BACKGROUND: Instability of the knee joint during gait is frequently reported by patients with knee osteoarthritis or an anterior cruciate ligament rupture. The assessment of instability in clinical practice and clinical research studies mainly relies on self-reporting. Alternatively, parameters measured with gait analysis have been explored as suitable objective indicators of dynamic knee (in)stability.RESEARCH QUESTION: This literature review aimed to establish an inventory of objective parameters of knee stability during gait.METHODS: Five electronic databases (Pubmed, Embase, Cochrane, Cinahl and SPORTDiscuss) were systematically searched, with keywords concerning knee, stability and gait. Eligible studies used an objective parameter(s) to assess knee (in)stability during gait, being stated in the introduction or methods section. Out of 10717 studies, 89 studies were considered eligible.RESULTS: Fourteen different patient populations were investigated with kinematic, kinetic and/or electromyography measurements during (challenged) gait. Thirty-three possible objective parameters were identified for knee stability, of which the majority was based on kinematic (14 parameters) or electromyography (12 parameters) measurements. Thirty-nine studies used challenged gait (i.e. external perturbations, downhill walking) to provoke knee joint instability. Limited or conflicting results were reported on the validity of the 33 parameters.SIGNIFICANCE: In conclusion, a large number of different candidates for an objective knee stability gait parameter were found in literature, all without compelling evidence. A clear conceptual definition for dynamic knee joint stability is lacking, for which we suggest : "The capacity to respond to a challenge during gait within the natural boundaries of the knee". Furthermore biomechanical gait laboratory protocols should be harmonized, to enable future developments on clinically relevant measure(s) of knee stability during gait.
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Knee joint instability is frequently reported by patients with knee osteoarthritis (KOA). Objective metrics to assess knee joint instability are lacking, making it difficult to target therapies aiming to improve stability. Therefore, the aim of this study was to compare responses in neuromechanics to perturbations during gait in patients with self-reported knee joint instability (KOA-I) versus patients reporting stable knees (KOA-S) and healthy control subjects.Forty patients (20 KOA-I and 20 KOA-S) and 20 healthy controls were measured during perturbed treadmill walking. Knee joint angles and muscle activation patterns were compared using statistical parametric mapping and discrete gait parameters. Furthermore, subgroups (moderate versus severe KOA) based on Kellgren and Lawrence classification were evaluated.Patients with KOA-I generally had greater knee flexion angles compared to controls during terminal stance and during swing of perturbed gait. In response to deceleration perturbations the patients with moderate KOA-I increased their knee flexion angles during terminal stance and pre-swing. Knee muscle activation patterns were overall similar between the groups. In response to sway medial perturbations the patients with severe KOA-I increased the co-contraction of the quadriceps versus hamstrings muscles during terminal stance.Patients with KOA-I respond to different gait perturbations by increasing knee flexion angles, co-contraction of muscles or both during terminal stance. These alterations in neuromechanics could assist in the assessment of knee joint instability in patients, to provide treatment options accordingly. Furthermore, longitudinal studies are needed to investigate the consequences of altered neuromechanics due to knee joint instability on the development of KOA.
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The wrist allows the hand to combine dorsopalmar flexion and radioulnar deviation, a unique combination of functions that is made possible by a highly complex system of joints. The morphologic features of the carpal bones and of the radiocarpal and intercarpal contacts can be functionally interpreted by the mechanism that underlies the movements of the hand to the forearm. Displacements of the carpals take place in longitudinal articulation chains, with the proximal carpals having the position of an intercalated bone. The three articulation chains, radial, central, and ulnar, have interdependent movements at the radiocarpal and midcarpal levels. The linkage of movements in the longitudinal direction is associated to a transverse linkage by mutual joint contacts and by specific ligamentous interconnections. Kinematic analyses of the carpal joint motions have provided convincing evidence that each motion of the hand to the forearm demonstrates a specific motion pattern of the carpal bones. The stability of the carpus essentially depends on the integrity of the ligamentous system which consists of interwoven fiber bundles that differ in length, direction, and mechanical properties. Distinct separations into morphologic entities are difficult to make. From a functional point of view, the ligamentous interconnections can be regarded as a system that passively restricts movements of the carpals on one another and on the radius, but in a very differentiated way. The ligamentous system controls the linkage of the movements of the carpals, with the geometries of the bones and of the joint surfaces being, first of all, responsible for the kinematic behavior of the carpal joint.
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Introduction: Falling causes long term disability and can even lead to death. Most falls occur during gait. Therefore improving gait stability might be beneficial for people at risk of falling. Recently arm swing has been shown to influence gait stability. However at present it remains unknown which mode of arm swing creates the most stable gait. Aim: To examine how different modes of arm swing affect gait stability. Method: Ten healthy young male subjects volunteered for this study. All subjects walked with four different arm swing instructions at seven different gait speeds. The Xsens motion capture suit was used to capture gait kinematics. Basic gait parameters, variability and stability measures were calculated. Results: We found an increased stability in the medio-lateral direction with excessive arm swing in comparison to normal arm swing at all gait speeds. Moreover, excessive arm swing increased stability in the anterior–posterior and vertical direction at low gait speeds. Ipsilateral and inphase arm swing did not differ compared to a normal arm swing. Discussion: Excessive arm swing is a promising gait manipulation to improve local dynamic stability. For excessive arm swing in the ML direction there appears to be converging evidence. The effect of excessive arm swing on more clinically relevant groups like the more fall prone elderly or stroke survivors is worth further investigating. Conclusion: Excessive arm swing significantly increases local dynamic stability of human gait.
