Harmonising knee pain patient-reported outcomes: a systematic literature review and meta-analysis of Patient Acceptable Symptom State (PASS) and individual participant data (IPD).

OBJECTIVE: In order to facilitate data pooling between studies, we explored harmonisation of patient-reported outcome measures (PROMs) in people with knee pain due to osteoarthritis or knee trauma, using the Patient Acceptable Symptom State scores (PASS) as a criterion. METHODS: We undertook a systematic literature review (SLR) of PASS scores, and performed individual participant data (IPD) analysis of score distributions from concurrently completed PROM pairs. Numerical rating scales (NRS), visual analogue scales, KOOS and WOMAC pain questionnaires were standardised to 0 to 100 (worst) scales. Meta-regression explored associations of PASS. Bland Altman plots compared PROM scores within individuals using IPD from WebEx, KICK, MenTOR and NEKO studies. RESULTS: SLR identified 18 studies reporting PASS in people with knee pain. Pooled standardised PASS was 27 (95% CI: 21 to 35; n = 6,339). PASS was statistically similar for each standardised PROM. Lower PASS was associated with lower baseline pain (ß = 0.49, P = 0.01) and longer time from treatment initiation (Q = 6.35, P = 0.04). PASS scores were lowest in ligament rupture (12, 95% CI: 11 to 13), but similar between knee osteoarthritis (31, 95% CI: 26 to 36) and meniscal tear (27, 95% CI: 20 to 35). In IPD, standardised PROMs each revealed similar group mean scores, but scores within individuals diverged between PROMs (LoA between -7 to -38 and +25 to 52). CONCLUSION: Different standardised PROMs give similar PASS thresholds in group data. PASS thresholds may be affected more by patient and treatment characteristics than between PROMs. However, different PROMs give divergent scores within individuals, possibly reflecting different experiences of pain.

Is the association between physical activity and fatigue mediated by physical function or depressive symptoms in symptomatic knee osteoarthritis? The Multicenter Osteoarthritis Study.

Objectives: To examine whether physical activity (PA) was associated with fatigue, and quantify the extent of potential mediation through depressive symptoms or physical function (PF) on the relationship between PA and fatigue in symptomatic knee osteoarthritis (KOA).Method: This longitudinal study used data from the Multicenter Osteoarthritis Study (n = 484), comprising subjects aged ≥ 50 years. Baseline PA was quantified via an ankle-worn accelerometer. The outcome was fatigue, measured using a 0-10 rating scale at 2 year follow-up. Mediators included gait speed as a measure of PF and depressive symptoms at 2 year follow-up. Mediation analysis was carried out after adjustment for baseline confounders. Stratified analysis by baseline fatigue status [no/low (< 4) and high (≥ 4) fatigue] was performed.Results: A significant direct association was found between PA and fatigue at 2 years [unstandardized coefficient (B) = -0.054; 95% confidence interval (CI) -0.107, -0.002, p = 0.041]. The PA-fatigue relationship was not mediated by gait speed (B = -0.006; 95% CI -0.018, 0.001) or depressive symptoms (B = 0.009; 95% CI 0.009, 0.028). In the subgroup with high baseline fatigue, direct associations were found between PA and fatigue (gait speed model:, B = -0.107; 95% CI -0.212, -0.002, p = 0.046; depressive symptoms model: B = -0.110; 95% CI -0.120, -0.020, p = 0.017); but in the no/low baseline fatigue group, no significant association was found between PA and fatigue.Conclusion: In the symptomatic KOA population, higher baseline PA was directly associated with reduced fatigue 2 years later, especially in those with high baseline fatigue. However, this relationship was not mediated by depressive symptoms or PF.

A consensus-based framework for conducting and reporting osteoarthritis phenotype research.

