Muscle strength and osteoarthritis of the knee: a systematic review and meta-analysis of longitudinal studies

The Influence of an Eight-Week Home Exercise Program on Spatiotemporal and Kinetic Characteristics of Gait and Knee Function in Women with Severe Knee Osteoarthritis Scheduled for Arthroplasty

Background and Objectives: The increased prevalence of knee osteoarthritis (OA) and need for total knee arthroplasty (TKA) indicate a growing need for effective prehabilitation. The effect of preoperative home exercise programs (HEPs) on gait in patients with severe knee OA is under-investigated. This study aimed to evaluate the influence of an 8-week preoperative HEP on gait characteristics, leg extensor muscle strength, knee function, and health status in women with severe knee OA scheduled for TKA and to compare them with healthy control data. Material and Methods: Eighteen women with severe knee OA (KOA, aged 61.8 ± 1.6 years) and ten age-matched healthy women (CON) participated in this study. The KOA group performed an HEP with 15 exercises aimed at improving lower limb muscle strength, motion, balance, and coordination. Gait spatiotemporal and kinetic characteristics during the loading response, isometric leg extensor strength, knee active range of motion (AROM), and The Western Ontario and McMaster Universities Arthritis Index (WOMAC) were investigated. Associations between characteristics were analyzed. Results: Improvements in ground reaction force (GRF) during the loading response of gait, leg extensor muscle strength, the knee AROM, and the WOMAC index were found post-HEP. The KOA group demonstrated lower (p < 0.05) spatiotemporal and GRF characteristics than the CON group. Knee extension moment (KEM) was lower pre-HEP (p < 0.05) but did not differ significantly from the CON group post-HEP. Gait characteristics and WOMAC were associated with leg extensor muscle strength and knee AROM and pain in the KOA group. Conclusions: An eight-week preoperative HEP improved GRF and KEM during the loading response of gait, muscle strength, knee function, and self-reported knee OA-related health status in women with severe knee OA. Preoperative HEP before TKA, focusing on leg extensor muscle strength, range of motion, and pain relief, is an effective alternative to supervised exercise therapy in women with severe knee OA.

Which pathway of the possible sarcopenia algorithm of the AWGS 2019 guideline is the best in Korean community-dwelling older men and women?

OBJECTIVE

To compare the diagnostic accuracy of possible sarcopenia identification pathways, as suggested by Asian Working Group for Sarcopenia (AWGS) in 2019, by gender among Korean community-dwelling older adults.

DESIGN

Cross-sectional analysis of data from 2,129 community-dwelling adults (70-84 years, 50.4% men) enrolled in Korean Frailty and Aging Cohort Study.

METHODS

Based on AWGS 2019 guideline, possible sarcopenia was defined by low handgrip strength (HGS) or slow five-times chair stand test (5CST) time, referred to as "assessments." "Case-findings" (low calf circumference [CC], SARC-F ≥4, or SARC-CalF ≥11) were recommended for screening 'possible sarcopenia' before assessment. For the six 'possible sarcopenia' pathways (combining three case-finding and two assessment tools), area under the curve (AUC) and F1 score are compared.

RESULTS

For case-finding in men, CC demonstrated the highest AUC (0.657) and F1 score (0.504) for predicting sarcopenia compared with SARC-F and SARC-CalF (p <0.001, =0.001). Among men with low CC, ΔAUC between HGS and 5CST was not significant as assessment (p=0.079) (AUCs: 0.763 vs. 0.707; F1 scores: 0.713 vs. 0.650). For case-finding in women, SARC-CalF demonstrated the highest AUC (0.631) and F1 score (0.389) compared with CC and SARC-F (p=0.012, <0.001). Subsequently, ΔAUC between HGS and 5CST was not significant in women (p=0.069) (AUCs: 0.566 vs. 0.636; F1 scores: 0.387 vs. 0.514).

CONCLUSIONS

Based on AWGS 2019 guideline, CC in men and SARC-CalF in women was the best case-finding tool for community-dwelling older adults. After the best case-finding in each gender, two assessment pathways demonstrated insignificant difference in both genders.

BRIEF SUMMARY

For case-finding of possible sarcopenia, using calf circumference in older men and using SARC-CalF in older women demonstrated the highest diagnostic accuracy for predicting sarcopenia. After the best case-finding in each gender, two assessment pathways (handgrip strength and five-times chair stand test) of possible sarcopenia demonstrated insignificant difference in both genders.

The global burden of osteoarthritis knee: a secondary data analysis of a population-based study

BACKGROUND

Osteoarthritis knee poses a substantial and pervasive global health challenge.

