M. van der Esch

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.

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.

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.

Falls Associated with Muscle Strength in Patients with Knee Osteoarthritis and Self-reported Knee Instability

Objective. We aimed to evaluate the associations between knee muscle strength (MS) and falls, controlling for knee joint proprioception, varus-valgus knee joint laxity, and knee pain, among patients with knee osteoarthritis (OA) reporting knee instability. Methods. A sample of 301 subjects (203 women, 98 men, 35–82 yrs) with established knee OA and self-reported knee instability was studied. The occurrence of at least 1 fall in the previous 3 months was assessed by questionnaire. Maximum knee extension and flexion strength were measured isokinetically. Additionally, proprioception, varus-valgus laxity, and pain were assessed. Student t tests were used to assess differences between subgroups. The association of muscle strength and falls was calculated using univariate and multivariate logistic regression analysis. Results. Over 10% of the subjects (31 out of 301) reported a fall in the previous 3 months. High knee extension muscle strength (crude OR 0.3, 95% CI 0.1–0.8, p = 0.022) and high knee flexion muscle strength (crude OR 0.2, 95% CI 0.0–1.0, p = 0.048) were associated with a lower risk of falls. Proprioception and laxity did not confound this relationship. After adjusting for pain, extensor strength had an adjusted OR of 0.5 (95% CI 0.2–1.4, p = 0.212) for falls and flexor strength had an adjusted OR of 0.4 (95% CI 0.1–2.3, p = 0.312). Conclusion. High knee extension and flexion muscle strength decreased the risk of falls in patients with knee OA and self-reported knee instability. After considering the effect of pain, there was insufficient statistical power to detect an association between muscle strength and falls, which might be because of the low number of subjects who fell (n = 31).

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.

Proprioception, laxity, muscle strength and activity limitations in early symptomatic knee osteoarthritis: results from the CHECK cohort.

OBJECTIVE To establish whether proprioception and varus-valgus laxity moderate the association between muscle strength and activity limitations in patients with early symptomatic knee osteoarthritis. DESIGN A cross-sectional study. SUBJECTS A sample of 151 participants with early symptomatic knee osteoarthritis from the Cohort Hip and Cohort Knee study. METHODS Regression analyses were performed to establish the associations between muscle strength, proprioception (knee joint motion detection threshold in the anterior--posterior direction), varus-valgus laxity and activity limitations (self-reported and performance-based). Interaction terms were used to establish whether proprioception and laxity moderated the association between muscle strength and activity limitations. RESULTS Proprioception moderated the association between muscle strength and activity limitations: the negative association between muscle strength and activity limitations was stronger in participants with poor proprioception than in participants with accurate proprioception (performance-based activity limitations p = 0.02; self-reported activity limitations p = 0.08). The interaction between muscle strength and varus-valgus laxity was not significantly associated with activity limitations. CONCLUSION The results of the present study support the theory that in the absence of adequate proprioceptive input, lower muscle strength affects a patients level of activities to a greater degree than in the presence of adequate proprioceptive input.

Increased knee muscle strength is associated with decreased activity limitations in established knee osteoarthritis: Two-year follow-up study in the Amsterdam Osteoarthritis cohort

OBJECTIVE To examine the association between changes in knee muscle strength (extensor and flexor muscles separately, and mean values) and changes in activity limitations in patients with established knee osteoarthritis at 2 years. METHODS Data from 186 patients with knee osteoarthritis, part of the Amsterdam Osteoarthritis cohort, were gathered at baseline and at 2-year follow-up. Strength of the knee extensor and flexor muscles were assessed using an isokinetic dynamometer. Activity limitations were assessed using the Western Ontario and McMaster University Osteoarthritis Index (WOMAC) - Physical Function subscale, the Get Up and Go test (GUG), and the 12-steps stairs test. Univariate and multivariate linear regression analyses were used to assess the association between changes in muscle strength and changes in activity limitations, adjusting for relevant confounders and baseline activity limitations. RESULTS There was an overall 16% increase in mean knee muscle strength (p < 0.001), 19% increase in knee extensor muscle strength (p < 0.001), and 17% increase in knee flexor muscle strength (p < 0.001) at 2 years. Increased mean knee muscle strength and knee flexor muscle strength were associated with better self-reported physical function (WOMAC) (b = -5.7, p = 0.03 and b = -6.2, p = 0.05), decreased time on the GUG (b = -1.2, p = 0.003 and b = -1.4, p = 0.05) and decreased time on the stairs test (b = -4.4, p < 0.001 and b = -6.6, p < 0.001). Increased extensor muscle strength was associated only with decreased time on the stairs test (b = -2.7, p < 0.001). CONCLUSION Increased knee muscle strength, mainly in the knee flexors, was associated with decreased activity limitations in patients with knee osteoarthritis at 2 years. Thus, differences in muscle strength may partially explain the between-patients variability in activity limitations.

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.

Gait retraining using real-time feedback in patients with medial knee osteoarthritis: Feasibility and effects of a six-week gait training program

BACKGROUND The knee adduction moment (KAM) is often elevated in medial knee osteoarthritis (KOA). The aim of this study was to evaluate effects on KAM and patient-reported outcomes of a six-week gait training program. METHODS Twenty-one patients (61 ± 6 years) with KOA participated in a six-week biofeedback training program to encourage increased toe-in (all patients) and increased step-width (five patients). Patients received real-time visual feedback while walking on an instrumented treadmill. We analysed the effect of the gait modification(s) on peak KAM in week six and three and six months post-training. We also evaluated the effect on pain and functional ability. RESULTS Of 21 patients starting the program, 16 completed it with high attendance (15 and 16 respectively) at the three and six month follow-ups. First peak KAM was significantly reduced by up to 14.0% in week six with non-significant reductions of 8.2% and 5.5% at the follow-ups. Functional ability (assessed using the WOMAC questionnaire) improved significantly after the training (eight point reduction, p = 0.04 in week six and nine point reduction, p = 0.04 at six-month follow-up). There was also a trend towards reduction in WOMAC pain (p = 0.06) at follow-up. CONCLUSIONS Biofeedback training to encourage gait modifications is feasible and leads to short-term benefits. However, at follow-up, reductions in KAM were less pronounced in some participants suggesting that to influence progression of KOA in the longer term, a permanent regime to reinforce the effects of the training program is needed. Trial number: ISRCTN14687588.

Factors associated with upper leg muscle strength in knee osteoarthritis: A scoping review

OBJECTIVE Muscle weakness is common and strongly related to clinical outcome in patients with knee or hip osteoarthritis. To date, there is no clear overview of the information on factors associated with muscle strength in knee and hip osteoarthritis. The aim of this paper is to provide an overview of current knowledge on factors associated with upper leg muscle strength in this population. DESIGN The framework of a scoping review was chosen. MEDLINE database was searched systematically up to 22 April 2017. Studies that described a relationship between a factor and muscle strength in knee or hip osteoarthritis were included. RESULTS A total of 65 studies met the inclusion criteria. In studies of knee osteoarthritis, 4 factors were consistently found to be associated with lower muscle strength. Due to the low number of studies on hip osteoarthritis no conclusions could be drawn on associations. CONCLUSION Lower muscle quality, physical inactivity, more severe joint degeneration, and higher pain are reported to be associated with lower strength in the upper leg muscles in knee osteoarthritis. Future research into knee osteoarthritis should focus on other potential determinants of muscle strength, such as muscle quantity, muscle activation, nutrition and vitamins, and inflammation. In hip osteoarthritis, more research is needed into all potential determinants.