Influence of using knee sleeve and lateral wedge insole on knee loading among healthy individuals during stair negotiation

BackgroundFor individuals with knee osteoarthritis (OA), stair negotiation is a challenging task and the first task during which they report pain due to the high knee loading required. The use of lateral wedge insole (LWI) has been found to reduce loading in patients with OA but not to reduce pain, whereas the use of knee sleeve has been shown to result in good pain reduction. Understanding the effect of combining LWI and knee sleeve use on healthy individuals before testing on individuals with knee OA is an important step.Research questionThe current study aimed to evaluate the effect of combining the use of LWI and knee sleeve and compare the results with the application of each treatment separately and with the control condition.MethodsThis randomised cross-over study included 17 healthy participants who underwent 3D gait analysis. Participants performed ascending and descending stair activities with the following four treatment conditions: five-degree LWI, off-the-shelf knee sleeve, both LWI and knee sleeve and control condition. External knee adduction moment (EKAM) and knee frontal plane range of motion (ROM) were evaluated as primary outcomes. Repeated measure ANOVA or the Friedman test was selected based on meeting the assumption followed by multiple pairwise comparisons with Bonferroni correction.ResultsIn general, the use of LWI reduced the first peak EKAM significantly (p < 0.001) compared to the control condition in stir ascending (12% reduction) but not in stair descending (p > 0.05). Interestingly, knee sleeve use did not result in any reduction in the first peak EKAM compared to the control or any other condition. However, knee sleeve use led to a significant reduction in the knee frontal plane ROM during stair descending. The combined treatment was not superior to the LWI use when compared to control in the EKAM reduction.SignificanceCombined knee sleeve and LWI use was not superior to LWI use alone in reducing the knee loading, but it may be beneficial for individuals with knee OA since it helped in reduction of the knee frontal plane ROM during stair descending. Importantly, the effect of LWI use or any other treatment must be investigated for each different activity, and the results found in one activity must not be generalised across other activities.     

Knee adduction moments are not increased in obese knee osteoarthritis patients during stair negotiation

BackgroundNegotiating stairs is an important activity of daily living that is also associated with large loads on the knee joint. In medial compartment knee osteoarthritis, the knee adduction moment during level walking is considered a marker for disease severity. It could be argued that the discriminative capability of this parameter is even better if tested in a strenuous stair negotiation task.Research questionWhat is the relation with knee osteoarthritis on the knee adduction moment during the stance phase of both stair ascent and descent in patients with and without obesity?MethodsThis case control study included 22 lean controls, 16 lean knee osteoarthritis patients, and 14 obese knee osteoarthritis patients. All subjects ascended and descended a two-step staircase at a self-selected, comfortable speed. Three-dimensional motion analysis was performed to evaluate the knee adduction moment during stair negotiation.ResultsObese knee osteoarthritis patients show a prolonged stance time together with a more flattened knee adduction moment curve during stair ascent. Normalized knee adduction moment impulse, as well as the first and second peaks were not different between groups. During stair descent, a similar increase in stance time was found for both osteoarthritis groups.SignificanceThe absence of a significant effect of groups on the normalized knee adduction moment during stair negotiation may be explained by a lower ambulatory speed in the obese knee osteoarthritis group, that effectively lowers vertical ground reaction force. Decreasing ambulatory speed may be an effective strategy to lower knee adduction moment during stair negotiation.     

Foot alignments influence the effect of knee adduction moment with lateral wedge insoles during gait