BACKGROUND: The concept of osteoarthritis (OA) heterogeneity is evolving and gaining renewed interest. According to this concept, distinct subtypes of OA need to be defined that will likely require recognition in research design and different approaches to clinical management. Although seemingly plausible, a wide range of views exist on how best to operationalize this concept. The current project aimed to provide consensus-based definitions and recommendations that together create a framework for conducting and reporting OA phenotype research. METHODS: A panel of 25 members with expertise in OA phenotype research was composed. First, panel members participated in an online Delphi exercise to provide a number of basic definitions and statements relating to OA phenotypes and OA phenotype research. Second, panel members provided input on a set of recommendations for reporting on OA phenotype studies. RESULTS: Four Delphi rounds were required to achieve sufficient agreement on 11 definitions and statements. OA phenotypes were defined as subtypes of OA that share distinct underlying pathobiological and pain mechanisms and their structural and functional consequences. Reporting recommendations pertaining to the study characteristics, study population, data collection, statistical analysis, and appraisal of OA phenotype studies were provided. CONCLUSIONS: This study provides a number of consensus-based definitions and recommendations relating to OA phenotypes. The resulting framework is intended to facilitate research on OA phenotypes and increase combined efforts to develop effective OA phenotype classification. Success in this endeavor will hopefully translate into more effective, differentiated OA management that will benefit a multitude of OA patients.

Is a model of stratified exercise therapy by physical therapists in primary care feasible in patients with knee osteoarthritis? : a mixed methods study.

OBJECTIVES: To explore the feasibility of a newly developed model of stratified exercise therapy in primary care for patients with knee osteoarthritis (OA). DESIGN: Mixed method design (process, outcome and qualitative evaluation). SETTING: Six physical therapy practices in primary care around Amsterdam. PARTICIPANTS: Fifty eligible patients with knee OA, visiting one of the participating physical therapists (PTs). INTERVENTION: Patients were allocated to a subgroup based on a simple stratification tool and received subgroup-specific, protocolized, 4-month, exercise therapy. MAIN OUTCOME MEASURES: Feasibility of this model of stratified exercise therapy was explored by multiple process parameters, outcome measures (physical functioning and knee pain; at baseline and 4-months follow-up) and experiences from patients and PTs. RESULTS: From 97 potentially eligible patients, fifty patients were included and allocated to the 'high muscle strength subgroup' (n=17), 'depression subgroup' (n=4), 'obesity subgroup' (n=6) or 'low muscle strength subgroup' (n=23). Three patients dropped out during the study period. PTs provided relatively low numbers of sessions (on average 10 sessions), although exceedance of the recommended maximum number of sessions did occur frequently. We found clinically relevant improvements on physical functioning and knee pain (P<0.001 for both) for the total group. In general, the model of stratified exercise therapy was considered to be easily applicable and of added value for daily practice. CONCLUSIONS: Our model of stratified exercise therapy seems to be feasible in primary care, although a number of limitations were reported. Future research should determine the (cost-)effectiveness of an adapted model, compared to usual, non-stratified exercise therapy.

Classification of patients with knee osteoarthritis in clinical phenotypes: Data from the osteoarthritis initiative.

OBJECTIVES: The existence of phenotypes has been hypothesized to explain the large heterogeneity characterizing the knee osteoarthritis. In a previous systematic review of the literature, six main phenotypes were identified: Minimal Joint Disease (MJD), Malaligned Biomechanical (MB), Chronic Pain (CP), Inflammatory (I), Metabolic Syndrome (MS) and Bone and Cartilage Metabolism (BCM). The purpose of this study was to classify a sample of individuals with knee osteoarthritis (KOA) into pre-defined groups characterized by specific variables that can be linked to different disease mechanisms, and compare these phenotypes for demographic and health outcomes. METHODS: 599 patients were selected from the OAI database FNIH at 24 months' time to conduct the study. For each phenotype, cut offs of key variables were identified matching the results from previous studies in the field and the data available for the sample. The selection process consisted of 3 steps. At the end of each step, the subjects classified were excluded from the further classification stages. Patients meeting the criteria for more than one phenotype were classified separately into a 'complex KOA' group. RESULTS: Phenotype allocation (including complex KOA) was successful for 84% of cases with an overlap of 20%. Disease duration was shorter in the MJD while the CP phenotype included a larger number of Women (81%). A significant effect of phenotypes on WOMAC pain (F = 16.736 p <0.001) and WOMAC physical function (F = 14.676, p < 0.001) was identified after controlling for disease duration. CONCLUSION: This study signifies the feasibility of a classification of KOA subjects in distinct phenotypes based on subgroup-specific characteristics.

