Association of dynamic joint power with functional limitations in older adults with symptomatic knee osteoarthritis

Sex Differences in Ambulatory Biomechanics: A Meta-Analysis Providing a Mechanistic Insight into Knee Osteoarthritis

PURPOSE

Females typically present with a higher prevalence of knee osteoarthritis (KOA), and such a higher prevalence may be due to unique knee biomechanics during walking. However, the sex-dependent ambulatory mechanics has been yet to be clarified. To address this critical knowledge gap, this study implemented a series of computational approaches 1) to identify sex-related knee joint biomechanics during ambulation in persons with KOA and 2) to compare these biomechanical measures between individuals with versus without KOA, stratified by sex.

METHODS

We searched five electronic databases for studies reporting sex-specific knee biomechanics in persons with and/or without KOA. Summary estimates were computed using random-effects meta-analysis and stratified by sex.

RESULTS

The systematic review identified 18 studies (308 males and 383 females with KOA; 740 males and 995 females without KOA). A series of meta-analyses identified female-specific knee biomechanics in a disease-dependent manner. Females with KOA had lower first peak knee adduction moment and peak knee adduction compared with male counterparts. On the other hand, healthy females had lower peak knee flexion moment than male counterparts. Effect estimate in each meta-analysis displayed poor quality of evidence according to the GRADE approach.

CONCLUSIONS

The current study is the first to consider sex as a biological variable into ambulatory mechanics in the development of KOA. We discovered that sex-dependent alterations in knee biomechanics is a function of the presence of KOA, indicating that KOA disease may be a driver of the sex-dependent biomechanical alterations or vice versa. Although no strong conclusion can be drawn because of the low quality of evidence, these findings provide new insight into the sex differences in ambulatory knee biomechanics and progression of KOA.

Knee extensor functional demand in individuals with knee osteoarthritis

BACKGROUND

Knee 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.

Prevalence of Contralateral Hip Abductor Tears and Factors Associated With Symptomatic Progression

BACKGROUND

Patients with gluteus medius tendinopathy present with laterally based hip pain that can be diagnosed under the greater trochanteric pain syndrome diagnosis. Magnetic resonance imaging (MRI) can assist in diagnosing pathology of the symptomatic hip, and when a pelvic MRI that includes both hips, the clinician may identify asymptomatic tears in the nonsurgical hip. In patients who undergo unilateral gluteus medius repairs, little is known about the prevalence or subsequent onset of clinical symptoms in the nonsurgical hip.

PURPOSE

To describe (1) the prevalence of asymptomatic contralateral gluteus medius tears in patients with unilateral symptoms, (2) the presentation and time before symptom onset, and (3) the morphological characteristics on MRI of future symptomatic tears.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

A total of 51 consecutive patients who underwent gluteus medius tear surgery were reviewed for contralateral hip pathology; of these, 43 patients were 2 years out from index surgery with reviewable preoperative MRI scans. A musculoskeletal radiologist reviewed the MRI scans for tear size, tendon retraction, and fatty infiltration using the Goutallier-Fuchs grading system. Medical record review identified contralateral hips requiring subsequent treatment.

RESULTS

Of the original 43 patients, 10 (23%) had no contralateral tear, 19 (44%) had low-grade partial tears, 9 (20%) had high-grade partial tears, and 5 (11%) had full-thickness tears. Thirty-seven patients had unilateral symptoms; the other 6 had mild contralateral hip pain at enrollment. Of the 37 patients with unilateral symptoms, 27 (73%) had a contralateral tear; of those, 10 became symptomatic at an average of 24 months after index presentation (range, 6-50 months). In patients with symptomatic progression, 7 had low-grade partial tears, 1 had a high-grade partial tear, and 2 had full-thickness tears, with an average retraction of 17 mm. Tendon tear grade on MRI did not always correlate with symptoms or future presentation. All symptomatic progression remained mild to moderate. Seven patients required a corticosteroid injection, and none needed contralateral hip surgery within 2 years.

CONCLUSION

Of patients who underwent surgery for a gluteus medius tear, 73% (27/37) had an incidental MRI-confirmed contralateral hip abductor tear. Of these, 37% (10/27) developed symptoms consistent with greater trochanteric pain syndrome during the 2-year study period.