Lateral wedge insoles (LWIs) reduce the peak external knee adduction moment (KAM). However, the efficacy of LWIs is limited in certain individuals for whom they fail to decrease KAM. Possible explanations for a lack of desired LWI response are variations in foot alignments. The purpose of this study was to evaluate whether the immediate biomechanical effects of LWIs depend on individual foot alignments during gait. Fifteen healthy adults participated in this study. Their feet were categorized as normal, pronated, and supinated using the foot posture index. All subjects were subsequently requested to perform a normal gait under barefoot and LWI conditions. A three-dimensional motion analysis system was used to record the kinematic and kinetic data, included peak KAM, KAM impulse (KAAI), center of pressure displacement, and knee-ground reaction force lever arm (KLA). Furthermore, lower limb frontal plane kinematic parameters at the rear foot, ankle, knee, and hip were evaluated. Among all feet, there was no significant difference in the peak KAM and KAAI between the conditions. In contrast, the peak KAM was significantly reduced under the LWI condition relative to the barefoot condition in the normal foot group. Reductions in the peak KAM were correlated with a more lateral center of pressure and reduced KLA. In addition, a reduced KLA was correlated with decreased hip adduction. LWIs significantly reduced the peak KAM in normal feet, indicating that biomechanical effects of LWIs vary between individual foot alignments. Our findings suggest that it is helpful to assess individual foot alignment to ensure adequate insole treatment for patients with knee osteoarthritis.     

Influence of foot posture on immediate biomechanical responses during walking to variable-stiffness supported lateral wedge insole designs

BackgroundNovel designs of lateral wedge insoles with arch support can alter walking biomechanics as a conservative treatment option for knee osteoarthritis. However, variations in foot posture may influence individual responses to insole intervention and these effects are not yet known.Research questionHow does foot posture influence biomechanical responses to novel designs of lateral wedge insoles with arch support?MethodsThis exploratory biomechanical investigation categorized forty healthy volunteers (age 23–34) into pronated (n = 16), neutral (n = 15), and supinated (n = 9) foot posture groups based on the Foot Posture Index. Three-dimensional gait analysis was conducted during walking with six orthotic insole conditions: flat control, lateral wedge, uniform-stiffness arch support, variable-stiffness arch support, and lateral wedge + each arch support. Frontal plane knee and ankle/subtalar joint kinetic and kinematic outcomes were compared among insole conditions and foot posture groups using a repeated measures analysis of variance.ResultsThe lateral wedge alone and lateral wedge + variable-stiffness arch support were the only insole conditions effective at reducing the knee adduction moment. However, the lateral wedge + variable-stiffness arch support had a smaller increase in peak ankle/subtalar eversion moment than the lateral wedge alone. Supinated feet had smaller ankle/subtalar eversion excursion and moment impulse than neutral and pronated feet, across all insole conditions.SignificanceSupinated feet have less mobile ankle/subtalar joints than neutral and pronated feet and, as a result, may be less likely to respond to biomechanical intervention from orthotic insoles. Supported lateral wedge insoles incorporating an arch support design that is variable-stiffness may be better than uniform-stiffness since reductions in the knee adduction moment can be achieved while minimizing increases in the ankle/subtalar eversion moment.     

Body weight support through a walking cane in inexperienced users with knee osteoarthritis

BackgroundWalking canes are a self-management strategy recommended for people with knee osteoarthritis (OA) by clinical practice guidelines. Ensuring that an adequate amount of body-weight support (%BWS) is taken through the walking cane is important as this reduces measures of knee joint loading.Research question1) How much body weight support do people with knee OA place through a cane? 2) Do measures of body weight support increase following a brief simple training session?MethodsSeventeen individuals with knee pain who had not used a walking cane before were recruited. A standard-grip aluminum cane was then used for 1 week with limited manufacturer instructions. Following this, participants were evaluated using an instrumented force-measuring cane to assess body weight support (% total body weight) through the cane. Force data were recorded during a 430-metre walk undertaken twice; once before 10 min of cane training administered by a physiotherapist, and once immediately after training. Measures of BWS (peak force, average force, impulse equal to the average cane force times duration, and cane-ground contact duration) were extracted. Using bathroom scales, training aimed to take at least 10% body weight support through the cane.ResultsBefore training, the average peak BWS was 7.2 ± 2.5% of total body weight. Following 10 min of training, there was a significant increase in average peak BWS by 28%, average BWS by 25%, and BWS impulse by 54% (p < 0.05). However, individual BWS responses to training were variable. Duration of cane placement increased by 22% after training (p = 0.02). Timing of peak BWS through the cane occurred at 51% of contact phase before training, and at 53% after training (p = 0.05).SignificanceA short training session can increase the transfer of body weight through a walking cane. However, more sophisticated feedback may be needed to achieve target levels of BWS.     