Chronic widespread pain prevalence in the general population: A systematic review.

Chronic widespread pain (CWP) is a significant burden in communities. Understanding the impact of population-dependent (e.g., age, gender) and contextual-dependent (e.g. survey method, region, inequality level) factors have on CWP prevalence may provide a foundation for population-based strategies to address CWP. Therefore, the purpose of this study was to estimate the global prevalence of CWP and evaluate the population and contextual factors associated with CWP. A systematic review of CWP prevalence studies (1990-2017) in the general population was undertaken. Meta-analyses were conducted to determine CWP prevalence, and study population data and contextual factors were evaluated using a meta-regression. Thirty-nine manuscripts met the inclusion criteria. Study CWP prevalence ranged from 1.4% to 24.0%, with CWP prevalence in men ranging from 0.8% to 15.3% and 1.7% to 22.1% in women. Estimated overall CWP prevalence was 9.6% (8.0-11.2%). Meta-regression analyses showed gender, United Nations country development status, and human development index (HDI) influenced CWP prevalence, while survey method, region, methodological and reporting quality, and inequality showed no significant effect on the CWP estimate. Globally CWP affects one in ten individuals within the general population, with women more likely to experience CWP than men. HDI was noted to be the socioeconomic factor related to CWP prevalence, with those in more developed countries having a lower CWP prevalence than those in less developed countries. Most CWP estimates were from developed countries, and CWP estimates from countries with a lower socioeconomic position is needed to further refine the global estimate of CWP. SIGNIFICANCE: This systematic review and meta-analysis updates the current global CWP prevalence by examining the population-level (e.g. age, gender) and contextual (e.g. country development status; survey style; reporting and methodologic quality) factors associated with CWP prevalence. This analyses provides evidence to support higher levels of CWP in countries with a lower socioeconomic position relative to countries with a higher socioeconomic position.

Knee internal contact force in a varus malaligned phenotype in knee osteoarthritis (KOA).

PURPOSE: Multiple phenotypes characterized by different disease mechanisms have been hypothesized to explain the large variability in the knee osteoarthritis (KOA) population. The purpose of this study was: to estimate and compare the medial and lateral knee compression forces (CF) during gait of three subgroups of KOA subjects characterized by different alignment and cartilage disruption patterns. METHODS: A secondary data analysis was conducted on a sample of 39 KOA subjects and 18 controls (C). The patients were classified in the different groups according to the following criteria: Varus medial disease (VMD) (12): varus alignment and predominant medial cartilage degeneration Varus generalized disease (VGD) (17): varus alignment and cartilage degeneration that extends to the lateral compartment. Neutral alignment (NA) (10): neutral alignment. The total, medial and lateral CF corrected for body weight were estimated using an inverse dynamics model (AnyBody Modeling System, AnyBody Technology) during stance. RESULTS: The impulse of the medial compressive force (MCF) (overall effect of the CF over the stance) was significantly higher (P < 0.01) in the VMD compared to all the other groups. Peak MCF was higher in the VMD compared to all the other groups, but the difference reached significance only when compared to the VGD group (P < 0.05). The results of the regression analysis showed a significant relationship in the VMD group between alignment and impulse of the MCF (R2 = 0.62; P < 0.01). This relationship disappears in the other groups. CONCLUSIONS: These findings suggest the existence of a phenotype characterized by increased MCF.

Identification of clinical phenotypes in knee osteoarthritis: a systematic review of the literature.