A machine learning-based diagnostic model associated with knee osteoarthritis severity

Knee osteoarthritis (KOA) is characterized by pain and decreased gait function. We aimed to find KOA-related gait features based on patient reported outcome measures (PROMs) and develop regression models using machine learning algorithms to estimate KOA severity. The study included 375 volunteers with variable KOA grades. The severity of KOA was determined using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). WOMAC scores were used to classify disease severity into three groups. A total of 1087 features were extracted from the gait data. An ANOVA and student's t-test were performed and only features that were significant were selected for inclusion in the machine learning algorithm. Three WOMAC subscales (physical function, pain and stiffness) were further divided into three classes. An ANOVA was performed to determine which selected features were significantly related to the subscales. Both linear regression models and a random forest regression was used to estimate patient the WOMAC scores. Forty-three features were selected based on ANOVA and student's t-test results. The following number of features were selected from each joint: 12 from hip, 1 feature from pelvic, 17 features from knee, 9 features from ankle, 1 feature from foot, and 3 features from spatiotemporal parameters. A significance level of < 0.0001 and < 0.00003 was set for the ANOVA and t-test, respectively. The physical function, pain, and stiffness subscales were related to 41, 10, and 16 features, respectively. Linear regression models showed a correlation of 0.723 and the machine learning algorithm showed a correlation of 0.741. The severity of KOA was predicted by gait analysis features, which were incorporated to develop an objective estimation model for KOA severity. The identified features may serve as a tool to guide rehabilitation and progress assessments. In addition, the estimation model presented here suggests an approach for clinical application of gait analysis data for KOA evaluation.

Joint moments and power in the acceleration phase of bend sprinting

Joint kinetics of the lower limb (hip, knee, ankle, midfoot and metatarsophalangeal joints) were investigated during the acceleration phase of bend sprinting and straight-line sprinting. Within the bend sprinting literature, it is generally accepted that sprint performance on the bend is restricted by moments in the non-sagittal plane preventing the production of force in the sagittal plane. However, there is limited evidence in conditions representative of elite athletics performance that supports this hypothesis. Three-dimensional kinematic and ground reaction force data were collected from seven participants during sprinting on the bend (36.5 m radius) and straight, allowing calculation of joint moment, power and energy. No changes in extensor moment were observed at the hip and knee joints. Large effect sizes (g = 1.07) suggest a trend towards an increase in left step peak ankle plantarflexion moment. This could be due to a greater need for stabilisation of the ankle joint as a consequence of non-sagittal plane adaptations of the lower limb. In addition, the observed increase in peak MTP joint plantar-flexor moment might have implications for injury risk of the fifth metatarsal. Energy generation, indicated by positive power, in the sagittal plane at the MTP and ankle joints was moderately lower on the bend than straight, whilst increases in non-sagittal plane energy absorption were observed at the ankle joint. Therefore, energy absorption at the foot and ankle may be a key consideration in improving bend sprinting performance.

Validation of Physical Performance Tests in Individuals with Advanced Knee Osteoarthritis

BACKGROUND

Individuals with advanced osteoarthritis (OA) of the knee experience significant impairments in balance and in essential physical functions such as walking and rising from a chair. There is limited evidence on valid outcome measures to capture these impairments.

QUESTIONS/PURPOSES

We sought to examine the construct validity of three physical performance measures in patients with advanced knee OA: a gait speed (GS) test, the Short Physical Performance Battery (SPPB), and the Timed Up and Go (TUG) test.

METHODS

We designed a cross-sectional clinical measurement study in which patients with advanced knee OA completed two self-reported measures: the Knee Injury and Osteoarthritis Outcome Score-Physical Function Shortform (KOOS-PS) and a four-part numeric pain rating scale (Q-NPRS). They were also administered the GS test, TUG test, and SPPB. Convergent and divergent construct validity were assessed by examining relationships between the GS test, the SPPB, the TUG test, the KOOS-PS, and the Q-NPRS and calculating Pearson correlation coefficients (r). The scores for the GS, TUG test, and SPPB were compared with established normative values for age-matched healthy controls.

