Knee Extensor Muscle Strength Is More Important Than Postural Balance for Stair-Climbing Ability in Elderly Patients with Severe Knee Osteoarthritis

Systematic Evaluation of Isometric Maximal Muscle Strength in an Orthopaedic Cohort

BACKGROUND

Although the lower extremities are essential for movement function and human gait, no normalized isometric maximum strength values, which include the factors gender, age, weight, height, and body mass index (BMI), have been defined to date for orthopaedic patients.

OBJECTIVE

To systematically analyze the isometric maximal muscle strength of a cohort in an orthopaedic outpatient clinic and to evaluate its relation to gender, age, weight, height, BMI, and the differences between diseases.

STUDY DESIGN

Cross-sectional study.

LEVEL OF EVIDENCE

Level 4.

METHODS

Isometric maximal muscle strength of knee extension, knee flexion, hip abduction, and hip adduction was measured in orthopaedic patients of an outpatient clinic using a specific muscle strength measurement device. Correlation analysis was performed for age, gender, height, weight, and BMI. Patients were grouped by disease characteristics.

RESULTS

The cohort consisted of 311 subjects (sex: 164 male, 147 female; age: 48.63 years, SD = 16.595; BMI: 26.56 kg/m², SD = 4.9). Age correlated significantly with maximal isometric muscle strength. At the age of 54 years onward, based on 133 patients, a decline in maximum isometric muscle strength was detected. Gender showed a strong influence on maximal isometric muscle strength, with significantly higher values for male patients. Furthermore, weight and height, but not BMI, correlated significantly with muscle strength.

CONCLUSION

For clinical studies comparing different evidence-based training interventions for rehabilitation, it is important to consider determinants such as gender, age, weight, and height for isometric maximum strength measurement. For further validation, follow-up examinations taking into account the performance level, other target groups, and other muscle groups are required to avoid the wide dispersion of isometric maximum strength values. These results and associated determinants are highly clinically relevant and can be used as a reference for further studies in the field of musculoskeletal regeneration.

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

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

Impact of Resistance Exercise and Nitrate Supplementation on Muscle Function and Clinical Outcomes After Knee Osteoarthritis Surgery in Middle-Aged Women with Sarcopenia: A Randomized, Double-Blind, Placebo-Controlled Clinical Trial

Background/Objectives: Sarcopenia, characterized by reduced muscle mass and strength, is associated with osteoarthritis (OA), particularly in middle-aged women, and may worsen postoperatively. Resistance exercise (RE) can resolve sarcopenia; however, recovery is often suboptimal. Nitrate (NO3-) supplementation may enhance muscle recovery and complement RE. We investigated whether NO3- supplementation combined with RE improves thigh muscle mass and strength in middle-aged women during postoperative rehabilitation. Methods: We conducted a prospective randomized placebo-controlled double-blind study including 36 middle-aged women with sarcopenia and cartilage defects undergoing mesenchymal stem cell implantation. Participants were assigned to RE with NO3- supplementation (NG, n = 18) or with placebo (PG, n = 18) groups. Both groups underwent 12 weeks of supervised RE. The primary outcomes were thigh muscle cross-sectional area (CSA) and knee strength, whereas functional and clinical measures, including the Short Physical Performance Battery (SPPB), skeletal muscle index (SMI), International Knee Documentation Committee (IKDC), and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores, were secondary outcomes. Results: Thigh muscle CSA decreased in the PG but was maintained in the NG. Knee extension strength improved significantly in the NG compared with that in the PG at 6 and 12 weeks. Knee flexion strength also improved rapidly in the NG, with a significant increase at 6 weeks. SPPB and IKDC scores improved significantly in the NG. However, similar improvements were observed for WOMAC scores in both groups. Conclusions: NO3- supplementation combined with RE effectively prevented muscle atrophy and enhanced muscle strength in our study participants, indicating potential for improving postoperative recovery.

