Is the relationship between increased knee muscle strength and improved physical function following exercise dependent on baseline physical function status?

Muscle strength is a key predictor of physical function in advanced knee osteoarthritis

Skeletal muscle strength of the lower limbs is negatively impacted in advanced knee osteoarthritis. However, its role in predicting physical function of these patients remains unclear. Therefore, we aimed to evaluate hierarchical linear regression associations between lower limbs' maximal muscle strength, rate of force development and physical function in 50 patients (age: 65 ± 8 years; 22 males and 28 females; and BMI: 31 ± 5 kg/m2) with advanced knee osteoarthritis. Results revealed that leg press maximal strength and leg extension maximum voluntary contraction were associated with sit-to-stand and stair climbing performance (all p < 0.001) and accounted for variances of 29 % and 38 % in 30-s sit-to-stand and 37 % and 24 % in stair climbing performance, respectively. Leg press maximal strength and leg extension maximum voluntary contraction were also associated with Knee Injury and Osteoarthritis Outcome Score - Physical Function Short Form (KOOS-PS) (both p = 0.041), each accounting for 7 % of the variance. Similarly, rate of force development was associated with 30-s sit-to-stand (p < 0.001) and stair climbing performance (p = 0.05), explaining 22 % and 6 % of additional variances, respectively. No association was observed between measures of muscle strength and 40 m fast-paced walking. The present study highlights maximal muscle strength, and in part rate of force development, as powerful predictors of physical function in patients with advanced knee osteoarthritis and may be used as simple, valuable measures when evaluating patients' physical function.

Mobilization with movement on reducing pain and disability for knee osteoarthritis: a systematic review and meta-analysis of randomized controlled trials

INTRODUCTION

Knee osteoarthritis (OA), affecting both tibiofemoral and patellofemoral compartments, causes pain and reduced quality of life. The Mulligan Concept of mobilization with movement (MWM) may relieve symptoms by modifying sensory input, enhancing central inhibition, and improving motor activation. This study conducted a systematic review and meta-analysis with subgroup analysis to evaluate MWM's efficacy in improving pain and disability in knee OA.

METHODS

Electronic databases were searched from inception to January 2025 for randomized controlled trials (RCTs) on the effects of MWM on knee OA. Pain intensity and disability improvement, standardized using Hedges' g, were the primary and secondary outcomes. Two reviewers independently assessed study quality, extracted data, and performed a meta-analysis using a random-effects model. Subgroup analyses considered intervention regimens, technique including weight-bearing or not, Kellgren-Lawrence (K-L) classification grades, and control group comparisons.

RESULTS

From 23 RCTs (996 participants; mean age 37-61 years), MWM significantly reduced pain (Hedges' g = -0.984, 95% CI = -1.375 to -0.593) and improved disability (Hedges' g = -1.041, 95% CI = -1.477 to - 0.606).. Greater effect sizes were observed when MWM was combined with other therapies, including weight-bearing positions, and among participants without advanced K-L grades. MWM also demonstrated significant effects in comparison with active controls.

CONCLUSION

This meta-analysis showed that MWM reduces pain and disability in individuals with knee osteoarthritis, especially when incorporated into treatment protocols featuring weight-bearing positions and combined physical therapies. Clinically, MWM could be incorporated into rehabilitation programs to enhance pain relief and functional recovery. Future studies should extend follow-ups and address bias.

Exploring the modification factors of exercise therapy on biomechanical load in patients with knee osteoarthritis: a systematic review and meta-analysis