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.     

In-shoe plantar pressure measurements for patients with knee osteoarthritis: Reliability and effects of lateral heel wedges

Although plantar pressure measurement systems are being used increasingly during gait analyses to investigate foot orthotics, there is limited information describing test–retest reliability of such measurements. Objectives of this study were to (1) examine the test–retest reliability of lateral heel pressure (LHP) and centre of pressure (COP) during walking with and without lateral heel wedges, and (2) evaluate the effects of 4° and 8° lateral heel wedges on the magnitude of LHP, the pathway of the COP and the peak external knee adduction moment (KAM) in subjects with and without knee osteoarthritis (OA). Twenty-six subjects, 12 patients with knee OA and 14 healthy subjects, were evaluated during three lateral heel wedge conditions (control, 4° and 8°) with standardized footwear. Three-dimensional analyses of gait with optical motion capture, floor-mounted force plate and in-shoe plantar pressure were completed on two occasions. Intraclass correlation coefficients (ICC_{2, 1}) for LHP were excellent (0.79–0.83) while ICCs for COP in the medial–lateral and anterior–posterior directions were more variable (0.66–0.86). Reliability was slightly diminished when using heel wedges. Standard errors of measurement suggested considerable day-to-day variability in an individual's measures. Lateral heel wedges significantly (p < 0.001) increased LHP, shifted COP anteriorly and laterally, and decreased the KAM. No significant differences were observed between subjects with and without OA. Although the day-to-day variability appears too large to confidently evaluate changes in individual patients, and decreases in reliability with increases in wedge size indicate caution, these results suggest in-shoe measurement of LHP and COP are appropriate for use in studies evaluating biomechanical effects of foot orthoses for knee OA.     

Concurrent validity and measurement error of stair climb test in people with pre-radiographic to mild knee osteoarthritis

BackgroundStair climbing is the task first affected in patients with knee osteoarthritis (OA); therefore, the precise measurement of time required to climb stairs is important to identify mobility limitations, particularly in the early phase of knee OA.Research questionThis study aimed to examine the test-retest reliability, measurement error, and concurrent validity of the stopwatch-based stair-climb test (SCT) in adults with pre-radiographic to mild knee OA.MethodsFifty-nine participants (mean age, 59.1 [range, 50–69] years; 72.9% female) with Kellgren and Lawrence grade ≤2 disease underwent an 11-step SCT (11-SCT) in accordance with the Osteoarthritis Research Society International recommended method while wearing pressure sensor-mounted standard shoes that is used as a gold standard procedure. Test-retest reliability, measurement errors, and the concurrent validity of the stopwatch-based 11-SCT were evaluated.ResultsThe test-retest reliability of the stopwatch-based 11-SCT was excellent (intra-class correlation coefficient_1,1 [ICC_1,1], 0.952; 95% confidence interval [CI], 0.560 to 0.985; p < 0.001) and the minimal detectable change₉₅ was 0.102 s. Concurrent validity was excellent (ICC_2,1: 0.957; 95% CI: 0.661 to 0.986; p < 0.001).SignificanceThe stopwatch-based 11-SCT had high test-retest reliability and high concurrent validity, which justify its clinical use for identifying mobility limitations in individuals with pre-radiographic to mild knee OA. A difference of 0.2 s in the stopwatch-based 11-SCT time would be considered a true difference beyond a 95% measurement error.     

