Transitions to mobility difficulty associated with lower extremity osteoarthritis in high functioning older women: longitudinal data from the Women's Health and Aging Study II

Comparison of physical function, proprioception, muscle strength, postural balance, and walking in older women with and without total knee arthroplasty

The benefit of total knee arthroplasty (TKA) is that it alleviates pain caused by osteoarthritis; however, other postoperative effects on physical function are unclear. This study aimed to investigate the differences in physical function, proprioception, muscle strength, postural balance, and walking in older women with and without TKA. A total of 36 participants were included in this study; the TKA group comprised older women who underwent TKA (n = 18) and the non TKA group comprised older women who did not undergo TKA (n = 18). All the participants were evaluated for physical function, proprioception, muscle strength, postural balance, and walking. The outcome measures were compared between the 2 groups using an independent t test. Correlations were assessed using Pearson correlation coefficients. Participants in the TKA group had significantly reduced physical function, postural balance, and walking ability compared with those in the non TKA group (P < .05). In the TKA group, physical function was statistically correlated with proprioception, postural balance, and walking (P < .05); in particular, it had a strong correlation with proprioception (R > .60). In the non TKA group, postural balance was significantly associated with muscle strength and walking (P < .05). In particular, it was strongly correlated with walking (R > .90). This study demonstrated that older women undergoing TKA need to actively perform interventions to improve physical function, postural balance, and walking compared with older women with osteoarthritis.

Utilization of Mid-Thigh Magnetic Resonance Imaging to Predict Lean Body Mass and Knee Extensor Strength in Obese Adults

Purpose

To train and test a machine learning model to automatically measure mid-thigh muscle cross-sectional area (CSA) to provide rapid estimation of appendicular lean mass (ALM) and predict knee extensor torque of obese adults.

Methods

Obese adults [body mass index (BMI) = 30–40 kg/m², age = 30–50 years] were enrolled for this study. Participants received full-body dual-energy X-ray absorptiometry (DXA), mid-thigh MRI, and completed knee extensor and flexor torque assessments via isokinetic dynamometer. Manual segmentation of mid-thigh CSA was completed for all MRI scans. A convolutional neural network (CNN) was created based on the manual segmentation to develop automated quantification of mid-thigh CSA. Relationships were established between the automated CNN values to the manual CSA segmentation, ALM via DXA, knee extensor, and flexor torque.

Results

A total of 47 obese patients were enrolled in this study. Agreement between the CNN-automated measures and manual segmentation of mid-thigh CSA was high (>0.90). Automated measures of mid-thigh CSA were strongly related to the leg lean mass (r = 0.86, p < 0.001) and ALM (r = 0.87, p < 0.001). Additionally, mid-thigh CSA was strongly related to knee extensor strength (r = 0.76, p < 0.001) and moderately related to knee flexor strength (r = 0.48, p = 0.002).

Conclusion

CNN-measured mid-thigh CSA was accurate compared to the manual segmented values from the mid-thigh. These values were strongly predictive of clinical measures of ALM and knee extensor torque. Mid-thigh MRI may be utilized to accurately estimate clinical measures of lean mass and function in obese adults.

Cross-sectional and temporal differences in health-related quality of life of people with and without osteoarthritis: a 10-year prospective study

OBJECTIVE

To describe the impact of OA on health-related quality of life (HRQoL) in the forms of health state utilities (HSUs) and health-dimension scores, and to compare the longitudinal changes in HRQoL for people with and without OA, using an Australian population-based longitudinal cohort.

METHODS

Participants of the Tasmanian Older Adult Cohort with data on OA diagnosis and HRQoL were included [interviewed at baseline (n = 1093), 2.5 years (n = 871), 5 years (n = 760) and 10 years (n = 562)]. HRQoL was assessed using the Assessment of Quality of Life four-dimensions and analysed using multivariable linear mixed regressions.

RESULTS

Compared with participants without OA, HSUs for those with OA were 0.07 (95% confidence interval: 0.09, 0.05) units lower on average over 10 years. HSUs for participants with knee and/or hip OA were similar to those with other types of OA at the 2.5 year follow-up and then diverged, with HSUs of the former being up to 0.09 units lower than the latter. Those with OA had lower scores for psychological wellness, independent living and social relationships compared with those without OA. Independent living and social relationships were mainly impacted by knee and/or hip OA, with the effect on the former increasing over time.

