Muscle and exercise in the prevention and management of knee osteoarthritis: an internal medicine specialist's guide

Causal relationship between sarcopenia with osteoarthritis and the mediating role of obesity: a univariate, multivariate, two-step Mendelian randomization study

BACKGROUND

Recent genetic evidence supports a causal role for sarcopenia in osteoarthritis, which may be mediated by the occurrence of obesity or changes in circulating inflammatory protein levels. Here, we leveraged publicly available genome-wide association study data to investigate the intrinsic causal relationship between sarcopenia, obesity, circulating inflammatory protein levels, and osteoarthritis.

METHODS

In this study, we used Mendelian randomization analyses to explore the causal relationship between sarcopenia phenotypes (Appendicular lean mass [ALM], Low hand-grip strength [LHG], and usual walking pace [UWP]) and osteoarthritis (Knee osteoarthritis [KOA], and Hip osteoarthritis [HOA]). Univariable Mendelian randomization (UVMR) analyses were performed using the inverse variance weighted (IVW) method, MR-Egger, weighted median method, simple mode, and weighted mode, with the IVW method being the primary analytical technique. Subsequently, the independent causal effects of sarcopenia phenotype on osteoarthritis were investigated using multivariate Mendelian randomization (MVMR) analysis. To further explore the mechanisms involved, obesity and circulating inflammatory proteins were introduced as the mediator variables, and a two-step Mendelian randomization analysis was used to explore the mediating effects of obesity and circulating inflammatory proteins between ALM and KOA as well as the mediating proportions.

RESULTS

UVMR analysis showed a causal relationship between ALM, LHG, UWP and KOA [(OR = 1.151, 95% CI: 1.087-1.218, P = 1.19 × 10-6, PFDR = 7.14 × 10-6) (OR = 1.215, 95% CI: 1.004-1.470; P = 0.046, PFDR = 0.055) (OR = 0.503, 95% CI: 0.292-0.867; P = 0.013, PFDR = 0.027)], and a causal relationship between ALM, UWP and HOA [(OR = 1.181, 95% CI: 1.103-1.265, P = 2.05 × 10-6, PFDR = 6.15 × 10-6) (OR = 0.438, 95% CI: 0.226-0.849, P = 0.014, PFDR = 0.022)]. In the MVMR analyses adjusting for confounders (body mass index, insomnia, sedentary behavior, and bone density), causal relationships were observed between ALM, LHG, UWP and KOA [(ALM: OR = 1.323, 95%CI: 1.224- 1.431, P = 2.07 × 10-12), (LHG: OR = 1.161, 95%CI: 1.044- 1.292, P = 0.006), (UWP: OR = 0.511, 95%CI: 0.290- 0.899, P = 0.020)], and between ALM and HOA (ALM: OR = 1.245, 95%CI: 1.149- 1.348, P = 7.65 × 10-8). In a two-step MR analysis, obesity was identified to play a potential mediating role in ALM and KOA (proportion mediated: 5.9%).

CONCLUSIONS

The results of this study suggest that decreased appendicular lean mass, grip strength, and walking speed increase the risk of KOA and decreased appendicular lean mass increases the risk of HOA in patients with sarcopenia in a European population. Obesity plays a mediator role in the occurrence of KOA due to appendicular lean body mass reduction.

Multidisciplinary Rehabilitation after Hyaluronic Acid Injections for Elderly with Knee, Hip, Shoulder, and Temporomandibular Joint Osteoarthritis