METHODS

The data was extracted from the Global Burden of Disease 2021 Study database. First, numbers and age-standardized rates (ASRs) of incidence, prevalence, and disability-adjusted life years (DALYs) of osteoarthritis knee were assessed globally and by sub-types in 2021. Subsequently, we employed a linear regression model to analyze the temporal trends from 1990 to 2021. To predict the future burden, we utilized the age-period-cohort model and the Bayesian age-period-cohort model. Furthermore, we conducted a sensitivity analysis using the Autoregressive Integrated Moving Average model and the Exponential Smoothing model.

RESULTS

In 2021, osteoarthritis knee accounted for 30.85 million incidence cases, 374.74 million prevalence cases, and 12.02 million DALYs cases globally, with ASRs of 353.67, 4294.27, and 137.59, respectively. Females and individuals over 50 years old were identified as high-risk populations, while higher socio-demographic index regions emerged as high-risk areas. From 1990 to 2021, incidence cases rose from 14.13 million to 30.85 million, prevalence cases from 159.80 million to 374.74 million, and DALYs cases from 5.15 million to 12.02 million, accompanied by increases in their respective ASRs. Projections using the APC model predict a continued increase in incidence, prevalence, and DALYs cases for both genders until 2046. Specifically, male incidence cases are projected to increase to 18.45 million and female incidence to 25.60 million. Similarly, male prevalence cases are projected to rise to 235.41 million and female prevalence to 365.97 million. Male DALYs cases are expected to increase to 7.52 million and female DALYs to 11.55 million. The BAPC models also indicate an upward trend in number of cases.

CONCLUSION

In conclusion, osteoarthritis knee represents a formidable threat to global public health, necessitating the development of proactive and tailored strategic interventions that account for global-specific contexts. Key Points • Females and individuals over 50 years old were identified as high-risk populations. • Higher socio-demographic index regions were identified as high-risk areas. • The disease burden attributable to osteoarthritis knee increased from 1990 to 2019. • The number of deaths and DALYs cases would still increase in the next 25 years.

The association between endogenous sex hormones and knee osteoarthritis in women: A population-based cohort study

BACKGROUND

To describe the associations of endogenous sex hormones with the prevalence and occurrence of knee osteoarthritis (KOA) in women.

METHODS

We included 178,280 women (mean 56.0 years) from the UK Biobank who had data on sex hormone-binding globulin (SHBG), testosterone, or estradiol at baseline. Outcomes were the prevalence of KOA at baseline and incident KOA during the follow-up. We performed logistic regression and accelerated failure time models to explore the linear and nonlinear associations between endogenous sex hormone levels (per 1 standard deviation [SD] and in quartiles) and the prevalence and occurrence of KOA.

RESULTS

At baseline, women with higher testosterone levels were less likely to have KOA (odds ratios=0.91 per 1 SD increase in testosterone, 95% confidence interval 0.87-0.96). No evidence for disparity differences in SHBG or estradiol between women with and without KOA was found. For participants without KOA at baseline, the time to incident KOA was extended in women with higher testosterone at baseline (time ratio=1.04 per 1 SD increase in testosterone, 95% confidence interval 1.01-1.06) during a median follow-up of 13.6 years. We did not find evidence of nonlinear associations of sex hormones with the prevalence and occurrence of KOA after adjustment for multiple comparisons.

CONCLUSIONS

In middle-aged and older women, the risk of KOA is inversely associated with endogenous testosterone but not with SHBG or estradiol.

Tale of quadriceps and hamstring muscle strength after ACL reconstruction: a systematic review with longitudinal and multivariate meta-analysis

OBJECTIVE

This study aimed to investigate how knee extensor and flexor strength change over time after anterior cruciate ligament reconstruction (ACLR).

DESIGN

Systematic review with longitudinal meta-analysis.

DATA SOURCES

Medline, Embase, CINAHL, Scopus, Cochrane CENTRAL and SPORTDiscus to 28 February 2023.

ELIGIBILITY CRITERIA

Studies of primary ACLR (n≥50), with mean participant age 18-40 years, reporting a quantitative measure of knee extensor or flexor strength were eligible. Muscle strength had to be reported for the ACL limb and compared with: (1) the contralateral limb (within-person); and/or (2) an uninjured control limb (between-person).

RESULTS

We included 232 studies of 34 220 participants. Knee extensor and flexor strength showed sharp initial improvement postoperatively before tailing off at approximately 12-18 months post surgery with minimal change thereafter. Knee extensor strength was reduced by more than 10% compared with the contralateral limb and approximately 20% compared with uninjured controls at 1 year for slow concentric, fast concentric and isometric contractions. Knee flexor strength showed smaller deficits but was still 5%-7% lower than the contralateral limb at 1 year for slow concentric, fast concentric and isometric contractions. Between-person comparisons showed larger deficits than within-person comparisons.

