Knee extensor strength gains mediate symptom improvement in knee osteoarthritis: secondary analysis of a randomised controlled trial

A network pharmacology-based study to investigate the mechanism of curcumin-regulated regenerative repair of quadriceps femoris muscle in KOA rats

BACKGROUND

Knee osteoarthritis (KOA) is a very common musculoskeletal disorder, and patients with KOA often exhibit significant quadriceps femoris muscle atrophy. It is well established that curcumin (CUR) exerts protective effects on skeletal muscle. However, the efficacy of CUR in treating KOA-induced quadriceps femoris muscle atrophy and its underlying mechanisms remain uncertain. In this study, we employed network pharmacology to investigate the mechanism by which CUR promotes regenerative repair of the quadriceps femoris muscle in rats with KOA.

METHODS

The potential targets of CUR were obtained from Swiss Target Prediction. The targets of skeletal muscle regeneration were identified from GeneCard and OMIM. A Venn diagram was generated to visualize the intersection of CUR targets and skeletal muscle regeneration targets, and the core targets were identified using STRING. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses were conducted using DAVID. Finally, the network pharmacology results were further validated by establishing a KOA rat model using the Hulth method.

RESULTS

Network pharmacology analysis and molecular docking results revealed that CUR affects skeletal muscle regeneration through multiple targets and pathways. In vivo experimental results were validated by demonstrating that KOA causes atrophy and induces apoptosis in the quadriceps femoris muscle. Furthermore, CUR was shown to inhibit apoptosis in the quadriceps femoris muscle by regulating STAT3 and FOS, as well as the PI3K/AKT signaling pathway.

CONCLUSIONS

Our study revealed the apoptosis-inhibiting effects of CUR and its underlying mechanisms. Consequently, CUR has the potential to improve quadriceps femoris muscle atrophy caused by KOA.

The control group matters: Pain, physical function and strength improvements relative to the comparator intervention in knee and hip osteoarthritis

BACKGROUND

In knee and hip osteoarthritis (OA), the mechanism for resistance exercise improving clinical outcomes and the dose-response between strength and clinical outcomes are unknown; in part due to inconsistent trial designs across studies.

PURPOSE

To determine whether the effects of resistance exercise interventions on pain and function differ based on comparator group; and whether there is an association between improvements in lower extremity strength with improvements in pain and function in knee and hip OA.

METHODS

We searched 6 databases (inception to January 28 2023,) for randomized controlled trials (RCTs) comparing land-based, resistance exercise-only interventions with no intervention or any other intervention. There were four subgroups for comparator intervention: NONE (none/placebo/sham/usual care), EXE (other exercise interventions alone), NONEXE (non-exercise interventions alone), COMBO (combined exercise + non-exercise interventions). The between-group effect (ES) was calculated for immediate post-intervention pain and function (activities of daily living (ADL) and sports/recreation (SPORT)). Meta-regression analyses were completed to evaluate the association between improvements in lower extremity strength (independent variable) and improvements in pain, ADL and SPORT (dependent variables), irrespective of comparator intervention.

RESULTS

For knee OA (257 studies), there were large benefits for pain [ES (95 % CI) = -0.92 (-1.15, -0.69)], ADL [-0.79 (-1.01, -0.56)] and SPORT [-0.79 (-1.02, -0.56)] favouring resistance exercise interventions compared to NONE. For knee pain, there was also a moderate benefit favouring COMBO interventions compared to resistance exercise interventions [0.44 (0.23, 0.65)]. For hip OA (15 studies), there were moderate benefits for pain [-0.51 (-0.68, -0.33)], ADL [-0.57 (-0.78, -0.36)] and SPORT [-0.52 (-0.70, -0.35)] favouring exercise interventions compared to NONE. For hip pain, there was also a moderate benefit favouring NONEXE interventions compared to resistance exercise interventions [0.57 (0.17, 0.97)]. For knee OA, greater strength gains were associated with larger improvements in pain [β (95 % CI) = -0.24 (-0.38, -0.09)], ADL [-0.43 (-0.73, -0.12)] and SPORT [-0.37 (-0.73, -0.00)].

CONCLUSION

In knee and hip OA, the effects of resistance exercise on pain and function improvements depend on the comparator intervention. For knee OA, a dose-response relationship was observed between lower extremity strength gains with pain and function improvements.

The effect of resistance training on patients with knee osteoarthritis: a systematic review and meta-analysis

The objective of this study is to investigate the beneficial effects of resistance training (RT) on individuals suffering from knee osteoarthritis (KOA). In order to gather relevant studies from the beginning of various databases until January 2023, a comprehensive search was conducted on PubMed, Embase, Scopus, Web of Science, and The Cochrane Library. Additionally, manual searches were performed on the reference lists. The association between RT and KOA was analysed using a random-effects model. The results indicated that patients with KOA who underwent RT experienced a significant reduction in the WOMAC (Western Ontario and McMaster Universities Osteoarthritis) Pain index (WMD = -2.441; 95% CI = -3.610 to -1.273; p < 0.01), the WOMAC Stiffness index (WMD = -1.018; 95% CI = -1.744 to -0.293; p < 0.01), the WOMAC Function index (WMD = -7.208; 95% CI = -10.412 to -4.004; p < 0.01), and the VAS (Visual Analogue Scale) index (WMD = -5.721; 95% CI = -9.320 to -2.121; p < 0.01). These improvements were observed when compared to the control group. However, no significant difference was found in the 6-MWT (6-Minute Walk Test) index between the two groups (WMD = 2.659; 95% CI= -16.741 to 22.058; p = 0.788). Consequently, RT has the potential to positively enhance pain, stiffness, and function in patients with KOA, while the 6-MWT index may not exhibit significant improvement.

Effects of Long-Term Walking Exercise on Structural Progression, Symptoms, and Extensor Muscle Strength in Patients With Mild or at High Risk of Knee Osteoarthritis: Data From the Osteoarthritis Initiative

OBJECTIVE

The aim of the study is to assess the relationship between walking exercise and medial joint space narrowing progression, symptoms, and knee extensor muscle strength in early knee osteoarthritis patients.

METHODS

This nested cohort study within the Osteoarthritis Initiative included participants aged 50 yrs and older with knee osteoarthritis (Kellgren-Lawrence grades 0-2). Walking exercisers were identified using a modified Historical Physical Activity Survey Instrument. Differences in medial joint space narrowing, Knee Injury and Osteoarthritis Outcome Score, and knee extensor muscle strength were evaluated through the three-way analysis of variance.

RESULTS

Among 896 participants, 83.4% reported walking exercise. Female walkers showed significant improvements in symptoms (Knee Injury and Osteoarthritis Outcome Score-pain: P < 0.001; Knee Injury and Osteoarthritis Outcome Score-symptom: P < 0.001; Knee Injury and Osteoarthritis Outcome Score-quality of life: P < 0.001; Knee Injury and Osteoarthritis Outcome Score-function, sports, and recreational activities: P = 0.007). Similar results were observed in male walkers (Knee Injury and Osteoarthritis Outcome Score-pain: P < 0.001; Knee Injury and Osteoarthritis Outcome Score-symptom: P < 0.001; Knee Injury and Osteoarthritis Outcome Score-quality of life: P = 0.001; Knee Injury and Osteoarthritis Outcome Score-function, sports, and recreational activities: P = 0.009). Walkers showed significantly increased knee extensor muscle strength at 24 mos (female: P < 0.001; male: P = 0.003). Female nonwalkers had significantly decreased knee extensor muscle strength at 24 mos ( P < 0.001). Walkers showed significant improvement in medial joint space narrowing (odds ratio = 1.1, 95% confidence interval = 1.0-1.2) and Kellgren-Lawrence grade (OR = 1.0, 95% CI = 1.0-1.1) compared with nonwalkers.

CONCLUSIONS

Walking exercise prevents structural progression and improves symptoms. Meanwhile, the increased knee extensor muscle strength in all walkers further supports the validity of recommending walking exercises for early-stage knee osteoarthritis patients.

How Do Muscle Function and Quality Affect the Progression of KOA? A Narrative Review

Knee osteoarthritis (KOA) is widely recognized as a chronic joint disease characterized by degeneration of knee cartilage and subsequent bone hyperplasia. However, it is important to acknowledge the significant role of muscles in the development and progression of KOA. Muscle function (MF) and muscle quality (MQ) are key factors in understanding the involvement of muscles in KOA. Quantitative indices such as muscle mass, muscle strength, muscle cross-sectional area, muscle thickness, and muscle fatigue are crucial in assessing MF and MQ. Despite the growing interest in KOA, there is a scarcity of studies investigating the relationship between muscles and this condition. This review aims to examine the commonly used indices and measurement methods for assessing MF and MQ in clinical settings, while also exploring the association between muscles and KOA. Furthermore, this article highlights the importance of restoring MF and MQ to enhance symptom management and improve the quality of life for patients with KOA.

Mediators of the effects of exercise and manual therapy for people with knee and hip osteoarthritis: A secondary, exploratory analysis of the MOA trial

Objective

To explore whether pain beliefs and functional strength mediate the treatment effect of manual therapy (MT) and exercise therapy (ET) on the Western Ontario and McMaster Osteoarthritis Index (WOMAC) composite scores and its subscales in individuals with hip and/or knee osteoarthritis in the MOA trial.

Design

Secondary analysis of a randomised controlled trial that compared the incremental effects of supervised MT and ET in addition to usual care in patients with osteoarthritis of the hip or knee. 206 participants enrolled in the MOA trial were analysed. The primary outcome measure was the WOMAC composite score after 1 year.

Results

Pain belief mediated the effect of MT (b: -10.7, 95 ​% CI: -22.3, -0.9), ET (b: -14.5 95%CI: -26.0, -4.4). Functional strength did not mediate the effect of MT, ET, or MT ​+ ​ET. Mediation sensitivity analyses suggest findings are likely to change if small confounding between those mediators and WOMAC composite score is present.