Osteoarthritis (OA) is a prevalent degenerative joint condition characterized by cartilage deterioration, joint inflammation, and functional limitations, particularly impacting the elderly population. Rehabilitation and hyaluronic acid (HA) injections are common therapeutic approaches routinely used in clinical practice, but their synergistic potential is far from being fully characterized. Thus, the aim of this narrative review was to elucidate the multilevel benefits and synergies of integrating these two approaches in multidisciplinary OA rehabilitation. This narrative review follows the scale for the assessment of narrative review articles (SANRA) criteria and involves a comprehensive literature search from July to August 2023. Two independent reviewers screened studies, including those involving human subjects with OA, rehabilitation strategies, and outcomes following HA injection, published in English. Results: HA injections might improve joint biomechanics, reducing friction, absorbing shocks, and potentially regulating inflammation. Rehabilitation plays a pivotal role in strengthening muscles, increasing the range of motion, and enhancing overall function. Optimizing rehabilitation following HA injection might provide additional benefits in joint health. OA management requires a multidisciplinary approach integrating HA injections, rehabilitation, and personalized care. Challenges in patient adherence and healthcare resources currently exist, but emerging technologies offer opportunities to enhance patient engagement and monitoring optimizing sustainability and outcomes of patients with knee, hip, shoulder, and temporomandibular joint OA.

Evaluation on curative effects of isokinetic muscle strength training for improving muscle function in patients with knee osteoarthritis: A protocol for systematic review and meta-analysis

BACKGROUND

Knee osteoarthritis (KOA) refers to a chronic deteriorating disease distinguished by degeneration of joint cartilage. Many clinical studies have demonstrated that isokinetic muscle strength training can improve muscle function in patients with KOA. However, although such studies deduce an excellent effect, the results remain controversial. Therefore, the present systematic review seeks to explore the curative effects of isokinetic muscle strength training to establish if it can improve muscle function in patients experiencing KOA.

METHODS

This review will entail a systematic review and a comprehensive examination to establish all randomized controlled studies covering curative effects of isokinetic muscle strength training to improve muscle function in patients with KOA. We will obtain data from PubMed, Cochrane Library, EMBASE, China National Knowledge Infrastructure, and WanFang databases from inception to September 2021. In addition, the study will employ the criterion postulated by Cochrane to ascertain a quality evaluation and risk assessment of the studies included for analysis. Also, we will employ relative risk, mean differences, and standardized mean differences with 95% confidence intervals to estimate the effective measures. Also, we will employ Cochran Q test and I2 statics to assess heterogeneity among the 2 studies.

RESULTS

Overall, this study anticipates providing accurate results and balanced inferences on curative effects of isokinetic muscle strength training for improving muscle function in patients with KOA.

CONCLUSION

The study's inferences will offer evidence to decide whether isokinetic muscle strength training is an effective measure for improving muscle function in patients with KOA.

The effect of rehabilitation protocol using mobile health in overweight and obese patients with knee osteoarthritis: a clinical trial

OBJECTIVE

The objective of this randomized controlled trial (RCT) was to investigate the effectiveness of the lower limb rehabilitation protocol (LLRP) combined with mobile health (mHealth) applications on knee pain, mobility, functional activity and activities of daily living (ADL) among knee osteoarthritis (OA) patients who were overweight and obese.

METHODS

This study was a single-blind, RCT conducted at Teaching Bay of Rehmatul-Lil-Alameen Post Graduate Institute of Cardiology between February and November 2020. 114 knee OA patients who were overweight and obese were randomly divided by a computer-generated number into the rehabilitation group with mHealth (RGw-mHealth) to receive LLRP + instructions of daily care (IDC) combined with mHealth intervention, rehabilitation group without mHealth (RGwo-mHealth) to receive LLRP + IDC intervention and control group (CG) to receive IDC intervention. All three groups were also provided leaflets explaining about their intervention. The primary outcome measure was knee pain measured by the Western Ontario and McMaster Universities Osteoarthritis Index score. The secondary outcome measures were mobility measured by the Timed up and go (TUG) test, functional activity measured by the patient-specific functional scale (PSFS), and ADL measured by the Katz Index of independence in ADL scores.

RESULTS

Among the 114 patients who were randomized (mean age, 53 years), 96 (84%) completed the trial. After 3-months of intervention, patients in all three groups had statistically significant knee pain reduction (RGw-mHealth: 2.54; RGwo-mHealth: 1.47; and CG: 0.37) within groups (P < 0.05). Furthermore, patients in the RGw-mHealth and RGwo-mHealth had statistically significant improvement in mobility, functional activity, and ADL within groups (P < 0.05), but no improvement was noted in the CG (p > 0.05). As indicated in the overall analysis of covariance, there were statistically significant differences in the mean knee pain, mobility, functional activity, and ADL changes between groups after 3-months (p < 0.001). The pairwise between-group comparisons (Bonferroni post hoc analysis) of the knee pain, mobility, functional activity, and ADL scores at 3-months revealed that patients in the RGw-mHealth had significantly higher mean change in the knee pain, TUG test, functional activity, and ADL scores compared to patients in the RGwo-mHealth or CG.

