Measures of knee and gait function and radiographic severity of knee osteoarthritis - A cross-sectional study.

BACKGROUND: Pain reports show at most weak to moderate relationship with structural findings of knee osteoarthritis (OA). Less is known about the relationship between measures of knee and gait function and structural findings of knee OA. RESEARCH QUESTION: To test the hypothesis that patient-reported, performance-based and three-dimensional knee and gait measures can distinguish between individuals with varying degrees of radiographic knee OA severity. METHODS: To increase the spectrum of radiographic severity baseline data of individuals included in a cohort study and in a randomized controlled trial respectively were included in this cross-sectional study. Individuals completed the Knee injury and Osteoarthritis Outcome Score (KOOS), Single Limb Mini Squat (SLMS) test, and three-dimensional gait analysis. Radiographic severity was dichotomized into mild (Kellgren Lawrence (KL) 1-2) or severe (KL 3-4) knee OA. Proxies for medial knee joint loading were peak knee adduction moment (KAM) and KAM impulse, and summary measures of overall gait function were the Gait Deviation Index for kinematics (GDI) and kinetics (GDI-kinetic). Area under the receiver operating characteristic curves (AUC) and logistic regressions were used to evaluate whether KOOS-scores, SLMS test, peak KAM, KAM impulse, and GDI-scores could discriminate radiographic severity of knee OA. RESULTS: The sample (n = 115) consisted of 60% women, mean age 61 years (SD 8). Good discriminating abilities (AUC > 0.7) were demonstrated for all measures of knee function and gait, except for GDI and GDI-kinetic (0.62 and 0.36, respectively). Odds ratios from logistic regressions largely supported the AUC findings. SIGNIFICANCE: With the exception of gait summary measures, discriminating abilities were demonstrated by all measures of knee and gait function. Given the interest in interpreting OA as a multi-factorial disease, this information may assist researchers in selecting the most appropriate outcomes for biomechanical studies.

European consensus on the concepts and measurement of the pathophysiological neuromuscular responses to passive muscle stretch.

BACKGROUND AND PURPOSE: To support clinical decision-making in central neurological disorders, a physical examination is used to assess responses to passive muscle stretch. However, what exactly is being assessed is expressed and interpreted in different ways. A clear diagnostic framework is lacking. Therefore, the aim was to arrive at unambiguous terminology about the concepts and measurement around pathophysiological neuromuscular response to passive muscle stretch. METHODS: During two consensus meetings, 37 experts from 12 European countries filled online questionnaires based on a Delphi approach, followed by plenary discussion after rounds. Consensus was reached for agreement ≥75%. RESULTS: The term hyper-resistance should be used to describe the phenomenon of impaired neuromuscular response during passive stretch, instead of for example 'spasticity' or 'hypertonia'. From there, it is essential to distinguish non-neural (tissue-related) from neural (central nervous system related) contributions to hyper-resistance. Tissue contributions are elasticity, viscosity and muscle shortening. Neural contributions are velocity dependent stretch hyperreflexia and non-velocity dependent involuntary background activation. The term 'spasticity' should only be used next to stretch hyperreflexia, and 'stiffness' next to passive tissue contributions. When joint angle, moment and electromyography are recorded, components of hyper-resistance within the framework can be quantitatively assessed. CONCLUSIONS: A conceptual framework of pathophysiological responses to passive muscle stretch is defined. This framework can be used in clinical assessment of hyper-resistance and will improve communication between clinicians. Components within the framework are defined by objective parameters from instrumented assessment. These parameters need experimental validation in order to develop treatment algorithms based on the aetiology of the clinical phenomena.

EQ-5D-Y as a health-related quality of life measure in children and adolescents with functional disability in Sweden: testing feasibility and validity.