BACKGROUND: Knee Osteoarthritis (KOA) is a heterogeneous pathology characterized by a complex and multifactorial nature. It has been hypothesised that these differences are due to the existence of underlying phenotypes representing different mechanisms of the disease. METHODS: The aim of this study is to identify the current evidence for the existence of groups of variables which point towards the existence of distinct clinical phenotypes in the KOA population. A systematic literature search in PubMed was conducted. Only original articles were selected if they aimed to identify phenotypes of patients aged 18 years or older with KOA. The methodological quality of the studies was independently assessed by two reviewers and qualitative synthesis of the evidence was performed. Strong evidence for existence of specific phenotypes was considered present if the phenotype was supported by at least two high-quality studies. RESULTS: A total of 24 studies were included. Through qualitative synthesis of evidence, six main sets of variables proposing the existence of six phenotypes were identified: 1) chronic pain in which central mechanisms (e.g. central sensitisation) are prominent; 2) inflammatory (high levels of inflammatory biomarkers); 3) metabolic syndrome (high prevalence of obesity, diabetes and other metabolic disturbances); 4) Bone and cartilage metabolism (alteration in local tissue metabolism); 5) mechanical overload characterised primarily by varus malalignment and medial compartment disease; and 6) minimal joint disease characterised as minor clinical symptoms with slow progression over time. CONCLUSIONS: This study identified six distinct groups of variables which should be explored in attempts to better define clinical phenotypes in the KOA population.

Improvement in upper leg muscle strength underlies beneficial effects of exercise therapy in knee osteoarthritis: secondary analysis from a randomised controlled trial.

OBJECTIVES: Although exercise therapy is effective for reducing pain and activity limitations in patients with knee osteoarthritis (OA), the underlying mechanisms are unclear. This study aimed to evaluate if improvements in neuromuscular factors (i.e. upper leg muscle strength and knee proprioception) underlie the beneficial effects of exercise therapy in patients with knee OA. DESIGN: Secondary analyses from a randomised controlled trial, with measurements at baseline, 6 weeks, 12 weeks and 38 weeks. SETTING: Rehabilitation centre. PARTICIPANTS: One hundred and fifty-nine patients diagnosed with knee OA. INTERVENTION: Exercise therapy. MAIN OUTCOME MEASURES: Changes in pain [numeric rating scale (NRS)] and activity limitations [Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) physical function subscale and get-up-and-go test] during the study period. Independent variables were changes in upper leg muscle strength and knee joint proprioception (i.e. motion sense) during the study period. Longitudinal regression analyses (generalised estimating equation) were performed to analyse associations between changes in upper leg muscle strength and knee proprioception with changes in pain and activity limitations. RESULTS: Improved muscle strength was significantly associated with reductions in NRS pain {B coefficient -2.5 [95% confidence interval (CI) -3.7 to -1.4], meaning that every change of 1 unit of strength was linked to a change of -2.5 units of pain}, WOMAC physical function (-8.8, 95% CI -13.4 to -4.2) and get-up-and-go test (-1.7, 95% CI -2.4 to -1.0). Improved proprioception was not significantly associated with better outcomes of exercise therapy (P>0.05). CONCLUSIONS: Upper leg muscle strengthening is one of the mechanisms underlying the beneficial effects of exercise therapy in patients with knee OA.

Development and preliminary testing of a computerized animated activity questionnaire in patients with hip and knee osteoarthritis.

OBJECTIVE: To develop an Animated Activity Questionnaire (AAQ) based on video animations for assessing activity limitations in patients with hip/knee osteoarthritis (OA) that combines the advantages of self-reported questionnaires and performance-based tests without many of their limitations and to preliminarily assess its reliability and validity. We hypothesized that the AAQ would correlate highly with performance-based tests and moderately with self-reported questionnaires. METHODS: Item selection was based on the pilot AAQ, prespecified conditions, the International Classification of Functioning, Disability, and Health core set for OA, existing measurement instruments, and focus groups of patients. Test-retest reliability was assessed in 30 of 110 patients. In 110 patients, correlations were calculated between the AAQ and the self-reported Hip Disability/Knee Injury and Osteoarthritis Outcome Score activities of daily living subscale (H/KOOS). In 45 of 110 patients, correlations with performance-based tests (stair climbing test, timed up and go test, and 30-second chair stand test) were calculated. RESULTS: In total, 17 basic daily activities were chosen for the AAQ. Video animations were made showing a person performing each activity with 3-5 different levels of difficulty. Patients were asked to select the level that best matched their own performance. Reliability was high (intraclass correlation coefficient 0.97 [95% confidence interval 0.93-0.98]); the AAQ correlated highly with performance-based tests (0.62), but higher with the H/KOOS (0.76) than expected. CONCLUSION: A computerized AAQ for assessing activity limitations was developed. Content validity was considered good. Preliminary validation results showed high reliability, but construct validity needs further study with a larger sample size. Continuing research will focus on construct validity and crosscultural validity.