CONCLUSION

Reduction in knee pain, improvement in mobility, functional activity, and ADL were more among patients in the RGw-mHealth compared with the RGwo-mHealth or CG. Trial registration National Medical Research Registry: NMRR-20-1094-52911. Date of registration: 05-05-2020. URL: https://www.nmrr.gov.my .

Effect of Progressive Resistance Strength Training on Body Mass Index, Quality of Life and Functional Capacity in Knee Osteoarthritis: A Randomized Controlled Trial

Purpose

This study aimed to investigate the effectiveness of progressive resistance strength training of the lower limb rehabilitation protocol (LLRP) on body mass index (BMI), quality of life, and functional capacity in patients with knee osteoarthritis (OA) who were overweight and obese.

Patients and Methods

Fifty-six patients were allocated into either the Rehabilitation Protocol Group (RPG) or the Control Group (CG) by a computer-generated random number. The patients in the RPG performed the strengthening exercises of the LLRP and followed the instruction of daily care (IDC). The patients in the CG only followed the IDC as a usual care. Gait Speed Test, quality of life, and BMI were taken at pre-test and post-test measurements. Paired samples t-test and two way mixed analysis of variance were used to analyze the change of BMI within and compare the difference of BMI between the groups, respectively. Wilcoxon signed ranked test and Mann-Whitney U-test were used to analyze the changes of quality of life and functional capacity within and compare the differences of quality of life and functional capacity between the groups, respectively.

Results

The patients in the RPG reported a significant reduction in BMI (p = 0.025), improvement in quality of life (p ≤ 0.001), and functional capacity (p ≤ 0.001) within group. The patients in the CG also reported a significant improvements in quality of life (p < 0.05). The improvement in quality of life score was greater in the patients with RPG than the CG (p = 0.053).

Conclusion

The progressive resistance strength training of LLRP is effective in terms of reducing BMI, improving quality of life and functional capacity.

Trial Registration

Name: Iranian Registry of Clinical Trials. Number: IRCT20191221045846N3. Enrollment of first participant: 27-07-2020.

The effects of intensive dietary weight loss and exercise on gait in overweight and obese adults with knee osteoarthritis. The Intensive Diet and Exercise for Arthritis (IDEA) trial

The Intensive Diet and Exercise for Arthritis (IDEA) trial was an 18-month randomized controlled trial that enrolled 454 overweight and obese older adults with symptomatic and radiographic knee osteoarthritis (OA). Participants were randomized to either exercise (E), intensive diet-induced weight loss (D), or intensive diet-induced weight loss plus exercise (D + E) interventions. We previously reported that the clinical benefits of D + E were significantly greater than with either intervention alone (e.g., greater pain reduction, and better function, mobility, and health-related quality of life). We now test the hypothesis that D + E has greater overall benefit on gait mechanics compared to either intervention alone. Knee joint loading was analyzed using inverse dynamics and musculoskeletal modeling. Analysis of covariance determined the interventions' effects on gait. The D + E group walked significantly faster at 18-month follow-up (1.35 m s^-1) than E (1.29 m s^-1, p = 0.0004) and D (1.31 m s^-1, p = 0.0007). Tibiofemoral compressive impulse was significantly lower (p = 0.0007) in D (1069 N s) and D + E (1054 N s) compared to E (1130 N s). D had significantly lower peak hip external rotation moment (p = 0.01), hip abduction moment (p = 0.0003), and peak hip power production (p = 0.016) compared with E. Peak ankle plantar flexion moment was significantly less (p < 0.0001) in the two diet groups compared with E. There also was a significant dose-response to weight loss; participants that lost >10% of baseline body weight had significantly (p = 0.0001) lower resultant knee forces and lower muscle (quadriceps, hamstring, and gastrocnemius) forces than participants that had less weight loss. Compared to E, D produces significant load reductions at the hip, knee, and ankle; combining D with E attenuates these reductions, but most remain significantly better than with E alone.