CONCLUSION

Interventions to improve HRQoL should be tailored to specific OA types, health dimensions, and times. Support for maintaining psychological wellness should be provided, irrespective of OA type and duration. However, support for maintaining independent living could be more relevant to knee and/or hip OA patients living with the disease for longer.

Independent associations of socioeconomic factors with disability and pain in adults with knee osteoarthritis

BACKGROUND

The purpose of this study is to explore the relationship between function, pain and stiffness outcomes with individual and community socioeconomic status (SES) measures among individuals with radiographic knee osteoarthritis (rOA).

METHODS

Cross-sectional data from the Johnston County Osteoarthritis Project were analyzed for adults age 45 and older with knee rOA (n = 782) and a subset with both radiographic and symptomatic knee OA (n = 471). Function, pain and stiffness were measured using the Western Ontario and McMasters Universities Index of Osteoarthritis (WOMAC). Individual SES measures included educational attainment (<12 years, ≥12 years) and occupation type (managerial, non-managerial), while community SES was measured using Census block group poverty rate (<12%, 12-25%, ≥25%). SES measures were individually and simultaneously examined in linear regression models adjusting for age, gender, race, body mass index (BMI), occupational physical activity score (PAS), comorbidity count, and presence of hip symptoms.

RESULTS

In analyses among all individuals with rOA, models which included individual SES measures were observed to show that occupation was significantly associated with WOMAC Function (β =2.91, 95% Confidence Interval (CI) = 0.68-5.14), WOMAC Pain (β =0.93, 95% CI = 0.26-1.59) and WOMAC Total scores (β =4.05, 95% CI = 1.04-7.05), and education was significantly associated with WOMAC Function (β =3.57, 95% CI = 1.25-5.90) and WOMAC Total (β =4.56, 95% CI = 1.41-7.70) scores. In multivariable models including all SES measures simultaneously, most associations were attenuated. However, statistically significant results for education remained between WOMAC Function (β =2.83, 95% CI = 0.38-5.28) and WOMAC Total (β =3.48, 95% CI = 0.18-6.78), as well as for the association between occupation and WOMAC Pain (β =0.78, 95% CI = 0.08-1.48). In rOA subgroup analyses restricted to those with symptoms, we observed a significant increase in WOMAC Pain (β =1.36, 95% CI = 0.07-2.66) among individuals living in a block group with poverty rates greater than 25%, an association that remained when all SES measures were considered simultaneously (β =1.35, 95% CI = 0.06-2.64).

CONCLUSIONS

Lower individual and community SES are both associated with worse function and pain among adults with knee rOA.

Unilateral vs bilateral symptomatic knee osteoarthritis: associations between pain intensity and function

OBJECTIVE

The objective of this study was to determine if associations between pain distribution (unilateral vs bilateral) and measures of function (self-report vs performance-based) were influenced by knee pain intensity of the painful knee(s) in persons with moderate to severe symptomatic knee OA.

METHODS

Data from persons in the Osteoarthritis Initiative (OAI) dataset (n = 852) with symptomatic knee OA were studied. Key dependent variables were the WOMAC physical function, Knee Injury and Osteoarthritis Outcome Score (KOOS) quality of life, the repeated chair stand test and the 20-m walk test. In addition to covariates, the independent variables were the presence of unilateral or bilateral OA involvement (either Kellgren and Lawrence grade 3 or 4 or a grade <3) and pain category (mild, moderate or severe).

RESULTS

WOMAC physical function scores consistently showed the strongest association with pain intensity for persons with unilateral vs bilateral knee pain. For example, in persons with unilateral severe knee pain, WOMAC scores averaged 19.9 (S.D. = 12.0) points while persons with bilateral knee pain with at least one knee rated as severe had WOMAC scores ranging from 25.3 to 28.9, depending on pain severity of the contralateral knee. These differences were statistically significant (P < 0.001) as was the test for trend (P = 0.001). Self-report measures generally showed larger effect sizes than performance-based measures.

CONCLUSION

Knee pain intensity influences self-report and performance-based tests differently depending on whether knee pain is unilateral or bilateral. WOMAC scores are most strongly associated with pain intensity in persons with unilateral vs bilateral pain while walking tests are least influenced by pain intensity.