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A great deal of research has been undertaken to identify the factors affecting the success, failure, performance and stability of international equity joint ventures (EJVs) (see, for example, Beamish and Killing, 1996 for a review). Most of these studies, however, are static in nature. Although some scholars advocate a more dynamic approach to EJV research (for example, Parkhe, 1993; Stafford, 1995), to date only limited work has been done in this direction (Ring and van de Ven, 1994; Madhok, 1995a; Spekman et al., 1996; Ariño and de la Torre, 1996).
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Literature highlights the need for research on changes in lumbar movement patterns, as potential mechanisms underlying the persistence of low-back pain. Variability and local dynamic stability are frequently used to characterize movement patterns. In view of a lack of information on reliability of these measures, we determined their within- and between-session reliability in repeated seated reaching. Thirty-six participants (21 healthy, 15 LBP) executed three trials of repeated seated reaching on two days. An optical motion capture system recorded positions of cluster markers, located on the spinous processes of S1 and T8. Movement patterns were characterized by the spatial variability (meanSD) of the lumbar Euler angles: flexion–extension, lateral bending, axial rotation, temporal variability (CyclSD) and local dynamic stability (LDE). Reliability was evaluated using intraclass correlation coefficients (ICC), coefficients of variation (CV) and Bland-Altman plots. Sufficient reliability was defined as an ICC ≥ 0.5 and a CV < 20%. To determine the effect of number of repetitions on reliability, analyses were performed for the first 10, 20, 30, and 40 repetitions of each time series. MeanSD, CyclSD, and the LDE had moderate within-session reliability; meanSD: ICC = 0.60–0.73 (CV = 14–17%); CyclSD: ICC = 0.68 (CV = 17%); LDE: ICC = 0.62 (CV = 5%). Between-session reliability was somewhat lower; meanSD: ICC = 0.44–0.73 (CV = 17–19%); CyclSD: ICC = 0.45–0.56 (CV = 19–22%); LDE: ICC = 0.25–0.54 (CV = 5–6%). MeanSD, CyclSD and the LDE are sufficiently reliable to assess lumbar movement patterns in single-session experiments, and at best sufficiently reliable in multi-session experiments. Within-session, a plateau in reliability appears to be reached at 40 repetitions for meanSD (flexion–extension), meanSD (axial-rotation) and CyclSD.
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PURPOSE: To compare the responses in knee joint muscle activation patterns to different perturbations during gait in healthy subjects.SCOPE: Nine healthy participants were subjected to perturbed walking on a split-belt treadmill. Four perturbation types were applied, each at five intensities. The activations of seven muscles surrounding the knee were measured using surface EMG. The responses in muscle activation were expressed by calculating mean, peak, co-contraction (CCI) and perturbation responses (PR) values. PR captures the responses relative to unperturbed gait. Statistical parametric mapping analysis was used to compare the muscle activation patterns between conditions.RESULTS: Perturbations evoked only small responses in muscle activation, though higher perturbation intensities yielded a higher mean activation in five muscles, as well as higher PR. Different types of perturbation led to different responses in the rectus femoris, medial gastrocnemius and lateral gastrocnemius. The participants had lower CCI just before perturbation compared to the same phase of unperturbed gait.CONCLUSIONS: Healthy participants respond to different perturbations during gait with small adaptations in their knee joint muscle activation patterns. This study provides insights in how the muscles are activated to stabilize the knee when challenged. Furthermore it could guide future studies in determining aberrant muscle activation in patients with knee disorders.
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Background: Development of more effective interventions for nonspecific chronic low back pain (LBP), requires a robust theoretical framework regarding mechanisms underlying the persistence of LBP. Altered movement patterns, possibly driven by pain-related cognitions, are assumed to drive pain persistence, but cogent evidence is missing. Aim: To assess variability and stability of lumbar movement patterns, during repetitive seated reaching, in people with and without LBP, and to investigate whether these movement characteristics are associated with painrelated cognitions. Methods: 60 participants were recruited, matched by age and sex (30 back-healthy and 30 with LBP). Mean age was 32.1 years (SD13.4). Mean Oswestry Disability Index-score in LBP-group was 15.7 (SD12.7). Pain-related cognitions were assessed by the ‘Pain Catastrophizing Scale’ (PCS), ‘Pain Anxiety Symptoms Scale’ (PASS) and the task-specific ‘Expected Back Strain’ scale(EBS). Participants performed a seated repetitive reaching movement (45 times), at self-selected speed. Lumbar movement patterns were assessed by an optical motion capture system recording positions of cluster markers, located on the spinous processes of S1 and T8. Movement patterns were characterized by the spatial variability (meanSD) of the lumbar Euler angles: flexion-extension, lateralbending, axial-rotation, temporal variability (CyclSD) and local dynamic stability (LDE). Differences in movement patterns, between people with and without LBP and with high and low levels of pain-related cognitions, were assessed with factorial MANOVA. Results: We found no main effect of LBP on variability and stability, but there was a significant interaction effect of group and EBS. In the LBP-group, participants with high levels of EBS, showed increased MeanSDlateral-bending (p = 0.004, η2 = 0.14), indicating a large effect. MeanSDaxial-rotation approached significance (p = 0.06). Significance: In people with LBP, spatial variability was predicted by the task-specific EBS, but not by the general measures of pain-related cognitions. These results suggest that a high level of EBS is a driver of increased spatial variability, in participants with LBP.