The objective of this systematic review and meta-analysis is to clarify the effect of exercise therapy on the first peak knee adduction moment (KAM), as well as other biomechanical loads in patients with knee osteoarthritis (OA), and identify physical characteristics that influence differences in biomechanical load after exercise therapy. The data sources are PubMed, PEDro, and CINAHL, from study inception to May 2021. The eligibility criteria include studies evaluating the first peak (KAM), peak knee flexion moment (KFM), maximal knee joint compression force (KCF), or co-contraction during walking before and after exercise therapy in patients with knee OA. The risk of bias was independently assessed by two reviewers using PEDro and NIH scales. Among 11 RCTs and nine non-RCTs, 1119 patients with knee OA were included (average age: 63.7 years). As the results of meta-analysis, exercise therapy tended to increase the first peak KAM (SMD 0.11; 95% CI: -0.03-0.24), peak KFM (SMD 0.13; 95% CI: -0.03-0.29), and maximal KCF (SMD 0.09; 95% CI -0.05-0.22). An increased first peak KAM was significantly associated with a larger improvement in knee muscle strength and WOMAC pain. However, the quality of evidence regarding the biomechanical loads was low-to-moderate according to the GRADE approach. The improvement in pain and knee muscle strength may mediate the increase in first peak KAM, suggesting difficulty in balancing symptom relief and biomechanical load reduction. Therefore, exercise therapy may satisfy both aspects simultaneously when combined with biomechanical interventions, such as a valgus knee brace or insoles. Registration: PROSPERO (CRD42021230966).

Prospective comparative study between knee alignment-oriented static and dynamic balance exercise in patellofemoral pain syndrome patients with dynamic knee valgus

Exercise therapy has been reported as an effective treatment method for patellofemoral pain syndrome (PFPS). However, there is a lack of studies regarding the effectiveness of balance exercise in the treatment of patients with PFPS. This study aimed to prospectively compare changes in proprioception, neuromuscular control, knee muscle strength, and patient-reported outcomes between patients with PFPS treated with knee alignment-oriented static balance exercise (SBE) and dynamic balance exercise (DBE). The participants were divided into 2 groups: 17 knee alignment-oriented SBE group and 19 knee alignment-oriented DBE group. Proprioception was assessed by dynamic postural stability using postural stabilometry. Neuromuscular control and knee muscle strength were measured for acceleration time and peak torque in quadriceps muscle using an isokinetic device. Patient-reported outcomes were evaluated using a visual analog scale for pain and the Kujala Anterior Knee Pain Scale. There was greater improvement in dynamic postural stability (0.9 ± 0.3 vs 1.2 ± 0.5; 95% confidence interval [CI]: 0, 0.6; Effect size: 0.72; P = .021) and quadriceps AT (40.5 ± 14.3 vs 54.1 ± 16.9; 95% CI: 2.9, 24.2; Effect size: 0.86; P = .014) in the DBE group compared to the SBE group. Knee alignment-oriented DBE can be more effective in improving dynamic postural stability and quadriceps muscle reaction time compared with the knee alignment-oriented SBE in PFPS patients with dynamic knee valgus.

The effect of local muscle vibration on clinical and biomechanical parameters in people with knee osteoarthritis: A systematic review

Background: To identify and synthesize available published studies on the effect of local muscle vibration (LMV) on pain, stiffness, and function in individuals with knee OA. Methods: Five databases were searched to find relevant papers on April 29, 2020, including, PubMed, Scopus, EMBASE (Ovid), Science Citation Index, and COCHRANE Central Register for Controlled Trials (CENTRAL). Randomized controlled trials (RCTs) and nonrandomized-controlled-trials (non-RCTs), such as interrupted time series and prospective cohort studies were included. Two independent reviewers screened articles and assessed inclusion through predefined criteria. Participants' characteristics, study design, intervention characteristics, outcomes, and main results were collected independently by 2 reviewers. The risk of bias assessment of included studies was conducted using Cochrane risk of bias tools for RCTs and non-RCTs. Results: Six studies were included: 3 RCTs and 3 non-RCTs. The risk of bias in included studies was generally moderate to high. Improvement of pain, stiffness, and function following the application of LMV were reported in all studies. Conclusion: This review revealed the promising effect of LMV on pain, stiffness, function, and knee range of motion (ROM) improvements for individuals with knee Osteoarthritis (OA). However, further well-designed studies are required to have a convincing conclusion on the effect of LMV in individuals with knee OA.

Muscle strength and osteoarthritis progression after surgery or exercise for degenerative meniscal tears: Secondary analyses of a randomized trial

OBJECTIVE

To evaluate muscle strength changes following partial meniscectomy or exercise therapy for degenerative meniscal tears and the relationship between baseline muscle strength and osteoarthritis progression.