Conclusions

We identified possible mediators of MT and ET. Future confirmatory studies could be designed to assess the mechanisms through which manual therapy and exercise cause improvements in pain and function scores in patients with hip or knee osteoarthritis.

Does Walking Have an Association with Osteoarthritis? A Two-Sample Mendelian Randomization Analysis

Objective

Osteoarthritis (OA) is one of the major disabling human diseases. The related studies indicate a potential correlation between walking and OA. However, there is still a lack of evidence in genetics to support the correlation between walking and OA. Therefore, this study aimed to explore the relationship between walking and OA at the genetic level.

Methods

The publicly available Genome Wide Association Study (GWAS) data were used, with inverse variance weighting (IVW, the random-effects model) as the main analysis method, whereas MR-Egger, Weighted median, Simple mode, and Weighted mode as the secondary analysis methods. In addition, Cochran's Q test, pleiotropy test, and MR-Egger intercept test were conducted to examine the heterogeneity and pleiotropy of the outcome.

Results

In the MR analysis, IVW results showed a negative correlation between types of physical activity in last 4 weeks: Walking for pleasure (not as a means of transport) and OA (KOA or HOA) (odds ratio (OR) = 0.3224, 95% confidence interval (CI): 0.1261 to 0.8243), and the difference was of statistical significance (P = 0.0181). Moreover, IVW results also revealed a negative correlation between types of physical activity in last 4 weeks: Walking for pleasure (not as a means of transport) and KOA (OR = 0.1396, 95% CI: 0.0484 to 0.4026), and the difference was statistically significant (P = 0.0003). However, IVW results did not demonstrate any statistical significance types of physical activity in last 4 weeks: Walking for pleasure (not as a means of transport) and HOA (OR = 1.2075, 95% CI: 0.1978 to 7.3727, P = 0.8381).

Conclusion

From genetic studies, types of physical activity in last 4 weeks: Walking for pleasure (not as a means of transport) is negatively correlated with knee osteoarthritis (KOA), but there is no clear evidence supporting its correlation with hip osteoarthritis (HOA).

The effect of attending rehabilitation after traumatic knee joint injury on femoral articular cartilage morphology in collegiate rugby players with a history of intracapsular knee joint injury during two-year consecutive rugby seasons

Introduction

This present study aimed to compare ultrasonographic measures of femoral articular cartilage during two-year seasons between collegiate rugby players who have attended supervised rehabilitation following intracapsular knee joint injury and those without a history of knee injury.

Methods

Using a prospective observational study design, 12 male collegiate rugby players with a previous history of intracapsular knee joint injury who have received and completed supervised rehabilitation following their injury and 44 players without knee joint injury participated in this study. Ultrasonographic images were used to verify changes in femoral articular cartilage thickness and cross-sectional area (CSA) with or without a previous history of knee joint injury over two consecutive rugby seasons.

Results

Significant time main effects were observed for the lateral condylar thickness (p < 0.001), the intercondylar thickness (p = 0.001), the medial condylar thickness (p < 0.001), and CSA (p < 0.001). No significant interactions nor group main effects were identified for all femoral articular cartilage (p < 0.05).

Conclusions

Collegiate rugby players demonstrated a decrease in femoral articular cartilage thickness and CSA over two-year consecutive rugby seasons. These findings indicate that engaging in collegiate rugby induces alterations in femoral articular cartilage structure. Furthermore, there were no differences in all femoral cartilage outcome measures between rugby players with and without a previous history of traumatic knee joint injury. Therefore, attending supervised rehabilitation at the time of their knee joint injury appeared to reduce the impact of a previous history of intracapsular knee joint injury on the change in femoral articular cartilage thickness and CSA among active rugby players.

"Restoring That Faith in My Shoulder": A Qualitative Investigation of How and Why Exercise Therapy Influenced the Clinical Outcomes of Individuals With Rotator Cuff-Related Shoulder Pain

OBJECTIVE

Rotator cuff-related shoulder pain (RCRSP) is the most common form of shoulder pain. Exercise therapy is a first-line recommended treatment for RCRSP. However, the causal mechanisms underpinning the benefits of exercise for RCRSP are not well understood. Moreover, how individuals with lived experience of RCRSP believe exercise helped or did not help them is unknown. This study aimed to gain insights into how individuals with RCRSP believe exercise influenced their shoulder pain and identify the clinical conditions that promoted or inhibited their beliefs.

METHODS

This qualitative study was underpinned by a critical realist approach to thematic analysis. Participants were recruited using hybrid purposive and convenience sampling techniques. Each participant attended an online semi-structured interview. The data were coded by 2 members of the research team (J.K.P. and N.C.) and verified by a third (B.S.). Recruitment continued until theoretical sufficiency was achieved. Participants reviewed and validated preliminary causal explanations.

RESULTS

Three causal explanations were consistently expressed by 11 participants to explain the benefits of exercise therapy: (1) shoulder strength; (2) changes to psychoemotional status; and (3) exercise has widespread health effects. However, the activation of these causal mechanisms depended on (1) the presence of a strong therapeutic relationship; (2) the provision of a structured and tailored exercise program; and (3) experiencing timely clinical progress.

CONCLUSION

Participants believed exercise improved their shoulder pain through associated health benefits, improved shoulder strength, and psychoemotional variables. Whether an exercise program was able to cause a clinical improvement for an individual with RCRSP was contingent on clinical contextual features. Thus, the clinical context that an exercise program is delivered within may be just as important as the exercise program itself.

IMPACT

Exercise is a recommended first-line intervention to manage RCRSP. The results of this study suggest that a positive experience and outcome with exercise for RCRSP is contingent on several clinical contextual features, such as a strong therapeutic relationship. The clinical context that an exercise program is prescribed and delivered within should be considered by clinicians.

Effects of basic body awareness therapy on pain, balance, muscle strength and functionality in knee osteoarthritis: a randomised preliminary trial

PURPOSE

This study aimed to investigate the effects of basic body awareness therapy (BBAT) on pain, balance, muscle strength, and functionality in knee OA.

METHODS

Forty patients (mean age: 55.20 ± 6.40 years) with knee OA were randomly assigned to experimental and control groups. Both groups participated in a home-based exercise programme. The home-based exercise programme was performed daily for 6 weeks. In addition to the home-based programme, patients in the experimental group participated in BBAT 3 days a week for 6 weeks. The visual analogue scale, fall risk assessment, single-leg stability test, knee extension muscle strength, five times sit-to-stand test, joint range of motion assessment, Western Ontario and McMaster Universities Osteoarthritis Index, 6-minute walk test, and stair climb test were performed at baseline and after 6 weeks.

RESULTS

All outcomes in the experimental group significantly improved after 6 weeks (p < 0.05). There were significant differences between the two groups in terms of the experimental group in muscle strength (p = 0.018, η2= 0.191), five times sit-to-stand test (p < 0.001, η2= 0.510), and the stair climbing test (p = 0.012, η2=0.212).

CONCLUSION

This study showed that BBAT, in addition to a home-based exercise programme, can improve muscle strength and functionality in patients with knee OA.

CLINICAL TRIAL REGISTRATION NUMBER

NCT04165187.

How Does Exercise, With and Without Diet, Improve Pain and Function in Knee Osteoarthritis? A Secondary Analysis of a Randomized Controlled Trial Exploring Potential Mediators of Effects

OBJECTIVE

To explore the mediators of effects of two 6-month telehealth-delivered exercise programs, including exercise with and without weight-loss diet, on pain and function improvements in knee osteoarthritis (OA).

METHODS

Secondary analysis of 345 participants from a 3-arm randomized controlled trial of exercise (Exercise program) and exercise plus diet (Diet + Exercise program) versus information (Control program) was conducted. Outcomes were changes in pain (11-point numeric rating scale) and function (Western Ontario and McMaster Universities Osteoarthritis Index [score range 0-68]) at 12 months. Potential mediators were change at 6 months in attitudes toward self-management, fear of movement, arthritis self-efficacy, weight, physical activity, and willingness for knee surgery. For the Diet + Exercise program versus the Exercise program, only change in weight was evaluated.

RESULTS

Possible mediators of the Exercise program versus the Control program included reduced fear of movement (accounting for -1.11 units [95% confidence interval (95% CI) -2.15, -0.07] improvement in function) and increased arthritis self-efficacy (-0.40 units [95% CI -0.75, -0.06] reduction in pain, -1.66 units [95% CI -3.04, -0.28] improvement in function). The Diet + Exercise program versus the Control program mediators included reduced fear of movement (-1.13 units [95% CI -2.17, -0.08] improvement in function), increased arthritis self-efficacy (-0.77 units [95% CI -1.26, -0.28] reduction in pain, -5.15 units [95% CI -7.34, -2.96] improvement in function), and weight loss (-1.20 units [95% CI -1.73, -0.68] reduction in pain, -5.79 units [95% CI -7.96, -3.63] improvement in function). Weight loss mediated the Diet + Exercise program versus the Exercise program (-0.89 units [95% CI -1.31, -0.47] reduction in pain, -4.02 units [95% CI -5.77, -2.26] improvement in function).

CONCLUSION

Increased arthritis self-efficacy, reduced fear of movement, and weight loss may partially mediate telehealth-delivered exercise program effects, with and without diet, on pain and/or function in knee OA. Weight loss may partially mediate the effect of diet and exercise compared to exercise alone.

The association between knee muscle performance and clinical outcomes of knee function 1-4 years after a sport-related knee joint injury

OBJECTIVE

Estimate the association between index leg knee muscle strength and rate of torque development (RTD), and self-reported and performance-based (i.e., hop) knee function in persons 1-4 years after a sport-related knee joint injury.