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Purpose: Instability of the knee joint is reported by a majority (>65%) of patients with knee osteoarthritis (KOA) and is hypothesized to play a crucial role in the initiation and progression of KOA. A generally accepted objective metric of knee joint stability is lacking, making development of diagnostics and treatment options for knee joint instability more difficult. Such a metric should be based on how gait biomechanics and muscle activation in the unstable knee joint differ from those in a stable knee joint. To challenge knee joint instability, external perturbations during gait are needed to replicate the situations in daily life that require stability of the knee joint. Therefore, the aim of this study was to compare the responses in knee biomechanics and muscle activation patterns to different types of external perturbations during gait of patients with self-reported knee joint instability (KOA-I) versus patients reporting stable knees (KOA-S) and healthy control subjects.Methods: Forty patients (60% female) were included in this study with a mean age of 66 years (range: 52-82), body mass index of 26 (range: 19-32) and Kellgren and Lawrence grade of 2.5 (range 0-4). Patients were dichotomized in a KOA-I group (n=20) and KOA-S group (n=20) based on if they had perceived an episode of knee joint instability in the past four weeks. Furthermore, twenty age-, gender- and BMI-matched healthy control subjects were measured. The participants walked on a dual-belt instrumented treadmill while different external perturbations were applied, triggered by heel strike of the most affected leg (figure 1). The external perturbations consisted of sway left (SL) or sway right (SR) translations (4 cm) or accelerations (AC) or decelerations (DC) of one belt (1.6 m/s walking speed change in 0.23 seconds). Knee kinematics and muscle activation patterns of the perturbed gait cycles were collected using a motion capture system and surface electromyography. The three groups were compared using statistical parametric mapping (SPM) and discrete values by analysis of variance. The discrete values of the knee angles (initial contact, peak and range of motion (ROM) values) and muscle activation patterns (peak, mean and co-contraction index (CCI) values) were corrected for walking speed.Results: The SPM analysis results (example provided in figure 2) showed that in response to the SL perturbations the KOA-I group walked with greater knee flexion angles (KFA) during pre-swing compared to the control group (SPM, p<0.01) and during mid-swing compared to the KOA-S group and control group (SPM, p<0.01). Moreover, during the SR perturbed gait cycles the KOA-I group had greater KFA during mid-swing compared to the KOA-S group (SPM, p=0.01). In response to the AC perturbations the KOA-I group walked with a greater KFA during late terminal stance compared to the control group (SPM, p<0.01). Furthermore, the KOA-I group had greater KFA during the pre-swing phase of the DC perturbed gait cycles compared to the control group (SPM, p<0.01). The significant results from the comparison of the discrete values are presented in table 1. The KOA-I group had greater peak KFA during the swing phase of all perturbed gait cycles (independent of perturbation type) compared to the KOA-S group and control group (p<0.01). Moreover, during both sway perturbations (SL, SR) higher KFA ROM were observed in the KOA-I group compared to the KOA-S group (p<0.05). Besides this, the KOA-I group presented higher CCI of the medial muscles (vastus medialis and medial hamstring) compared to the KOA-S group during the DC perturbation (p=0.03). Furthermore, changes in vastus medialis and gluteus medius muscle activation in response to different external perturbations were observed in the KOA-S group compared to the control group and the KOA-I group (p<0.05).Conclusions: Patients with KOA-I walked with greater knee flexion angles during peak stance, late-terminal stance, pre-swing and mid-swing in response to different external perturbations, which could be a distinctive strategy of these patients to maintain stability of the knee joint during these phases of gait. Besides this, only few alterations were observed in the knee muscle activation patterns between the groups. This could be explained by the large variation between subjects in the muscle activations patterns which might indicate different neuromuscular strategies to respond to the external perturbations. Future studies with larger sample sizes are required to test the reliability and validity of the knee flexion angle as a candidate for the objective measurement of knee joint stability and to further investigate neuromuscular control of the unstable osteoarthritic knee.
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The aim of this project & work package is to develop a European action plan on mental health at work. A major and essential ingredient for this is the involvement of the relevant stakeholders and sharing experiences among them on the national and member state level. The Dutch Ministries of Health and Social Affairs and Employment have decided to participate in this “joint action on the promotion of mental health and well-being” with a specific focus on the work package directed at establishing a framework for action to promote taking action on mental health and well-being at workplaces at national level as well.
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