Is the severity of knee osteoarthritis on magnetic resonance imaging associated with outcome of exercise therapy?

OBJECTIVE: To evaluate associations between severity of knee osteoarthritis (OA) on magnetic resonance imaging (MRI) and treatment outcomes in knee OA patients treated with exercise therapy in an exploratory study. METHODS: Ninety-five participants with knee OA in a 12-week exercise program had obtained 3.0T MRI scans of the knee joint prior to treatment. MRI data were systematically assessed for OA severity of multiple features (cartilage integrity, bone marrow lesions, osteophyte formation, effusion/synovitis, and meniscal abnormalities) according to the Boston Leeds Osteoarthritis Knee Score method. Regression analyses were performed to analyze associations between OA severity on MRI (for the tibiofemoral and patellofemoral [PF] compartments) and outcome of exercise therapy, i.e., changes in activity limitations (Western Ontario and McMaster Universities Osteoarthritis Index physical function; primary outcome), pain and upper leg muscle strength, and treatment response (Outcome Measures in Rheumatology/Osteoarthritis Research Society International criteria). RESULTS: Improvements of 24%, 34%, and 21% on average in activity limitations, pain, and muscle strength, respectively, after 12-week exercise therapy were found (P < 0.001). Severity of abnormalities in PF cartilage integrity was significantly associated with fewer improvements in both activity limitations (P = 0.01) and muscle strength (P = 0.04). Severity of PF osteophyte formation was significantly associated with fewer improvements in muscle strength (P < 0.01). All other features on MRI were not associated with treatment outcome. CONCLUSION: Effectiveness of exercise therapy seems to be independent of OA severity on MRI, except for abnormalities in cartilage integrity and osteophyte formation, both in the PF compartment. Our study suggests that all grades of OA severity on MRI can benefit from professionally supervised exercise therapy, although the effects might be reduced in patients with advanced PF OA.

Knee joint stabilization therapy in patients with osteoarthritis of the knee: a randomized, controlled trial.

OBJECTIVE: To investigate whether an exercise program, initially focusing on knee stabilization and subsequently on muscle strength and performance of daily activities is more effective than an exercise program focusing on muscle strength and performance of daily activities only, in reducing activity limitations in patients with knee osteoarthritis (OA) and instability of the knee joint. DESIGN: A single-blind, randomized, controlled trial involving 159 knee OA patients with self-reported and/or biomechanically assessed knee instability, randomly assigned to two treatment groups. Both groups received a supervised exercise program for 12 weeks, consisting of muscle strengthening exercises and training of daily activities, but only in the experimental group specific knee joint stabilization training was provided. Outcome measures included activity limitations (Western Ontario and McMaster Universities Osteoarthritis Index - WOMAC physical function, primary outcome), pain, global perceived effect and knee stability. RESULTS: Both treatment groups demonstrated large (∼20-40%) and clinically relevant reductions in activity limitations, pain and knee instability, which were sustained 6 months post-treatment. No differences in effectiveness between experimental and control treatment were found on WOMAC physical function (B (95% confidence interval - CI) = -0.01 (-2.58 to 2.57)) or secondary outcome measures, except for a higher global perceived effect in the experimental group (P = 0.04). CONCLUSIONS: Both exercise programs were highly effective in reducing activity limitations and pain and restoring knee stability in knee OA patients with instability of the knee. In knee OA patients suffering from knee instability, specific knee joint stabilization training, in addition to muscle strengthening and functional exercises, does not seem to have any additional value. Dutch Trial Register (NTR) registration number: NTR1475.