RESULTS

Forty-four subjects (mean age, 66.9 ± 8.1 years) participated in the study. The GS test showed low concordance with the SPPB component tests and the TUG test. The relationships between the physical performance measures and the self-reported measures were low. The scores for the GS test, TUG test, and SPPB in our sample were significantly worse when compared with age-matched normative values, indicating impairments in physical performance.

CONCLUSION

These results advance the understanding of the validity of the GS test, TUG test, and SPPB in demonstrating the impairments in physical performance that patients with advanced knee OA experience in walking, balancing, and rising from a chair. Future research should examine the reproducibility and responsiveness of the GS test, TUG test, and SPPB in patients with advanced knee OA, in order to facilitate the integration of these measures into clinical practice.

Hip abductor strength–based exercise therapy in treating women with moderate-to-severe knee osteoarthritis: a randomized controlled trial

Objective:

To investigate whether hip abductor strength–based exercise therapy could result in further function improvement and more pain relief in women with knee osteoarthritis.

Design:

Randomized controlled trial.

Settings:

Rehabilitation department of Affiliated Hospital of Southwest Medical University from years 2016 to 2018.

Subjects:

In total, 82 women aged 50–70 years, with knee osteoarthritis grade II–IV on the Kellgren–Lawrence scale.

Intervention:

The experimental group engaged in hip abductor strength–based exercises under the supervision of physical therapists (once a day for six weeks), while the control group engaged in quadriceps femoris strength–based exercises.

Main measures:

Osteoarthritis severity measured by the Western Ontario and McMaster Universities Osteoarthritis Index, pain on a visual analogue scale and three objective functional tests were assessed at the sixth and 12th week. Repeated measures analysis of variance and multivariable analysis were applied.

Results:

Finally, 72 participants completed the study: 35 in the experimental group and 37 in the control group. The self-reported functional difficulties score in the experimental group was significantly lower than that in the control group both at the sixth week and at the 12th week ( P < 0.001). There were significant differences between groups in the stair ascent/descent task and Figure of 8 Walk test, but not in the Five Times Sit-to-Stand Test. The pain in the experimental group decreased compared with that in the control group at the sixth week ( P < 0.05), but not at the 12th week ( P > 0.05).

Conclusion:

Hip abductor strength–based exercises could result in better performance and higher self-reported function in women with symptomatic knee osteoarthritis.

Use of the Late-Life Function and Disability Instrument for Measuring Physical Functioning in Patients With Heart Failure

BACKGROUND AND PURPOSE

We evaluated the psychometric properties of the functioning component of the Late-Life Function and Disability Instrument (LLFDI) in individuals with heart failure (HF).

METHODS

Factor analyses were used (N = 151) to assess the dimensionality and structure of the basic and advanced lower extremity function subscales. Rasch model scores were compared to the raw means of the items.

RESULTS

Rasch scores correlated with the raw means of the items at r = .96, indicating raw means are comparable to the more complicated Rasch analysis in estimating physical functioning using the basic and advanced subscales.

CONCLUSIONS

The lower extremity physical functioning subscales of the LLFDI have potential as a clinical assessment tool to identify HF patients who are at high risk for functional limitations.

Intensive Gait Training for Older Adults with Symptomatic Knee Osteoarthritis

OBJECTIVE

The objective of this study was to determine whether individualized gait training is more effective than usual care for reducing mobility disability and pain in individuals with symptomatic knee osteoarthritis.

DESIGN

Adults aged 60 yrs or older with symptomatic knee osteoarthritis and mobility limitations were randomized to physical therapist-directed gait training on an instrumented treadmill, with biofeedback individualized to optimize knee movements, biweekly for 3 mos or usual care (control). Mobility disability was defined using Late Life Function and Disability Index Basic Lower Limb Function score (primary); mobility limitations, using timed 400-m walk, chair-stand, and stair-climb tests; and symptoms, using the Knee Injury/Osteoarthritis Outcome Score at baseline, as well as at 3, 6, and 12 mos. The analyses used longitudinal mixed models.

RESULTS

There were no significant intergroup differences between the 35 gait-training (74.3% women; age, 69.7 ± 8.2 yrs) and 21 control (57.1% women; age, 68.9 ± 6.5 yrs) participants at baseline. At 3 mos, the gait-training participants had greater improvement in mobility disability (4.3 ± 1.7; P = 0.0162) and symptoms (8.6 ± 4.1; P = 0.0420). However, there were no intergroup differences detected for pain, 400-m walk, chair-stand, or stair-climb times at 3 mos or for any outcomes at 6 or 12 mos.