Alterations in quadriceps muscle cellular and molecular properties in adults with moderate knee osteoarthritis

OBJECTIVE

Quadriceps muscle weakness is common in knee osteoarthritis (OA). While pain, disuse, and atrophy are commonly cited causes for muscle weakness in OA, emerging evidence suggests changes in muscle quality also occur. Alterations in muscle quality are not well understood, but likely include both cellular and morphologic adaptions. The purpose of this study was to conduct the first cellular-level analysis of the vastus lateralis in adults with moderate knee OA.

METHODS

Vastus lateralis biopsies were obtained from 24 subjects with moderate knee OA and 15 healthy controls. Quadriceps strength, muscle fiber cross sectional area (CSA), fiber type distribution, extracellular matrix (ECM) content, satellite cell abundance, and profibrotic gene expression were assessed.

RESULTS

Relative to controls, quadriceps strength was significantly lower in OA subjects (OA 62.23, 50.67-73.8 Nm vs 91.46, 75.91-107.0 Nm, P = 0.003) despite no difference in fiber CSA. OA subjects had significantly fewer Type I fibers (OA 41.51, 35.56-47.47% vs 53.07, 44.86-61.29%, P = 0.022) and more hybrid IIa/x fibers (OA 24.61, 20.61-28.61% vs 16.4, 11.60-21.20%, P = 0.009). Significantly greater ECM content, lower satellite cell density, and higher profibrotic gene expression was observed with OA, and muscle collagen content was inversely correlated to strength and satellite cell (SC) density.

CONCLUSION

Lower quadriceps function with moderate OA may not result from fiber size impairments, but is associated with ECM expansion. Impaired satellite cell density, high profibrotic gene expression, and a slow-to-fast fiber type transition may contribute to reduced muscle quality in OA. These findings can help guide therapeutic interventions to enhance muscle function with OA.

Dose-Response Effects of Tai Chi and Physical Therapy Exercise Interventions in Symptomatic Knee Osteoarthritis

BACKGROUND

Therapeutic exercise is a currently recommended nonpharmacological treatment for knee osteoarthritis (KOA). The optimal treatment dose (frequency or duration) has not been determined.

OBJECTIVE

To examine dose-response relationships, minimal effective dose, and baseline factors associated with the timing of response from 2 exercise interventions in KOA.

DESIGN

Secondary analysis of a single-blind, randomized trial comparing 12-week Tai Chi and physical therapy exercise programs (Trial Registry #NCT01258985).

SETTING

Urban tertiary care academic hospital PARTICIPANTS: A total of 182 participants with symptomatic KOA (mean age 61 years; BMI 32 kg/m², 70% female; 55% white).

METHODS

We defined dose as cumulative attendance-weeks of intervention, and treatment response as ≥20% and ≥50% improvement in pain and function. Using log-rank tests, we compared time-to-response between interventions, and used Cox regression to examine baseline factors associated with timing of response, including physical and psychosocial health, physical performance, outcome expectations, self-efficacy, and biomechanical factors.

MAIN OUTCOME MEASURES

Weekly Western Ontario and McMasters Osteoarthritis Index (WOMAC) pain (0-500) and function (0-1700) scores.

RESULTS

Both interventions had an approximately linear dose-response effect resulting in a 9- to 11-point reduction in WOMAC pain and a 32- to 41-point improvement in function per attendance-week. There was no significant difference in overall time-to-response for pain and function between treatment groups. Median time-to-response for ≥20% improvement in pain and function was 2 attendance-weeks and for ≥50% improvement was 4-5 attendance-weeks. On multivariable models, outcome expectations were independently associated with incident function response (hazard ratio = 1.47, 95% confidence interval 1.004-2.14).

CONCLUSIONS

Both interventions have approximately linear dose-dependent effects on pain and function; their minimum effective doses range from 2-5 weeks; and patient perceived benefits of exercise influence the timing of response in KOA. These results may help clinicians to optimize patient-centered exercise treatments and better manage patient expectations.

