The purpose of this study is to create an accurate experimental database for the passive (in vitro)freedom-of-motion characteristics of the human knee joint on a subject to subject basis, suitable for the verification and enhancement of mathematical knee-joint models. Knee-joint specimens in a six degree-of-freedom motion rig are moved through flexion under several combinations of external loads, including tibial torques, axial forces and AP-forces. Euler rotation angles and translation vectors, describing the relative, spatial motions of the joint are measured using an accurate Roentgen Stereo Photogrammetric system. Conceptually the joint is considered as a two degrees-of-freedom of motion mechanism (flexion-tibial rotation), whereby the limits of internal and external tibial rotation are defined at torques of ± 3 Nm. The motion pathways along these limits are denned as the envelopes of passive knee joint motion. It is found that these envelope pathways are consistent and hardly influenced by additional axial forces up to 300 N and AP-forces of 30 N. Within the envelope of motion, however, the motion patterns are highly susceptible to small changes in the external load configuration. It is shown that the external tibial rotation during extension ('screw-home mechanism') is not an obligatory effect of the passive joint characteristics, but a direct result of the external loads. Anatomical differences notwithstanding, the inter-individual discrepancies in the motion patterns of the four specimens tested, showed to be relatively small in a qualitative sense. Quantitative differences can be explained by small differences in the alignment of the coordinate systems relative to the joint anatomy and by differences in rotatory laxity.
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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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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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BACKGROUND: Patients with knee osteoarthritis can adapt their gait to unload the most painful knee joint in order to try to reduce pain and improve physical function. However, these gait adaptations can cause higher loads on the contralateral joints. The aim of the study was to investigate the interlimb differences in knee and hip frontal plane moments during gait in patients with knee osteoarthritis and in healthy controls.METHODS: Forty patients with knee osteoarthritis and 19 healthy matched controls were measured during comfortable treadmill walking. Frontal plane joint moments were obtained of both hip and knee joints. Differences in interlimb moments within each group were assessed using statistical parametric mapping and discrete gait parameters.FINDINGS: No interlimb differences were observed in patients with knee osteoarthritis and control subjects at group level. Furthermore, the patients presented similar interlimb variability as the controls. In a small subgroup (n = 12) of patients, the moments in the most painful knee were lower than in the contralateral knee, while the other patients (n = 28) showed higher moments in the most painful knee compared to the contralateral knee. However, no interlimb differences in the hip moments were observed within the subgroups.INTERPRETATION: Patients with knee osteoarthritis do not have interlimb differences in knee and hip joint moments. Patients and healthy subjects demonstrate a similar interlimb variability in the moments of the lower extremities. In this context, differences in knee pain in patients with knee osteoarthritis did not induce any interlimb differences in the frontal plane knee and hip moments.
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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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Introduction: Patient information holds an important role in knee arthroplasty surgery regarding patients’ expectations and outcomes after surgery. The purpose of the present study was to explore the experiences and opinions of patients undergoing knee arthroplasty (KA) surgery on an information brochure provided preoperatively. Methods: A qualitative case study of 8 patients using individual semi-structured interviews was conducted to explore patients’ opinions on an information brochure in KA surgery. Results: Patients rated the brochure as good and recommended its use. Unsatisfactory information regarding wound healing, pain expectations, postoperative exercises and use of walking aids was reported. Patients stated that the table of contents was insufficient and the size of the brochure (A4-format) too large. Patients reported to have no need for additional digital sources (e.g. applications, websites). Conclusion: These opinions support the use of an information brochure. The reported opinions were used to improve the brochure. Future research should focus on the improvement of information sources by involving patients (and other users) in the development process in which the information is tailored towards patient needs.
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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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Background: Knee and hip osteoarthritis (OA) among older adults account for substantial disability and extensive healthcare use. Effective pain coping strategies help to deal with OA. This study aims to determine the long-term relationship between pain coping style and the course of healthcare use in patients with knee and/or hip OA over 10 years. Methods: Baseline and 10-year follow-up data of 861 Dutch participants with early knee and/or hip OA from the Cohort Hip and Cohort Knee (CHECK) cohort were used. The amount of healthcare use (HCU) and pain coping style were measured. Generalized Estimating Equations were used, adjusted for relevant confounders. Results: At baseline, 86.5% of the patients had an active pain coping style. Having an active pain coping style was significantly (p = 0.022) associated with an increase of 16.5% (95% CI, 2.0–32.7) in the number of used healthcare services over 10 years. Conclusion: Patients with early knee and/or hip OA with an active pain coping style use significantly more different healthcare services over 10 years, as opposed to those with a passive pain coping style. Further research should focus on altered treatment (e.g., focus on self-management) in patients with an active coping style, to reduce HCU.
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Background The gait modification strategies Trunk Lean and Medial Thrust have been shown to reduce the external knee adduction moment (EKAM) in patients with knee osteoarthritis which could contribute to reduced progression of the disease. Which strategy is most optimal differs between individuals, but the underlying mechanism that causes this remains unknown. Research question Which gait parameters determine the optimal gait modification strategy for individual patients with knee osteoarthritis? Methods Forty-seven participants with symptomatic medial knee osteoarthritis underwent 3-dimensional motion analysis during comfortable gait and with two gait modification strategies: Medial Thrust and Trunk Lean. Kinematic and kinetic variables were calculated. Participants were then categorized into one of the two subgroups, based on the modification strategy that reduced the EKAM the most for them. Multiple logistic regression analysis with backward elimination was used to investigate the predictive nature of dynamic parameters obtained during comfortable walking on the optimal modification gait strategy. Results For 68.1 % of the participants, Trunk Lean was the optimal strategy in reducing the EKAM. Baseline characteristics, kinematics and kinetics did not differ significantly between subgroups during comfortable walking. Changes to frontal trunk and tibia angles correlated significantly with EKAM reduction during the Trunk Lean and Medial Thrust strategies, respectively. Regression analysis showed that MT is likely optimal when the frontal tibia angle range of motion and peak knee flexion angle in early stance during comfortable walking are high (R2Nagelkerke = 0.12). Significance Our regression model based solely on kinematic parameters from comfortable walking contained characteristics of the frontal tibia angle and knee flexion angle. As the model explains only 12.3 % of variance, clinical application does not seem feasible. Direct assessment of kinetics seems to be the most optimal strategy for selecting the most optimal gait modification strategy for individual patients with knee osteoarthritis.
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Scar contractures are a common complication after burn injuries. These contractures are characterized by impairment of joint mobility, leading to a risk for limitations during daily activities, and restrictions in participation in society. Qualifying its severity is not well established in burn care. This study, therefore, examined different approaches to determine the severity of limited mobility in the knee joint due to scar contracture.To determine the severity of burn scar contractures development of the knee over time, the following approaches were analyzed: prevalence, the degree of limitation, the ability to perform basic daily activities, and the need for reconstructive surgery. Range of motion data of the knee joint was extracted from a 12-month prospective multicenter cohort study in the Netherlands.Based on prevalence, mean degree of limitation, and the classification based on mathematical division, limitations in knee flexion would be seen as giving the most problems. On the other hand, when classified in terms of impact on function, limitations in extension were found to be giving most problems, although flexion limitations interfered slightly longer with the basic activities of standing, walking, and climbing stairs.Depending on the chosen approach, the severity of burn scar contractures is projected differently. Interpreting the severity of a burn scar contracture of the knee, preferably should be based on a function-based classification system of the degree of range of motion impairment, activity limitations and participation restrictions in society. Because that does justice to the real impact of burn scar contracture on the individual burn survivor.
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