women.MethodsThirty-four young women who demonstrated dynamic knee valgus during step-down were divided into two groups. The experimental group underwent three weekly sessions of strengthening exercises for eight weeks, and the control group continued their usual activities. The following evaluations were carried out: (a) isokinetic maximum concentric and eccentric work of hip lateral rotators, (b) isokinetic hip passive torque of lateral rotation and resting transverse plane position, and (c) three-dimensional kinematics of the lower limb during step-down.FindingsThe strengthening program increased concentric (P < 0.001) and eccentric (P < 0.001) work of hip lateral rotators, and changed hip resting position toward lateral rotation (P < 0.001). The intervention did not significantly change hip passive torque (P = 0.089, main effect). The program reduced hip (P = 0.002), thigh (P = 0.024) and shank (P = 0.005) adduction during step-down task. Hip, thigh and knee kinematics in transverse plane and foot kinematics in frontal plane did not significantly modify after intervention (P ≥ 0.069, main effect).InterpretationHip and trunk strengthening reduced lower limb adduction during step-down. The changes in hip maximum work and resting position may have contributed to the observed kinematic effects.     

Co-activation is not altered in the contra-lateral limb of individuals with moderate knee osteoarthritis compared to healthy controls

BackgroundContra-lateral knee joint function in individuals with moderate knee osteoarthritis is not well understood, despite the functional burden of bilateral osteoarthritis on end stage clinical management. The purpose of this study was to determine whether co-activation and joint biomechanics are altered in the contra-lateral limb compared to age-matched controls.Methods20 Individuals with moderate knee osteoarthritis and 20 asymptomatic individuals walked on an instrumented dual belt treadmill at a self-selected speed. Surface electromyography of the knee joint musculature, including quadriceps, hamstrings and gastrocnemius muscles, normalized to maximum voluntary isometric contractions, as well as sagittal plane motion and sagittal and frontal plane moments were collected. Co-contraction indices were calculated and discrete variables from motion and moment data were extracted. Two-sample t-tests and 2-sample mixed model ANOVAs were performed with alpha <0.05.FindingsContra-lateral knee muscle co-activation differences were not found between groups (p > 0.65). Peak knee adduction moment (0.41 Nm/kg vs. 0.32 Nm/kg) and knee adduction moment impulse (0.14 Nm s/kg vs. 0.10 Nm s/kg) were higher in the contra-lateral limb compared to the asymptomatic group respectively, whereas the sagittal motion (9.8° vs. 14.4°) and moment ranges (0.66 Nm/kg vs. 0.86 Nm/kg) during stance were less dynamic (p < 0.03).InterpretationThe contra-lateral limb was functioning differently biomechanically despite no changes present in muscle co-activation. Findings suggest biomechanical changes are occurring without greater demand on the neuromuscular system to preserve contra-lateral joint function in moderate knee osteoarthritis gait. A greater focus should be made to address biomechanical abnormalities in both knees of individuals with moderate unilateral symptomatic knee osteoarthritis.     

Are there different gait profiles in patients with advanced knee osteoarthritis? A machine learning approach

BackgroundDetermine whether knee kinematics features analyzed using machine-learning algorithms can identify different gait profiles in knee OA patients.Methods3D gait kinematic data were recorded from 42 patients (Kellgren-Lawrence stages III and IV) walking barefoot at individual maximal gait speed (0.98 ± 0.34 m/s). Principal component analysis, self-organizing maps, and k-means were applied to the data to identify the most relevant and discriminative knee kinematic features and to identify gait profiles.FindingsFour different gait profiles were identified and clinically characterized as type 1: gait with the knee in excessive varus and flexion (n = 6, 14%, increased knee adduction and increased maximum and minimum knee flexion, p < 0.01); type 2: gait with knee external rotation, either in varus or valgus (n = 11, 26%, excessive maximum and minimum external rotation, p < 0.001); type 3: gait with a stiff knee (n = 17, 40%, decreased knee flexion range of motion, p < 0.001); and type 4: gait with knee varus ‘thrust’ and decreased rotation (n = 8, 19%, increased and reduced range of motion in the coronal and transverse plane, respectively, p < 0.05).InterpretationIn a group of patients with homogeneous Kellgren-Lawrence classification of knee OA, gait kinematics data permitted to identify four different gait profiles. These gait profiles can be a valuable tool for helping surgical decisions and treatment. To allow generalization, further studies should be carried with a larger and heterogeneous population.     