The effect of kinesio taping on joint range of motion and balance in total knee replacement patients

We adopted a within-subjects quasi-experimental approach to assess the impact of kinesio taping (KT) on joint range of motion (ROM), static balance, and dynamic balance. The research subjects were 15 patients who had, within the previous 3 weeks, undergone total knee replacement (TKR) by an orthopedic surgeon in 2022. We measured the ROM, static balance, and dynamic balance of the knee joint before and after applying KT. We then compared the pre- and post-tape measurements to assess the effects of KT on joint function and balance. The ROM of the knee joint was measured using a goniometer in the supine position before the KT application. The static and dynamic balance were assessed using a balance assessment device by measuring the sway area and length of the center of gravity during the measurement period. The effects of KT on the ROM and static and dynamic balance of the knee joint were investigated. The differences in joint ROM and static and dynamic balance between pre- and post-KT applications were analyzed using a paired-sample t-test. This study found that the ROM of the knee joint was significantly increased after applying KT. For static and dynamic balance, both the sway area and length of the center of gravity decreased after applying KT, indicating a significant improvement in static and dynamic balance. KT, when combined with standard physiotherapy, can be a useful therapeutic approach for TKR patients, effectively enhancing joint ROM and balance function.

The effects of various stair-climbing exercises on functional mobility and trunk muscle activation in community-dwelling older adults: A pilot randomized controlled trial

BACKGROUND

Stair-climbing (SC) is an essential daily life skill, and stair-climbing exercise (SCE) serves as a valuable method for promoting physical activity in older adults. This study aimed to compare the impact of SCEs with heel contact (HC) and heel off (HO) during SC on functional mobility and trunk muscle (TM) activation amplitudes in community-dwelling older adults.

METHODS

In the pilot randomized controlled trial, participants were randomly allocated to either the HC group (n = 17; mean age 75.9 ± 6.3 years) or the HO group (n = 17; mean age 76.5 ± 4.6 years). The HC participants performed SCE with the heel of the ankle in contact with the ground, while the HO participants performed SCE with the heel of the ankle off the ground during SC. Both groups participated in progressive SCE for one hour per day, three days per week, over four consecutive weeks (totaling 12 sessions) at the community center. We measured timed stair-climbing (TSC), timed up and go (TUG), and electromyography (EMG) amplitudes of the TMs including rectus abdominis (RA), external oblique (EO), transverse abdominus and internal oblique abdominals (TrA-IO), and erector spinae (ES) during SC before and after the intervention.

RESULTS

Both groups showed a significant improvement in TSC and TUG after the intervention (P < .01, respectively), with no significant difference between the groups. There was no significant difference in the EMG activity of the TMs between the groups after the intervention. The amplitude of TMs significantly decreased after the intervention in both groups (P < .01, respectively).

CONCLUSION

Both SCE methods could improve balance and SC ability in older adults while reducing the recruitment of TMs during SC. Both SCE strategies are effective in improving functional mobility and promoting appropriate posture control during SC in older adults.

Lower extremity muscle strength equation of older adults assessed by Five Time Sit to Stand Test (FTSST)

Background

The decline in lower limb muscle strength, one of the risk factors for falling in the older adults, puts older persons at an increased risk of falling. The assessment of the lower limb muscle strength is very important.

Objective

The purpose of this study was to construct the equation for predicting knee extensor muscle strength based on demographic data and the results of the Five-Time Sit-to-Stand Test (FTSST).

Methods

A total of 121 healthy elders (mean age 68 . 00 ± 7 . 26 ) were asked to complete the FTSST and submit the demographic information. By using a stationary push-pull dynamometer, the knee extensor strength of each participant was assessed. The multiple regression analysis was used to explore knee extensor strength prediction equation.

Results

The findings demonstrated that the knee extensor strength equation was developed using variables obtained from gender, weight, and time to complete the FTSST. The equation was found to have a high correlation (r = 0 . 838 ) and 70.1% estimation power. Its formula was as follows: Knee extensor strength = 32 . 735 + 3 . 688 (gender; female = 0 or male = 1 ) + 0.189 (weight) - 2.617 (time to complete the FTSST). However, there was an estimating error in this equation of 4.72 kg.

Conclusion

The determining factors influencing knee extensor strength, which can be utilized to estimate the strength in elderly individuals, are demographic variables including gender, weight, and the time taken to complete the FTSST.