Coordination of lower limbs in patients with knee osteoarthritis during walking

BackgroundThe movement coordination in patients with knee osteoarthritis may be impaired and the identification of the deficits in lower limb inter-segmental coordination is crucial to understand the effect of knee osteoarthritis on knee function.Research questionThis study utilizes continuous relative phase to investigate the pattern and variability of lower limb inter-segmental coordination in patients with knee osteoarthritis and in healthy subjects during walking, and to evaluate inter-segmental coordination alterations in patients.MethodsGait was measured by a three-dimensional motion capture system for 44 patients with late-stage knee osteoarthritis and 22 healthy subjects. Segmental kinematic parameters, continuous relative phase and its variability were calculated. Independent samples t-tests were used to detect differences between patients and healthy subjects.ResultsThigh-shank continuous relative phase of patients is significantly decreased by 16.04° and 16.18° during late stance and swing phase as compared with healthy subjects (P < 0.05). Shank-foot continuous relative phase of patients is significantly decreased by 6.89° during early stance and significantly increased by 5.49° and 6.39° during late stance and swing phase (P < 0.05). Patients also exhibit increased variability of thigh-shank continuous relative phase during late stance and swing phase by 1.90° and 1.65° respectively, and increased variability of shank-foot continuous relative phase during early stance and swing phase by 0.83° and 0.88° respectively as compared to healthy subjects (P < 0.05).SignificancePatients with knee osteoarthritis exhibit altered coordination patterns and increased coordination variability of thigh-shank and shank-foot. Knee dysfunction results in altered lower limbs coordination and unstable motor control during walking. Investigation of inter-segmental coordination could therefore provide insights into changes in neuromuscular control of gait in patients with knee osteoarthritis.     

Study on three-dimensional kinematics and electromyography of ACL deficient knee participants wearing a functional knee brace during running

This investigation examined the muscular activity and 3D knee joint kinematic changes of anterior cruciate ligament-deficient (ACLD) participants in the involved leg under bracing condition during running. Different adaptation strategies have been found between patients who can cope with the injury and patients who cannot. One of the expected changes can be the muscle activation characteristic of the injured knee during strenuous activity with and without a functional knee brace. Three-dimensional kinematic and electromyographical (EMG) data were collected from 11 participants for 10 consecutive gait cycles during running on a treadmill under both braced and unbraced conditions. Participants were administered the “Knee Outcome Survey Activities of Daily Living Scale” to distinguish functional and non-functional candidates. No significant differences on 3D kinematics and EMG data were noted between functional and non-functional participants, thus data analysis focused on comparisons of bracing conditions for one combined group. Bracing significantly reduced total range of motion in the frontal and transverse planes (P<0.05). Muscle activity at heel-strike showed a consistent trend to increase for the hamstrings and decrease for the quadriceps under the braced condition when compared to the unbraced condition. Our findings indicate that bracing the ACLD knee alters the kinematics of the injured leg while running. Tendencies toward reductions in quadriceps and increases in hamstrings activity at heel-strike indicate that bracing might have resulted in added stability of the injured knee. The adaptations to bracing found in this preliminary study further support the potential mechanical and proprioceptive contributions of the functional knee brace to protect the ACLD knee.     

Immediate effects of valgus bracing on knee joint moments during walking in knee-healthy individuals: Potential modifying effects of body height

BackgroundThe goal of valgus knee brace treatment is to reduce medial knee joint loading during walking, often indicated by external knee adduction moment (KAM) measures. However, existing healthy-subjects studies have been equivocal in demonstrating KAM reduction with valgus knee bracing.Research questionWhat are the immediate effects of valgus bracing at different tension levels on KAM during walking at a controlled speed and does body height modify the brace-KAM associations?MethodsData from 32 knee-healthy participants were analysed in this randomized crossover trial. Participants performed walking trials at controlled speed (1.3 ± 0.065 m/s) both with and without an Ossür Unloader One® brace. During the bracing condition, valgus tension was incrementally increased, from zero tension to normal tension and to maximum tolerable tension.ResultsValgus bracing minimally increased knee flexion at heel-strike (P < 0.001) in a dose-dependent manner and minimally reduced gait velocity (∼0.015m/s) across all tension levels. Valgus bracing, overall, did not significantly reduce the various KAM measures. However, brace use at maximal tension was associated with a 0.04Nm/kg (9.2 %) increase in first peak KAM amongst participants with a body height of 1.75 m and a 0.03Nm/kg (7.6 %) decrease in first peak KAM amongst participants with a body height of 1.55 m.SignificanceValgus bracing did not reduce the various KAM measures during walking; however, body height may play a moderating role. Given knee brace sizes vary more in circumference than length, this result may be due to the ratio between effective moment arm length relative to limb length. A deeper understanding of the potential neuro-biomechanical effects of valgus knee bracing and how these effects are potentially modified by body height may be critical to the design of effective knee braces.     