CONCLUSIONS

Compared with usual care, individualized gait training resulted in immediate improvements in mobility disability knee symptoms in adults with symptomatic knee osteoarthritis, but these effects were not sustained.

Sex-specific age associations of ankle proprioception test performance in older adults: results from the Baltimore Longitudinal Study of Aging

OBJECTIVES

this study was aimed to test the hypothesis that ankle proprioception assessed by custom-designed proprioception testing equipment changes with ageing in men and women.

METHODS

ankle proprioception was assessed in 289 participants (131 women) of the Baltimore Longitudinal Study of Aging (BLSA); the participants aged 51-95 years and were blinded during testing.

RESULTS

the average minimum perceived ankle rotation was 1.11° (SE = 0.07) in women and 1.00° (SE = 0.06) in men, and it increased with ageing in both sexes (P < 0.001, for both). Ankle tracking performance, which is the ability to closely follow with the left ankle, a rotational movement induced on the right ankle by a torque motor, declines with ageing in both men and women (P = 0.018 and P = 0.011, respectively).

CONCLUSIONS

a simple, standardised method for assessing ankle proprioception was introduced in this study using a customized test instrument, software and test protocol. Age-associated reduction in ankle proprioception was confirmed from two subtests of threshold and tracking separately for women and men. Findings in this study prompt future studies to determine whether these age-associated differences in the threshold for passive motion detection and movement tracking are evident in longitudinal study and how these specific deficits in ankle proprioception are related to age-associated chronic conditions such as knee or hip osteoarthritis and type II diabetes and affect daily activities such as gait.

Biomechanical loads during common rehabilitation exercises in obese individuals

BACKGROUND

Squats and lunges are commonly prescribed rehabilitation exercises used to improve performance across a wide spectrum of patient populations. However, biomechanical studies have mainly examined young, normal weight populations performing these exercises at a difficulty level potentially too challenging for obese individuals. Understanding how obesity and different levels of difficulty affect lower extremity biomechanics could help to inform rehabilitation approaches used for obese individuals.

PURPOSE

The purpose of this study was to analyze and compare the lower extremity kinematics and kinetics in obese and normal weight females during performance of progressively more difficult squat and lunge exercises.

STUDY DESIGN

Cross-sectional study design.

METHODS

Ten obese females (mean age, 37.4 years; BMI 39.2 ± 3.7 kg/m(2)) and ten normal-weight, age-matched female controls (38.1 years, BMI < 23 kg/m(2)) volunteered for the study. Each group performed two exercises, each in three different iterations: squatting at three standardized knee angles (60°, 70°, and 80°) and lunging at three standardized distances (1.0, 1.1, and 1.2 times tibial length). Three dimensional motion analysis using infrared markers and force plates was used to calculate range of motion as well as hip, knee, ankle and support moments (normalized for body weight). A repeated measures ANOVA model was used to determine between and within group differences.

RESULTS

Support moments were higher in obese females for squat 70° (p=0.03) and 80° (p=0.01). Ankle extensor moments were higher in obese females for squat 80° (p=0.04). During lunge at all levels (1.0, 1.1, and 1.2), hip extensor moments were higher in obese subjects (p=0.004, 0.003, and 0.007 respectively). Within group, the support moments were significantly higher during squat 80° than squat 60° (p=0.01) in obese females. A non-linear relationship was found between hip moments and BMI during squat 60°, 70°, and 80°.

CONCLUSION

During two commonly prescribed rehabilitation exercises (squat and lunge), there were significantly greater support moments in obese individuals compared to normal controls. The non-linear associations between kinetic and anthropometric measures make the assessment of how best to approach exercise in obese individuals challenging.

LEVEL OF EVIDENCE

Level 3.

Association of thigh muscle strength with knee symptoms and radiographic disease stage of osteoarthritis: data from the Osteoarthritis Initiative

OBJECTIVE

To determine whether thigh muscle strength differs between symptomatic and asymptomatic knees, and/or different radiographic strata of knee osteoarthritis (KOA).