AIM: The EQ-5D-Y is a newly developed generic instrument measuring health-related quality of life in children and adolescents. The aim of the study was to test the feasibility and validity of the EQ-5D-Y in a Swedish patient sample of children and adolescents with functional motor, orthopaedic and medical disabilities and to compare the results with a general population sample. METHODS: Two samples of children and adolescents answered the EQ-5D-Y and a core set of internationally standardised instruments, variables and socio-demographic questions. Patients with functional disability (n = 71, aged seven to 17 years) and individuals from the general population (n = 407, aged eight to 16 years) were included in this study. RESULTS: There was a low number of missing answers. Significantly more problems were reported in all dimensions in the patient sample, and the mean visual analogue scale (VAS) score was significantly lower. Any problems were reported by 83% of the patients and by 37% of the general population. In the patient sample, 21% reported problems at the most severe level, compared with 1.5% in the general population sample. By subgroup analyses by diagnoses, the frequency of reported problems in the different dimensions varied. CONCLUSION: Even though feasibility and discriminative validity of the EQ-5D-Y were supported in our study, further studies are needed including more patients and patient groups.

Quantifying gait deviations in individuals with rheumatoid arthritis using the Gait Deviation Index.

OBJECTIVES: In this study we evaluated the usability of the Gait Deviation Index (GDI), an index that summarizes the amount of deviation in movement from a standard norm, in adults with rheumatoid arthritis (RA). The aims of the study were to evaluate the ability of the GDI to identify gait deviations, assess inter-trial repeatability, and examine the relationship between the GDI and walking speed, physical disability, and pain. METHOD: Sixty-three adults with RA and 59 adults with typical gait patterns were included in this retrospective case-control study. Following a three-dimensional gait analysis (3DGA), representative gait cycles were selected and GDI scores calculated. To evaluate the effect of walking speed, GDI scores were calculated using both a free-speed and a speed-matched reference set. Physical disability was assessed using the Health Assessment Questionnaire (HAQ) and subjects rated their pain during walking. RESULTS: Adults with RA had significantly increased gait deviations compared to healthy individuals, as shown by lower GDI scores [87.9 (SD = 8.7) vs. 99.4 (SD = 8.3), p < 0.001]. This difference was also seen when adjusting for walking speed [91.7 (SD = 9.0) vs. 99.9 (SD = 8.6), p < 0.001]. It was estimated that a change of ≥ 5 GDI units was required to account for natural variation in gait. There was no evident relationship between GDI and low/high RA-related physical disability and pain. CONCLUSIONS: The GDI seems to useful for identifying and summarizing gait deviations in individuals with RA. Thus, we consider that the GDI provides an overall measure of gait deviation that may reflect lower extremity pathology and may help clinicians to understand the impact of RA on gait dynamics.

Change in Gait Deviation Index after anti-tumour necrosis factor-α treatment in individuals with rheumatoid arthritis: a pilot study.

OBJECTIVES: Anti-tumour necrosis factor-alpha (TNF-α) inhibitors provide fast, effective resolution of rheumatoid arthritis (RA) inflammation. In this study we aimed to quantify the impact of TNF-α treatment on gait dynamics. METHOD: The sample comprised 16 subjects [11 female, median age 56 (range 48-66) years, median disease duration 9.5 (range 4.6-20.6) years] with RA who met the American College of Rheumatology (ACR) criteria, had lower extremity involvement, did not use walking aids, and had started TNF-α treatment within 1 week of baseline gait analysis. Gait analysis focused on three-dimensional (3D) lower extremity joint kinematics, kinetics, time and distance parameters. The Gait Deviation Index (GDI) and GDI-Kinetic were calculated. Data on gait, disease activity, and physical disability were collected at baseline and at 3.5 months. RESULTS: Following treatment with TNF-α, statistically significant improvements were found in disease activity [using the 28-joint Disease Activity Score based on C-reactive protein (DAS28-CRP); median difference (m(d)) = 2.3, p < 0.01], physical disability [Health Assessment Questionnaire (HAQ) m(d) = 0.4, p < 0.01], and pain during walking [visual analogue scale (VAS) m(d) = 11.0, p < 0.05]. Reductions in gait deviations were noted (GDI m(d) = 3.7, p = 0.04; GDI-Kinetic m(d) = 4.1, p = 0.05) along with reductions in dimensionless time and distance parameters. A moderate to good negative correlation existed between baseline GDI and GDI change scores (r(s) = -0.7, p < 0.01). CONCLUSIONS: Treatment with TNF-α improved gait dynamics in adults with RA. Significant gait deviations were, however, still present after treatment. In this study, GDI and GDI-Kinetic scores appeared to be useful outcome measures to quantify changes in gait deviations after this intervention.