LEVEL OF EVIDENCE

II.

Longitudinal (4 year) change of thigh muscle and adipose tissue distribution in chronically painful vs painless knees--data from the Osteoarthritis Initiative

OBJECTIVE

To evaluate 4-year longitudinal change in thigh muscle and adipose tissue content in chronically painful vs painless knees.

METHODS

Knees from Osteoarthritis Initiative (OAI) participants with non-acceptable symptom status (numerical rating scale (NRS) ≥4) and frequent pain (≥6 months at baseline, year 2 and year 4 follow-up) were studied. These were matched with painless controls (bilateral NRS pain intensity ≤1 and ≤infrequent pain at all 3 timepoints). 4-year longitudinal changes in thigh muscle anatomical cross-sectional areas (CSAs), isometric muscle strength, and in subcutaneous (SCF) and intermuscular fat (IMF) CSAs were obtained from magnetic resonance images (MRI) and were compared between groups (paired t-tests).

RESULTS

43 participants fulfilled the inclusion criteria of chronic pain, had complete thigh muscle MRI acquisitions and strength measurements, and a matched control. Quadriceps CSAs, but not extensor strength, showed a significant longitudinal decrease in chronically painful knees (-3.9%; 95% confidence interval [95 CI] -6.3%, -1.5%) and in painless controls (-2.4%; 95% CI -4.1%, -0.7%); the difference in change was not statistically significant (P = 0.33). There was a significant 4-year gain in SCF in painful knees (8.1%; 95% CI 3.1%, 13%) but not in controls (0.0%; 95% CI -4.4%, +4.4%) with the difference in change being significant (P = 0.03). The gain in IMF (∼5.2%) was similar between painful and painless knees.

CONCLUSION

This is the first paper to show a significant impact of (chronic) knee pain on longitudinal change in local subcutaneous adipose tissue. The effect of pain on subcutaneous fat appeared stronger than that on intermuscular adipose tissue and on muscle status.

Relative distribution of quadriceps head anatomical cross-sectional areas and volumes--sensitivity to pain and to training intervention

INTRODUCTION

Quadriceps heads are important in biomechanical stabilization and in the pathogenesis osteoarthritis of the knee. This is the first study to explore the relative distribution of quadriceps head anatomical cross-sectional areas (ACSA) and volumes, and their response to pain and to training intervention.

METHODS

The relative proportions of quadriceps heads were determined in 48 Osteoarthritis Initiative participants with unilateral pain (65% women; age 45-78 years). Quadriceps head volumes were also measured in 35 untrained women (45-55 years) before and after 12-week training intervention. Cross-sectional areas of the vastus medialis (VM), inter-medius (VIM), and lateralis (VL), and of the rectus femoris (RF) were determined from axial T1-weighted MR images.

RESULTS

The proportion of the VM on the total quadriceps ACSA increased from proximal to distal. The difference in quadriceps ACSA of painful (vs. pain-free) limbs was -5.4% for the VM (p<0.001), -6.8% for the VL (p<0.01), -2.8% for the VIM (p=0.06), and +3.4% for the RF (p=0.67) but the VM/VL ratio was not significantly altered. The muscle volume increase during training intervention was +4.2% (p<0.05) for VM, +1.3% for VL, +2.0% for VIM (p<0.05) and +1.6% for RF.

CONCLUSION

The proportion of quadriceps head relative to total muscle ACSA and volume depends on the anatomical level studied. The results suggest that there may be a differential response of the quadriceps heads to pain-induced atrophy and to training-related hypertrophy. Studies in larger samples are needed to ascertain whether the observed differences in response to pain and training are statistically and clinically significant.

Effect of eccentric isokinetic strengthening in the rehabilitation of patients with knee osteoarthritis: Isogo, a randomized trial

Background

Femorotibial knee osteoarthritis is associated with muscle weakness in the lower limbs, particularly in the quadriceps, which results in disease progression. The interest of having muscular strengthening as part of the therapeutic arsenal for the medical treatment of knee osteoarthritis is now well established.