METHODS

Isometric extensor and flexor strength were analyzed in 3,809 Osteoarthritis Initiative participants (2,201 women and 1,608 men) with central radiographic Kellgren/Lawrence (K/L) grade readings. Isometric strength measurements were stratified by radiographic disease status (K/L grades 0, 1, 2, and 3/4) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain scores. Age-adjusted, separate-slopes analysis of covariance models was used to compare strength between "symptomatic" (WOMAC score range 5-20) and "asymptomatic" (WOMAC score = 0) legs within and across K/L grade strata. Exploratory analyses focused on strength normalized to body weight and symptom frequency.

RESULTS

Isometric strength was significantly lower in symptomatic than in asymptomatic legs: -11 to -13% for extensor strength and -7 to -16% for flexor strength (P < 0.0001 for both) in men, and -9 to -17% (P = 0.029) for extensor strength, and -10 to -21% (P = 0.049) for flexor strength in women. Similar observations were made for pain frequency strata. Extensor and flexor strength were not significantly different across K/L grade strata in asymptomatic legs in either sex (P ≥ 0.12). However, strength normalized to body weight was lower at higher K/L grades in both sexes (P ≤ 0.02) because the body mass index was greater in participants with more advanced radiographic disease.

CONCLUSION

Knee symptoms (i.e., pain) appear to be the relevant determinant of isometric knee extensor and flexor strength in KOA, whereas no direct association between strength and radiographic severity was observed. These findings suggest that the reduction in thigh muscle strength in KOA is related to pain but not to the structural (radiographic) disease status.

The avoidance model in knee and hip osteoarthritis: a systematic review of the evidence

The avoidance model in patients with knee and hip osteoarthritis (OA) hypothesizes that pain and psychological distress lead to avoidance of activities, and thereby to muscle weakness and activity limitations. This paper systematically reviews the scientific evidence for the validity of this avoidance model. A qualitative data synthesis was used to identify levels of evidence. Sixty studies were included. In knee OA, strong evidence was found that avoidance of activities is associated with activity limitations via muscle weakness (mediation by muscle weakness), strong evidence was found for an association between muscle weakness and activity limitations, and weak evidence was found that pain and psychological distress are associated with muscle weakness via avoidance of activities (mediation by avoidance). In hip OA, weak evidence was found for mediation by muscle weakness; and strong evidence was found for an association between muscle weakness and activity limitations. More research is needed on the consecutive associations between pain or psychological distress, avoidance of activities and muscle weakness, and to confirm causal relationships.

Psychometric properties of the Late-Life Function and Disability Instrument: a systematic review

Background

The choice of measure for use as a primary outcome in geriatric research is contingent upon the construct of interest and evidence for its psychometric properties. The Late-Life Function and Disability Instrument (LLFDI) has been widely used to assess functional limitations and disability in studies with older adults. The primary aim of this systematic review was to evaluate the current available evidence for the psychometric properties of the LLFDI.

Methods

Published studies of any design reporting results based on administration of the original version of the LLFDI in community-dwelling older adults were identified after searches of 9 electronic databases. Data related to construct validity (convergent/divergent and known-groups validity), test-retest reliability and sensitivity to change were extracted. Effect sizes were calculated for within-group changes and summarized graphically.

Results

Seventy-one studies including 17,301 older adults met inclusion criteria. Data supporting the convergent/divergent and known-groups validity for both the Function and Disability components were extracted from 30 and 18 studies, respectively. High test-retest reliability was found for the Function component, while results for the Disability component were more variable. Sensitivity to change of the LLFDI was confirmed based on findings from 25 studies. The basic lower extremity subscale and overall summary score of the Function component and limitation dimension of the Disability component were associated with the strongest relative effect sizes.

Conclusions

There is extensive evidence to support the construct validity and sensitivity to change of the LLFDI among various clinical populations of community-dwelling older adults. Further work is needed on predictive validity and values for clinically important change. Findings from this review can be used to guide the selection of the most appropriate LLFDI subscale for use an outcome measure in geriatric research and practice.

Ankle rotation changes and its influences in knee osteoarthritis

BACKGROUND

Biomechanical factors are known to be important in knee osteoarthritis (OA) development and progression. This study was designed to determine changes of hamstrings muscle activation, knee adduction moment and ankle rotation angle in two knee osteoarthritis (mild and moderate) and a healthy control group.