CONCLUSION

Knee extensor muscle strength is meaningfully reduced (>10%) at 1 year, with limited improvement after this time up to and beyond 5 years post surgery. Many people likely experience persistent and potentially long-term strength deficits after ACLR. Comparison within person (to the contralateral limb) likely underestimates strength deficits in contrast to uninjured controls.

'The right advice': a qualitative study examining enablers and barriers to recreational running and beliefs about knee health following knee surgery

OBJECTIVES

To examine the experiences, knowledge and beliefs of recreational runners with a history of knee surgery regarding (i) enablers and barriers to running participation, (ii) the association of running and knee joint health, and (iii) perceived benefits and motivations for running.

METHODS

17 runners (≥3 times/week, ≥10 km/week) with a history of knee surgery (7±7 years post-surgery, 9 women, age 36±8 years) participated in one-on-one semi-structured interviews. Interviews were recorded, transcribed verbatim and analysed using reflexive thematic analysis. Trustworthiness was built by following established qualitative research guidelines and by participant validation of findings in the final analysis stages.

RESULTS

We identified 9 themes (5 subthemes) for aim (i); 3 themes (10 subthemes) for aim (ii); and 2 themes (4 subthemes) for aim (iii). Positive health professional support including education, exercise rehabilitation and a tailored return-to-run plan enabled participants to return to running following surgery. Effective load management either independently or with coach assistance, and consistent strength training were considered key to maintaining participation. Barriers to running following surgery included unhelpful health professional encounters, persistent knee symptoms and muscle weakness, new running-related injuries, anxiety and fear about reinjury, and difficulty finding time. Participants had varying beliefs about running and knee joint health, although most believed that running benefited long-term knee health. Improved mental health and social connection were the most common motivators to run.

CONCLUSION

Our qualitative findings may inform strategies to support adults to commence, or return to, and maintain running participation following knee surgery.

Effects of Aquatic Exercise in Older People with Osteoarthritis: Systematic Review of Randomized Controlled Trials

Objective: In this study, the objective is to analyze the efficacy of different aquatic physical exercise programs in the treatment of osteoarthritis in older people. Material and Methods: The systematic review was conducted until April 2024 and updated in November 2024 in five electronic databases. Randomized controlled studies in people over 60 years of age with a diagnosis of osteoarthritis were included. Water-based exercise interventions were assessed for their impact on osteoarthritis symptoms, walking ability, muscle strength, depressive symptoms, range of motion, body composition, fear of falling, fall risk, quality of life, range of motion, and dual task function. The methodological quality of included studies was assessed using the Physiotherapy Evidence Database. Results: A total of 12 studies were included, with sample sizes ranging from 35 to 312 participants. The presence of osteoarthritis in the sample was manifested in different joints. The methodological quality of the included studies varied from fair to good. Based on the results of this review, aquatic exercise significantly improved balance, stiffness, pain, and walking ability compared to non-exercise controls (p < 0.05). Compared with land-based exercise groups, only one study found significant differences between the two groups. Conclusions: Water-based exercise programs do not provide significantly superior benefits compared to other exercise modalities and appear to have limited effectiveness in the management of OA. However, the feasibility and high adherence make these programs a recommendable option for older people with OA. Future studies should investigate the impact of exercise intensity on the short- and long-term efficacy of aquatic therapy.

The effect of single-task versus dual-task assessment on muscle strength and performance in individuals with knee osteoarthritis

BACKGROUND

Dual-task activities, which involve performing two separate tasks simultaneously, often result in reduced motor function and daily activity performance among individuals with knee osteoarthritis (OA).

OBJECTIVE

This study aimed to investigate the impact of single- and dual-task conditions on muscle strength and performance in individuals with knee OA and examine how cognitive load influences physical task performance in this population.

METHODS

Sixty patients with knee OA were included. Baseline data included demographic characteristics, pain (Visual Analog Scale), and physical function (Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC)). Muscle strength and performance were assessed using isokinetic and sit-to-stand tests, initially under single-task conditions, and then under dual-task conditions three days later. Dual-tasking involved physical tasks with varying cognitive exercises (changed between sessions) and familiarization sessions to minimize learning effects.

RESULTS

The investigation revealed that individuals with knee OA showed reduced muscle strength and impaired sit-to-stand performance during dual-task activities, with lower peak torque (p = .0025), total work (p = .026), and longer time to peak torque (p = .011). Decreased muscle performance correlated with worse WOMAC scores (p ≤ .01, r = -0.506), particularly in dual-task conditions. Regression analysis identified extension total work and the sit-to-stand test as key predictors of dual-task performance, explaining 32.2% of the variance.

CONCLUSION

Dual-task performance impairs muscle strength and physical function in individuals with knee OA, demonstrated by reduced peak torque, total work, and sit-to-stand performance. Extension total work and sit-to-stand test emerged as key predictors of dual-task performance, emphasizing the need to address cognitive load in rehabilitation strategies.