Gait initiation and lateral wedge insole for individuals with early knee osteoarthritis

BackgroundPeople with knee osteoarthritis are at higher risk of postural deficits and locomotor adaptations which could be manifested in transient tasks like gait initiation. To better understand the effect of early knee osteoarthritis on gait initiation, we measured the gait initiation in two groups of early knee osteoarthritis and healthy age-matched controls and assessed the effect of lateral wedge insole in knee osteoarthritis group.MethodsTwenty-one individuals with early knee osteoarthritis, mean (SD) age = 53.1 (7.4, years), and 19 age- and sex-matched asymptomatic healthy individuals, mean (SD) age = 47.5 (11.2, years), participated. Centre of pressure trajectories were used to quantify the two phases of gait initiation in barefoot condition: anticipatory postural adjustment, and locomotor phase. The immediate and four-week effect of lateral wedge insole and shod condition were also compared for individuals in knee osteoarthritis group.FindingsLonger duration of anticipatory postural adjustment phase (P = 0.046), locomotor phase (P = 0.049), and total duration of gait initiation (P = 0.035) with lower length and velocity of the center of pressure trajectories in anticipatory postural adjustment phase (P = 0.002, and 0.008, respectively) were observed in knee osteoarthritis group compared to controls. Lateral wedge insole could increase the length and velocity of the centre of pressure in locomotor phase compared to barefoot condition (P = 0.001, and 0.002, respectively).InterpretationOur study outlined that people with early knee osteoarthritis adopt different gait initiation strategies mainly in postural preparation phase. The potential effect of lateral wedge insole was shown with better performance of the locomotor phase.Clinical trial registry numberIRCT2016060628310N1.     

Dynamic stability during stair negotiation after total knee arthroplasty

BackgroundThe assessment of dynamic stability is crucial for the prevention of falls in the elderly and people with functional impairments. Evidence that total knee arthroplasty improves balance in patients with severe osteoarthritis is scarce and no information exists about how the surgery affects dynamic stability during stair negotiation.MethodsThis study aims to investigate if patients before and one year after surgery are less stable compared to asymptomatic controls. Seventeen control and twenty-seven patient participants with end-stage knee osteoarthritis that were scheduled to undergo unilateral total knee arthroplasty were recruited in this study. Participants' assessment was carried out by means of marker-based optical full-body motion capture with force platforms. The extrapolated Centre of mass and the margin of stability metrics were used to examine dynamic stability during stair ascent and descent.FindingsPatient participants, during both pre-operative and post-operative assessments, were equally balanced to the asymptomatic controls during stair gait (p > .188). Additionally, the patients' overall stability did not improve significantly one year after arthroplasty surgery (p > .252).InterpretationEven if pain from arthritis and fear of falling is decreased following surgery, our results indicate that stability in stair walking in not affected by osteoarthritis and total knee arthroplasty.Clinical trial registration number: NCT02422251.     

Patients with osteoarthritic knees have shorter orientation and tangent indicatrices during gait

BackgroundThis study introduces two novel outcomes that could be used to identify people with knee osteoarthritis from healthy controls. These outcomes examine the lengths of paths on a sphere derived from knee angle and knee position during gait.MethodsParticipants with moderate knee osteoarthritis (n = 47) and no knee pathology (n = 51) walked overground. The time-varying orientation matrices and position vectors of the knee (leg relative to the thigh) were measured, then arclength (constant speed) parameterized. The orientation matrix column aligned with the long axis of the leg, and the tangent, normal and binormal vectors (Frenet Frame) along the position vectors were calculated. These unit length vectors all scribe paths (indicatrices) on a unit sphere. The path lengths of these indicatrices, for all or part of a gait cycle, were the novel outcomes. A stepwise discriminant analysis defined a linear function that included those outcomes that best allocated a participant to the osteoarthritis or control group.FindingsGroup differences were best detected with the indicatrix lengths associated with the orientation of the leg’s long axis over a gait cycle (P < 0.001) and the tangent vector over the stance phase (P = 0.014). Both outcomes were smaller in the knee osteoarthritis compared to control group. Walking speed was poorly correlated with all indicatrix lengths (ρ < |0.484|) and a discriminate analysis correctly classified 83.7% of the participants.InterpretationSmaller indicatrix measures distinguished those with knee osteoarthritis from healthy controls. These outcomes introduce a promising new kinematic approach when examining gait data.     

