J. Knoop

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.

Identification of phenotypes with different clinical outcomes in knee osteoarthritis: data from the Osteoarthritis Initiative

To identify subgroups or phenotypes of knee osteoarthritis (OA) patients based on similarities of clinically relevant patient characteristics, and to compare clinical outcomes of these phenotypes.

Association of lower muscle strength with self-reported knee instability in osteoarthritis of the knee: Results from the Amsterdam Osteoarthritis Cohort

To determine whether muscle strength, proprioceptive accuracy, and laxity are associated with self‐reported knee instability in a large cohort of knee osteoarthritis (OA) patients, and to investigate whether muscle strength may compensate for impairment in proprioceptive accuracy or laxity, in order to maintain knee stability.

Biomechanical factors and physical examination findings in osteoarthritis of the knee: associations with tissue abnormalities assessed by conventional radiography and high-resolution 3.0 Tesla magnetic resonance imaging

IntroductionWe aimed to explore the associations between knee osteoarthritis (OA)-related tissue abnormalities assessed by conventional radiography (CR) and by high-resolution 3.0 Tesla magnetic resonance imaging (MRI), as well as biomechanical factors and findings from physical examination in patients with knee OA.MethodsThis was an explorative cross-sectional study of 105 patients with knee OA. Index knees were imaged using CR and MRI. Multiple features from CR and MRI (cartilage, osteophytes, bone marrow lesions, effusion and synovitis) were related to biomechanical factors (quadriceps and hamstrings muscle strength, proprioceptive accuracy and varus-valgus laxity) and physical examination findings (bony tenderness, crepitus, bony enlargement and palpable warmth), using multivariable regression analyses.ResultsQuadriceps weakness was associated with cartilage integrity, effusion, synovitis (all detected by MRI) and CR-detected joint space narrowing. Knee joint laxity was associated with MRI-detected cartilage integrity, CR-detected joint space narrowing and osteophyte formation. Multiple tissue abnormalities including cartilage integrity, osteophytes and effusion, but only those detected by MRI, were found to be associated with physical examination findings such as crepitus.ConclusionWe observed clinically relevant findings, including a significant association between quadriceps weakness and both effusion and synovitis, detected by MRI. Inflammation was detected in over one-third of the participants, emphasizing the inflammatory component of OA and a possible important role for anti-inflammatory therapies in knee OA. In general, OA-related tissue abnormalities of the knee, even those detected by MRI, were found to be discordant with biomechanical and physical examination features.

Is the Severity of Knee Osteoarthritis on Magnetic Resonance Imaging Associated With Outcome of Exercise Therapy

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.

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.

Osteoarthritis of the knee: multicompartmental or compartmental disease?

OBJECTIVE Knee OA has been conceptualized as a multicompartmental disease, as a compartmental disease or as a combination of these two disease processes. The aim of this study was to determine the associations between four radiographic features (joint space narrowing, osteophyte formation, sclerosis and cysts) across and within the three knee compartments (medial tibiofemoral, lateral tibiofemoral and patellofemoral compartment) in knee OA. METHODS Data from the Amsterdam OA Cohort were used. In 298 patients diagnosed with knee OA, radiographic features were examined in three knee joint compartments. Radiographic features were scored according to standardized scoring methods. Factor analysis was used to examine associations between the four radiographic features across and within compartments. RESULTS A bifactor model showed a general multicompartmental factor: 10 of 12 radiographic features across the entire joint were associated with the general factor. The bifactor model also showed three compartmental factors-one for each compartment: joint space narrowing, sclerosis and to a lesser extent osteophyte formation were associated with these compartmental factors. CONCLUSION These findings suggest a multicompartmental disease process in the knee, characterized by associations among features across the entire joint, as well as compartmental disease processes in each knee compartment, characterized by associations among features within specific compartments. Longitudinal studies are needed to explore the possibility of the development from a compartmental disease to a multicompartmental disease and the impact of contributing factors on the development.

Analgesic use in patients with knee and/or hip osteoarthritis referred to an outpatient center: a cross-sectional study within the Amsterdam Osteoarthritis Cohort

Although analgesics are widely recommended in current guidelines, underuse and inadequate prescription of analgesics seem to result in suboptimal treatment effects in patients with knee and/or hip osteoarthritis (OA). This study aimed (i) to describe the use of analgesics; and (ii) to determine factors that are related to analgesic use in patients with knee and/or hip OA referred to an outpatient center. A cross-sectional study with data from 656 patients with knee and/or hip OA referred to an outpatient center (Amsterdam Osteoarthritis (AMS-OA) cohort) was conducted. Self-reported use of analgesic (yes/no) was administered and subdivided into acetaminophen, non-steroidal anti-inflammatory drugs (NSAIDs, including coxibs) and opioids. Logistic regression analyses were performed to analyze the association between analgesic use and disease-related, predisposing and enabling factors. Analgesic use was reported by 63% of the patients, with acetaminophen, NSAIDs and opioid use reported by 50, 30 and 12%, respectively. Factors related to analgesic use were higher pain severity, longer duration of symptoms, higher radiographic hip OA severity, overweight/obesity and psychological distress. These factors explained 21% of the variance of analgesic use. More than one-third of patients with established knee and/or hip OA referred to an outpatient center did not use any analgesics. Although multiple, mostly disease-related associated factors were found, analgesic use remained predominantly unexplained. Our study seems to indicate that prescription of analgesics should be guided more dominantly by clinical symptoms and needs, and preceded by a thorough shared decision-making process between patient and physician.

Exercise Therapy Targeting Neuromuscular Mechanisms

This chapter presents the rationale of innovative exercise modalities that target neuromuscular mechanisms for patients with osteoarthritis. An overview of different modalities of exercise therapy targeting neuromuscular mechanisms and three examples of specific programs will be provided. Available evidence for the effectiveness of exercise therapy targeting neuromuscular mechanisms in patients with osteoarthritis is presented.

AB0780 Identification of Knee OA Phenotypes: A Replication Study Using Data from the Amsterdam Osteoarthritis Cohort

Background We previously identified 5 clinically relevant phenotypes from a heterogeneous knee OA population (Osteoarthritis Initiative [OAI] cohort), which needs to be replicated for validation. Objectives The present study aims to replicate this phenotype identification for validation in a clinical setting using data from the Amsterdam Osteoarthritis (AMS-OA) cohort. Methods K-means clustering analysis was performed in 374 knee OA patients from the AMS-OA cohort, using 4 clinically relevant and easily obtainable patient characteristics or clustering variables: radiographic severity (Kellgren/Lawrence [K/L] grade), body mass index (BMI), upper leg muscle strength, and depression (from Hospital Anxiety and Depression Scale [HADS] questionnaire). The cluster solution with the highest Pseudo F value was considered the most adequate number of clusters or phenotypes in the dataset. This solution was compared with the original study. Results The most adequate number of phenotypes was 5, similar as in the original study. Moreover, the 5 identified phenotypes represented in general similar phenotypes compared to the original study, namely a “minimal joint disease phenotype”, a “strong muscle phenotype”, a “non-obese weak muscle phenotype” (although obesity was more prevalent compared to the original study), an “obese weak muscle phenotype”, and a “depressive phenotype” (although depression was less prevalent compared to the original study). Conclusions The identification of phenotypes from the OAI cohort could be replicated, except for two minor differences that are presumably attributable to differences in study population. The phenotype identification seems therefore a valid finding, with phenotypes possibly representing different etiological subtypes of knee OA in which phenotype-specific interventions may be needed. Disclosure of Interest None declared DOI 10.1136/annrheumdis-2014-eular.3277