膝骨关节炎患者平衡功能下降的影响因素分析

目的 明确膝骨关节炎(knee osteoarthritis,KOA)患者平衡功能下降的主要影响因素.方法 对89例KOA患者进行人口统计学基本信息采集、视觉模拟疼痛评分(visual analogue pain scale,VAS)、患膝关节的影像学分级、稳定极限测试(limits of stability,LOS)及双下肢的反应性测试、位置觉测试和等速肌力测试.结果 以年龄为控制因素,经Pearson偏相关分析发现患膝的VAS评分、反应时间、整体反应时间、复位误差平均值和60°峰力矩与LOS总分密切相关(P<0.05);经多元线性回归分析发现,患膝的复位误差平均值、60°伸肌峰力矩和反应时间是LOS总分的主要影响因素(P<0.01).结论 超重、膝关节疼痛、KOA病程、膝关节影像学分级不是导致KOA患者平衡功能下降的主要影响因素,而因膝关节疼痛导致的下肢肌力下降、本体感觉减退和患膝关节对新刺激做出知觉反应能力的减慢是导致KOA患者平衡功能较之无KOA者更差的疾病自身特征性主要影响因素.     

Measurement and comparison of the difference in normal medial and lateral knee joint opening

This paper reports the amount of medial and lateral knee joint opening in the general population. Knee joint lateral and medial opening at 20° knee flexion was quantified on manual varus and valgus stress test, respectively, with custom made device. One hundred men and women between the ages of 20–60 years were evaluated for their joint openings. Patients with previous knee surgeries or chronic knee pains were excluded from the study. Measurements were done twice by two different orthopedic surgeons who were blinded from each other. The mean age of the study group was 39 years (range 20–60 years) and 43 years for women (range 20–60 years) and 34 years for men (range 20–60). The mean lateral and medial knee joint space opening was 7.0° (range 3–9°) and 4.1° (range 2–7°), respectively, in the overall population; in the male population, it was 6.7° (range 3–9°) and 3.9° (range 2–7°), respectively, and in the female population, it was 7.2° (range 3–9°) and 4.3° (range 3–7°), respectively. Conversion to displacement in millimetres, the overall mean lateral and medial joint displacement was 9.3 mm (range 5.1–13.6 mm) and 4.8 mm (range 3.5–10.7 mm), respectively; for males, it was 9.1 (range 5.1–11.9 mm) and 4.6 mm (range 3.5–7.9 mm), respectively, for females, it was 9.8 mm (range 7.2–13.6 mm) and 4.9 mm (range 3.7–10.7 mm), respectively. The prevalence of the overall population that exceeds 6 mm or more lateral joint space opening was 91% (male 90% and female 92%) and medial joint space was 8% (male 4% and female 12%). Statistically, significant differences were seen between medial and lateral opening in male, female and the overall population (p<0.001). The female population exhibited wider opening in both medial and lateral joint opening than the male population (p<0.05). The interexaminer reliability showed no significant difference (p>0.05). More than 91% of the Korean population showed wide lateral joint space opening in the bilateral knee. However, none complained of functional instability or symptoms except for non-pathologic laxity detected by the physician. We strongly recommend bilateral comparison of the knee that has wide lateral joint opening.     

Lower limb kinematics during the swing phase in patients with knee osteoarthritis measured using an inertial sensor