METHODS

Secondary analysis of a randomized trial (n=140 participants). Isokinetic quadriceps and hamstrings strength (peak torque [N·m/kg] and total work [J/kg]) were assessed at baseline, three-, 12-month, and five-year follow-up. Between-group differences were analyzed using intention-to-treat linear mixed models. The relationship between baseline muscle strength and osteoarthritis progression (Kellgren and Lawrence, ≥1 grade increase) were assessed using logistic regression models.

RESULTS

We found statistically significant between-group differences favoring exercise therapy at three months (quadriceps: -0.30 N·m/kg, 95% CI -0.40, -0.20; hamstrings: -0.10 N·m/kg, 95% CI -0.15, -0.04) and 12 months (quadriceps: -0.13 N·m/kg, 95% CI -0.23, -0.03; hamstrings: -0.08 N·m/kg, 95% CI -0.14, -0.03). At five years, between-group differences were -0.10 N·m/kg (95% CI -0.21 to 0.01) for quadriceps and -0.07 N·m/kg (95% CI -0.13 to -0.01) for hamstrings. Quadriceps muscle weakness at baseline was associated with knee osteoarthritis progression over five years: adjusted odds ratio of 1.40 for every 0.2 N·m/kg decrease (95% CI 1.15 to 1.71). The adjusted odds ratio for hamstrings was 1.14 (95% CI 0.97-1.35) for every 0.1 N·m/kg decrease.

CONCLUSION

Exercise therapy was effective in improving muscle strength at three and 12-month follow-up compared to partial meniscectomy, but the effect was attenuated at five years. Quadriceps muscle weakness at baseline was associated with higher odds of osteoarthritis progression over five years.

The efficacy of resistance training in addition to usual care for adults with acute burn injury: A randomised controlled trial

Resistance training immediately after a burn injury has not been investigated previously. This randomised, controlled trial assessed the impact of resistance training on quality of life plus a number of physical, functional and safety outcomes in adults with a burn injury. Patients were randomly assigned to receive, in addition to standard physiotherapy, four weeks of high intensity resistance training (RTG) or sham resistance training (CG) three days per week, commenced within 72h of the burn injury. Outcome data was collected at six weeks, three and six months after burn injury. Quality of life at 6 months was the primary endpoint. Data analysis was an available cases analysis with no data imputed. Regression analyses were used for all longitudinal outcome data and between-group comparisons were used for descriptive analyses. Forty-eight patients were randomised resistance training (RTG) (n=23) or control group (CG) (n=25). The RTG demonstrated improved outcomes for the functional domain of the Burn Specific Health Scale-Brief (p=0.017) and the Quick Disability of Arm Shoulder and Hand (p<0.001). Between group differences were seen for C-reactive protein and retinol binding protein (p=0.001). Total quality of life scores, lower limb disability, muscle strength and volume were not seen to be different between groups (p>0.05). Resistance training in addition to usual rehabilitation therapy showed evidence of improving functional outcomes, particularly in upper limb burn injuries. Additionally, resistance training commenced acutely after a burn injury was not seen to be harmful to patients.

Identifying participants with knee osteoarthritis likely to benefit from physical therapy education and exercise: A hypothesis-generating study

BACKGROUND

The purpose of this investigation was to undertake a hypothesis-generating study to identify candidate variables that characterize people with knee osteoarthritis who are most likely to experience a positive response to exercise.

METHODS

One hundred and fifty participants with knee osteoarthritis participated in this observational, longitudinal study. All participants received a standard exercise intervention that consisted of 20-min sessions two to three times a week for three months. The classification and regression tree methodology (CART) was used to develop prediction of positive clinical outcome. Positive pain and disability outcomes (dependent variables) were defined as an improvement in pain intensity by >50% or an improvement of five or more on the Oxford knee score, respectively. The predictor variables considered included age, sex, body mass index, knee osteoarthritis severity (Kellgren/Lawrence grade), pain duration, use of medication, range of knee motion, pain catastrophizing, self-efficacy and knee self-perception.