Sex-specific poor physical performance in Korean community-dwelling older adults

BACKGROUND

Poor physical performance appears to be different across age and sex. The aim of this study was to examine changes in physical performance across age groups by sex.

METHODS

A cross-sectional study was conducted with 292 community-dwelling older adults (144 males, 148 females; age: 74.7 ± 5.2 years, body mass index: 23.8 ± 2.7 kg/m2). Physical performance tests included (i) strength (handgrip, knee extension, ankle dorsiflexion, ankle plantarflexion, and toe grip), (ii) functional mobility (5 sit-to-stand, 4-m gait speed, and 4-m fast gait speed), and (iii) postural control (timed single-leg stance). Physical performance was compared across four different age groups by sex using ANOVA tests, T-score, and linear regression analysis. All statistical analysis was set at 0.05.

RESULTS

ANOVA showed a significant age effect (p < 0.05) on physical performance measures with only exception for ankle muscle strength. T-score and linear regression analyses revealed sex-specific trends. In males, postural control showed the most significant poor performance, followed by strength. In females, the most notable poor performance was also observed in postural control, followed by functional mobility.

CONCLUSIONS

Most main outcome measures in physical performance worsened over time across age groups while poor performance pattern was different between older males (strength) and females (functional mobility). We highlighted the importance of assessing strength, functional mobility, and postural control in older adults. Based on observed poor performance patterns across age groups by sex, sex-specific interventions should be implemented.

The Effects of Resistance Training on Pain, Strength, and Function in Osteoarthritis: Systematic Review and Meta-Analysis

Background/Objectives: Pain is the most common symptom of osteoarthritis (OA), and it leads to functional decline, such as decreased mobility and limitations in activities of daily living, which leads to difficulties in social participation, increased social isolation, and economic burden. Muscle weakness can be a cause of OA symptoms. The purpose was to analyze the effects of resistance training on improving pain, strength, and function in OA and to analyze the effects by intervention duration and joint. Methods: The study search was conducted on 14 September 2024, and the period of study inclusion covered studies available in the databases from their inception to the search date. The databases used were PubMed, CHINAL, Cochrane Library, and Embase. Inclusion criteria were studies that targeted OA and compared a resistance training intervention with a no resistance training intervention group and measured pain, strength, and function. Subgroup analysis was used to analyze the effects by intervention duration (4 weeks or less, 5 to 8 weeks, 9 weeks or more) and joint (knee, hip). Results: A total of 27 studies included 1712 subjects, and significant improvements were observed in pain (SMD: -0.48, CI: -0.58~-0.37, I2: 45%), strength (SMD: 0.4, CI: 0.32~0.47, I2: 0%), and function (SMD: -0.56, CI: -0.65~-0.47, I2: 30%). In the effects by intervention duration, both pain and strength showed significant improvements, but no effect on function was observed for less than 4 weeks. For effects by joint, both the knee and hip showed significant improvements. Conclusions: Resistance training was effective in improving pain, strength, and function in patients with knee and hip OA.

[Blood flow restriction training (BFRT) in patients before and after total knee arthroplasty]

BACKGROUND

In healthy individuals, blood flow restriction training (BFRT) has shown positive effects on muscle mass, strength, fatigue resistance, as well as tendon and bone metabolism. BFRT reduces blood flow in the extremities using inflatable cuffs, creating local muscular hypoxia, which produces an anabolic metabolic environment. This promotes significant muscular and cardiovascular adaptations even at low mechanical training loads.

KNEE ENDOPROSTHESES

BFRT also shows promising initial results in pre- and postoperative applications for knee endoprostheses (KTEP). Both preoperative and postoperative BFRT can improve muscle strength and joint function, accelerate recovery, and alleviate pain. Although the method is generally safe, potential risks such as discomfort and rare side effects must be considered. Clear application protocols are still lacking, necessitating further research and individualized programs to achieve optimal training effects. BFRT thus offers an innovative way to effectively rehabilitate patients despite their low load tolerance.

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.

Effectiveness of whole-body electromyostimulation on knee pain and physical function in knee osteoarthritis: a randomized controlled trial

In a randomized, controlled study, whole-body electromyostimulation (WB-EMS) was investigated as a promising alternative treatment technique compared to conventional strength training for the management of knee osteoarthritis (OA). Seventy-two overweight participants with symptomatic knee OA were randomly assigned to WB-EMS (n = 36) or a usual care group (UCG, n = 36). For seven months, the WB-EMS group received three times per fortnight a WB-EMS training, while the UCG was prescribed six-times physiotherapeutic treatments. We observed significant effects for the primary outcome "pain", as determined by the Knee injury and Osteoarthritis Outcome Score (KOOS), with more favourable changes in the WB-EMS group vs UCG (between-group difference 9.0 points, 95%CI 2.9-15.1, p = 0.004). Secondary outcomes, including the other KOOS subscales (symptoms, function in daily living, function in sports/recreational activities and quality of life), 7 day pain diary, hip/leg extensor strength and lower limb function (30s sit-to-stand test), were also statistically significant in favour of the WB-EMS group. Overall, WB-EMS was found to be effective in relieving knee pain symptoms and improving physical function in individuals with symptomatic knee OA compared to usual care treatment. WB-EMS could be used as an alternative therapy in the management of knee OA; particularly for patients that cannot be motivated for conventional training.

