Lower Quadriceps Rate of Force Development Is Associated With Worsening Physical Function in Adults With or at Risk for Knee Osteoarthritis: 36-Month Follow-Up Data From the Osteoarthritis Initiative

Knee joint pathology and efferent pathway dysfunction: Mapping muscle inhibition from motor cortex to muscle force

BACKGROUND

Dysfunction in efferent pathways after knee pathology is tied to long-term impairments in quadriceps and hamstrings muscle performance, daily function, and health-related quality of life. Understanding the underlying etiology is crucial for effective treatment and prevention of poor outcomes, such as post-traumatic osteoarthritis or joint replacement.

OBJECTIVES

To synthesize recent evidence of efferent pathway dysfunction (i.e., motor cortex, motor units) among individuals with knee pathology.

DESIGN

Commentary.

METHOD

We summarize the current literature investigating the motor cortex, corticospinal tract, and motoneuron pool in individuals with three common knee pathologies: anterior cruciate ligament (ACL) injury, anterior knee pain (AKP), and knee osteoarthritis (OA). To offer a complete perspective, we draw from studies applying a range of neuroimaging and neurophysiologic techniques.

RESULTS

Adaptations within the motor cortices, corticospinal tract, and motoneuron pool are present in those with knee pathology and underline impairments in quadriceps and hamstrings muscle function. Each pathology has evidence of altered motor system excitability and reduced volitional muscle activation and force-generating capacity, but few impairments were common across ACL injury, AKP, and OA studies. These findings underscore the central role of the motor cortex and motor unit behavior in the long-term outcomes of individuals with knee pathology.

CONCLUSIONS

Adaptations in the efferent pathways underlie persistent muscle dysfunction across three common knee pathologies. This review provides an overview of these changes and summarizes key findings from neurophysiology and neuroimaging studies, offering direction for future research and clinical application in the rehabilitation of joint injuries.

Association between quadriceps tendon elasticity and neuromuscular control in individuals with knee osteoarthritis

BACKGROUND

Knee osteoarthritis is a complex condition with established risk factors such as female sex, increasing age and body mass index, reduced quadriceps muscle strength and knee injury. Despite known associated risks, the role and behaviour of knee tendons in knee osteoarthritis remains unclear. This study explores the association between quadriceps tendon elasticity, muscle strength, neuromuscular control, proprioception and patient reported outcome measures in individuals with knee osteoarthritis.

METHODS

Adults with doctor-diagnosed knee osteoarthritis were recruited from rheumatology clinics and general practitioner practices. Quadriceps tendon elasticity was estimated using sonoelastography. Neuromuscular control data including electromyography, electromechanical delay and proprioception measures were included. Participants completed the Knee Injury and Osteoarthritis Outcome Score. Associations between elasticity values, physical and neuromuscular data and patient reported outcomes scores were evaluated using Spearman's correlations.

FINDINGS

Thirty-nine adults with knee osteoarthritis were eligible for inclusion. Increased tendon stiffness was negatively associated with rate of force development, time to half peak force and passive positioning sense in individuals with knee osteoarthritis. Similarly, patient reported symptoms were found to be associated with sonoelastography findings with moderate-strong associations observed between activities of daily living sport and recreation, pain and symptoms and between neuromuscular control measures and muscle strength.

INTERPRETATION

Stiffer tendon identified within the knee osteoarthritis group was associated with reduced neuromuscular control and knee joint proprioception. Stiffer quadriceps tendon may contribute to the poorer reported symptoms by knee osteoarthritis individuals. These findings may impact disease symptoms and progression which could lead to further joint impairment.

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.

Normative Reference Values for Knee Extensor Muscle Rate of Torque Development and Torque Steadiness in Adolescents and Adults

OBJECTIVE

The aim of this study was to establish reference values for rate of torque development (RTD) and muscle torque steadiness (MTS) of knee extensors across the lifespan, and evaluate if these measures are independently associated with Osteoarthritis Research Society International (OARSI)-recommended performance-based measures (6-minute walk test, 30-second chair stand test, stair climb test) and other clinical variables.