The functional disability induced by knee osteoarthritis manifests itself principally when walking, notably downhill, during which the muscles are called upon to contract eccentrically.

We can therefore think that eccentric muscular strengthening could bring a functional benefit that is superior to concentric muscular strengthening.

Methods/Design

This is a prospective, randomized, bicenter, parallel-group, international study. Eighty patients aged from 40 to 75 years old, suffering from medical-stage knee osteoarthritis, will undertake 6 weeks of isokinetic muscular strengthening. Randomization determines the mode of muscular strengthening: either exclusively eccentric or exclusively concentric.

The principal objective is to demonstrate the superiority of the improvement in the quadriceps isokinetic torque after isokinetic muscular strengthening by the eccentric mode compared to the concentric mode.

The following parameters are also evaluated: the variations in the level of pain, the parameters of walking (maximum speed over 10 and 200 meters, analysis on a computerized Gaitrite™ treadmill), static equilibrium (on a FUSYO™ force platform), and the functional status of the patient using the Western Ontario and MacMaster Universities osteoarthritis index (WOMAC) questionnaire after the strengthening period and at 6 months.

Discussion

A better knowledge of the most effective mode of muscular strengthening is needed to optimize the functional benefits to the patients. In case of superiority in terms of efficacy of the eccentric mode, the latter could be given priority in the rehabilitation treatment of knee osteoarthritis patients.

Trial registration

Clinical trials.gov number: NCT01586130.

Acute resistance exercise and pressure pain sensitivity in knee osteoarthritis: a randomised crossover trial

OBJECTIVE

To determine whether a single bout of resistance exercise produces an analgesic effect in individuals with knee osteoarthritis (OA).

DESIGN

Eleven participants with knee OA (65.9 ± 10.4 yrs), and 11 old (61.3 ± 8.2 yrs) and 11 young (25.0 ± 4.9 yrs) healthy adults performed separate bouts of upper and lower body resistance exercise. Baseline and post-exercise pressure pain thresholds were measured at eight sites across the body and pressure pain tolerance was measured at the knee.

RESULTS

Pressure pain thresholds increased following exercise for all three groups, indicating reduced pain sensitivity. For the young and old healthy groups this exercise-induced analgesia (EIA) occurred following upper or lower body resistance exercise. In contrast, only upper body exercise significantly raised pain thresholds in the knee OA group, with variable non-significant effects following lower body exercise. Pressure pain tolerance was unchanged in all groups following either upper or lower body exercise.

CONCLUSION

An acute bout of upper or lower body exercise evoked a systemic decrease in pain sensitivity in healthy individuals irrespective of age. The decreased pain sensitivity following resistance exercise can be attributed to changes in pain thresholds, not pain tolerance. While individuals with knee OA experienced EIA, a systemic decrease in pain sensitivity was only evident following upper body exercise.

Longitudinal sensitivity to change of MRI-based muscle cross-sectional area versus isometric strength analysis in osteoarthritic knees with and without structural progression: pilot data from the Osteoarthritis Initiative

OBJECT

Biomechanical measurement of muscle strength represents established technology in evaluating limb function. Yet, analysis of longitudinal change suffers from relatively large between-measurement variability. Here, we determine the sensitivity to change of magnetic resonance imaging (MRI)-based measurement of thigh muscle anatomical cross sectional areas (ACSAs) versus isometric strength in limbs with and without structural progressive knee osteoarthritis (KOA), with focus on the quadriceps.

MATERIALS AND METHODS

Of 625 "Osteoarthritis Initiative" participants with radiographic KOA, 20 had MRI cartilage and radiographic joint space width loss in the right knee isometric muscle strength measurement and axial T1-weighted spin-echo acquisitions of the thigh. Muscle ACSAs were determined from manual segmentation at 33% femoral length (distal to proximal).