METHODS

Data were collected at baseline of a clinical trial. Assessments included the Knee injury and Osteoarthritis Outcome Score Sport & Recreation subscale (KOOSsport), 6-m timed hop (TH), and peak concentric isokinetic knee extensor and flexor torque and isometric RTD. Associations between peak torque and RTD with KOOSsport and TH were assessed using multivariable regression with nonlinear transformations.

RESULTS

53 participants (64.2% female) were included. Knee extensor peak torque was nonlinearly related to TH time, with a strong inverse relationship at lower torque values that changed as torque increased. Results were inconsistent for flexor peak torque, extensor RTD and flexor RTD, with inconsistencies in relationship shape and estimates of association between primary and sensitivity analyses. There was no association between strength/RTD and KOOSsport.

CONCLUSION

There was a nonlinear relationship between knee extensor strength and hop function, with lower strength being associated with a stronger relationship. As strength values increased, the relationship attenuated. Knee extensor and flexor strength, or RTD, were not associated with self-reported function.

Home-Based Remote Rehabilitation Leads to Superior Outcomes for Older Women With Knee Osteoarthritis: A Randomized Controlled Trial

OBJECTIVES

To examine the effects of a home-based lower-extremity strengthening exercise program in community-dwelling older women with knee osteoarthritis.

DESIGN

Randomized controlled trial.

SETTING AND PARTICIPANTS

Women aged ≥60 years with knee osteoarthritis and Kellgren-Lawrence grade 1 or 2 on anteroposterior/lateral radiographs of both knee joints.

METHODS

Patients (n = 36) were randomly divided into experimental (EG) and control (CG) groups. The EG performed home-based remote rehabilitation lower-extremity strengthening exercises for 8 weeks, whereas the CG received no intervention. Assessment was performed at baseline and week 8. The primary outcome was the five-times sit-to-stand test (FTSST) result. Secondary outcomes included timed up-and-go (TUG) test results, knee extensor and flexor strength, quadriceps (rectus femoris) muscle activity, skeletal muscle index, blood pressure (BP), visual analog scale (VAS) scores, C-reactive protein level, and erythrocyte sedimentation rate.

RESULTS

A statistically significant difference in the FTSST times was observed between the groups after 8 weeks of intervention (EG: 7.95 ± 1.08 seconds, CG: 10.01 ± 2.03 seconds, P < .001). In the EG, the TUG test score decreased by 0.75 ± 0.80 seconds (P = .002), right and left knee flexor strength increased by 4.69 ± 6.05 kg (P = .007) and 3.98 ± 6.98 kg (P = .038), respectively, and the right knee extensor root mean square (RMS) ratio increased by 1.24 ± 0.39 (P = .027). Additionally, systolic and diastolic BP decreased by 9.50 ± 10.75 mm Hg (P = .005) and 4.25 ± 4.91 mm Hg (P = .003), respectively. In the CG, the VAS scores decreased by 9.10 ± 13.68 mm (P = .022).

CONCLUSIONS AND IMPLICATIONS

The home-based exercise program using a remote rehabilitation medical device was effective in improving lower extremity strength and function in community-dwelling older women with knee osteoarthritis. This finding suggests that the remote rehabilitation medical device may be used as an alternative to exercise interventions for patients with knee osteoarthritis.

Dose-Response Relationships of Resistance Training in Adults With Knee Osteoarthritis: A Systematic Review and Meta-analysis

BACKGROUND AND PURPOSE

To determine the effects of resistance training (RT) on symptoms, function, and lower limb muscle strength in patients with knee osteoarthritis (KOA), and to determine the optimal dose-response relationships.

DATA SOURCES

We searched the PubMed, MEDLINE, Embase, Cochrane Central Register of Controlled Trials (CENTRAL), Web of Science, and ClinicalTrials.gov databases from inception to January 23, 2022.

ELIGIBILITY CRITERIA

Randomized controlled trials that examined the effects of RT in KOA patients (mean age ≥50 years) were included.

DATA SYNTHESIS

We applied Hedges' g of the random-effects model to calculate the between-subject standardized mean difference (SMDbs). A random-effects metaregression was calculated to explain the influence of key training variables on the effectiveness of RT. We used the Grading of Recommendations Assessments, Development and Evaluation (GRADE) method to appraise the certainty of evidence.

RESULTS

A total of 46 studies with 4289 participants were included. The analysis revealed moderate effects of RT on symptoms and function (SMDbs =-0.52; 95% CI: -0.64 to -0.40), and lower limb muscle strength (SMDbs = 0.53; 95% CI: 0.42 to 0.64) in the intervention group compared with the control group. The results of the metaregression revealed that only the variable "training period" (P< .001) had significant effects on symptoms, function, and lower limb muscle strength, and the 4 to 8 weeks of training subgroup showed greater effects than other subgroups (SMDbs =-0.70, -0.91 to -0.48; SMDbs = 0.76, 0.56 to 0.96).

CONCLUSIONS

Compared with inactive treatments, RT is strongly recommended to improve symptoms, function, and muscle strength in individuals with KOA. Dose-response relationship analysis showed that 4 to 8 weeks of RT had more benefits.

Mechanisms of action of therapeutic exercise for knee and hip OA remain a black box phenomenon: an individual patient data mediation study with the OA Trial Bank

OBJECTIVES

To evaluate mediating factors for the effect of therapeutic exercise on pain and physical function in people with knee/hip osteoarthritis (OA).

METHODS

For Subgrouping and TargetEd Exercise pRogrammes for knee and hip OsteoArthritis (STEER OA), individual participant data (IPD) were sought from all published randomised controlled trials (RCTs) comparing therapeutic exercise to non-exercise controls in people with knee/hip OA. Using the Counterfactual framework, the effect of the exercise intervention and the percentage mediated through each potential mediator (muscle strength, proprioception and range of motion (ROM)) for knee OA and muscle strength for hip OA were determined.

RESULTS

Data from 12 of 31 RCTs of STEER OA (1407 participants) were available. Within the IPD data sets, there were generally statistically significant effects from therapeutic exercise for pain and physical function in comparison to non-exercise controls. Of all potential mediators, only the change in knee extension strength was statistically and significantly associated with the change in pain in knee OA (β -0.03 (95% CI -0.05 to -0.01), 2.3% mediated) and with physical function in knee OA (β -0.02 (95% CI -0.04 to -0.00), 2.0% mediated) and hip OA (β -0.03 (95% CI -0.07 to -0.00), no mediation).

CONCLUSIONS

This first IPD mediation analysis of this scale revealed that in people with knee OA, knee extension strength only mediated ±2% of the effect of therapeutic exercise on pain and physical function. ROM and proprioception did not mediate changes in outcomes, nor did knee extension strength in people with hip OA. As 98% of the effectiveness of therapeutic exercise compared with non-exercise controls remains unexplained, more needs to be done to understand the underlying mechanisms of actions.

Mechanisms hypothesized for pain-relieving effects of exercise in fibromyalgia: a scoping review

Background

Exercise is one of the most recommended management strategies by treatment guidelines for fibromyalgia (FM); however, the mechanism through which exercise improves pain in FM is still unknown.

Objective

We aimed to summarize the hypothesized theoretical mechanisms for the pain-relieving effects of exercise in people with FM.

Eligibility Criteria

Randomized controlled trials (RCTs) in English reporting mechanisms for pain-relieving effects of exercise in the 'Introduction' and 'Discussion' sections and significant within- group or between-group effects of exercise interventions were included.

Sources of Evidence

We searched the databases Ovid MEDLINE(R), EMBASE, CINAHL, COCHRANE, Sports Discuss, and AMED with the keywords: exercise and fibromyalgia until December 2021.

Charting Methods

Two authors independently performed title/abstract, full-text review, and data abstraction using a data abstraction form. The hypothesized mechanisms from individual studies were grouped into three categories.

Results

The literature search resulted in 2147 studies, out of which 220 studies were considered for full-text review. A total of 50 RCTs proposing 29 unique mechanisms for the pain-relieving effects of exercise were included. These mechanisms were divided into three categories: physical, neuro-physiological, and psychological. The neuro-physiological category was further subdivided into exercise-induced hypoalgesia (EIH), pain sensitization, the autonomic system, the immune system, the endocrine system, and miscellaneous categories. The most frequently hypothesized mechanisms were EIH (n = 15), autonomic modulation (n = 7), improved sleep (n = 6), muscle oxygenation (n = 6), self-efficacy (n = 5), mental health (n = 4), and benefits of the aquatic environment (n = 12). While all exercise interventions involved FM patients, most of the supporting evidence for these mechanisms was cited from previous studies conducted on healthy samples. No studies performed analyses to demonstrate causal associations between the mechanisms and outcomes.

Conclusion

Multiple mechanisms were hypothesized for the positive influence of exercise in people with FM. Future studies using causal analyses, such as mediation analysis, are recommended to validate these mechanisms.

High-Intensity Training for Knee Osteoarthritis: A Narrative Review

Knee osteoarthritis (OA) is the most common joint disease worldwide. Exercise therapy has been identified as a first-line treatment option in patients suffering from knee OA. High-intensity training (HIT) is an innovative exercise modality with potential in improving various disease-related outcomes. The purpose of this review is to explore the impact of HIT on knee OA symptoms and physical functioning. A comprehensive search of scientific electronic databases was conducted to identify articles on the effects of HIT on knee OA. Thirteen studies were included in this review. Ten compared the effects of HIT with those of low-intensity training, moderate-intensity continuous training, or a control group. Three evaluated the effects of HIT alone. Eight reported a decrease in knee OA symptoms (especially pain), and eight reported an increase in physical functioning. HIT was shown to improve knee OA symptoms and physical functioning, but also aerobic capacity, muscle strength, and quality of life with minimal or no adverse events. However, compared with other exercise modalities, no clear superiority of HIT was found. HIT is a promising exercise strategy in patients with knee OA; nonetheless, the actual quality of evidence remains very low, and more high-quality studies are needed to confirm these promising outcomes.