The influence of sex and obesity on gait biomechanics in people with severe knee osteoarthritis scheduled for arthroplasty

BackgroundSex and body mass may influence knee biomechanics associated with poor total knee arthroplasty (TKA) outcomes for knee osteoarthritis (OA). This study aimed to determine if gait differed between men and women, and overweight and class I obese patients with severe knee OA awaiting TKA.Methods34 patients with severe knee OA (average age 70.0 (SD 7.2) years, body mass index 30.3 (4.1 kg/m²)) were recruited from a TKA waiting list. Three-dimensional gait analysis was performed at self-selected walking speed. Comparisons were made between men and women, and overweight (body mass index (BMI) 25.0–29.9 kg/m²) and class I obese (BMI 30.0–34.9 kg/m²) participants. Biomechanical outcomes included absolute and body size-adjusted peak knee adduction moment (KAM), KAM impulse, peak knee flexion moment, as well as peak knee flexion and varus-valgus angles, peak varus-valgus thrust, and peak vertical ground reaction force (GRF).FindingsMen had a higher absolute peak KAM, KAM impulse and peak GRF compared to women, and this sex-difference in frontal plane moments remained after adjusting for body size. However, when additionally adjusting for static knee alignment, differences disappeared. Knee biomechanics were similar between obesity groups after adjusting for the greater body weight of those with class I obesity.InterpretationMen had greater KAM and KAM impulse even after adjustment for body size; however adjustment for their more varus knees removed this difference. Obesity group did not influence knee joint kinematics or moments. This suggests sex- and obesity-differences in these variables may not be associated with TKA outcomes.     

What is the influence of severity levels of knee osteoarthritis on gait initiation?

BackgroundThe anticipatory postural adjustments required for gait initiation have not yet been investigated in older adults with different levels of severity of knee osteoarthritis. This study aimed to evaluate the anticipatory postural adjustments adopted by older adults with different severity levels of knee osteoarthritis during gait initiation.MethodsSixty-seven older adults with knee osteoarthritis (mild, moderate, and severe levels) and 11 healthy older adults control were evaluated bilaterally with a force plate to analyze gait initiation. The center of pressure trajectory during gait initiation was divided into four phases: three anticipatory postural adjustments, and a locomotor phase. The length, duration, and velocity of each phase were calculated.FindingsThe results showed that during the right and left limbs swing forward, the severe and moderate knee osteoarthritis groups presented a significant reduction in the length of anticipatory postural adjustment phases, locomotion, duration, and velocity (P < 0.05). The severe knee osteoarthritis group presented a significantly higher body mass index (P < 0.003) than the other groups. However, just the healthy group presented a correlation between body mass index and anticipatory postural adjustments.InterpretationOur results demonstrated that older adults with severe and moderate levels of knee osteoarthritis adopt longer lasting and slower anticipatory postural adjustment phases, lower locomotion, and lower center of pressure displacement during gait initiation, suggesting that this population has adaptive strategy in performing gait initiation, which is significantly changed by the knee osteoarthritis severity level.     

Comparison of peak knee adduction moment and knee adduction moment impulse in distinguishing between severities of knee osteoarthritis

Background

The peak knee adduction moment is a valid proxy for medial knee joint loading. However as it only measures load at one instance of stance, knee adduction moment impulse, a measure that takes into account both the magnitude and duration of the stance phase, may provide more comprehensive information. This study directly compared the abilities of peak knee adduction moment and knee adduction moment impulse to distinguish between knee osteoarthritis severities.

Methods

169 participants with medial knee osteoarthritis completed radiographic and magnetic resonance imaging, the Western Ontario and McMaster Universities Arthritis Index to assess pain and a three-dimensional gait analysis. Participants were classified using four dichotomous classifications: Kellgren–Lawrence grading, alignment, medial tibiofemoral bone marrow lesions, and pain.

Findings

When using Kellgren–Lawrence grade and alignment classifications, the area under the receiver operator curves were significantly greater for knee adduction moment impulse than for peak knee adduction moment. Based on analysis of covariance, knee adduction moment impulse was significantly different between Kellgren–Lawrence grade and alignment groups while peak knee adduction moment was not significantly different. Both peak knee adduction moment and knee adduction moment impulse distinguished between bone marrow lesion severities while neither measure was significantly different between pain severity groups.

Interpretations

Findings suggest knee adduction moment impulse is more sensitive at distinguishing between disease severities and may provide more comprehensive information on medial knee joint loading. Future studies investigating biomechanics of knee osteoarthritis should include knee adduction moment impulse in conjunction with peak knee adduction moment.