RESULTS

Fifty-five participants (36.6%) were classified as responders for pain intensity and 36.6% were classified as responders for disability. The CART model identified impairments in knee self-perception and knee osteoarthritis severity as the discriminators for pain intensity reduction following exercise. No variables predicted reduction of disability level following exercise.

CONCLUSIONS

Such findings suggest that both body perception and osteoarthritis severity may play a role in treatment outcome with exercise. It also raises the possibility that those with higher levels of disrupted body perception may need additional treatment targeted at restoring body perception prior to undertaking exercise.

SIGNIFICANCE

Regardless age, sex, body mass index, pain duration, use of medication, knee range of motion, pain catastrophizing and self-efficacy, participants with knee osteoarthritis who report low levels of body perception disruption (a FreKAQ score ≦ 17) and minimal structural changes (KL grade I) demonstrate significantly better outcomes from exercise therapy than other participants.

Viscosupplementation improves pain, function and muscle strength, but not proprioception, in patients with knee osteoarthritis: a prospective randomized trial

OBJECTIVES

This study aimed to evaluate the clinical outcomes of intra-articular infiltration with hyaluronic acid and dexamethasone alone and in combination in the treatment of knee osteoarthritis (OA).

METHOD

This prospective randomized trial evaluated 44 patients undergoing treatment for OA. Patients were selected through clinical and radiological analysis using the American College of Rheumatology criteria. We included patients aged between 50 and 70 years who presented with K-L stage ≤2 knee OA and normal limb alignment. Patients with a previous history of knee injury (ligamentous, meniscal or traumatic), infection, patellofemoral OA or chondroprotective drug use in the previous year were excluded. Participants were randomized into 3 groups and underwent treatment with viscosupplementation (VS, n=16), viscosupplementation plus dexamethasone (VD, n=16) or dexamethasone (DX, n=12). All patients were evaluated before and 6 weeks, 3 months and 6 months after infiltration. Analysis included a physical examination, the Western Ontario and McMaster Universities Arthritis Index (WOMAC) questionnaire (total score and domain subscores) and an evaluation of knee extensor and flexor strength and proprioception using an isokinetic dynamometer.

RESULTS

VS significantly improved the WOMAC total score and subscores for pain, stiffness and function for up to 6 months after infiltration. It also improved knee extensor and flexor strength during the same period. Proprioception was not affected by any of the treatments.

CONCLUSIONS

VS alone improved pain, stiffness and function according to the WOMAC total score and subscores and improved knee extensor and flexor strength, but not proprioception, for up to six months after infiltration. These findings suggest that VS has a positive effect on quadriceps arthrogenic inhibition.

A Walking Intervention to Increase Weekly Steps in Dialysis Patients: A Pilot Randomized Controlled Trial

RATIONALE & OBJECTIVE

Patients receiving dialysis report very low physical activity. We implemented a pilot trial to assess the feasibility of a pedometer-based intervention to gather preliminary evidence about its impact on physical activity, symptoms, and surrogates of cardiovascular risk.

STUDY DESIGN

Pilot randomized controlled trial.

SETTING & PARTICIPANTS

60 dialysis patients from San Francisco dialysis clinics.

INTERVENTION

Participants were randomly assigned 1:1 to receiving pedometers with weekly step goals or usual care for 3 months.

OUTCOMES

The primary outcome was step counts, measured using pedometers. Secondary outcomes included physical performance using the Short Physical Performance Battery, the Physical Function and Vitality scales of the 36-Item Short Form Health Survey, the Dialysis Symptoms Index, and the Center for Epidemiologic Studies-Depression Scale, with endothelial function as a secondary and heart rate variability as an exploratory surrogate measure of cardiovascular risk. Targeted enrollment was 50% and targeted completion was 85%.

RESULTS

49% of approached patients were enrolled, and 92% completed the study. After 3 months, patients randomly assigned to the intervention (n=30) increased their average daily steps by 2,256 (95% CI, 978-3,537) more than the 30 controls (P<0.001). Heart rate variability (standard deviation of N-N intervals) increased by 14.94 (95% CI, 0.31-33.56) millisecondsin the intervention group as compared with controls (P = 0.05). There were no statistically significant differences across intervention groups in symptoms, physical performance, or endothelial function. Participants in the intervention group reverted to baseline steps during the postintervention follow-up.