Reasons why multimorbidity increases the risk of participation restriction in older adults with lower extremity osteoarthritis: a prospective cohort study in primary care

OBJECTIVE

To determine why multimorbidity causes participation restriction in adults ages ≥50 years who consult primary care with lower extremity osteoarthritis (OA).

METHODS

This was a population-based prospective cohort study of 1,053 consulters for lower extremity OA who were free of participation restriction at baseline. Path analysis was used to test proposed mechanisms by examining for mediation of the association between multimorbidity at baseline, defined by self-report and consultation data separately, and incident participation restriction at 3 years by lower extremity pain severity, obesity, locomotor disability, and depression.

RESULTS

Multimorbidity was associated with incident participation restriction (adjusted odds ratio [OR] 2.83, 95% confidence interval [95% CI] 2.03-3.94 for multimorbidity [self-report]; OR 1.59, 95% CI 1.15-2.21 for multimorbidity [consultation data]). The extent of mediation of the association of baseline multimorbidity, defined by self-report, and incident participation restriction was greater for severe lower extremity pain than obesity (standardized beta coefficients for indirect effect 0.032 [SE 0.015] and 0.020 [SE 0.019], respectively). The addition of depression and locomotor disability increased the amount of mediation (0.115 [SE 0.028]) and reduced the proportion explained by severe lower extremity pain (0.014 [SE 0.015]) and obesity (0.006 [SE 0.010]). Locomotor disability was the strongest mediator.

CONCLUSION

The additional impact on participation in social and domestic life that multimorbidity places on individuals with lower extremity OA appears to be mediated through further restriction of locomotor disability, as well as through depression. The results suggest that the effect of multimorbidity on the daily lives of people with lower extremity OA will be ameliorated by active management of depression and locomotor disability.

Shut-In? Impact of Chronic Conditions on Community Participation Restriction among Older Adults

Community participation may be especially important for older adults, who are often at risk for unwanted declines in participation. We estimated the prevalence of community participation restriction (PR) due to perceived environmental barriers among older adults (≥50 years) and compared the impact among those with selected chronic conditions. Individuals with low-prevalence conditions reported high community PR (9.1–20.4%), while those with highly prevalent conditions (e.g., arthritis) had relatively low community PR (5.1–10.0%) but represented the greatest absolute numbers of condition-associated burden (>1 million). Across all conditions, more than half of those with community PR reported being restricted “always or often.” Community PR most often resulted from modifiable environmental barriers. Promising targets to reduce community PR among adults ≥50 years with chronic conditions, particularly arthritis, include building design, sidewalks/curbs, crowd control, and interventions that improve the built environment.

The contribution of osteoarthritis to functional limitations and disability

This article uses the Disablement Model conceptual framework to guide an analysis of the importance of osteoarthritis (OA) in the development of disability. The Disablement Model describes the development and progression of disablement from impairments to specific functional limitations and disability, and the hypothesized role of predisposing risk factors, extra-individual factors, and intra-individual factors. A wide range of population and clinical studies have characterized the unequivocal contribution of arthritis to the development of functional limitations and disability. Evidence overwhelmingly supports a significant, moderate independent contribution of arthritis to the onset and progression of functional limitations and disability. With respect to important risk factors for the development of functional limitations and disability among those with OA, the evidence provides strong support for the role of physical impairments along with other predisposing and intra-individual factors such as age, body mass index, obesity, lack of exercise, comorbid conditions, depression, and depressive symptoms. Extra-individual factors included need for aids and assistance, and lack of access to public or private transportation. Future disablement research must clarify the causal mechanisms behind a potential risk factor's impact on disability and delineate the interplay between and among the various hypothesized steps in the disablement process.

Strength training in older adults: the benefits for osteoarthritis

This review summarizes the findings of randomized controlled trials of progressive resistance training (PRT) by older people with osteoarthritis (OA). A significant benefit was found in lower-extremity extensor strength, function, and pain reduction. Across all 3 outcomes, the estimated effect size was moderate, which contrasted with trials of PRT in non-OA-specific groups of older adults where a large effect was found in strength but a small effect on function. This suggests that strength training has strong functional benefits for older adults with OA. Older adults with OA benefit from a strength-training program that provides progressive overload to maintain intensity throughout an exercise program.