Physiotherapists nearly always prescribe exercise for rotator cuff-related shoulder pain; but why? A cross-sectional international survey of physiotherapists

BACKGROUND AND AIMS

This cross-sectional international survey explored the beliefs of physiotherapists regarding the possible mechanisms of benefit of exercise for rotator cuff-related shoulder pain (RCRSP). Clinical practice guidelines recommend physiotherapists use exercise as a primary treatment to help people with RCRSP, but the explanations provided to patients by physiotherapists regarding its mechanism of effect is unknown.

MATERIALS AND METHODS

Registered physiotherapists were surveyed about 'how and why' they believe exercise provides a clinical benefit for people with RCRSP. Information was also gathered about commonly used exercise types and preferred diagnostic labels. The survey was designed and reported in concordance with Consensus-Based Checklist for Reporting of Survey Studies guidelines.

RESULTS

Four hundred and eighty physiotherapists from forty-nine countries completed the survey. Psychosocial and biomedical mechanisms of exercise were evenly selected by participants. Improving muscle strength, muscle endurance, pain self-efficacy and reducing kinesiophobia, and fear avoidance beliefs were the most common individual mechanisms thought to underpin exercise therapy for RCRSP. Rotator cuff-related shoulder pain was the most commonly used diagnostic label.

DISCUSSION AND CONCLUSION

Physiotherapists hold beliefs regarding exercise mechanisms that is largely concordant with the current evidence base, which is commendable. Future research should consider the patients perspective and consider testing commonly selected mechanisms of exercise, such as shoulder muscle strength, pain self-efficacy and kinesiophobia as possible mediators of recovery.

How Do Nonsurgical Interventions Improve Pain and Physical Function in People With Osteoarthritis? A Scoping Review of Mediation Analysis Studies

OBJECTIVE

Nonsurgical interventions are recommended for osteoarthritis (OA). However, how interventions change pain and physical function is unclear. Therefore, the objectives of this scoping review were to 1) identify what potential mediators of nonsurgical interventions on pain and physical function have been evaluated and 2) summarize the findings according to intervention, joint, and outcome.

METHODS

We searched Medline, Embase, CINAHL, Cochrane Central Register of Controlled Trials, and Scopus databases. Studies were included if they conducted a mediation analysis on a randomized controlled trial evaluating a nonsurgical intervention on OA of any joint. Outcomes were pain and physical function.

RESULTS

Nine knee OA studies, evaluating diet plus exercise, exercise, unloading shoes, high-expectation communication during acupuncture, and telephone-based weight loss plus exercise were identified. Except for weight loss and self-efficacy, putative mediators (knee muscle perfusion/extensor strength/adduction moment, systemic inflammatory biomarkers, physical activity, dietary intake, and pain beliefs) were evaluated by single studies. Ten mediators partially mediated intervention (diet plus exercise, exercise, high-expectation communication) effects on pain and physical function. Eight mediators were common to pain and function (reduced weight, increased knee extensor strength, and increased self-efficacy). Constant knee flexor muscle perfusion partially mediated exercise effects on pain, and knee pain relief partially mediated exercise effects on function.

CONCLUSION

In knee OA, some evidence suggests that the benefits of 1) diet and exercise are mediated through changes in body weight, systemic inflammation, and self-efficacy; 2) exercise is mediated through changes in knee muscle strength and self-efficacy; and 3) high-expectation communication style is mediated through changes in self-efficacy.

Concentric or eccentric physical activity for patients with symptomatic osteoarthritis of the knee: a randomized prospective study

Background:

Knee osteoarthritis–related pain limits physical function and leads to functional disability. Physical activity is one of the central recommendations for the management of knee osteoarthritis. Although concentric muscle activities are often preferred to eccentric ones, the corresponding rationale remains controversial.

Objective:

To explore the effect of a 6-week exercise program on function, pain, and performance in patients with symptomatic knee osteoarthritis.

Methods:

Patients with symptomatic knee osteoarthritis were included in the prospective EX-ART project (Walking performance in osteoARThritic subjects: effect of an ECCentric muscle strengthening program) and randomized in a 6-week rehabilitation program including either eccentric or concentric activities. Metrics of interest chosen as end points measured before and after the rehabilitation were WOMAC score, pain, and muscular performance (quadriceps power P_MAX and contraction strength M_MAX). MRI was also used to assess muscle volume and fat infiltration changes.

Results:

30 patients were included in each group; mean age was 74 (±7.6); 69% were women. At week 6, both groups showed a significant improvement in the WOMAC without difference between the two groups (p = 0.7). No difference between the two groups was identified for the pain reduction (p = 0.7). A significant improvement in the change in P_MAX and M_MAX at high velocity (p = 0.001 and p = 0.002) was observed in the eccentric group only. A vastus medialis hypertrophy was quantified in the eccentric group only (p = 0.002), whereas fat infiltration in the quadriceps muscles was unchanged.

Conclusion:

Physical activity, whether eccentric or concentric, has a benefit on function and pain in patients with symptomatic knee osteoarthritis. A few differences have been identified between the two types of rehabilitation. More particularly, a gain in muscle performance and vastus medialis volume was found with eccentric rehabilitation only.

Registration:

www.ClinicalTrials.gov, registration number NCT03167502.

High-intensity versus low-intensity resistance training in patients with knee osteoarthritis: A randomized controlled trial

OBJECTIVES

To assess whether (i) high-intensity resistance training (RT) leads to increased muscle strength compared to low-intensity RT in patients with knee osteoarthritis (OA); and (ii) RT with vitamin D supplementation leads to increased muscle strength compared to placebo in a subgroup with vitamin D deficiency.

DESIGN

Randomized controlled trial.

SETTING

Outpatient rehabilitation centre.

SUBJECTS

Patients with knee OA.

INTERVENTIONS

12 weeks of RT at high-intensity RT (70-80% of 1-repetition maximum (1-RM)) or low-intensity RT (40-50% of 1-RM) and 24 weeks of vitamin D (1200 International units vitamin D3 per day) or placebo supplementation.

MAIN MEASURES

Primary outcome measure was isokinetic muscle strength. Other outcome measure for muscle strength was the estimated 1-RM. Secondary outcome measures were knee pain and physical functioning.

RESULTS

177 participants with a mean age of 67.6 ± 5.8 years were included, of whom 50 had vitamin D deficiency. Isokinetic muscle strength (in Newton metre per kilogram bodyweight) at start, end and 24 weeks after the RT was 0.98 ± 0.40, 1.11 ± 0.40, 1.09 ± 0.42 in the high-intensity group and 1.02 ± 0.41, 1.15 ± 0.42, 1.12 ± 0.40 in the low-intensity group, respectively. No differences were found between the groups, except for the estimated 1-RM in favour of the high-intensity group. In the subgroup with vitamin D deficiency, no difference on isokinetic muscle strength was found between the vitamin D and placebo group.

CONCLUSIONS

High-intensity RT did not result in greater improvements in isokinetic muscle strength, pain and physical functioning compared to low-intensity RT in knee OA, but was well tolerated. Therefore these results suggest that either intensity of resistance training could be utilised in exercise programmes for patients with knee osteoarthritis. No synergistic effect of vitamin D supplementation and RT was found, but this finding was based on underpowered data.

Knee Pain from Osteoarthritis: Pathogenesis, Risk Factors, and Recent Evidence on Physical Therapy Interventions

For patients presenting knee pain coming from osteoarthritis (OA), non-pharmacological conservative treatments (e.g., physical therapy interventions) are among the first methods in orthopedics and rehabilitation to prevent OA progression and avoid knee surgery. However, the best strategy for each patient is difficult to establish, because knee OA's exact causes of progression are not entirely understood. This narrative review presents (i) the most recent update on the pathogenesis of knee OA with the risk factors for developing OA and (ii) the most recent evidence for reducing knee pain with physical therapy intervention such as Diathermy, Exercise therapy, Ultrasounds, Knee Brace, and Electrical stimulation. In addition, we calculated the relative risk reduction in pain perception for each intervention. Our results show that only Brace interventions always reached the minimum for clinical efficiency, making the intervention significant and valuable for the patients regarding their Quality of Life. In addition, more than half of the Exercise and Diathermy interventions reached the minimum for clinical efficiency regarding pain level. This literature review helps clinicians to make evidence-based decisions for reducing knee pain and treating people living with knee OA to prevent knee replacement.

Test-Retest Reliability of Isokinetic Strength Measurements in Lower Limbs in Elderly

Strength is essential for carrying out the usual activities of daily life. As there is a loss of strength in elderly, many treatments are based on delaying the loss of strength or maintaining it. Isokinetic dynamometry is the gold standard for assessing strength. It is essential that studies are conducted to allow us to identify the reliability of isokinetic strength assessments in older people. This study aimed to test the absolute and relative intra-session reliability of peak torque and work of a concentric knee extension-flexion performed at 60°/s in elderly. Fifty-two elderly subjects performed three repetitions of bilateral concentric knee extension-flexion at 60°/s using an isokinetic dynamometer. The relative and absolute reliability were calculated between the second and third repetition. The intra-class correlation coefficient values were between 0.94 and 0.98 for peak torque and work in all measures, which is considered “excellent”, except for left leg flexors in women, with values between 0.85 and 0.88, which is considered “good”. The standard error of measurement (SEM) percentage oscillated from 3.9% to 10.5%, with a smallest real difference (SRD) percentage of 10.9% to 29.2% for peak torque. The relative reliability of peak torque and work were excellent for all measures except flexors in women, evidencing the utility of isokinetic dynamometry for monitoring lower limb maximal muscle strength and work of concentric knee extension-flexion at 60°/s/s in the elderly. In addition, an SRD > 19.9% in peak torque and an SRD > 23.1% in work is considered a true change.

