Isabel Baert

Gait characteristics and lower limb muscle strength in women with early and established knee osteoarthritis

BACKGROUNDnBased on novel classification criteria using magnetic resonance imaging, a subpopulation of early knee osteoarthritis patients was clearly defined recently. This study assessed whether these early osteoarthritis patients already exhibit gait adaptations (knee joint loading in particular) and changes in muscle strength compared to control subjects and established knee osteoarthritis patients.nnnMETHODSnFourteen female patients with early knee joint degeneration, defined by magnetic resonance imaging (early osteoarthritis), 12 female patients with established osteoarthritis and 14 female control subjects participated. Specific gait parameters and lower limb muscle strength were analyzed and compared between groups. Within the osteoarthritis groups, association between muscle strength and dynamic knee joint loading was also evaluated.nnnFINDINGSnEarly osteoarthritis patients presented no altered gait pattern, no significant increase in knee joint loading and no significant decrease in hamstring muscle strength compared to controls, while established osteoarthritis patients did. In contrast, early osteoarthritis patients experienced significant quadriceps weakness, comparable to established osteoarthritis patients. Within the osteoarthritis groups, muscle strength was not correlated with knee joint loading during gait.nnnINTERPRETATIONnThe results suggest that gait changes reflect mechanical overload and are most likely the consequence of structural degeneration in knee osteoarthritis. Quadriceps weakness might however contribute to the onset and progression of the disease. This study supports the relevance of classification of early osteoarthritis patients and assists in identifying their functional characteristics. This helps to understand the trajectory of disease onset and progression and further develop more targeted strategies for prevention and treatment of knee osteoarthritis.

Weak associations between structural changes on MRI and symptoms, function and muscle strength in relation to knee osteoarthritis

PurposeTo explore associations between MRI-defined structural abnormalities and clinical features related to knee osteoarthritis (OA).MethodsStructural and clinical knee OA features were assessed in 87 women (45 with knee OA symptoms). Structural features were quantified by the Kellgren and Lawrence grade on radiography and by the Boston-Leeds Osteoarthritis Knee Score on MRI. Clinical features were assessed using the Knee Injury and Osteoarthritis Outcome Score, functional tests and muscle strength measurements. Associations were examined using regression analyses.ResultsLimited significant associations between structural and clinical features were found. An increased meniscal signal was associated with more pain/symptoms (Pxa0<xa00.027). An anterior cruciate ligament tear was associated with poorer stair climbing test performance (Pxa0=xa00.045). In a stepwise linear regression model, patellofemoral cartilage integrity and pain explained 28xa0% of the isometric quadriceps strength variability. The amount of cartilage lesions, loose bodies and pain explained 38xa0% of the isokinetic quadriceps strength variability. Synovitis/effusion and patellofemoral cartilage integrity combined with pain explained 34xa0% of the isometric hamstring strength variability.ConclusionAlthough MRI-detected cartilage lesions, synovitis/effusion and loose bodies did explain part of the muscle strength variability, results suggest that MRI does not improve the link between joint degeneration and the clinical expression of knee OA. MRI contributes less than expected to the understanding of pain and function in knee OA and possibly offers little opportunity to develop structure-modifying treatments in knee OA that could influence the patient’s pain and function.Level of evidenceCase series with no comparison groups, Level IV.

Proprioceptive accuracy in women with early and established knee osteoarthritis and its relation to functional ability, postural control, and muscle strength

The purpose of this study was to identify differences in knee proprioceptive accuracy between subjects with early knee osteoarthritis (OA), established knee OA, and healthy controls. Furthermore, the relation between proprioceptive accuracy on the one hand and functional ability, postural balance, and muscle strength on the other hand was also explored. New MRI-based classification criteria showing evidence of beginning joint degeneration have been used to identify subjects with early knee OA. A total of 45 women with knee OA (early OA, nu2009=u200921; established OA, nu2009=u200924) and 20 healthy female control subjects participated in the study. Proprioceptive accuracy was evaluated using the repositioning error of a knee joint position sense test using a three-dimensional motion analysis system. Subjective and objective functional ability was assessed by the knee injury and osteoarthritis outcome score, the timed “Up & Go” test, and the stair climbing test. The sensory organization test measured postural control. Muscle strength was measured by isokinetic dynamometry. Early OA subjects showed no significant differences in proprioceptive accuracy compared to healthy controls. In contrast, established OA subjects showed a higher repositioning error compared to early OA subjects (+29xa0%, Pu2009=u20090.033) and healthy controls (+25xa0%, Pu2009=u20090.068). Proprioceptive accuracy was not significantly associated with functional ability, postural balance, and muscle strength. Knee joint proprioceptive deficits were observed in established OA but not in early OA, suggesting that impaired proprioception is most likely a consequence of structural degeneration, rather than a risk factor in the pathogenesis of knee OA. Impaired proprioceptive accuracy was not associated with disease-related functionality in knee OA patients. Treatment strategies designed to address proprioceptive deficits may be not effective in prevention of knee OA progression and may have no impact on patients’ functionality. However, this should be confirmed further in well-designed clinical trials.