Evolution of sarcopenia research

The term "saropenia" was coined by Irwin Rosenberg in 1989 to refer to age-related loss of skeletal muscle mass. The purpose of this current opinion is to provide an evolutionary overview of sarcopenia research since 1989. This includes the creation of an operational definition of sarcopenia; consideration of the impacts of sarcopenia on physical function, chronic disease, and mortality risk; the distinction between the process of sarcopenia and the process of age-related loss of muscle strength, a phenomenon that has recently been termed dynapenia; a comparison of the independent effects of sarcopenia and dynapenia on physical function, chronic disease, and mortality risk; and consideration of the combined influence of sarcopenia and dynapenia with obesity (i.e., sarcopenic-obesity and dynapenic-obesity) on physical function, chronic disease, and mortality risk.

The independent effect of pain in one versus two knees on the presence of low physical function in a multicenter knee osteoarthritis study

OBJECTIVE

Although knee pain severity is thought to greatly impact function, the additional contribution of pain in 1 versus 2 knees is not known. We examined the relationship between unilateral versus bilateral pain with low physical functioning at baseline and 30 months while accounting for knee pain severity.

METHODS

The Multicenter Osteoarthritis Study is a cohort study of people who have or are at high risk for knee osteoarthritis. We defined low physical function as Western Ontario and McMaster Universities Osteoarthritis Index physical functioning scores > or = 28 of 68, consistent with poor functional outcome. Incidence and improvement from low physical function were defined as scores that declined below and improved above this threshold at 30 months. We examined the association between pain in 1 or 2 knees with low physical function with risk ratios (RRs) adjusting for known confounders.

RESULTS

Of the 2,069 subjects (mean +/- SD age 63 +/- 8 years, mean +/- SD body mass index 31 +/- 6 kg/m(2), 63% women), the prevalence of low physical functioning was 50% lower among persons with unilateral pain compared with those with bilateral pain (adjusted prevalence ratio 0.5 [95% confidence interval (95% CI) 0.3-0.7]). Of those without low physical functioning at baseline, the risk of incidence at 30 months was 30% less for unilateral compared with bilateral pain (adjusted RR 0.7 [95% CI 0.5-1.0]). Of those with low physical functioning at baseline, improvement was 1.7 times more likely for those with unilateral compared with bilateral pain (adjusted RR 1.7 [95% CI 1.3-2.2]).

CONCLUSION

The presence of pain in 1 versus 2 knees provides important information regarding present and future physical functioning.

A computer-adaptive disability instrument for lower extremity osteoarthritis research demonstrated promising breadth, precision, and reliability

OBJECTIVE

To develop and evaluate a prototype measure (OA-DISABILITY-CAT) for osteoarthritis research using item response theory (IRT) and computer-adaptive test (CAT) methodologies.

STUDY DESIGN AND SETTING

We constructed an item bank consisting of 33 activities commonly affected by lower extremity (LE) osteoarthritis. A sample of 323 adults with LE osteoarthritis reported their degree of limitation in performing everyday activities, and completed the Health Assessment Questionnaire-II (HAQ-II). We used confirmatory factor analyses to assess scale unidimensionality and IRT methods to calibrate the items and examine the fit of the data. Using CAT simulation analyses, we examined the performance of OA-DISABILITY-CATs of different lengths compared with the full-item bank and the HAQ-II.

RESULTS

One distinct disability domain was identified. The 10-item OA-DISABILITY-CAT demonstrated a high degree of accuracy compared with the full-item bank (r=0.99). The item bank and the HAQ-II scales covered a similar estimated scoring range. In terms of reliability, 95% of OA-DISABILITY reliability estimates were over 0.83 vs. 0.60 for the HAQ-II. Except at the highest scores, the 10-item OA-DISABILITY-CAT demonstrated superior precision to the HAQ-II.

CONCLUSION

The prototype OA-DISABILITY-CAT demonstrated promising measurement properties compared with the HAQ-II, and is recommended for use in LE osteoarthritis research.

The natural history of disability and its determinants in adults with lower limb musculoskeletal pain

OBJECTIVE

To investigate determinants of deterioration or improvement in disability in people with chronic hip and knee pain.

METHODS

We analyzed data from the Somerset and Avon Survey of Health, a longitudinal, community-based cohort study containing data collected in 1994-95 and again in 2002-03. The Medical Outcomes Study Short-Form 36 was completed by subjects at both timepoints, and used to categorize people as disabled or not. Baseline data were used to explore possible determinants of change in functional status over the 8-year time period. Adjusted odds ratios (OR) were derived from a multivariate, multinomial logistic model.