The preventive and therapeutic role of physical activity in knee osteoarthritis

The aim of this narrative review is to discuss the results of studies investigating the role of physical activity in knee osteoarthritis (OA). We also formulated two evidence-based exercise programs that could be prescribed to patients with symptomatic knee OA or after joint replacement. The PubMed and Google Scholar databases were searched for articles related to knee OA and physical activity. A total of 86 papers written in English and published from 1957 to 2021 were selected. Adapted physical activity, even at high intensity, does not appear to trigger or exacerbate knee OA; on the contrary, it may prevent obesity or lower limb muscle weakness, both of which are considered predisposing factors for the disease. In patients already diagnosed with knee OA, scientific evidence suggests that both land-based and aquatic activities combining aerobics, strength, and endurance programs are safe and effective. Physical interventions tailored to the patient may also accelerate recovery time after knee arthroplasty. Knee OA is a painful and disabling rheumatic disease that is very common in the elderly population. Pharmacotherapy has a modest effect in controlling disease progression, possibly due to the still limited understanding of OA pathogenesis. Non-pharmacologic interventions, including dietary and lifestyle changes and physical activity, may be more effective and safer than drugs in preventing or treating knee OA.

Comparing Video-Based, Telehealth-Delivered Exercise and Weight Loss Programs With Online Education on Outcomes of Knee Osteoarthritis : A Randomized Trial

BACKGROUND

Scalable knee osteoarthritis programs are needed to deliver recommended education, exercise, and weight loss interventions.

OBJECTIVE

To evaluate two 6-month, telehealth-delivered exercise programs, 1 with and 1 without dietary intervention.

DESIGN

3-group, parallel randomized (5:5:2) trial. (Australian New Zealand Clinical Trials Registry: ACTRN12618000930280).

SETTING

Australian private health insurance members.

PARTICIPANTS

415 persons with symptomatic knee osteoarthritis and a body mass index between 28 and 40 kg/m2 who were aged 45 to 80 years.

INTERVENTION

All groups received access to electronic osteoarthritis information (control). The exercise program comprised 6 physiotherapist consultations via videoconference for exercise, self-management advice, and behavioral counseling, plus exercise equipment and resources. The diet and exercise program included an additional 6 dietitian consultations for a ketogenic very-low-calorie diet (2 formulated meal replacements and a low-carbohydrate meal daily) followed by a transition to healthy eating, as well as nutrition and behavioral resources.

MEASUREMENTS

Primary outcomes were changes in knee pain (numerical rating scale [NRS] of 0 to 10, higher indicating worse) and physical function (Western Ontario and McMaster Universities Osteoarthritis Index [WOMAC]; scale, 0 to 68, higher indicating worse) at 6 months (primary time point) and 12 months. Secondary outcomes were weight, physical activity, quality of life, mental health, global change, satisfaction, willingness to have surgery, orthopedic appointments, and knee surgery.

RESULTS

A total of 379 participants (91%) provided 6-month primary outcomes, and 372 (90%) provided 12-month primary outcomes. At 6 months, both programs were superior to control for pain (between-group mean difference in change on NRS: diet and exercise, -1.5 [95% CI, -2.1 to -0.8]; exercise, -0.8 [CI, -1.5 to -0.2]) and function (between-group mean difference in change on WOMAC: diet and exercise, -9.8 [CI, -12.5 to -7.0]; exercise, -7.0 [CI, -9.7 to -4.2]). The diet and exercise program was superior to exercise (pain, -0.6 [CI, -1.1 to -0.2]; function, -2.8 [CI, -4.7 to -0.8]). Findings were similar at 12 months.

LIMITATION

Participants and clinicians were unblinded.

CONCLUSION

Telehealth-delivered exercise and diet programs improved pain and function in people with knee osteoarthritis and overweight or obesity. A dietary intervention conferred modest additional pain and function benefits over exercise.

PRIMARY FUNDING SOURCE

Medibank, the Medibank Better Health Foundation Research Fund, and a National Health and Medical Research Council Centre of Research Excellence.

Expression of Matrix Metalloprotein 13 in Injury Model of Articular Chondrocyte in Rabbits and Analysis of Nano-Drug-Loading System

This study aimed to analyze the application of a responsive nano-drug-loading system in injury model of articular chondrocyte in rabbits, as well as its effect on expression of matrix metalloprotein 13 (MMP13). The nanoprecipitation method was adopted to prepare camptothecin (CPT)-loaded poly ethylene glycol (PEG)-Poly caprolactone (PCL) and PEG-PCL nanoparticles without CPT. Afterward, the above mentioned nano-drug-loaded system was used to treat an in vitro scratch model of articular chondrocytes. According to different treatment plans, they were divided into groups: G0 (administered CPT-PEG-PCL nanomedicine), G1 (administered PEG-PCL drug), G2 (saline control), and G3 (healthy control). Results showed that the drug-loading capacity and efficiency of CPT-PEG-PCL was higher than that of PEG-PCL. The levels of type II collagen and hyaluronic acid in G0 was higher than that in G1 and G2. The levels of type II collagen and hyaluronic acid in G0 were not obviously different from those in G3. The level of MMP13 in G0 was lower than that in G1 and G2 and the level of tissue inhibitor of metalloproteinases 1 (TIMP1) in G0 was higher than that in G1 and G2. The proliferation activity of cells in G0 was higher than that in G1 and G2, but there was no obvious difference when compared with G3. In conclusion, CPT-PEG-PCL has stronger long-term circulation capacity and drug-loading efficiency. It can effectively up-regulate the levels of type II collagen, hyaluronic acid, and TIMP1, as well as reduce the synthesis and secretion of MMP13 and promote the repair of articular cartilage damage.

Effect of low-load resistance training with different degrees of blood flow restriction in patients with knee osteoarthritis: study protocol for a randomized trial

BACKGROUND

Knee osteoarthritis (KOA) is a common degenerative disease that causes pain, functional impairment, and reduced quality of life. Resistance training is considered as an effective approach to reduce the risk of muscle weakness in patients with KOA. Blood flow restriction (BFR) with low-load resistance training has better clinical outcomes than low-load resistance training alone. However, the degree of BFR which works more effectively with low-load resistance training has not been determined. The purpose of this study is to evaluate the effectiveness of different degrees of BFR with low-load resistance training in patients with KOA on pain, self-reported function, physical function performance, muscle strength, muscle thickness, and quality of life.

METHODS

This is a study protocol for a randomized, controlled trial with blinded participants. One hundred individuals will be indiscriminately assigned into the following groups: two training groups with a BFR at 40% and 80% limb occlusion pressure (LOP), a training group without BFR, and a health education group. The three intervention groups will perform strength training for the quadriceps muscles twice a week for 12 weeks, while the health education group will attend sessions once a week for 12 weeks. The primary outcome is pain. The secondary outcomes include self-reported function, physical function performance, muscle strength of the knee extensors, muscle mass of the quadriceps, quality of life, and adverse events. Intention-to-treat analysis will be conducted for individuals who withdraw during the trial.

DISCUSSION

Previous studies have shown that BFR with low-load resistance training is more effective than low-load resistance training alone; however, a high degree of BFR may cause discomfort during training. If a 40% LOP for BFR could produce similar clinical outcomes as an 80% LOP for BFR, resistance training with a low degree of BFR can be chosen for patients with KOA who are unbearable for a high degree of BFR.

TRIAL REGISTRATION

Chinese Clinical Trial Registry ChiCTR2000037859 ( http://www.chictr.org.cn/edit.aspx?pid=59956&htm=4 ). Registered on 2 September 2020.

How Do Hip Exercises Improve Pain in Individuals With Patellofemoral Pain? Secondary Mediation Analysis of Strength and Psychological Factors as Mechanisms

OBJECTIVE

To determine whether the effect of hip exercise on patellofemoral pain is mediated through changes in hip muscle strength or psychological factors.

DESIGN

Secondary mediation analysis of a randomized clinical trial, in which 218 participants with patellofemoral pain were randomly assigned to receive foot orthoses or hip exercises.

METHODS

Pain (Knee injury and Osteoarthritis Outcome Score pain subscale) and number of pain-free squats at 12 weeks were the outcomes for this mediation analysis, as they are pathognomonic of patellofemoral pain. Hip strength dynamometry (abduction, adduction, and external rotation) and psychological characteristics (pain catastrophizing, kinesiophobia, and anxiety) measured at 6 weeks were considered as potential mediators. We used mediation analysis to decompose the total effect of treatment on the outcome into (1) the "indirect effect" (ie, the portion acting through the mediator) and (2) the "direct effect."

RESULTS

The effect of hip exercise on pain and squats was not mediated by any of the strength or psychological mediators analyzed. All indirect effects were small and showed wide 95% confidence intervals (CIs) that contained zero (eg, for pain-free squats: abduction strength, -0.13; 95% CI: -0.49, 0.23; Tampa Scale of Kinesiophobia, -0.17; 95% CI: -0.64, 0.30).

CONCLUSION

Hip strength improved after hip exercise, yet strength did not mediate improvements in pain and pain-free squats, and alternative psychological mediators were not implicated. J Orthop Sports Phys Ther 2021;51(12):602-610. doi:10.2519/jospt.2021.10674.

Loss of Autophagy Causes Increased Apoptosis of Tibial Plateau Chondrocytes in Guinea Pigs with Spontaneous Osteoarthritis

OBJECTIVE

The goal of the present study was to observe the effect of autophagy in tibial plateau chondrocytes on apoptosis in spontaneous knee osteoarthritis (OA) in guinea pigs.