RESULTS

In progressor knees, the reduction in quadriceps ACSA between baseline and 2-year follow-up was -2.8 ± 7.9 % (standardized response mean [SRM] = -0.35), and it was -1.8 ± 6.8% (SRM = -0.26) in matched, non-progressive KOA controls. The decline in extensor strength was more variable than that in ACSAs, both in progressors (-3.9 ± 20%; SRM = -0.20) and in non-progressive controls (-4.5 ± 28%; SRM = -0.16).

CONCLUSION

MRI-based analysis of quadriceps muscles ACSAs appears to be more sensitive to longitudinal change than isometric extensor strength and is suggestive of greater loss in limbs with structurally progressive KOA than in non-progressive controls.

Efficacy of strength and aerobic exercise on patient-reported outcomes and structural changes in patients with knee osteoarthritis: study protocol for a randomized controlled trial

BACKGROUND

Despite an extensive literature on treatment interventions for patients with knee osteoarthritis, studies comparing the efficacy of different exercise interventions and living the life as usual on quality of life, cartilage quality and cost-effectiveness are lacking. The aim of the present study is to compare the efficacy of two different exercise programs compared to a control group in individuals with established radiographic and symptomatic knee osteoarthritis on self-reported knee-related quality of life, knee pain, physical function, and cartilage quality.

METHODS/DESIGN

A three-armed randomized controlled trial involving two exercise interventions and a control group of individuals doing as they usually do is described. The patients will have mild to moderate radiographic osteoarthritis according to the Kellgren and Lawrence classification (grade 2-3), and fulfill the American College of Rheumatology clinical criteria, be aged between 45 and 65 years, and have no other serious physical or mental illnesses. The patients will be randomly allocated to a strength exercise group; a cycling group, or a control group. The primary outcome is the Knee injury and Osteoarthritis Outcome Score knee-related quality of life subscale. Secondary outcomes include all five Knee Injury and Osteoarthritis Outcome Score subscales, morphological evaluation of cartilage including focal thickness, subchondral bone marrow edema, proteoglycan content and collagen degradation (measured using magnetic resonance imaging clinical sequences, T2 mapping and T1ρ), specific serum biomarkers, isokinetic muscle strength, maximal oxygen uptake, quality of life (EuroQol 5D), and self-efficacy (Arthritis Self-Efficacy Scale). A sample size calculation on the primary outcome showed that 207 individuals, 69 in each group, is needed to detect a clinically relevant difference of 10 points with 80% power and a significance level of 5%. Assessments will be conducted at baseline, 14 weeks, 1 year and 2 years post-randomization. The interventions will be a 14 weeks exercise program.

DISCUSSION

Although exercise therapy has been found to be effective in knee osteoarthritis, the knowledge of the underlying mechanisms for why exercise works is lacking. This study will contribute with knowledge on the efficacy of strength exercise versus cycling on patient-reported outcomes, cartilage quality and cost-effectiveness.

TRIAL REGISTRATION

Clinicaltrial.gov Identifier: NCT01682980.

Baseline and longitudinal change in isometric muscle strength prior to radiographic progression in osteoarthritic and pre-osteoarthritic knees--data from the Osteoarthritis Initiative

OBJECTIVE

To test whether cross-sectional or longitudinal measures of thigh muscle isometric strength differ between knees with and without subsequent radiographic progression of knee osteoarthritis (KOA), with particular focus on pre-osteoarthritic female knees (knees with risk factors but without definite radiographic KOA).

METHODS

Of 4,796 Osteoarthritis Initiative participants, 2,835 knees with Kellgren Lawrence grade (KLG) 0-3 had central X-ray readings, annual quantitative joint space width (JSW) and isometric muscle strength measurements (Good strength chair). Separate slope analysis of covariance (ANCOVA) models were used to determine differences in strength between "progressor" and "non-progressor" knees, after adjusting for age, body mass index, and pain.

RESULTS

466 participant knees exceeded the smallest detectable JSW change during each of two observation intervals (year 2→4 and year 1→3) and were classified as progressors (213 women, 253 men; 128 KLG0/1, 330 KLG2/3); 946 participant knees did not exceed this threshold in either interval and were classified as non-progressors (588 women, 358 from men; 288KLG0/1, 658KLG2/3). Female progressor knees, including those with KLG0/1, tended to have lower extensor and flexor strength at year 2 and at baseline than those without progression, but the difference was not significant after adjusting for confounders. No significant difference was observed in longitudinal change of muscle strength (baseline→year 2) prior to radiographic progression. No significant differences were found for muscle strength in men, and none for change in strength concomitant with progression.