RESULTS

Data were available on 1072 subjects, all of whom reported chronic hip and/or knee pain at baseline. At baseline, 56.8% of women and 42.0% of men were disabled. Of 545 people with disabilities at baseline, 107 (19.6%) reported no disability at followup; of 527 with no disability at baseline, 177 (33.6%) became disabled. The development of disability was significantly associated with older age (OR 2.1), living in the most deprived areas (2.4), the presence of 3 or more comorbidities (3.6), more problems with physical function at baseline (2.0), and more severe pain (2.4). The determinants of improvement mirrored those of deterioration. The data suggest a "threshold effect" at which recovery becomes unlikely.

CONCLUSION

Of people presenting with hip or knee pain, healthcare professionals should be most concerned about those who are older, of lower socioeconomic status, with comorbidities, and who have more severe pain. Much longstanding disability might be preventable.

At the tipping point: predicting severe mobility difficulty in vulnerable older women

OBJECTIVES

To identify clinical measures that aid detection of impending severe mobility difficulty in older women.

DESIGN

Cross-sectional and longitudinal cohort study.

SETTING

Urban community in Baltimore, Maryland.

PARTICIPANTS

One thousand two community-dwelling, moderate to severely disabled women aged 65 and older in the Women's Health and Aging Study I.

MEASUREMENTS

Self-report and performance measures representing six domains necessary for mobility: central and peripheral nervous systems, muscles, bones and joints, perception, and energy. Severe mobility difficulty was defined as usual gait of 0.5 m/s or less, any reported difficulty walking across a small room, or dependence on a walking aid during a 4-m walking test.

RESULTS

Four hundred sixty-seven out of 984 (47%) had severe mobility difficulty at baseline, and 104/474 (22%) developed it within 12 months. Baseline mobility difficulty was correlated with poor vision, knee pain, feelings of helplessness, inability to stand with feet side by side for 10 seconds, difficulty keeping balance while dressing or walking, inability to rise from a chair five times, and cognitive impairment. Of these, knee pain (odds ratio (OR)=1.74, 95% confidence interval (CI)=1.05-2.89), helplessness (OR=1.87, 95% CI=1.10-3.24), poor vision (OR=2.03, 95% CI=1.06-3.89), inability to rise from a chair five times (OR=2.50, 95% CI=1.15-5.41), and cognitive impairment (OR=4.75, 95% CI=1.67-13.48) predicted incident severe mobility difficulty within 12 months, independent of age.

CONCLUSION

Five simple measures may aid identification of disabled older women at high risk of severe mobility difficulty. Further studies should determine generalizability to men and higher-functioning individuals.

Total knee arthroplasty: muscle impairments, functional limitations, and recommended rehabilitation approaches

The number of total knee arthroplasty (TKA) surgeries performed each year is predicted to steadily increase. Following TKA surgery, self-reported pain and function improve, though individuals are often plagued with quadriceps muscle impairments and functional limitations. Postoperative rehabilitation approaches either are not incorporated or incompletely address the muscular and functional deficits that persist following surgery. While the reason for quadriceps weakness is not well understood in this patient population, it has been suggested that a combination of muscle atrophy and neuromuscular activation deficits contribute to residual strength impairments. Failure to adequately address the chronic muscle impairments has the potential to limit the long-term functional gains that may be possible following TKA. Postoperative rehabilitation addressing quadriceps strength should mitigate these impairments and ultimately result in improved functional outcomes. The purpose of this paper is to describe these quadriceps muscle impairments and discuss how these impairments can contribute to the related functional limitations following TKA. We will also describe the current concepts in TKA rehabilitation and provide recommendations and clinical guidelines based on the current available evidence.

LEVEL OF EVIDENCE

Therapy, level 5.

Obesity and inpatient rehabilitation outcomes following knee arthroplasty: a multicenter study

OBJECTIVE

This multicenter study examined whether inpatient rehabilitation outcomes following total knee arthroplasty (TKA) were influenced by BMI.

METHODS AND PROCEDURES

This was a retrospective, comparative study conducted using a computerized medical database and medical records derived from TKA patients, at 15 independent rehabilitation hospitals (N = 5,428). Patients were separated into four groups based on BMI: non-obese (BMI < 25 kg/m(2)), overweight (25-29.9 kg/m(2)), moderately obese (30-40 kg/m(2)), severely obese (BMI > or = 40 kg/m(2)). All patients completed an interdisciplinary inpatient rehabilitation program post-TKA. Total and individual functional independence measure (FIM) scores, length of stay (LOS), FIM efficiency scores, itemized hospital charges, and discharge disposition location, were collected.