Adiposity and cartilage lesions following ACL reconstruction

OBJECTIVE

To determine if global, central, or peripheral adiposity is associated with prevalent and worsening cartilage lesions following anterior cruciate ligament reconstruction (ACLR).

METHODS

In 107 individuals one-year post-ACLR, adiposity was assessed globally (body mass index), centrally (waist circumference), and peripherally (knee subcutaneous adipose tissue thickness) from magnetic resonance imaging (MRI). Tibiofemoral and patellofemoral cartilage lesions were assessed from knee MRIs at 1- and 5-years post-ACLR. Poisson regression evaluated the relation of adiposity with prevalent and worsening tibiofemoral and patellofemoral cartilage lesions adjusting for age, sex, and activity level.

RESULTS

The prevalence ratios of adiposity with tibiofemoral (presence in 49%) and patellofemoral (44%) cartilage lesions ranged from 0.99 to 1.03. Adiposity was more strongly associated with longitudinal changes in tibiofemoral (worsening in 21%) and patellofemoral (44%) cartilage lesions. One-unit increase in global (kg/m2), central (cm), and peripheral (mm) adiposity was associated with a higher risk of worsening tibiofemoral cartilage lesions by 17% (risk ratios [95% confidence interval (CI)]: 1.17 [1.09 to 1.23]), 5% (1.05 [1.02 to 1.08]), and 9% (1.09 [1.03 to 1.16]), and patellofemoral cartilage lesions by 5% (1.05 [1.00 to 1.12]), 2% (1.02 [1.00 to 1.04]) and 2% (1.02 [1.00 to 1.04]), respectively.

CONCLUSION

Greater adiposity was a risk factor for worsening cartilage lesions up to 5 years post-ACLR. Clinical interventions aimed at mitigating excess adiposity may be beneficial in preventive approaches for early post-traumatic osteoarthritis.

Association between hip muscle strength/function and hip cartilage defects in sub-elite football players with hip/groin pain

OBJECTIVE

To explore associations between hip muscle strength and cartilage defects (presence and severity) on magnetic resonance imaging (MRI) in young adults with hip/groin pain participating in sub-elite football.

DESIGN

Sub-elite football players with hip/groin pain (>6 months) completed assessments of isometric hip strength and functional task performance. Hip cartilage defects were assessed using the Scoring Hip Osteoarthritis with MRI tool. This exploratory, cross-sectional study used logistic and negative binomial models to assess the relationships between hip muscle strength or functional task performance and hip cartilage defects, controlling for body mass index, age, testing site and cam morphology, incorporating sex-specific interaction terms.

RESULTS

One hundred and eighty-two (37 women) sub-elite (soccer or Australian football) players with hip/groin pain (age 26 ± 7 years) were included. Greater hip extension strength was associated with higher cartilage total score (adjusted incidence rate ratio [aIRR] 1.01, 95%CI: 1.0 to 1.02, p = 0.013) and superolateral cartilage score (adjusted odds ratio (aOR) 1.03, 95% confidence interval (CI): 1.01 to 1.06, p < 0.01). In female sub-elite football players, greater hip external rotation strength was associated with lateral cartilage defects (aOR 1.61, 95%CI: 1.05 to 2.48, p = 0.03) and higher cartilage total score (aIRR 1.25, 95%CI: 1.01 to 1.66, p = 0.042). A one-repetition increase in one-leg rise performance was related to lower odds of superomedial cartilage defects (aOR 0.96, 95%CI: 0.94 to 0.99, p < 0.01).

CONCLUSIONS

Overall, there were few associations between peak isometric hip muscle strength and overall hip cartilage defects. It is possible that other factors may have relevance in sub-elite football players. Additional studies are needed to support or refute our findings that higher one leg rise performance was associated with reduced superomedial cartilage defect severity and greater hip extension strength was related to higher cartilage defect severity scores.

Are the Effects of Resistance Exercise on Pain and Function in Knee and Hip Osteoarthritis Dependent on Exercise Volume, Duration, and Adherence? A Systematic Review and Meta-Analysis

OBJECTIVE

The purpose of this study was to determine dose parameters for resistance exercise associated with improvements in pain and physical function in knee and hip osteoarthritis (OA) and whether these improvements were related to adherence.