Proprioception in knee osteoarthritis: a narrative review.

OBJECTIVE: To give an overview of the literature on knee proprioception in knee osteoarthritis (OA) patients. METHOD: A literature search was performed and reviewed using the narrative approach. RESULTS: (1) Three presumed functions of knee proprioception have been described in the literature: protection against excessive movements, stabilization during static postures, and coordination of movements. (2) Proprioceptive accuracy can be measured in different ways; correlations between these methods are low. (3) Proprioceptive accuracy in knee OA patients seems to be impaired when compared to age-matched healthy controls. Unilateral knee OA patients may have impaired proprioceptive accuracy in both knees. (4) Causes of impaired proprioceptive accuracy in knee OA remain unknown. (5) There is currently no evidence for a role of impaired proprioceptive accuracy in the onset or progression of radiographic osteoarthritis (ROA). (6) Impaired proprioceptive accuracy could be a risk factor for progression (but not for onset) of both knee pain and activity limitations in knee OA patients. (7) Exercise therapy seems to be effective in improving proprioceptive accuracy in knee OA patients. CONCLUSIONS: Recent literature has shown that proprioceptive accuracy may play an important role in knee OA. However, this role needs to be further clarified. A new measurement protocol for knee proprioception needs to be developed. Systematic reviews focusing on the relationship between impaired proprioceptive accuracy, knee pain and activity limitations and on the effect of interventions (in particular exercise therapy) on proprioceptive accuracy in knee OA are required. Future studies focusing on causes of impaired proprioceptive accuracy in knee OA patients are also needed, taking into account that also the non-symptomatic knee may have proprioceptive impairments. Such future studies may also provide knowledge of mechanism underlying the impact of impaired proprioceptive accuracy on knee pain and activity limitations.

Determinants of range of joint motion in patients with early symptomatic osteoarthritis of the hip and/or knee: an exploratory study in the CHECK cohort.

OBJECTIVE: Reduced range of motion (ROM) is supposed to be a characteristic feature of osteoarthritis (OA). Because little is known about determinants of ROM, the objective of the present study was to explore the association between demographic, articular, and clinical factors and ROM in patients with early symptomatic knee and/or hip OA. DESIGN: Baseline data of 598 participants of the Cohort Hip and Cohort Knee (CHECK) study were used in this cross-sectional study. METHODS: Separate analyses were performed for participants with knee and participants with hip symptoms. Active knee flexion, and hip internal rotation, external rotation, flexion, adduction, and abduction were assessed using a goniometer. Participants underwent a standardised physical and radiographic examination, and completed a questionnaire. Exploratory regression analyses were performed to explore the association between ROM and demographic [i.e., age, gender, body mass index (BMI)], articular [i.e., osteophytosis, joint space narrowing (JSN)], and clinical (i.e., pain, stiffness) factors. RESULTS: In patients with early symptomatic knee OA, osteophytosis, bony enlargement, crepitus, pain, and higher BMI were associated with lower knee flexion. JSN was associated with lower ROM in all planes of motion. In addition, osteophytosis, flattening of the femoral head, femoral buttressing, pain, morning stiffness, male gender, and higher BMI were found to be associated with lower hip ROM in two planes of motion. CONCLUSION: Features of articular degeneration are associated with lower knee ROM and lower hip ROM in patients with early OA. Pain, stiffness, higher BMI, and male gender are associated with lower ROM as well.

Recreational exercise in rheumatic diseases.