Modified Squat Test for Predicting Knee Muscle Strength in Older Adults

BACKGROUND

Methods for evaluating the strength of the knee extensor muscles play a vital role in determining the functionality of the lower limbs and monitoring any alterations that occur over time in older individuals. This study assessed the validity of the Modified Squat Test (MST) in predicting knee extensor muscle strength in older adults.

METHODS

This study included a total of 110 older adults. We collected demographic information such as sex, age, body weight, height, and thigh circumference. Muscle strength was assessed by measuring the maximum voluntary isometric contraction of the knee extensors, and by performing the MST (5 and 10 repetitions) and single-leg standing balance test. Stepwise multiple linear regression analysis was used to investigate multiple factors impacting the prediction of knee extensor strength.

RESULTS

Factors such as age, sex, thigh circumference, performance on the single-leg standing eye-open (SSEO) task, and the time required to complete the 10 MST repetitions together explained 77.8% of the variation in knee extensor muscle strength among older adults. We further developed a predictive equation to calculate strength as follows: strength = 36.78 - 0.24 (age) + 6.16 (sex) + 0.19 (thigh circumference) + 0.05 (SSEO) - 0.54 (time required to complete 10 MST repetitions) ± 5.51 kg.

CONCLUSION

The 10-repetition MST is an invaluable instrument for establishing an equation to accurately predict lower limb muscle strength.

Development and validation of a portable articulated dynamometry system to assess knee extensor muscle strength

Muscle strength assessment is important in predicting clinical and functional outcomes in many disorders. Manual muscle testing, although commonly used, offers suboptimal accuracy and reliability. Isokinetic dynamometers (IKDs) have excellent accuracy and reliability; but are bulky and expensive, offering limited accessibility. This study aimed to design a portable dynamometer that is accessible, accurate and reliable, and to validate the device in a general population. The portable articulated dynamometry system (PADS) is a portable device with an embedded high-precision load cell, designed to measure muscle strength with optimal accuracy. Seventy-two participants underwent maximal isometric and isokinetic knee extensor torque measurement with the PADS and IKD, respectively. The PADS results were cross-validated against IKD results using change in mean (CIM). Interrater and intra-rater reliabilities were assessed using intraclass correlation coefficients, standard error of measurement, and minimal detectable change. The PADS maximal knee extensor strength results were not significantly different from those by IKD (CIM: - 2.13 Nm; 95% CI - 4.74, 0.49 Nm). The PADS showed interrater reliability (Pearson's r: 0.958; ICC: 0.979; SEM: 5.51%) and excellent intra-rater reliability (Pearson's r: 0.912; ICC: 0.954; SEM: 8.38%). The proposed PADS may be an effective alternative to IKD, offering good accuracy, reliability, and potentially better accessibility.

Radiological and clinical outcomes of concurrent hamstring stretching with quadriceps strengthening in patients with knee osteoarthritis: A randomized clinical trial

BACKGROUND: Hamstring shortening altered joint reaction forces during activities of daily living (ADL), causing knee pain. Moreover, weak quadriceps may negatively distribute the compressive and shear forces at the knee joint. PURPOSE: The study examined the effect of adding hamstring stretching to quadriceps strengthening exercises on joint space narrowing (JSN), medial joint space width (mJSW), and physical abilities in patients with knee osteoarthritis (KOA). METHODS: A total of 42 osteoarthritis patients, aged from 50 to 65 years, were randomized and assigned into 2 groups: the study and the control groups. Quadriceps strengthening exercises were given to both groups, while static hamstring stretching was applied to only the study group. Patients of both groups were screened with a weight-bearing x-ray beam to investigate the JSN, mJSW, and functional abilities measured in the WOMAC scale. The Outcomes were evaluated at the baseline and immediately after 6 weeks of treatment. RESULTS: The mJSW improved in the study group (p< 0.001) compared to the control group (p= 0.07). The OARSI JSN was enhanced significantly in both groups, but in favor of the study group (p< 0.001) over the control group (p= 0.046). Both MVIC and total score of WOMAC were significantly improved in both groups (p< 0.001). CONCLUSION: Adding static hamstring stretching to quadriceps strengthening exercises provided a substantial effect on mJSW, JSN, and functional abilities in KOA patients.