METHODS

We searched six databases, from inception to January 28, 2023, for randomized controlled trials comparing land-based, resistance exercise-only interventions with no intervention, or any other intervention. There were four subgroups of intervention duration: 0 to <3 months, 3 to 6 months, >6 to <12 months, ≥12 months. The between-group effect was calculated for immediate postintervention pain and physical function (activities of daily living [ADL] and sports/recreation [SPORT]).

RESULTS

For both knee and hip, data from 280 studies showed moderate benefit for pain, physical function ADL, and physical function SPORT in favor of interventions 3 to 6 months. For the knee, there was also a moderate benefit for physical function ADL in favor of interventions >6 to <12 months. From 151 knee and hip studies that provided total exercise volume data (frequency, time, duration), there was no association between volume with the effect size for pain and physical function. A total of 74 studies (69 knee, 5 hip) reported usable adherence data. There was no association between adherence with the effect size for pain and physical function.

CONCLUSION

In knee and hip OA, resistance exercise interventions 3 to 6 months (and for the knee >6 to <12 months) duration improve pain and physical function. Improvements do not depend on exercise volume or adherence, suggesting exercise does not require rigid adherence to a specific dose.

No sign of weakness: a systematic review and meta-analysis of hip and calf muscle strength after anterior cruciate ligament injury

OBJECTIVE

We aimed to determine hip and lower-leg muscle strength in people after ACL injury compared with an uninjured control group (between people) and the uninjured contralateral limb (between limbs).

DESIGN

Systematic review with meta-analysis.

DATA SOURCES

MEDLINE, EMBASE, CINAHL, Scopus, Cochrane CENTRAL and SportDiscus to 28 February 2023.

ELIGIBILITY CRITERIA

Primary ACL injury with mean age 18-40 years at time of injury. Studies had to measure hip and/or lower-leg muscle strength quantitatively (eg, dynamometer) and report muscle strength for the ACL-injured limb compared with: (i) an uninjured control group and/or (ii) the uninjured contralateral limb. Risk of bias was assessed according to Cochrane Collaboration domains.

RESULTS

Twenty-eight studies were included (n=23 measured strength ≤12 months post-ACL reconstruction). Most examined hip abduction (16 studies), hip extension (12 studies) and hip external rotation (7 studies) strength. We found no meaningful difference in muscle strength between people or between limbs for hip abduction, extension, internal rotation, flexion or ankle plantarflexion, dorsiflexion (estimates ranged from -9% to +9% of comparator). The only non-zero differences identified were in hip adduction (24% stronger on ACL limb (95% CI 8% to 42%)) and hip external rotation strength (12% deficit on ACL limb (95% CI 6% to 18%)) compared with uninjured controls at follow-ups >12 months, however both results stemmed from only two studies. Certainty of evidence was very low for all outcomes and comparisons, and drawn primarily from the first year post-ACL reconstruction.

CONCLUSION

Our results do not show widespread or substantial muscle weakness of the hip and lower-leg muscles after ACL injury, contrasting deficits of 10%-20% commonly reported for knee extensors and flexors. As it is unclear if deficits in hip and lower-leg muscle strength resolve with appropriate rehabilitation or no postinjury or postoperative weakness occurs, individualised assessment should guide training of hip and lower-leg strength following ACL injury.

PROSPERO REGISTRATION NUMBER

CRD42020216793.

Weight-Bearing Physical Activity, Lower-Limb Muscle Mass, and Risk of Knee Osteoarthritis

Importance

It has been demonstrated that total physical activity is not associated with risk of osteoarthritis. However, the association of different types of physical activity with incident knee osteoarthritis remains unclear.

Objective

To determine whether weight-bearing recreational physical activities are associated with increased risk of incident knee osteoarthritis.

Design, Setting, and Participants

This prospective cohort study used data from the Rotterdam Study (1996 to 2009), including participants with knee x-ray measurements at baseline and follow-up examinations. Participants with knee osteoarthritis at baseline were excluded. Residents aged 45 years and older of the Ommoord district in the city of Rotterdam in The Netherlands were invited to join the Rotterdam Study (78% response rate). Analysis was conducted in June 2023.

Exposure

Total, weight-bearing, and non-weight-bearing recreational physical activities collected by questionnaires at baseline.

Main Outcomes and Measures

Incident radiographic knee osteoarthritis measured by knee x-ray was the primary outcome, and incident symptomatic knee osteoarthritis defined by x-ray and knee pain questionnaire was the secondary outcome. The association of different types of recreational physical activity with radiographic knee osteoarthritis was examined using logistic regression within generalized estimating equation framework after adjusting for potential confounders. A prespecified stratification analysis was planned on the basis of lower-limb muscle mass index (LMI) tertiles, measured by dual-energy x-ray absorptiometry.