Determinants of cardiorespiratory fitness at 3, 6 and 12 months poststroke

Purpose: To better delineate intervention programs, knowledge of the factors that are associated with physical fitness in stroke survivors is crucial. This study aimed to predict cardiorespiratory fitness based on standardized measures along the several dimensions of the International Classification of Functioning, Disability and Health (ICF) model at several time intervals in the first year after stroke. Methods: Forty patients were assessed at 3, 6 and 12 months poststroke. A symptom-limited graded cycle ergometer test was used to assess cardiorespiratory fitness. Outcome variables were VO2 peak and the Oxygen Uptake Efficiency Slope (OUES). Impairments, activity limitations, participation restrictions, personal and environmental factors were assessed to determine predictive factors. Results: Explained variance at 3, 6 and 12 months poststroke was 39%, 55% and 91% for VO2 peak and 55%, 63% and 79% for OUES. A strong association between knee muscle strength and cardiorespiratory fitness was found at each measurement time, explaining up to 72 % of the variance in fitness. At 12 months poststroke, functional mobility, body mass index (BMI) and emotional status also contributed to explain variance. Conclusions: Knee muscle strength was found to be a very strong predictor of cardiorespiratory fitness during the first year after stroke and functional mobility became important at 12 months poststroke. Implications for Rehabilitation Knee muscle strength was found to be a very strong predictor of cardiorespiratory fitness during the first year after stroke and functional mobility became important at 12 months post-stroke. Cardiorespiratory endurance training should be implemented with strength-developing exercises of both lower limbs, with emphasis on the weaker paretic side.

Dynamic and static knee alignment at baseline predict structural abnormalities on MRI associated with medial compartment knee osteoarthritis after 2 years

BACKGROUNDnDynamic and static varus alignment, both, have been reported as risk factors associated with structural progression of knee osteoarthritis. However the association of none of the static and dynamic alignment with structural, clinical, and functional progression associated with knee osteoarthritis has not been assessed yet in a longitudinal study.nnnMETHODSnForty-seven women with early and established medial knee osteoarthritis were evaluated. Static and dynamic alignment as well as MRI detected structural features, clinical, and functional characteristics of patients were assessed at baseline and at 2 years follow-up. Associations between baseline static and dynamic alignment with structural, functional, and clinical characteristics at the time of entry, as well as the changes over 2 years were evaluated.nnnFINDINGSnBoth static and dynamic varus alignment at baseline were significantly associated with osteoarthritis related tibio-femoral joint structural abnormalities detected on MRI, at the time of entry. Only the magnitude of varus thrust at baseline was predictive of the changes in the presence of meniscal maceration over two years. None of the static or dynamic measures of knee joint alignment were associated with clinical characteristics associated with medial knee osteoarthritis.nnnINTERPRETATIONnThe key finding of this study is that both frontal plane dynamic and static alignment, are associated with structural abnormalities in patients with medial knee osteoarthritis.

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

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

Biomechanical and neuromuscular adaptations during the landing phase of a stepping-down task in patients with early or established knee osteoarthritis.

BACKGROUNDnTo compare the knee joint kinematics, kinetics and EMG activity patterns during a stepping-down task in patients with knee osteoarthritis (OA) with control subjects.nnnMETHODSn33 women with knee OA (early OA, n=14; established OA n=19) and 14 female control subjects performed a stepping-down task from a 20cm step. Knee joint kinematics, kinetics and EMG activity were recorded on the stepping-down leg during the loading phase.nnnRESULTSnDuring the stepping-down task patients with established knee OA showed greater normalized medial hamstrings activity (p=0.034) and greater vastus lateralis-medial hamstrings co-contraction (p=0.012) than controls. Greater vastus medialis-medial hamstrings co-contraction was found in patients with established OA compared to control subjects (p=0.040) and to patients with early OA (p=0.023). Self-reported knee instability was reported in 7% and 32% of the patients with early and established OA, respectively.nnnCONCLUSIONSnThe greater EMG co-activity found in established OA might suggest a less efficient use of knee muscles or an attempt to compensate for greater knee laxity usually present in patients with established OA. In the early stage of the disease, the biomechanical and neuromuscular control of stepping-down is not altered compared to healthy controls.