METHODS

In this cross-sectional observational study, knee extensor strength of 764 participants (12-89 years) from the 1000 Norms Project was assessed via fixed dynamometry. Age- and sex-stratified normative RTD (Nms-1 kg-1) and MTS (Nm kg-1) values were presented as means and 95% confidence intervals. Correlations and multiple regression analyses were calculated to identify factors (age, sex, height, weight, OARSI-recommended performance-based measures, Knee Injury and Osteoarthritis Outcome Score, vertical jump, long jump, grip strength, basic gait-related knee biomechanics) independently associated with RTD or MTS.

RESULTS

Age- and sex-stratified normative RTD and MTS reference values were generated. Male subjects exhibited higher RTD but poorer MTS (less steady) than female subjects across all age groups. Better performance in OARSI-recommended performance-based measures, vertical jump, long jump, and grip strength were associated with greater RTD but poorer MTS. Thirty-second chair stand test, stair climb test, vertical jump, long jump, and grip strength were independent determinants of RTD and MTS.

CONCLUSIONS

The RTD and MTS demonstrated associations with clinical variables relevant to knee osteoarthritis. The normative reference values generated may help identify the presence and extent of impairments in RTD and MTS associated with knee osteoarthritis and assist in developing responsive outcome measures for therapeutic trials.

Rate of force development in the quadriceps of individuals with severe knee osteoarthritis: A preliminary cross-sectional study

Knee osteoarthritis (KOA) is a leading cause of knee pain and disability due to irreversible cartilage degeneration. Previous studies have not identified modifiable risk factors for KOA. In this preliminary cross-sectional study, we aimed to test the following hypotheses: individuals with severe KOA would have a significantly lower quadriceps rate of force development (RFD) than individuals with early KOA, and the decrease in quadriceps RFD would be greater than the decrease in maximum quadriceps strength in individuals with severe KOA. The maximum isometric strength of the quadriceps was assessed in individuals with mild (Kellgren and Lawrence [K&L] grade 1–2) and severe KOA (K&L grade 3–4) using a handheld dynamometer. The RFD was analyzed at 200 ms from torque onset and normalized to the body mass and maximum voluntary isometric contraction torque. To test whether the quadriceps RFD was lowered and whether the lower in the quadriceps RFD was greater than the lower in maximum quadriceps strength in individuals with severe knee OA, the Mann–Whitney U-test and analysis of covariance were performed, respectively. The effect size (ES) based on Hedges’ g with a 95% confidence interval (CI) was calculated for the quadriceps RFD and maximum quadriceps strength. Sixty-six participants were analyzed. Individuals with severe KOA displayed significantly lower quadriceps RFD (p = 0.009), the lower being greater than the lower in maximum quadriceps strength (between-group difference, ES: 0.88, -1.07 vs. 0.06, -0.22). Our results suggest that a decreased quadriceps RFD is a modifiable risk factor for progressive KOA. Our finding could help in the early detection and prevention of severe KOA.

Knee Extensor and Flexor Torque Variability During Maximal Strength Testing and Change in Knee Pain and Physical Function at 60-Mo Follow-Up: The Multicenter Osteoarthritis Study (MOST)

ABSTRACT

As the population ages, there is a growing burden owing to musculoskeletal diseases, such as knee osteoarthritis, and subsequent functional decline. In the absence of a cure, there is a need to identify factors amenable to intervention to prevent or slow this process. The Multicenter Osteoarthritis Study cohort was developed for this purpose. In this study, associations between variability in peak knee flexor and extensor torque at baseline and worsening of pain and physical function over the subsequent 60 mos were assessed in a cohort of 2680 participants. The highest quartile of baseline knee flexor torque variability was found to be associated longitudinally with worsening pain (fourth quartile ß estimate, mean ± SE, 0.49 ± 0.19; P = 0.0115; with R2 = 0.28 and P for trend across quartiles = 0.0370) and physical function scores (fourth quartile ß estimate, mean ± SE, 1.39 ± 0.64; P = 0.0296; with R2 = 0.25 and P for trend across quartiles = 0.0371), after adjusting for baseline knee osteoarthritis and maximum knee flexor torque. There were no associations between baseline knee extensor torque and worsening pain or physical function by 60 mos. The presence of greater variability in maximum knee flexor strength may identify patients who may benefit from therapies aimed at preventing worsening knee pain and physical function.