Results

A total of 5003 individuals (2804 women [56.0%]; mean [SD] age, 64.5 [7.9] years) were included. The knee osteoarthritis incident rate was 8.4% (793 of 9483 knees) for a mean (SD) follow-up time of 6.33 (2.46) years. Higher weight-bearing activity was associated with increased odds of incident knee osteoarthritis (odds ratio [OR], 1.22; 95% CI, 1.10-1.35; P < .001), but non-weight-bearing activity was not (OR, 1.04; 95% CI, 0.95-1.15; P = .37). In the analysis stratified by LMI tertiles, the association of weight-bearing activity with incident osteoarthritis was found only among 431 patients in the lowest LMI tertile (OR, 1.53; 95% CI, 1.15-2.04; P = .003), but not among patients in the middle or high LMI tertile.

Conclusions and Relevance

The findings of this study suggest that weight-bearing activity is associated with incident knee osteoarthritis in people with low levels of lower-limb muscle mass, which might be a promising avenue for tailored advice for physical activity.

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.

Mediating effect of lower extremity muscle on the relationship between obesity and osteoarthritis in middle-aged and elderly women in Korea: based on the 2009-2011 Korea National Health and Nutrition Examination Survey

OBJECTIVES

This study investigated whether the lower extremity muscle mass index (LMI) mediates the relationship between general obesity, central obesity, and knee osteoarthritis in middle-aged and elderly women in Korea.

METHODS

Data of 2,843 women aged ≥50 years were collected from the Korean National Health and Nutrition Examination Survey conducted between 2009 and 2011. General obesity and central obesity were evaluated based on body mass index (BMI) and waist circumference (WC), calculated through anthropometric measurements and body composition assessments. LMI was calculated by dividing the muscle mass in both legs-measured using the dual-energy X-ray absorptiometry-by body weight. Knee osteoarthritis was defined as a Kellgren-Lawrence scale (KL) grade of ≥2 as assessed through radiographic images.

RESULTS

Knee osteoarthritis prevalence, indicated by KL grades, was significantly higher in the general obesity and central obesity groups compared to the normal group, and conversely, lower with varying LMI levels. Using mediation analysis with bootstrapping and adjusting for covariates, we found that LMI mediated the relationship between BMI and KL (β, 0.005; 95% confidence interval [CI], 0.000 to 0.010) and WC and KL grade (β, 0.002; 95% CI, 0.001 to 0.003), explaining 4.8% and 6.7% of the total effects of BMI and WC on KL grade, respectively.

CONCLUSIONS

The study suggested that LMI partially mediates the link between general obesity and/or central obesity and knee osteoarthritis, proposing that a higher proportion of lower limb muscle mass relative to body weight can alleviate the increased risk of knee osteoarthritis caused by obesity.

Improving muscle capacity utilization with a 12-week strengthening program for females with symptomatic knee osteoarthritis

BACKGROUND

Strengthening exercise improves symptoms in knee osteoarthritis (OA), but it remains unclear if biomechanical mechanisms contribute to this improvement. Muscle capacity utilization, which reflects the proportion of maximum capacity required to complete tasks, may provide insight into how strengthening exercise improves clinical outcomes in painful knee OA.

PURPOSE

The purpose of this secondary analysis was to determine if a 12-week strengthening intervention reduced muscle capacity utilization during walking, squat and lunge tasks in females with painful knee OA.

METHODS

Data from 28 females (age 59.6 ± 6.2 years old; body mass index 29.1 ± 4.7 kg/m2) with clinical knee OA were included. Participants completed a strengthening intervention 3 times per week for 12 weeks. Knee extensor isometric torque was measured on a commercial dynamometer; peak values from three exertions were averaged. Peak KFM was extracted and averaged from five walking trials. Mean KFM was extracted and averaged from three trials for each of static lunges and squats. Muscle capacity utilization was the ratio of mean peak KFM to peak extensor torque for walking; and mean KFM to peak extensor torque for squats and lunges. Paired t-tests determined differences between peak extensor torque, peak KFM and muscle capacity utilization from pre to post intervention (p < 0.05).

RESULTS & SIGNIFICANCE

Peak extensor torque increased at follow up (p = 0.02). Peak KFM during walking decreased (p = 0.005). Muscle capacity utilization during walking (p = 0.008) and squat (p = 0.002) decreased. Mean KFM and muscle capacity utilization during lunge remained unchanged from pre to post intervention. The reduction in muscle capacity utilization at follow up indicates the strengthening intervention produced a decrease in proportion of the maximal capacity a participant used to complete walking and squat tasks. Strengthening both increases maximal muscle capacity and decreases the net moment required during daily tasks in knee OA.