DESIGN

Fifty 2-month-old female Hartley guinea pigs were divided into a normal group (10 animals, all euthanized after 7 months) and an OA group (40 animals, 10 of which were euthanized after 10 months). Immunohistochemistry, RT-qPCR and Western blotting were used to evaluate autophagy levels, intracellular glycogen accumulation and apoptosis in tibial plateau chondrocytes in vivo and in vitro. The remaining 30 guinea pigs in the OA group were divided into 3 groups: a rapamycin group, a normal saline group, and a 3-methyladenine (3-MA) group. Intracellular glycogen accumulation and chondrocyte apoptosis were assessed by altering the level of autophagy in chondrocytes in vivo.

RESULTS

When spontaneous OA occurred in guinea pigs, autophagy levels in tibial plateau chondrocytes decreased, while intracellular glycogen accumulation and the rate of chondrocyte apoptosis increased. After enhancing the level of autophagy in tibial plateau chondrocytes in guinea pigs with OA, intracellular glycogen accumulation and the rate of chondrocyte apoptosis decreased, while inhibiting autophagy had the opposite effects.

CONCLUSION

The results indicate that the function of autophagy in chondrocytes may at least partly involve the catabolism of glycogen. In guinea pigs with OA, the level of autophagy in tibial plateau chondrocytes decreased, and chondrocytes were unable to degrade intracellular glycogen into glucose, leading to less energy for chondrocytes and increased apoptosis.

Choosing what works for whom: towards a better use of mechanistic knowledge in clinical practice

BACKGROUND

Clinicians commonly try to use mechanism-based knowledge to make sense of the complexity and uncertainty of chronic pain treatments to create a rationale for their clinical decision-making. Although this seems intuitive, there are some problems with this approach.

DISCUSSION

The widespread use of mechanism-based knowledge in clinical practice can be a source of confusion for clinicians, especially when complex interventions with different proposed mechanisms of action are equally effective. Although the available mechanistic evidence is still of very poor quality, in choosing from various treatment options for people with chronic pain, an approach that correctly incorporates mechanistic reasoning might aid clinical thinking and practice.

CONCLUSION

By explaining that not all evidence of mechanism is the same and by making a proposal to start using mechanism-based knowledge in clinical practice properly, we hope to help clinicians to incorporate mechanistic reasoning to prioritize and start choosing what may best work for whom.

The Relationship Between Changes in Movement and Activity Limitation or Pain in People With Knee Osteoarthritis: A Systematic Review

OBJECTIVE

To report whether changes in knee joint movement parameters recorded during functional activities relate to change in activity limitation or pain after an exercise intervention in people with knee osteoarthritis (OA).

DESIGN

Etiology systematic review.

LITERATURE SEARCH

Four databases (MEDLINE, Embase, CINAHL, and AMED) were searched up to January 22, 2021.

STUDY SELECTION CRITERIA

Randomized controlled trials or cohort studies of exercise interventions for people with knee OA that assessed change in knee joint movement parameters (moments, kinematics, or muscle activity) and clinical outcomes (activity limitation or pain).

DATA SYNTHESIS

A descriptive synthesis of functional activities, movement parameters, and clinical outcomes.

RESULTS

From 3182 articles, 22 studies met the inclusion criteria, and almost all were of low quality. Gait was the only investigated functional activity. After exercise, gait parameters changed 26% of the time, and clinical outcomes improved 90% of the time. A relationship between group-level changes in gait parameters and clinical outcomes occurred 24.5% of the time. Two studies directly investigated an individual-level relationship, reporting only 1 significant association out of 8 correlations tested.

CONCLUSION

Most studies reported no change in gait-related movement parameters despite improvement in clinical outcomes, challenging the belief that changing movement parameters is always clinically important in people with knee OA. J Orthop Sports Phys Ther 2021;51(10):492-502. doi:10.2519/jospt.2021.10418.

Osteoarthritis Progression: Mitigation and Rehabilitation Strategies

Osteoarthritis is the most common form of arthritis and is a substantial burden for patients with the disease. Currently, there is no cure for osteoarthritis, but many emerging therapies have been developed to aid in the mitigation of disease progression. When osteoarthritis reaches the end-stage of disease many patients undergo total joint arthroplasty to improve quality of life, yet some experience persistent pain and mobility limitations for extended periods following surgery. This review highlights recent therapeutic advancements in osteoarthritis treatment consisting of pharmacologics, nutraceuticals, biologics, and exercise while emphasizing the current state of post-arthroplasty rehabilitation.

Reduced knee extensor torque production at low to moderate velocities in postmenopausal women with knee osteoarthritis

This study aimed to determine deficits in knee extensor muscle function through the torque-time and torque-velocity relationships and whether these deficits are associated with reduced functional performance in postmenopausal women with knee osteoarthritis (KOA). A clinical sample of postmenopausal women with established KOA (n = 18, ≥55 years) was compared to an age-matched healthy control sample (CON) (n = 26). The deficits in different parameters of the knee extensor torque-time (maximal isometric torque and rate of torque development) and torque-velocity relationship (maximum muscle power, maximal velocity and torque at 0-500°·s^-1 ) were assessed through a protocol consisting of isometric, isotonic and isokinetic tests. Functional performance was evaluated with sit-to-stand and stair-climbing tasks using a sensor-based technology (ie, time- and power-based outcomes). Postmenopausal women with KOA showed reduced maximal isometric torque (Hedge's g effect size (g) = 1.05, p = 0.001) and rate of torque development (g = 0.77-1.17, all p ≤ 0.02), combined with impaired torque production at slow to moderate velocities (g = 0.92-1.70, p ≤ 0.004), but not at high or maximal velocities (g = 0.16, p > 0.05). KOA were slower (g = 0.81-0.92, p ≤ 0.011) and less powerful (g = 1.11-1.29, p ≤ 0.001) during functional tasks. Additionally, knee extensor deficits were moderately associated with power deficits in stair climbing (r = 0.492-0.659). To conclude, knee extensor muscle weakness was presented in postmenopausal women with KOA, not only as limited maximal and rapid torque development during isometric contractions, but also dynamically at low to moderate velocities. These deficits were related to impaired functional performance. The assessment of knee extensor muscle weakness through the torque-time and torque-velocity relationships might enable individual targets for tailored exercise interventions in KOA.

Construct validity of the OCTOPuS stratification algorithm for allocating patients with knee osteoarthritis into subgroups

BACKGROUND

We recently developed a model of stratified exercise therapy, consisting of (i) a stratification algorithm allocating patients with knee osteoarthritis (OA) into one of the three subgroups ('high muscle strength subgroup' representing a post-traumatic phenotype, 'low muscle strength subgroup' representing an age-induced phenotype, and 'obesity subgroup' representing a metabolic phenotype) and (ii) subgroup-specific exercise therapy. In the present study, we aimed to test the construct validity of this algorithm.

METHODS

Data from five studies (four exercise therapy trial cohorts and one cross-sectional cohort) were used to test the construct validity of our algorithm by 63 a priori formulated hypotheses regarding three research questions: (i) are the proportions of patients in each subgroup similar across cohorts? (15 hypotheses); (ii) are the characteristics of each of the subgroups in line with their proposed underlying phenotypes? (30 hypotheses); (iii) are the effects of usual exercise therapy in the 3 subgroups in line with the proposed effect sizes? (18 hypotheses).

RESULTS

Baseline data from a total of 1211 patients with knee OA were analyzed for the first and second research question, and follow-up data from 584 patients who were part of an exercise therapy arm within a trial for the third research question. In total, the vast majority (73%) of the hypotheses were confirmed. Regarding our first research question, we found similar proportions in each of the three subgroups across cohorts, especially for three cohorts. Regarding our second research question, subgroup characteristics were almost completely in line with the proposed underlying phenotypes. Regarding our third research question, usual exercise therapy resulted in similar, medium to large effect sizes for knee pain and physical function for all three subgroups.

CONCLUSION

We found mixed results regarding the construct validity of our stratification algorithm. On the one hand, it is a valid instrument to consistently allocate patients into subgroups that aligned our hypotheses. On the other hand, in contrast to our hypotheses, subgroups did not differ substantially in effects of usual exercise therapy. An ongoing trial will assess whether this algorithm accompanied by subgroup-specific exercise therapy improves clinical and economic outcomes.

Muscle function, quality, and relative mass are associated with knee pain trajectory over 10.7 years

ABSTRACT

Periarticular muscle plays an important role in the pathogenesis of musculoskeletal pain. We recently reported that pain population consists of distinct subgroups of which the causes and mechanisms may differ. This study aimed to examine the association of lean mass, muscle strength, and quality with 10.7-year pain trajectory. Nine hundred forty-seven participants from a population-based cohort study were analysed. Dual-energy X-ray absorptiometry was used to assess lean and fat mass. Leg strength, knee extensor strength, and lower-limb muscle quality were measured/calculated. Knee pain was assessed by the Western Ontario and McMaster Universities Osteoarthritis Index pain questionnaire. Radiographic knee osteoarthritis was assessed by X-ray. Three distinct pain trajectories were identified: "Minimal pain" (53%), "Mild pain" (34%), and "Moderate pain" (13%). Higher total and lower-limb lean mass were associated with an increased risk of "Mild pain" and "Moderate pain" trajectories relative to the "Minimal pain" trajectory group, but these associations became nonsignificant after further adjustment for fat mass. Total lean mass percentage was associated with a lower risk of "Mild pain" (relative risk ratio [RRR]: 0.95, 95% confidence interval 0.92-0.98) and "Moderate pain" trajectory (RRR: 0.92, 95% confidence interval 0.87-0.96). Greater leg and knee extensor strength and muscle quality were associated with "Mild pain" and "Moderate pain" trajectories (RRR: 0.52-0.65, all P < 0.05). Similar results were found in those with radiographic knee osteoarthritis. Higher lower-limb muscle strength and quality, and relative lean mass, are associated with a reduced risk of severe knee pain trajectories, suggesting that improving muscle function and composition may protect against persistent unfavourable knee pain courses.