The purpose of this study was to evaluate changes in health-related quality of life after eight to twelve months of recreational exercise in patients with rheumatic diseases (inflammatory joint disease, osteoarthritis, fibromyalgia and other generalized pain syndromes), and to determine whether patient (age, sex, diagnosis) and exercise characteristics (follow-up time, type of activity, frequency of participation) are related to health-related quality of life change. Health-related quality of life was assessed twice in 138 patients with rheumatic diseases. 1) At enrolment in a centre for outpatient recreational exercise and 2) following eight to twelve months of recreational exercise. Health-related quality of life was measured using the Short-Form Health Survey 36 and three numeric rating scales for pain, fatigue and general condition. Multiple linear regression was used to analyze the influence of patient and exercise characteristics on follow-up HRQoL-score. Patients showed significant improvements in pain and general condition, and reported a positive change in health. A diagnosis of inflammatory joint disease (e. g. rheumatoid arthritis, polyarthritis, spondylitis) or osteoarthritis, participating in sports activities two to three times per week, and following land-based fitness classes were associated with the most improvement in health-related quality of life. Regular participation in recreational exercise contributes to improved health-related quality of life in patients with rheumatic diseases.

Reliability of the KT1000 arthrometer and the Lachman test in patients with an ACL rupture.

The underlying study is a cross sectional study on the reliability of the KT1000 arthrometer and the Lachman test to determine the within-session inter-rater reliability and intra-rater reliability of the KT1000 arthrometer and the Lachman test. Twenty patients with a complete tear of the anterior cruciate ligament (ACL) were examined in a single session each. During the assessment, two physical therapists measured the anterior-posterior translation of the knee using both the KT1000 arthrometer and the Lachman test. One examiner performed a repeated measurement of each test for determination of intra-rater reliability. The examiners were blinded to the findings of their colleague. The intraclass correlation coefficient (ICC) was used to describe the degree of reliability of the measurements. High ICCs were found for the intra-rater reliability and the inter-rater reliability of the Lachman test (ICC=1.0 and 0.77). For the KT1000 arthrometer both ICCs were clearly lower (ICC=0.47 and 0.14). The KT1000 arthrometer shows inadequate reliabilities, even when measurements are repeated within a single measurement session. Contrastingly, the Lachman test is a reliable measurement to determine the anterior-posterior laxity of the ACL deficit knee. The results of the present study suggest good within-session intra-rater reliability as well as inter-rater reliability for the Lachman test.

Varus-valgus motion and functional ability in patients with knee osteoarthritis.

OBJECTIVE: To assess the relationship between knee varus-valgus motion and functional ability, and the impact of knee varus-valgus motion on the relationship between muscle strength and functional ability in patients with osteoarthritis (OA) of the knee. METHODS: Sixty-three patients with knee OA were tested. Varus-valgus motion was assessed by optoelectronic recording and three-dimensional motion analysis. Functional ability was assessed by observation, using a 100 m walking test, a Get Up and Go test, and WOMAC questionnaire. Muscle strength was measured by a computer-driven isokinetic dynamometer. Regression analyses were performed to assess the relationships between varus-valgus motion and functional ability, and to assess the impact of varus-valgus motion on the relationship between muscle strength and functional ability. RESULTS: In patients with high varus-valgus range of motion, muscle weakness was associated with a stronger reduction in functional ability (ie, longer walking time and Get Up and Go time) than in patients with low varus-valgus range of motion. A pronounced varus position and a difference between the left and right knees in varus-valgus position were related with reduced functional ability. CONCLUSIONS: In patients with knee OA with high varus-valgus range of motion, muscle weakness has a stronger impact on functional ability than in patients with low varus-valgus range of motion. Patients with knee OA with more pronounced varus knees during walking show a stronger reduction in functional ability than patients with less pronounced varus knees or with valgus knees.

Knee varus-valgus motion during gait--a measure of joint stability in patients with osteoarthritis?

OBJECTIVE: To determine the validity of varus-valgus motion as a measure of knee joint stability by establishing the relationship of varus-valgus motion with muscle strength, joint proprioception, joint laxity and skeletal alignment in patients with knee osteoarthritis (OA). METHODS: Sixty-three patients with OA of the knee were tested. Varus-valgus motion was determined with a video-based optoelectronic gait analysis system. Muscle strength was measured using a computer-driven isokinetic dynamometer. Proprioceptive acuity was assessed by establishing the joint motion detection threshold in the anterior-posterior direction. Laxity was assessed using a device which measures the passive angular deviation of the knee in the frontal plane. Alignment was assessed using a goniometer. Regression analyses were performed to assess the relationship between varus-valgus motion, muscle strength, joint proprioception, joint laxity and skeletal alignment. RESULT: Varus-valgus motion was not related to muscle strength, joint proprioception, joint laxity and skeletal alignment. CONCLUSIONS: Knee joint stability cannot be measured as varus-valgus motion. Rather, a number of independent factors seem to contribute to the process of stabilization of the knee joint.