BackgroundDuring gait, the swing limb requires flexible control to adapt to ever changing environmental circumstances. However, few studies have focused on the mechanics of swing limb control in patients with knee osteoarthritis (OA). Investigating the variability of swing limb kinematics, which can be represented by variables such as the peak shank angular velocity during the swing phase obtained from an inertial sensor, provides insights into the adaptability of swing limb control. The purpose of this study was to investigate how patients with knee OA control the swing limb and whether the degree of impairment and disability due to knee OA affects swing limb control.MethodsTwelve subjects diagnosed with knee OA and 11 healthy control subjects participated in this study. Subjects walked on a treadmill for 10 min. The mean, coefficient of variation, and fractal scaling exponent α of the peak shank angular velocity during the swing phase were calculated.FindingsThere were no significant differences between the groups for any of the kinematic parameters. The Knee Injury and Osteoarthritis Outcome Score (KOOS) activities of daily living (ADL) subsection correlated with the coefficient of variation (r = −0.677, p = 0.016) and the scaling exponent α (r = 0.604, p = 0.037) of the peak shank angular velocity.InterpretationControl of the swing limb was associated with the degree of impairment and disability. Larger and more random variability of peak shank angular velocity may indicate decreased ADL ability in patients with knee OA.     

The effects of gluteus medius and tibialis anterior kinesio taping on postural control,knee kinematics,and knee proprioception in female athletes with dynamic knee valgus

ObjectivesThis study aimed to investigate the effects of Kinesio taping on postural control, kinematics, and knee proprioception in female athletes with dynamic knee valgus (DKV).Design: a single-blind randomized clinical trial.Participants40 female athletes between the age of 18 and 28 years with DKV in single-leg drop landing (>13°) participated in this study. They were randomly classified into the Kinesio taping (KT) and placebo control (PC) groups.Main outcome measuresAll the evaluations and measurements were performed on each subject in the pre-test and post-test stages (with an interval of 72 h). The dynamic balance (Y balance test), proprioception (Knee position sense error), and knee kinematics (flexion and DKV angles) of the subjects were measured, prior and post gluteus medius and tibialis anterior KT.ResultsThe results of study demonstrate that the DKV angle and knee position sense error significantly decreased and YBT increased in the KT group from pre-test to post-test (p < 0.05). Nevertheless, there was no significant difference in knee flexion angle (p > 0.05).ConclusionThe results of the present study indicated that KT improves dynamic balance and proprioception and reduces the DKV angle. Therefore, KT is recommended for female athletes with DKV.     

Changes in proprioceptive weighting during quiet standing in women with early and established knee osteoarthritis compared to healthy controls

ObjectivesKnee osteoarthritis (OA) is highly prevalent in people above the age of 60, and is typically associated with pain, stiffness, muscle weakness and proprioceptive deficits. Muscle-tendon vibration has been used to assess the spatial reweighting of proprioceptive input during standing. The current study aimed to investigate whether weighting of proprioceptive input is altered in patients with early and established knee OA compared to asymptomatic controls.MethodsThe upright posture of 27 participants with early OA, 26 with established OA, and 27 asymptomatic controls was perturbed by vibrating (frequency: 70 Hz and amplitude: approximately 0.5 mm) ankle muscles (i.e. tibialis anterior and triceps surae) and knee muscles (vastus medialis). Center of pressure displacements of the participants were recorded using a force plate.ResultsBoth patients with early and established OA were more sensitive to triceps surae vibration compared to their healthy peers (P < 0.01 for both). No such difference was found for the vibration of tibialis anterior or vastus medialis muscles between patients with knee OA and healthy controls.ConclusionsThese results suggest that the early stages of knee OA may already lead to reweighting of proprioceptive information, suggesting more reliance on ankle proprioceptive input for postural control.     

Reliability and validity of knee angles and moments in patients with osteoarthritis using a treadmill-based gait analysis system