METHODS

16 females (10 with mild and 6 with moderate medial knee osteoarthritis) and 10 control matched females were recruited. A 3D gait analysis was performed on the subjects while they walked along the walkway. Electromyography data was also collected during gait from lateral and medial hamstrings. Post Hoc Tukey HSD (multi comparison) was performed to compare knee adduction moment, ankle rotation angle and medial and lateral hamstrings activity at early and late stance, between three groups.

RESULTS

Ankle rotation angle, knee adduction moment and lateral hamstrings activation showed no significant difference between three groups. Interestingly, medial hamstrings activity was significantly higher at late stance in moderate group compared with asymptomatic and mild groups (p=0.03, 0.02 respectively). Also knee adduction moment at late stance was significantly and directly correlated with ankle rotation angle, and lateral hamstrings activity at early stance was significantly and inversely correlated with this angle.

CONCLUSIONS

It can be concluded that, increased lateral hamstrings activity can increase external ankle rotation and consequently decrease knee adduction moment.

Mechanical contributors to sex differences in idiopathic knee osteoarthritis

The occurrence of knee osteoarthritis (OA) increases with age and is more common in women compared with men, especially after the age of 50 years. Recent work suggests that contact stress in the knee cartilage is a significant predictor of the risk for developing knee OA. Significant gaps in knowledge remain, however, as to how changes in musculoskeletal traits disturb the normal mechanical environment of the knee and contribute to sex differences in the initiation and progression of idiopathic knee OA. To illustrate this knowledge deficit, we summarize what is known about the influence of limb alignment, muscle function, and obesity on sex differences in knee OA. Observational data suggest that limb alignment can predict the development of radiographic signs of knee OA, potentially due to increased stresses and strains within the joint. However, these data do not indicate how limb alignment could contribute to sex differences in either the development or worsening of knee OA. Similarly, the strength of the knee extensor muscles is compromised in women who develop radiographic and symptomatic signs of knee OA, but the extent to which the decline in muscle function precedes the development of the disease is uncertain. Even less is known about how changes in muscle function might contribute to the worsening of knee OA. Conversely, obesity is a stronger predictor of developing knee OA symptoms in women than in men. The influence of obesity on developing knee OA symptoms is not associated with deviation in limb alignment, but BMI predicts the worsening of the symptoms only in individuals with neutral and valgus (knock-kneed) knees. It is more likely, however, that obesity modulates OA through a combination of systemic effects, particularly an increase in inflammatory cytokines, and mechanical factors within the joint. The absence of strong associations of these surrogate measures of the mechanical environment in the knee joint with sex differences in the development and progression of knee OA suggests that a more multifactorial and integrative approach in the study of this disease is needed. We identify gaps in knowledge related to mechanical influences on the sex differences in knee OA.

Power at hip, knee and ankle joints are compromised in women with mild and moderate knee osteoarthritis

BACKGROUND

Analyses of the biomechanical characteristics of gait of women with mild and moderate knee osteoarthritis may identify parameters that could be targeted by physical therapy interventions. Therefore, the purpose of the present study was to compare the joint power profiles during gait between a group of elderly women with mild and moderate levels of knee osteoarthritis and a group of age-matched asymptomatic women.

METHODS

Thirty-nine women diagnosed with osteoarthritis at the medial compartment of the knee and 39 healthy women with no diagnosis of knee osteoarthritis participated in the study. Joint power profiles of the hip, knee and ankle joints in the sagittal plane during gait were performed using video and force data obtained using Qualisys ProReflex System synchronized with two force plates. Principal component analysis was applied to extract features from the joint power waveforms characterizing their main modes of temporal variation. The extracted features were compared between groups.

FINDINGS

Women with knee osteoarthritis absorbed and generated less energy at the hip and ankle joints, and absorbed less energy at the knee when compared to the asymptomatic group.

INTERPRETATION

The observed power pattern in women with knee osteoarthritis may be related to their reduced gait speed, a suboptimal strategy possibly used to reduce reaction forces at the knee. Clinical studies should investigate whether interventions designed to improve muscular resources, as a means to control the flow of forces at the knee, would optimize power patterns and gait performance in women with knee osteoarthritis.