Adapted protocol of rate of force development and relaxation scaling factor for neuromuscular assessment in patients with knee osteoarthritis

BACKGROUND

The linear relationship between muscle torque and rate of torque rise/relaxation during rapid muscle contractions has been recently introduced as a novel measure of muscle quickness, termed rate of torque development/relaxation scaling factor (RTD-SF/RTR-SF). Because the standard assessment protocol includes potentially painful muscle contractions, the first purpose of this study was to validate an adapted RTD-SF/RTR-SF protocol for knee extensor muscles that utilizes lower submaximal intensities and can be used in knee osteoarthritis patients.

METHODS

A cross-sectional study was performed on a group of healthy controls (n = 24) who underwent the standard RTD-SF/RTR-SF protocol (20-80% of maximum) and the knee osteoarthritis group (n = 24) who underwent the adapted protocol (20-60% of maximum). We calculated the RTD-SF, RTR-SF and the linearity (r²) for both relationships, based on both protocols in controls.

RESULTS

The validity of the adapted protocol was acceptable (intraclass correlation coefficient = 0.77-0.93), with low within-participant variation (coefficient of variability <10%) for both outcome measures. Compared with the control group, the knee osteoarthritis group had similar RTD-SF, but lower linearity of RTD-SF (0.90 vs. 0.82). The RTR-SF (8.0/s vs. 6.7/s) and its linearity (0.87 vs. 0.73) were significantly reduced. Comparing the affected and the unaffected leg in the knee osteoarthritis group, the unaffected leg had greater maximal torque (96.2 vs. 84.1 Nm) and higher linearity for RTD-SF (0.86 vs. 0.80) and RTR-SF (0.82 vs. 0.73).

CONCLUSIONS

We confirmed the validity of the adapted RTD/RTR-SF protocol and its sensitivity to impairments associated with knee osteoarthritis.

Osteoarthritis year in review 2019: mechanics

Mechanics play a critical - but not sole - role in the pathogenesis of osteoarthritis, and recent research has highlighted how mechanical constructs are relevant at the cellular, joint, and whole-body level related to osteoarthritis outcomes. This review examined papers from April 2018 to April 2019 that reported on the role of mechanics in osteoarthritis etiology, with a particular emphasis on studies that focused on the interaction between movement and tissue biomechanics with other clinical outcomes relevant to the pathophysiology of osteoarthritis. Studies were grouped by themes that were particularly prevalent from the past year. Results of the search highlighted the large exposure of knee-related research relative to other body areas, as well as studies utilizing laboratory-based motion capture technology. New research from this past year highlighted the important role that rate of exerted loads and rate of muscle force development - rather than simply force capacity (strength) - have in OA etiology and treatment. Further, the role of muscle activation patterns in functional and structural aspects of joint health has received much interest, though findings remain equivocal. Finally, new research has identified potential mechanical outcome measures that may be related to osteoarthritis disease progression. Future research should continue to combine knowledge of mechanics with other relevant research techniques, and to identify mechanical markers of joint health and structural and functional disease progression that are needed to best inform disease prevention, monitoring, and treatment.

Isokinetic eccentric training is more effective than constant load eccentric training on the quadriceps rehabilitation following partial meniscectomy: A randomized clinical trial

OBJECTIVES

To compare the effects of conventional (constant load) eccentric training and isokinetic eccentric training on quadriceps muscle mass, strength and functionality of recreational athletes following partial meniscectomy.

DESIGN

Randomized controlled trial.

SETTING

XXXX, Brazil.

PARTICIPANTS

32 recreational male athletes (∼27 years old) who underwent partial meniscectomy performed a 6-week quadriceps strength training program in one of the experimental groups: conventional group (CG) or icokinetic group (IG).

MAIN OUTCOME MEASURES

Quadriceps muscle mass, strength, and patients' objective and self-reported function.

RESULTS

Both groups enhanced muscle mass, strength and functionality outcomes. The IG presented higher increases than CG for muscle mass (ES = 0.99-1.41), strength (ES = 1.48-2.35), and Lysholm score (ES = 1.0). The magnitude-based inference supports that results 'very likely' or 'almost certainly' favour IG compared to CG for all outcomes, except for the single leg hop test (i.e., between-group similar change).

CONCLUSION

After partial meniscectomy, isokinetic eccentric training is more effective than conventional eccentric training to restore quadriceps muscle mass, strength, and functional capacity.