LIMITATIONS

The Northern California study setting may limit generalizability. Walking does not capture the full spectrum of physical activity.

CONCLUSIONS

A short-term pedometer-based intervention led to increased step counts in dialysis patients, but the increase was not sustained. Pedometer-based interventions are feasible for dialysis patients, but future studies are needed to address whether more prolonged interventions can improve physical function or symptoms.

FUNDING

Supported by grants from the American Kidney Fund, National Institutes of Health-National Institute of Diabetes and Digestive and Kidney Diseases, and International Society of Nephrology.

TRIAL REGISTRATION

Registered at ClinicalTrials.gov with study identifier NCT02623348.

Influence of Component Geometry on Patellar Mechanics in Posterior-Stabilized Rotating Platform Total Knee Arthroplasty

BACKGROUND

Patellofemoral complications may cause pain and discomfort, sometimes leading to revision surgery for total knee arthroplasty patients, and patellar implant design has an impact on function of the reconstructed knee. The purpose of this in vivo biomechanics study was to understand the kinematic, functional, strength, and patient-reported outcome data of patients with anatomic and dome patellar implants.

METHODS

Satisfactory age-matched, gender-matched, and body mass index-matched patients who underwent rotating-platform total knee arthroplasty from one joint replacement system with either dome (n = 16) or anatomic (n = 16) patellar components were tested in a human motion laboratory using high-speed stereoradiography during an unweighted seated knee extension and a weight-bearing lunge activity. Patellar kinematics, range of motion, strength, and patient-reported outcomes were compared between subjects with anatomic or dome component geometry.

RESULTS

Both groups of patients achieved similar functional knee range of motion and reported similar outcomes and satisfaction. On average, patients with the anatomic component had 36% greater extensor strength compared with dome subjects. Patients with anatomic patellar components demonstrated significantly greater flexion of the patella relative to the femur and lower external rotation during the weighted lunge activity.

CONCLUSIONS

Relative to the modified dome geometry, patients with anatomic patellar geometry achieved greater patellar flexion which may better replicate normal patellar motion. Patients with anatomic implants may regain more extensor strength compared to patients with dome implants due to geometric differences in the patellar component designs.

Higher Physical Activity Is Associated With Less Fatigue and Insomnia Among Patients on Hemodialysis

Introduction

Patients on hemodialysis experience a heavy burden of symptoms that may be related to the low levels of physical activity reported in this population. We hypothesized that physical activity would be inversely related to symptom severity and that depression might mediate this association.

Methods

We designed a cross-sectional study of 48 patients receiving hemodialysis at 3 San Francisco dialysis clinics. Physical activity was measured using pedometers and recorded within 1 week of symptom assessment. Symptoms were assessed using total symptom burden and severity on the Dialysis Symptom Index (DSI; burden 0–29, severity 0–145), individual symptoms on the DSI (0–5), Kidney Disease Quality of Life Vitality scores, (0–100), and the Center for Epidemiologic Study-Depression (0–60).

Results

Median daily step count was 2631 (25th, 75th percentile 1125, 5278). Seventy-three percent of patients reported fatigue. After adjustment for age, sex, diabetes, and serum albumin, physical activity was associated with 0.2 points lower fatigue severity per 1000 steps per day (95% confidence interval [CI] −0.3 to 0.0), P = 0.04. Physical activity was also associated with higher Vitality score (2.36 points per 1000 steps; 95% CI 0.07–4.65) and lower insomnia scores (−0.1 points per 1000 steps; 95% CI −0.3 to 0.0], P < 0.05) in our adjusted models. Physical activity was not associated with other symptoms.

Conclusion

Because the study was cross-sectional, we cannot determine whether physical activity lowers fatigue and insomnia or whether less insomnia and fatigue increase physical activity. However, interventions to increase physical activity should be considered alongside current strategies as a possible approach to managing fatigue and insomnia.