Tolerance of an aquatic power training program by older adults with symptomatic knee osteoarthritis

Objective. To determine the tolerance and feasibility of aquatic-based power training for improving lower limb muscle power, impairments, and mobility in adults with symptomatic knee OA. Participants. Twenty-nine adults, age 50 years and over, with symptomatic knee OA (ACR clinical criteria) and mobility limitation (400-meter walk time slower than median for sex and decade) completed 45-minute aquatic power training sessions twice weekly for 6 weeks. Main Outcome Measurements. Prospective outcomes included tolerance of the program, as well as change in stair climb power, 400-meter walk time, overall and knee-specific pain, activities of daily living (ADL), quality of life (QOL), and lower limb function at 6- and 12-week follow-up. Results. The training intensity required modification for 9 of the 29 participants. Lower limb muscle power, ADL, QOL, and overall pain were improved immediately and 6 weeks following completion (all P < 0.05). However, 400-meter walk times, and lower limb function did not differ from baseline. Conclusions. A 6-week aquatic rehabilitation program appears to be well tolerated by adults with symptomatic knee OA with mobility limitations and may result in improved lower limb muscle power, symptoms, ADL, and QOL. However, this intervention may have insufficient specificity or intensity for improving physical function.

Massive weight loss-induced mechanical plasticity in obese gait

We examined the hypothesis that metabolic surgery-induced massive weight loss causes mass-driven and behavioral adaptations in the kinematics and kinetics of obese gait. Gait analyses were performed at three time points over ∼1 yr in initially morbidly obese (mass: 125.7 kg; body mass index: 43.2 kg/m(2)) but otherwise healthy adults. Ten obese adults lost 27.1% ± 5.1 (34.0 ± 9.4 kg) weight by the first follow-up at 7.0 mo (±0.7) and 6.5 ± 4.2% (8.2 ± 6.0 kg) more by the second follow-up at 12.8 mo (±0.9), with a total weight loss of 33.6 ± 8.1% (42.2 ± 14.1 kg; P = 0.001). Subjects walked at a self-selected and a standard 1.5 m/s speed at the three time points and were also compared with an age- and gender-matched comparison group at the second follow-up. Weight loss increased swing time, stride length, gait speed, hip range of motion, maximal knee flexion, and ankle plantarflexion. Weight loss of 27% led to 3.9% increase in gait speed. An additional 6.5% weight loss led to an additional 7.3% increase in gait speed. Sagittal plane normalized knee torque increased and absolute ankle and frontal plane knee torques decreased after weight loss. We conclude that large weight loss produced mechanical plasticity by modifying ankle and knee torques and gait behavior. There may be a weight loss threshold of 30 kg limiting changes in gait kinematics. Implications for exercise prescription are also discussed.

Abnormal joint powers before and after the onset of claudication symptoms

OBJECTIVE

Claudication is the most common manifestation of peripheral arterial disease, producing significant ambulatory compromise. Our study evaluated patients with bilateral lower limb claudication and characterized their gait abnormality based on advanced biomechanical analysis using joint torques and powers.

METHODS

Twenty patients with bilateral claudication (10 with isolated aortoiliac disease and 10 with combined aortoiliac and femoropopliteal disease) and 16 matched controls ambulated on a walkway while 3-dimensional biomechanical data were collected. Patients walked before and after onset of claudication pain. Joint torques and powers at early, mid, and late stance for the hip, knee, and ankle joints were calculated for claudicating patients before and after the onset of claudication pain and were compared to controls.

RESULTS

Claudicating patients exhibited significantly reduced hip and knee power at early stance (weight-acceptance phase) due to decreased torques produced by the hip and knee extensors. In mid stance (single-limb support phase), patients had significantly reduced knee and hip power due to the decreased torques produced by the knee extensors and the hip flexors. In late stance (propulsion phase), reduced propulsion was noted with significant reduction in ankle plantar flexor torques and power. These differences were present before and after the onset of pain, with certain parameters worsening in association with pain.

CONCLUSIONS

The gait of claudication is characterized by failure of specific and identifiable muscle groups needed to perform normal walking (weight acceptance, single-limb support, and propulsion). Parameters of gait are abnormal with the first steps taken, in the absence of pain, and certain of these parameters worsen after the onset of claudication pain.