RESULTS

The percentage of total FIM change was 7.5% greater by the time of discharge in the non-obese than in the very severely obese (P < 0.05). FIM efficiency was lowest in the severely obese as compared to the remaining groups (3.7 points (pts)/day vs. 4.0-4.3 pts/day; P = 0.044). The change in the motor FIM score from admission to discharge was 6.7-15.6% greater in the non-obese than in the remaining groups (P < 0.05). The changes in cognition FIM, toilet transfer and walking without assistance scores were higher in the non-obese as compared to the severely obese group (P < 0.05). The severely obese group had higher total, physical and occupational therapy and pharmacy charges than the remaining groups (P < 0.05).

DISCUSSION

An excessive BMI does not prevent gains during inpatient rehabilitation; however, these gains are made less efficiently and at a higher cost than those made when the BMI is low.

Electromyographic patterns suggest changes in motor unit physiology associated with early osteoarthritis of the knee

OBJECTIVE

To assess characteristics of active motor units (MUs) during volitional vastus medialis (VM) activation in adults with symptomatic knee osteoarthritis (OA) across the spectrum of radiographic severity and age-comparable healthy control volunteers.

METHODS

We evaluated 39 participants (age 65+/-3 years) in whom weight-bearing knee X-rays were assigned a Kellgren & Lawrence (KL) grade (18 with KL grade=0; four each with KL grades=1, 2 and 4; nine with grade 3). Electromyography (EMG) signals were simultaneously acquired using surface [surface EMG (S-EMG)] and intramuscular needle electrodes, and analyzed by decomposition-enhanced spike-triggered averaging to obtain estimates of size [surface-represented MU action potentials (S-MUAP) area], number [MU recruitment index (MURI)] and firing rates [MU firing rates (mFR)] of active MUs at 10%, 20%, 30% and 50% effort relative to maximum voluntary force [maximal voluntary isometric contraction (MVIC)] during isometric knee extension.

RESULTS

Knee extensor MVIC was lower in OA participants, especially at higher KL grades (P=0.05). Taking the observed force differences into account, OA was also associated with activation of larger MUs (S-MUAP area/MVICx%effort; P<0.0001). In contrast, the estimated number of active units (MURI/MVICx%effort) changed differently as effort increased from 10% to 50% and was higher with advanced OA (KL=3, 4) than controls (P=0.0002).

CONCLUSION

VM activation changes at the level of the MU with symptomatic knee OA, and this change is influenced by radiographic severity. Poor muscle quality may explain the pattern observed with higher KL grades, but alternative factors (e.g., nerve or joint injury, physical inactivity or muscle composition changes) should be examined in early OA.

Effect of weight reduction in obese patients diagnosed with knee osteoarthritis: a systematic review and meta-analysis

This review aims to assess by meta-analysis of randomised controlled trials (RCTs) changes in pain and function when overweight patients with knee osteoarthritis (OA) achieve a weight loss. Systematic searches were performed and reference lists from the retrieved trials were searched. RCTs were enclosed in the systematic review if they explicitly stated diagnosis of knee OA and reported a weight change as the only difference in intervention from the control group. Outcome Measures for Arthritis Clinical Trials III outcome variables were considered for analysis. Effect size (ES) was calculated using RevMan, and meta-regression analyses were performed using weighted estimates from the random effects analyses. Among 35 potential trials identified, four RCTs including five intervention/control groups met our inclusion criteria and provided data from 454 patients. Pooled ES for pain and physical disability were 0.20 (95% CI 0 to 0.39) and 0.23 (0.04 to 0.42) at a weight reduction of 6.1 kg (4.7 to 7.6 kg). Meta-regression analysis showed that disability could be significantly improved when weight was reduced over 5.1%, or at the rate of >0.24% reduction per week. Clinical efficacy on pain reduction was present, although not predictable after weight loss. Meta-regression analysis indicated that physical disability of patients with knee OA and overweight diminished after a moderate weight reduction regime. The analysis supported that a weight loss of >5% should be achieved within a 20-week period--that is, 0.25% per week.