Reproducibility of the measurement of knee joint proprioception in patients with osteoarthritis of the knee.

OBJECTIVE: To estimate the inter- and intrarater reliability and agreement of instrumented knee joint proprioception measurement in subjects with knee osteoarthritis (OA) and healthy subjects; to assess the effect of variations in the measurement procedure on agreement parameters. METHODS: Proprioception was measured by a computer-controlled knee angular motion-detecting device in a movement-detecting task. The angular displacement between the starting position and the position at the instant of movement detection by the subject was recorded. Two raters independently assessed knee joint proprioception. After 14 days the assessment was repeated. Complete data were obtained from 24 subjects with knee OA and 26 healthy subjects. The inter- and intrarater reliability coefficients (intraclass correlation coefficients [ICC]) and inter- and intrarater agreement measures (standard error of measurement [SEM] and minimal detectable difference [MDD]) were calculated. Additionally, the effect of changing the velocity of angular displacement and applying headphone music during the measurement on the absolute error (i.e., SEM and MDD) was estimated at the second occasion. RESULTS: Interrater reliability was good in subjects with knee OA and healthy subjects (ICC 0.91 and 0.89, respectively). Interrater agreement was higher in subjects with knee OA than in healthy subjects (SEM 2.13 degrees versus 0.43 degrees , MDD 5.90 degrees versus 1.19 degrees ). Intrarater reliability was good in subjects with knee OA and healthy subjects (ICC 0.91 and 0.86, respectively). Intrarater agreement (SEM and MDD) was 2.26 degrees and 6.26 degrees in subjects with knee OA and 0.39 degrees and 1.08 degrees in healthy subjects. The original measurement and the 2 variations in measurement showed comparable measurement errors for subjects with knee OA and healthy subjects. CONCLUSION: In knee OA subjects and healthy subjects, knee proprioception measurement shows adequate intra- and interreliability. However, the absolute measurement error is rather high. Therefore, this measurement has limited value in the assessment of individual subjects, but can be recommended for scientific research in groups of individuals.

The relationship of disease duration to foot function, pain and disability in rheumatoid arthritis patients with foot complaints.

OBJECTIVE: To assess the relationship between disease duration and foot function (expressed as pressure and gait parameters), foot pain and disability, in patients with foot complaints secondary to rheumatoid arthritis (RA). METHODS: Sixty-two patients with RA-related foot complaints were included. Disease duration was defined as the time since RA was diagnosed. A pressure platform was used to measure both pressure parameters (i.e. pressure-time integrals and peak pressures in the forefoot) and gait parameters (i.e. total loading time and loading time in different foot regions). In addition, measurements of foot pain, disability (i.e. walking time and self reported disability), forefoot joint damage and disease activity were obtained. Data were analysed using partial correlations (Spearman), correcting for age. RESULTS: Disease duration was significantly correlated with the maximum pressure-time integral (PTI) measured under the forefoot (r = 0.330, p = 0.01). Disease duration was also significantly correlated with gait parameters, i.e. total loading time (r = 0.265, p = 0.04), duration of heel loading and duration of toe loading (r = 0.326, p = 0.01 and r = -0.288, p = 0.03 respectively), and walking time (r = 0.297, p = 0.02). Disease duration did not correlate with self-reported foot pain or disability. CONCLUSION: In patients with RA-related foot complaints, longer disease duration is associated with impaired foot function and reduced walking speed. These findings are interpreted as an alteration in pressure distribution and gait pattern during the course of disease, with a shift from a heel-to-toe roll-over process to a more shuffling gait.