The efficacy of strength or aerobic exercise on quality of life and knee function in patients with knee osteoarthritis. A multi-arm randomized controlled trial with 1-year follow-up

OBJECTIVE

To evaluate the efficacy of strength exercise or aerobic exercise compared to usual care on knee-related quality of life (QoL) and knee function at 4 months and 1 year in individuals with knee osteoarthritis.

METHODS

A three-arm randomized controlled trial (RCT) compared 12 weeks of strength exercise or aerobic exercise (stationary cycling) to usual care supervised by physiotherapists in primary care. We recruited 168 participants aged 35-70 years with symptomatic knee osteoarthritis. The primary outcome was The Knee Injury and Osteoarthritis Outcome Score (KOOS) QoL at 1 year. Secondary outcomes were self-reported function, pain, and self-efficacy, muscle strength and maximal oxygen uptake (VO2max) at 4 months and 1 year.

RESULTS

There were no differences between strength exercise and usual care on KOOS QoL (6.5, 95% CI -0.9 to 14), or for aerobic exercise and usual care (5.0, 95% CI -2.7 to 12.8), at 1 year. The two exercise groups showed better quadriceps muscle strength, and VO2max at 4 months, compared to usual care.

CONCLUSION

This trial found no statistically significant effects of two exercise programs compared to usual care on KOOS QoL at 1 year in individuals with symptomatic and radiographic knee osteoarthritis, but an underpowered sample size may explain lack of efficacy between the intervention groups and the usual care group.

CLINICALTRIALS

GOV IDENTIFIER

NCT01682980.

Does the one-leg rise test reflect quadriceps strength in individuals following anterior cruciate ligament reconstruction?

OBJECTIVE

To explore if one-leg rise test performance is associated with quadriceps strength following anterior cruciate ligament reconstruction (ACLR).

DESIGN

Cross-sectional.

PARTICIPANTS

100 individuals (50 females, 50 males) aged 18-40 years, 9-36 months post-ACLR with ongoing knee symptoms (KOOS4 <80/100).

MAIN OUTCOME MEASURES

Number of one-leg rise repetitions (using an adjustable-height plinth) and isometric quadriceps strength using isokinetic dynamometry (60° flexion, normalised to body mass). Multivariable fractional polynomial regression models adjusted for sex explored relationships between one-leg rise performance (repetitions) and quadriceps strength (Nm/kg) for each limb.

RESULTS

A non-linear, increasing association between one-leg rise performance and quadriceps strength was observed, with the rate of increase attenuating at higher values of one-leg rise performance. Similar relationships were observed in the ACLR (β = 0.15, 95%CI 0.10 to 0.20; adjusted r2 = 0.51) and contralateral limb (β = 0.14, 95%CI 0.08 to 0.19; r2 = 0.42).

CONCLUSION

The one-leg rise test can be an indicator of quadriceps strength in individuals after ACLR, enabling clinicians to easily monitor quadriceps strength recovery without specialised equipment. With the relationship between one-leg rise performance and quadriceps strength attenuating with a larger number of one-leg rises achieved, other factors (e.g., motivation, endurance) likely contribute to one-leg rise performance at higher values.

Hip rotation muscle strength is implicated in the progression of early post-traumatic osteoarthritis: A longitudinal evaluation up to 5 years following ACL reconstruction

INTRODUCTION

Following ACL reconstruction (ACLR), deficits in hip muscle strength and relationships to future outcomes are unknown.

METHODS

111 participants one year after ACLR, completed hip external rotation (ER) and internal rotation (IR) strength assessment. At 1 (n = 111) and 5 (n = 74) years post-ACLR, participants completed a battery of functional, symptomatic (Knee Osteoarthritis Outcome Score (KOOS)) and structural assessments (radiography, magnetic resonance imaging (MRI)). Cartilage health of the patellofemoral and tibiofemoral compartments was assessed with the semiquantitative MRI Osteoarthritis Knee Score. Hip rotation strength was compared between-limbs, and relationships between hip strength at 1 year and functional, symptomatic and cartilage outcomes at 1 and 5 years were investigated with regression models.

RESULTS

The index (ACLR) limb had weaker hip ER (but not IR) strength compared to the contralateral side (standardised mean difference ER = -0.33 (95%CI -0.60, -0.07; IR = -0.11 (95%CI -0.37, 0.15). Greater hip ER and IR strength was associated with superior function at 1 and 5 years, and better KOOS-Patellofemoral symptoms at 5 years. Greater hip ER strength was associated with lower odds of worsening tibiofemoral cartilage lesions at 5 years (odds ratio 0.01, 95%CI 0.00, 0.41).

CONCLUSION

Hip rotation strength may play a role in worsening function, symptoms and cartilage health after ACLR.