Experimental observation of the sequence of tibial plateau chondrocyte and matrix degeneration in spontaneous osteoarthritis in Guinea pigs

Background

To observe the sequence of chondrocyte degeneration and matrix degradation in the superficial surface cartilage of the tibial plateau in guinea pigs with spontaneous knee osteoarthritis (OA).

Methods

Sixty guinea pigs were euthanized at the ages of 8 months (n = 20),10 months (n = 20) and 12 months (n = 20) respectively. The degree of degeneration of the tibial plateau cartilage was evaluated by Osteoarthritis Research Society International (OARSI) score. The levels of Aggrecan,CollagenX,MMP-13 and Caspase-3 in the chondrocytes were detected by immunohistochemistry (IHC). The serum concentration of CTX-II was measured and compared. Western blot analysis was used to detect the levels of Aggrecan,CollagenX,MMP-13 and Caspase-3 in the cartilage tissue.

Results

The OARSI scores both in 8-month-old group and 10-month-old group were lower than that in the 12-month-old group. The levels of Aggrecan in articular chondrocyte were higher both in 8-month-old group and 10-month-old group than that in 12-month-old group. The level of Collagen X increased with the age of guinea pigs. And the levels of MMP-13 and caspase-3 both in 10-month-old group and 12-month-old group were higher than those in 8-month-old group. The concentration of CTX-II in serum increased significantly in 12 months old group.

Conclusion

The superficial chondrocytes of the tibial plateau first appeared to be hypertrophic and then apoptotic, and the matrix was further degraded when spontaneous knee osteoarthritis occurred in guinea pigs. Changes in the physiological state of chondrocytes are the initiating factors in the pathogenesis of knee OA.

Effect of High-Intensity Strength Training on Knee Pain and Knee Joint Compressive Forces Among Adults With Knee Osteoarthritis: The START Randomized Clinical Trial

IMPORTANCE

Thigh muscle weakness is associated with knee discomfort and osteoarthritis disease progression. Little is known about the efficacy of high-intensity strength training in patients with knee osteoarthritis or whether it may worsen knee symptoms.

OBJECTIVE

To determine whether high-intensity strength training reduces knee pain and knee joint compressive forces more than low-intensity strength training and more than attention control in patients with knee osteoarthritis.

DESIGN, SETTING, AND PARTICIPANTS

Assessor-blinded randomized clinical trial conducted at a university research center in North Carolina that included 377 community-dwelling adults (≥50 years) with body mass index (BMI) ranging from 20 to 45 and with knee pain and radiographic knee osteoarthritis. Enrollment occurred between July 2012 and February 2016, and follow-up was completed September 2017.

INTERVENTIONS

Participants were randomized to high-intensity strength training (n = 127), low-intensity strength training (n = 126), or attention control (n = 124).

MAIN OUTCOMES AND MEASURES

Primary outcomes at the 18-month follow-up were Western Ontario McMaster Universities Osteoarthritis Index (WOMAC) knee pain (0 best-20 worst; minimally clinically important difference [MCID, 2]) and knee joint compressive force, defined as the maximal tibiofemoral contact force exerted along the long axis of the tibia during walking (MCID, unknown).

RESULTS

Among 377 randomized participants (mean age, 65 years; 151 women [40%]), 320 (85%) completed the trial. Mean adjusted (sex, baseline BMI, baseline outcome values) WOMAC pain scores at the 18-month follow-up were not statistically significantly different between the high-intensity group and the control group (5.1 vs 4.9; adjusted difference, 0.2; 95% CI, -0.6 to 1.1; P = .61) or between the high-intensity and low-intensity groups (5.1 vs 4.4; adjusted difference, 0.7; 95% CI, -0.1 to 1.6; P = .08). Mean knee joint compressive forces were not statistically significantly different between the high-intensity group and the control group (2453 N vs 2512 N; adjusted difference, -58; 95% CI, -282 to 165 N; P = .61), or between the high-intensity and low-intensity groups (2453 N vs 2475 N; adjusted difference, -21; 95% CI, -235 to 193 N; P = .85). There were 87 nonserious adverse events (high-intensity, 53; low-intensity, 30; control, 4) and 13 serious adverse events unrelated to the study (high-intensity, 5; low-intensity, 3; control, 5).

CONCLUSIONS AND RELEVANCE

Among patients with knee osteoarthritis, high-intensity strength training compared with low-intensity strength training or an attention control did not significantly reduce knee pain or knee joint compressive forces at 18 months. The findings do not support the use of high-intensity strength training over low-intensity strength training or an attention control in adults with knee osteoarthritis.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT01489462.

Effect of exercise on pain processing and motor output in people with knee osteoarthritis: a systematic review and meta-analysis

OBJECTIVE

Guidelines recommend exercise as a core treatment for knee osteoarthritis. However, it is unclear how exercise affects measures of pain processing and motor function. The aim was to evaluate the effect of exercise on measures of pain processing and motor function in people with knee osteoarthritis.

METHODS

We searched five electronic databases (MEDLINE, EMBASE, CINAHL, SCOPUS and Cochrane Central Register of Controlled Trials) for studies on knee osteoarthritis, of any design, evaluating pain processing and motor function before and after exercise. Data were pooled with random-effects meta-analysis. Study quality was assessed using the Downs and Black and quality of evidence was assessed using the GRADE.

RESULTS

Eighteen studies were eligible and 16 were included. Following acute exercise, pressure pain threshold increased local to the study limb (standardised mean difference [95% confidence interval (CI)] 0.26, [0.02, 0.51], n = 159 from 5 studies), but there was no statistically significant change remote from the study limb (0.09, [-0.11, 0.29], n = 90 from 4 studies). Following an exercise program (range 5-12 weeks) there were no statistically significant changes in pressure pain threshold (local 0.23, [-0.01, 0.47], n = 218 from 8 studies; remote 0.33 [-0.13, 0.79], n = 76 from 4 studies), temporal pain summation (0.38 [-0.08, 0.85], n = 122 from 3 studies) or voluntary quadriceps muscle activation (4.23% [-1.84 to 10.30], n = 139 from 4 studies).

CONCLUSION

Very-low quality evidence suggests that pressure pain threshold increases following acute exercise. Very-low quality evidence suggests that pressure pain threshold, temporal pain summation or voluntary quadriceps activation do not change statistically significantly following exercise programs.

Patient-specific reference values for objective physical function tests: data from the Osteoarthritis Initiative

INTRODUCTION/OBJECTIVE

We aimed to establish sex-specific reference values of objective physical function tests among individuals with or at risk for knee osteoarthritis (KOA) across subsets of age, radiographic KOA severity, and body mass index (BMI).

METHOD

We included Osteoarthritis Initiative participants with data for objective physical function tests, sex, age, BMI, and radiographic KOA severity (Kellgren-Lawrence [KL] grade) at baseline. Objective physical function was quantified with 20-m walk speed, chair-stand speed, 400-m walk time, and knee extension and flexion strength. We created participant characteristic subsets for sex, age, KL grade, and BMI. Reference values were created as percentiles from minimum to maximum in 10% increments for each combination of participant characteristic subsets. Previously established clinically important differences for 20-m walk speed and knee extension strength were used to highlight clinically relevant differences.

RESULTS

Objective physical function reference values tables and an interactive reference value table were created across all combinations of sex, age, KL grade, and BMI among 3860 individuals with or at risk for KOA. Clinically relevant differences exist for 20-m walk speed and knee extension strength between males and females across age groups, KL grades, and BMI categories.

CONCLUSIONS

Establishing an individual's relative level of objective physical function by comparing their performance to individuals with similar sex, age, KL grade, or BMI may help improve interpretation of physical function performance. The interactive reference value table will provide clinicians and researchers a clinically accessible avenue to use these reference values.Key Points• Since greater age, radiographic knee osteoarthritis severity, and body mass index are all associated with worse objective physical function, reference values should consider the complex inter-play among these patient characteristics.• This study provides objective physical function reference values among subsets of individuals across the spectrum of sex, age groups, radiographic knee osteoarthritis severity, and body mass index categories.• These reference values offer a more patient-centered approach for interpreting an individual's relative level of objective physical function by comparing them to a more homogeneous group of individuals with similar participant characteristics.• We have provided a clinically accessible interactive table that will enable clinicians and researchers to input their patient's data to quickly and efficiently determine a patient's relative objective physical function compared to individual's with similar characteristics.

What type of exercise is most effective for people with knee osteoarthritis and co-morbid obesity?: The TARGET randomized controlled trial

OBJECTIVE

Different exercise types may yield different outcomes in osteoarthritis (OA) subgroups. The objective was to directly compare effectiveness of two exercise programs for people with medial knee OA and co-morbid obesity.

DESIGN

We performed a participant- and assessor-blinded randomized controlled trial. 128 people ≥50 years with medial knee OA and body mass index ≥30 kg/m² were recruited from the community. Interventions were home-based non-weight bearing (NWB) quadriceps strengthening or weight bearing (WB) functional exercise for 12 weeks. Primary outcomes were change in overall knee pain (numeric rating scale, range 0-10) and difficulty with physical function (Western Ontario and McMaster Universities Osteoarthritis Index, 0-68) over 12 weeks. Secondary outcomes included other pain measures, physical function, quality-of-life, global changes, physical performance, and lower-limb muscle strength.