Development of a Non-Contacting Muscular Activity Measurement System for Evaluating Knee Extensors Training in Real-Time

To give people more specific information on the quality of their daily motion, it is necessary to continuously measure muscular activity during everyday occupations in an easy way. The traditional methods to measure muscle activity using a combination of surface electromyography (sEMG) sensors and optical motion capture system are expensive and not suitable for non-technical users and unstructured environment. For this reason, in our group we are researching methods to estimate leg muscle activity using non-contact wearable sensors, improving ease of movement and system usability. In a previous study, we developed a method to estimate muscle activity via only a single inertial measurement unit (IMU) on the shank. In this study, we describe a method to estimate muscle activity during walking via two IMU sensors, using an original sensing system and specifically developed estimation algorithms based on ANN techniques. The muscle activity estimation results, estimated by the proposed algorithm after optimization, showed a relatively high estimation accuracy with a correlation efficient of R² = 0.48 and a standard deviation STD = 0.10, with a total system average delay of 192 ms. As the average interval between different gait phases in human gait is 250–1000 ms, a 192 ms delay is still acceptable for daily walking requirements. For this reason, compared with the previous study, the newly proposed system presents a higher accuracy and is better suitable for real-time leg muscle activity estimation during walking.

Methods and Strategies for Reconditioning Motor Output and Postural Balance in Frail Older Subjects Prone to Falls

In frail older subjects, the motor output of the antigravity muscles is fundamental in resisting falls. These muscles undergo accelerated involutions when they are inactive and the risk of falling increases during leisure and domestic physical activity. In order to reduce their risk of falling, frail older subjects limit their physical activities/exercises. The problem is that the less they exercise, the less they are able to exercise and the greater the risk in exercising. Hence, a vicious circle sets up and the antigravity muscles inevitably continue to deteriorate. This vicious circle must be broken by starting a reconditioning program based on developing the strength of antigravity muscles (especially lower-limb muscles). To begin with, for each increase in muscle strength, postural balance is improved. Once this increase reaches the threshold beyond which postural balance no longer improves, it seems appropriate to implement exercises aimed at concomitantly improving motor output and postural balance in order to counteract or even reverse the involution process of the postural balance system. Methods and strategies toward this end are proposed in this present communication. However, the transfer effects between strength increase and postural balance ability are not yet totally known and future research should evaluate the relationship between muscle strength and postural balance throughout rehabilitation programs (i.e., program follow-ups) in frail older subjects in order to advance knowledge of this relationship.

Immediate Effect of Restricted Knee Extension on Ground Reaction Force and Trunk Acceleration during Walking

Gait parameters calculated from trunk acceleration reflect the features of gait; however, they cannot evaluate the gait pattern corresponding to the gait cycle. This study is aimed at investigating the differences in gait parameters calculated from trunk acceleration during gait corresponding to the gait cycle in healthy subjects with restricted knee extension. Participants included eight healthy volunteers who walked normally (NW) and with knee orthosis that restricted knee extension (ER). The ground reaction force (GRF), joint angles, and trunk acceleration during walking were measured using four force plates, a three-dimensional motion analysis system, and an inertial measurement unit. The peak GRF of the vertical components, joint ranges of motion, and moments of force were analyzed. The root mean square (RMS) and amplitude peak ratio (AR) of autocorrelation function were calculated from the trunk acceleration waveform. The first peak GRF and peak ankle dorsiflexion angles significantly increased during ER. The peak hip extension, knee flexion, knee extension angles, and the peak moment of knee extension significantly decreased during ER compared to that during NW. The acceleration AR significantly decreased during ER compared to that during NW. There was no significant difference in the RMS between the two conditions. The acceleration AR may show the temporal postural structure with restricted knee extension from the terminal stance phase for the ipsilateral limb to the initial stance phase for the contralateral limb. These results suggest that novel metrics for accelerometry gait analysis can reveal gait abnormalities, with restricted knee extension corresponding to the gait cycle.