BackgroundAlthough commonly used to study knee osteoarthritis (OA), relatively little is known about the reliability and validity of three-dimensional (3D) gait biomechanics derived from treadmill-based systems.Research questionUsing a treadmill-based gait analysis system, our objectives were to: 1) estimate the test-retest reliability of frontal and sagittal plane knee angles and moments in knee OA patients; 2) examine concurrent validity by estimating the associations between treadmill-based and overground (gold standard) measures; and 3) examine known-groups validity by comparing measures between knee OA patients and matched healthy controls.Methods34 patients and 16 controls completed 3D gait analyses using treadmill-based and overground systems. Treadmill walking speed was matched to self-selected overground speed. Marker set, knee angle and moment calculations were consistent for both systems. Patients completed a second test session using the treadmill-based system <24 h later but within 1 week of the first test session. Variables calculated from knee angle and moment gait waveforms during stance were evaluated using Bland and Altman plots, Intraclass Correlation Coefficients (ICC), Pearson correlations (r) and t-tests.ResultsVisual inspection of the Bland and Altman plots did not reveal any systematic differences between test and retest sessions; however, limits of agreement (LoA) were larger for the sagittal plane than the frontal plane. Mean differences between sessions for knee angles were <0.25 degrees and <0.18 %BW*ht for knee moments. ICCs ranged from 0.57-to-0.93 for test-retest reliability. Pearson correlations between treadmill and overground systems ranged from 0.56-to-0.97. Although highly associated, there were substantial differences in the moments, emphasizing they cannot be used interchangeably. Patients had greater first peak knee adduction moments (KAM) than controls [mean difference (95 %CI): 0.55 (−1.07, −0.04), p = 0.03].SignificanceResults suggest frontal and sagittal plane knee angles and moments in patients with knee OA evaluated using a treadmill-based system are reliable and valid.     

Co-contraction in RA patients with a mobile bearing total knee prosthesis during a step-up task

It was hypothesized that rheumatoid arthritis (RA) patients with a total knee prosthesis that allows axial rotation of the bearing (MB) will show more co-contraction to stabilize the knee joint during a step-up task than RA patients with a fixed bearing total knee prosthesis (FB) where this rotational freedom is absent while having the same articular geometry. Surface EMG, kinematics and kinetics about the knee were recorded during a step-up task of a MB group (n = 5), a FB group (n = 4) and a control group (n = 8). Surface EMG levels of thigh muscles were calibrated to either knee flexion or extension moments by means of isokinetic contractions on a dynamometer. During the step-up task co-contraction indices were determined from an EMG-force model. Controls showed a higher active ROM during the step-up task than the patient group, 96° versus 88° (P = 0.007). In the control group higher average muscle extension, flexion and net moments during single limb support phase were observed than in the patient group. During the 20–60% interval of the single limb support, MB patients showed a significant higher level of flexor activity, resulting in a lower net joint moment, however co-contraction levels were not different. Compared to the control group arthroplasty patients showed a 40% higher level of co-contraction during this interval (P = 0.009). Control subjects used higher extension moments, resulting in a higher net joint moment. Visual analysis revealed a timing difference between the MB and FB group. The FB group seems to co-contract approximately 20% later compared to the MB group. RA patients after total knee arthroplasty show a lower net knee joint moment and a higher co-contraction than controls indicating avoidance of net joint load and an active stabilization of the knee joint. MB and FB patients showed no difference in co-contraction levels, although timing in FB is closer to controls than MB subjects. Since visual analysis revealed a timing difference between the MB and FB group, this may express compensation by coordination. Rehabilitation programs for RA patients should include besides muscle strength training, elements of muscle-coordination training.     

膝关节骨关节炎软骨下水肿与MRI及临床表现的相关性研究

目的 探讨膝关节骨关节炎(OA)软骨下骨髓水肿与一般临床指标及股四头肌面积、半月板分级的相关性.方法 收集在本院就诊的膝关节OA 患者72例,行膝关节正侧位X线及常规MRI检查,并在12个月后不同时间点复查X线平片和MRI.对各膝关节进行K-L分级、骨髓水肿评分、半月板分级及VAS评分.采用t检验和秩和检验对2组一般资料进行比较,采用Spearman进行双变量相关性分析.结果 初次随访中有骨髓水肿组的年龄及VAS评分明显低于无骨髓水肿组(P<0.05),骨髓水肿的程度与年龄及VAS评分中度相关,与其他指标相关性不大.12个月后随访中,骨髓水肿组的体质量指数(BMI)及股四头肌面积与无骨髓水肿组出现差异(P<0.05).骨髓水肿程度与年龄、股四头肌面积及VAS评分中度相关.结论 关节炎进展中骨髓水肿范围与年龄、股四头肌面积、BMI及VAS评分相关,MRI测量指标较X线更能反映膝关节OA进展,同时也揭示了与膝关节OA进展相关的部分因素.