RESULTS

123 (96%) participants were retained. There was no evidence of a between-group difference in change in pain (mean difference 0.73 units (95% confidence intervals (0.05,1.50)) or function (2.80 units (-1.17,6.76)), with both groups reporting improvements. For secondary outcomes, the WB group had greater improvement in quality-of-life (-0.043 units (-0.085,-0.001)) and more participants reporting global improvement (overall: relative risk 1.40 (0.98,2.01); pain 1.47 (0.97,2.24); function 1.43 (1.04,1.98). Although adverse events were minor, more NWB group participants reported ≥1 adverse event (26/66 (39%) vs 14/62 (23%), p = 0.04).

CONCLUSIONS

Both exercise types similarly improved primary outcomes of pain and function and can be recommended for people with knee OA and obesity. WB exercise may be preferred given fewer adverse events and potential additional benefits on some secondary outcomes.

REGISTRATION

Prospectively registered (Australian New Zealand Clinical Trials Registry #12617001013358, 14/7/2017).

Eccentric and Concentric Resistance Exercise Comparison for Knee Osteoarthritis

INTRODUCTION

This study aimed to compare the efficacy of eccentrically focused resistance exercise (ECC RT) to concentrically focused resistance exercise (CNC RT) on knee osteoarthritis (OA) symptoms and strength.

METHODS

Ninety participants consented. Participants were randomized to CNC RT, ECC RT, or a wait-list, no-exercise control group. Four months of supervised exercise training was completed using traditional weight machines (CNC RT) or modified-matched machines that overloaded the eccentric action (ECC RT). Main outcomes included one-repetition maximal strength (knee extension, leg flexion, and leg press), weekly rate of strength gain, Western Ontario and McMaster University Osteoarthritis Index (WOMAC) total score and subscores.

RESULTS

Fifty-four participants (60-85 yr, 61% women) completed the study. Both CNC RT and ECC RT groups showed 16%-28% improvement relative to the wait-list, no-exercise control group (P = 0.003-0.005) for all leg strength measures. The rate of weekly strength gain was greater for CNC RT than for ECC RT for leg press and knee flexion (by 2.9%-4.8%; both, P < 0.05) but not knee extension (0.7%; P = 0.38). There were no significant differences in WOMAC total and subscores across groups over time. Leg press strength change was the greatest contributor to change in WOMAC total scores (R = 0.223). The change in knee flexion strength from baseline to month 4 was a significant predictor of the change in WOMAC pain subscore (F ratio = 4.84, df = 45, P = 0.032). Both modes of strength training were well tolerated.

CONCLUSIONS

Both resistance training types effectively increased leg strength. Knee flexion and knee extension muscle strength can modify function and pain symptoms irrespective of muscle contraction type. Which mode to pick could be determined by preference, goals, tolerance to the contraction type, and equipment availability.

Concentric and Eccentric Resistance Training Comparison on Physical Function and Functional Pain Outcomes in Knee Osteoarthritis: A Randomized Controlled Trial

OBJECTIVE

The aim of the study was to compare the effectiveness of concentrically focused resistance training to eccentrically focused resistance training on physical function and functional pain in knee osteoarthritis.

DESIGN

This is a randomized, single-blinded controlled 4-mo trial. Older adults with knee osteoarthritis (N = 88; 68.3 ± 6.4 yrs, 30.4 ± 6.9 kg/m, and 67.4% women) were randomized to eccentrically focused resistance training, concentrically focused resistance training, or no-exercise control. Main outcomes included chair rise time, stair climb time, 6-min walk test distance, temporal-spatial parameters of gait, community ambulation, and functional pain.

RESULTS

Leg muscle strength improved in both training groups compared with no-exercise control. There were no significant group × time interactions for any functional performance score (chair rise time, stair climb time, 6-min walk test distance, gait parameters, community ambulation). Compared with no-exercise control, functional pain scores were reduced for chair rise (-38.6% concentrically focused resistance training, -50.3% eccentrically focused resistance training vs. +10.0%) and stair climb (-51.6% concentrically focused resistance training, -41.3% eccentrically focused resistance training vs. +80.7%; all P < 0.05). Pain scores were reduced during the 6-min walk and in early recovery with concentrically focused resistance training compared with the remaining two groups (P < 0.05).

CONCLUSIONS

Either resistance exercise type improves activity-related knee osteoarthritis pain, but concentrically focused resistance training more effectively reduced severity of ambulatory pain and pain upon walking cessation.

Best Evidence Rehabilitation for Chronic Pain Part 5: Osteoarthritis

Osteoarthritis (OA) is a leading cause of chronic pain and disability in older adults, which most commonly affects the joints of the knee, hip, and hand. To date, there are no established disease modifying interventions that can halt or reverse OA progression. Therefore, treatment is focused on alleviating pain and maintaining or improving physical and psychological function. Rehabilitation is widely recommended as first-line treatment for OA as, in many cases, it is safer and more effective than the best-established pharmacological interventions. In this article, we describe the presentation of OA pain and give an overview of its peripheral and central mechanisms. We then provide a state-of-the-art review of rehabilitation for OA pain—including self-management programs, exercise, weight loss, cognitive behavioral therapy, adjunct therapies, and the use of aids and devices. Next, we explore several promising directions for clinical practice, including novel education strategies to target unhelpful illness and treatment beliefs, methods to enhance the efficacy of exercise interventions, and innovative, brain-directed treatments. Finally, we discuss potential future research in areas, such as treatment adherence and personalized rehabilitation for OA pain.

Implementing international osteoarthritis guidelines in primary care: uptake and fidelity among health professionals and patients

OBJECTIVE

This paper evaluates the implementation fidelity of a strategy and intervention used to implement osteoarthritis (OA) treatment recommendations in primary care. We also evaluate uptake of core treatment (patient information, exercise and referral to weight management) among OA patients.

DESIGN

A stepped-wedge cluster-randomised controlled study (RCT) in primary care. The study involved general practitioners (GPs), physiotherapists (PTs) and patients with hip and/or knee OA in six Norwegian municipalities (clusters). Workshops for general practitioners (GPs) and PTs represented the main implementation activity. Uptake of core treatment (patient education, exercise and weight management) was evaluated using self-reported data from the patient intervention and control group, analysed with logistic regression models. Fidelity was evaluated using six components representing adherence to the content and dose instructions in the implementation strategy and assessed against a-priori criteria for high adherence.

RESULTS

Data were collected from 40 GPs, 37 PTs and 393 OA patients. The patient-reported data showed statistically significant higher uptake for exercise, patient education and referral to support for weight reduction, among the intervention group compared to the control group (P < 0.05). Evaluation of fidelity showed high adherence to GP and PT workshop attendance and physiotherapy use, partly adherence to PT knowledge after workshops, and low adherence to exercise attendance, dose and progression instructions.

CONCLUSIONS

The implementation strategy and intervention successfully improved OA patients' access to physiotherapy and uptake of recommended core treatment. However, the strategy was less effective in providing exercise programs with sufficient dose and progression and in supporting patients' adherence to the exercise program.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02333656.

Inflammatory cytokines mediate the effects of diet and exercise on pain and function in knee osteoarthritis independent of BMI

OBJECTIVE

Diet restriction and exercise form key treatments for osteoarthritis (OA) related symptoms in overweight and obese individuals. Although both interventions are known to influence systemic low-grade inflammation, which is related to pain levels and functional limitations, little is known about the potential changes in systemic inflammation as a working mechanism of diet restriction and exercise in knee OA.

DESIGN

Data from the Arthritis, Diet, and Activity Promotion Trial (ADAPT) were used. Through causal mediation analyses, the proportion of the effect of a 18 months diet and exercise intervention explained by the 18 months change in interleukin (IL)-6, TNF-α, soluble IL-6 receptor, soluble IL-1 receptor, CRP, and BMI were assessed, using self-reported pain and function as outcomes.

RESULTS

The change in inflammatory factors accounted for 15% of the total effect on pain and was totally independent of the change in BMI. The change in inflammatory factors accounted for 29% of the effect on function, with the change in BMI adding only 4% to the total mediated effect.

CONCLUSIONS

The change in inflammatory factors after the diet and exercise intervention was a 'medium' size mediator of the effect on pain and a 'strong' mediator for the effect on function in overweight and obese individuals with knee OA. The change in BMI added minimally to the mediated effect on function. These results highlight the relevance of changes in systemic inflammation as drivers for clinically relevant effects after diet and exercise in overweight and obese individuals with knee OA.

Concurrent Change in Quadriceps Strength and Physical Function Over Five Years in the Multicenter Osteoarthritis Study

OBJECTIVE

Quadriceps weakness, associated with functional limitations, is a target of treatment of knee osteoarthritis (OA). Limited data exist on the relationship between modest strength increases and improvements in function. The aim of this study was to evaluate concurrent change in strength and physical function over 5 years.

METHODS

Among subjects from the Multicenter Osteoarthritis (MOST) study, we excluded those with knee replacement after baseline. A 3-category variable defined whether, at 5 years, knee extensor strength increased, decreased, or remained within 15% of baseline, a clinically important cut-off. The outcomes were the 5-times sit-to-stand test, 20-meter walk test, Western Ontario and McMaster Universities Osteoarthritis (WOMAC) physical function score, and 3 individual physical functions from WOMAC: arising from a chair, going up stairs, and getting on/off toilet. Linear and logistic models, stratified by sex, evaluated associations between change in strength and change in physical function over 5 years. To compare weaker versus stronger women, we stratified analyses at 56 Nm baseline strength.

RESULTS

Among 1,534 participants (60.6% women), 22% of men and 30% of women increased strength by at least 15% at 5 years. Compared with women whose strength did not change, women whose strength increased had improved chair stand performance (odds ratio 2.27 [95% confidence interval 1.56, 3.30]) but no improvement in other functions. In men, an increase in strength was not associated with significant improvement in physical function. Similar results were observed for a 20% or 30% increase.

CONCLUSION

Modest improvement in quadriceps strength was associated with improved chair stand performance in women but not in men. Most functions did not improve with an increase in strength, and targeted interventions may be required to improve functional status.