CONCLUSION

This study provides no strong evidence that (changes in) isometric muscle strength precedes or is associated with structural (radiographic) progression of KOA.

Side differences of thigh muscle cross-sectional areas and maximal isometric muscle force in bilateral knees with the same radiographic disease stage, but unilateral frequent pain - data from the osteoarthritis initiative

OBJECTIVE

To determine whether anatomical thigh muscle cross-sectional areas (MCSAs) and strength differ between osteoarthritis (OA) knees with frequent pain compared with contra-lateral knees without pain, and to examine the correlation between MCSAs and strength in painful vs painless knees.

METHODS

Forty-eight subjects (31 women; 17 men; age 45-78 years) were drawn from 4,796 Osteoarthritis Initiative (OAI) participants, in whom both knees displayed the same radiographic stage (KLG2 or 3), one with frequent pain (most days of the month within the past 12 months) and the contra-lateral one without pain. Axial MR images were used to determine MCSAs of extensors, flexors and adductors at 35% femoral length (distal to proximal) and in two adjacent 5 mm images. Maximal isometric extensor and flexor forces were used as provided from the OAI database.

RESULTS

Painful knees showed 5.2% lower extensor MCSAs (P=0.00003; paired t-test), and 7.8% lower maximal extensor muscle forces (P=0.003) than contra-lateral painless knees. There were no significant differences in flexor forces, or flexor and adductor MCSAs (P>0.39). Correlations between force and MCSAs were similar in painful and painless OA knees (0.44<r<0.66).

CONCLUSIONS

Knees with frequent pain demonstrate lower MCSAs and force of the quadriceps (but not of other thigh muscles) compared with contra-lateral knees without knee pain with the same radiographic stage. Frequent pain does not appear to affect the correlations between MCSAs and strength in OA knees. The findings suggest that quadriceps strengthening exercise may be useful in treating symptomatic knee OA.

Effects of progressive resistance strength training on knee biomechanics during single leg step-up in persons with mild knee osteoarthritis

BACKGROUND

The goal of this study was to determine if increasing strength in primary knee extensors and flexors would directly affect net knee joint moments during a common functional task in persons with knee osteoarthritis.

METHODS

An exploratory single sample clinical trial with pre-post treatment measures was used to study volunteers with clinical diagnosis of mild knee osteoarthritis (OA) in one knee. Subjects participated in an individually supervised training program 3 times a week for eight weeks consisting of progressive resistive exercises for knee extensors and knee flexors. Pre and post training outcome assessments included: 1. Net internal knee joint moments, 2. Electromyography of primary knee extensors and flexors, and 3. Self-report measures of knee pain and function. The distribution of lower extremity joint moments as a percent of the total support moment was also investigated.

FINDINGS

Pain, symptoms, activities of daily life, quality of life, stiffness, and function scores showed significant improvement following strength training. Knee internal valgus and hip internal rotation moments showed increasing but non-statistically significant changes post-training. There were no significant differences in muscle co-contraction activation of the Quadriceps and Hamstrings.

INTERPRETATION

While exercise continues to be an important element of OA management, the results of this study suggest improvements in function, pain, and other symptoms, as a result of strength training may not be causally related to specific biomechanical changes in net joint moments.

Diet and exercise for obese adults with knee osteoarthritis

Osteoarthritis (OA) is a common chronic disease and there is a need for treatments that can be provided for the course of the disease with minimal adverse side effects. Exercise is a safe intervention in patients with knee OA with few contraindications or adverse events. Obesity is the most modifiable risk factor for knee OA. The mechanisms by which obesity affects OA are of great concern to researchers and clinicians who manage this disease. This article reviews the physiologic and mechanical consequences of obesity and exercise on older adults with knee OA, the effects of long-term weight loss and exercise interventions, and the utility and feasibility of translating these results to clinical practice.