Budget impact of the Walk With Ease program for knee osteoarthritis

Objective

Walk With Ease (WWE) is an effective low-cost walking program. We estimated the budget impact of implementing WWE in persons with knee osteoarthritis (OA) as a measure of affordability that can inform payers' funding decisions.

Methods

We estimated changes in two-year healthcare costs with and without WWE. We used the Osteoarthritis Policy (OAPol) Model to estimate per-person medical expenditures. We estimated total and per-member-per-month (PMPM) costs of funding WWE for a hypothetical insurance plan with 75,000 members under two conditions: 1) all individuals aged 45+ with knee OA eligible for WWE, and 2) inactive and insufficiently active individuals aged 45+ with knee OA eligible. In sensitivity analyses, we varied WWE cost and efficacy and considered productivity costs.

Results

With eligibility unrestricted by activity level, implementing WWE results in an additional $1,002,408 to the insurance plan over two years ($0.56 PMPM). With eligibility restricted to inactive and insufficiently active individuals, funding WWE results in an additional $571,931 over two years ($0.32 PMPM). In sensitivity analyses, when per-person costs of $10 to $1000 were added with 10-50% decreases in failure rate (enhanced sustainability of WWE benefits), two-year budget impact varied from $242,684 to $6,985,674 with unrestricted eligibility and from -$43,194 (cost-saving) to $4,484,122 with restricted eligibility.

Conclusion

Along with the cost-effectiveness of WWE at widely accepted willingness-to-pay thresholds, these results can inform payers in deciding to fund WWE. In the absence of accepted thresholds to define affordability, these results can assist in comparing the affordability of WWE with other behavioral interventions.

The association between obesity, knee pain, and gait during stair descent in older adults with knee osteoarthritis

BACKGROUND

Obesity and knee osteoarthritis adversely affect activities of daily living in older adults. Together, the complexities of their interaction on mobility, including stair negotiation, are unresolved. The purpose of this study was to determine the relationship between obesity, pain, and stair negotiation in older adults with knee osteoarthritis.

METHODS

Older adults with symptomatic knee osteoarthritis and overweight or obesity participated in the study (n = 28; age range = 57.0-78.0 yrs.; body mass index range = 26.6-42.8 kg•m-2). The Western Ontario and McMaster Universities Osteoarthritis Index pain subscale was used to measure knee pain. Measurements included a three-dimensional biomechanical analysis during descent on a set of force plate-instrumented stairs and a timed stair descent test. Pearson's r was used to determine associations between body mass index and pain, stair descent weight-acceptance phase vertical ground reaction force (vGRF) variables and lower extremity joint kinematics and kinetics, and timed stair descent performance.

FINDINGS

Significant correlations existed between body mass index and pain (r = 0.41; p = 0.03), peak vGRF (r = 0.39; p = 0.04), vertical impulse (r = 0.49; p = 0.008), and peak ankle plantar flexor moments (r = 0.50; p = 0.007) in older adults with knee osteoarthritis.

INTERPRETATION

Greater obesity in older adults with knee osteoarthritis was associated with greater knee pain and higher ankle joint loads during stair descent. These results support the recommendations of osteoarthritis treatment guidelines for weight-loss as a first-line of treatment for older adults with obesity and knee osteoarthritis.

Clinical, Health-Related Quality of Life, and Gait Differences Among Obesity Classes in Adults With Knee Osteoarthritis

OBJECTIVE

The purpose of this study was to determine whether clinical, health-related quality of life (HRQL), and gait characteristics in adults with knee osteoarthritis (OA) differed by obesity category.

METHODS

This cross-sectional analysis of 823 older adults (mean age 64.6 years, SD 7.8 years) with knee OA and overweight or obesity compared clinical, HRQL, and gait outcomes among obesity classifications (overweight or class I, body mass index [BMI] 27.0-34.9; class II, BMI 35.0-39.9; class III BMI ≥40.0).

RESULTS

Patients with class III obesity had worse Western Ontario McMasters Universities Arthritis Index knee pain (0-20) than the overweight or class I (mean 8.6 vs 7.0; difference 1.5; 95% confidence interval [CI] 1.0-2.1; P < 0.0001) and class II (mean 8.6 vs 7.4; difference 1.1; 95% CI 0.6-1.7; P = 0.0002) obesity groups. The Short Form 36 physical HRQL measure was lower in the class III obesity group compared to the overweight or class I (mean 31.0 vs 37.3; difference -6.2; 95% CI -7.8 to -4.7; P < 0.0001) and class II (mean 31.0 vs 35.0; difference -3.9; 95% CI -5.6 to -2.2; P < 0.0001) obesity groups. The class III obesity group had a base of support (cm) during gait that was wider than that for the overweight or class I (mean 14.0 vs 11.6; difference 3.3; 95% CI 2.6-4.0; P < 0.0001) and class II (mean 14.0 vs 11.6; difference 2.4; 95% CI 1.6-3.2; P < 0.0001) obesity groups.

CONCLUSION

Among adults with knee OA, those with class III obesity had significantly higher pain levels and worse physical HRQL and gait characteristics compared to adults with overweight or class I or class II obesity.

Cost-Effectiveness of Community-Based Diet and Exercise for Patients with Knee Osteoarthritis and Obesity or Overweight

OBJECTIVE

Obesity exacerbates pain and functional limitation in persons with knee osteoarthritis (OA). In the Weight Loss and Exercise for Communities with Arthritis in North Carolina (WE-CAN) study, a community-based diet and exercise (D + E) intervention led to an additional 6 kg weight loss and 20% greater pain relief in persons with knee OA and body mass index (BMI) >27 kg/m2 relative to a group-based health education (HE) intervention. We sought to determine the incremental cost-effectiveness of the usual care (UC), UC + HE, and UC + (D + E) programs, comparing each strategy with the "next-best" strategy ranked by increasing lifetime cost.

METHODS

We used the Osteoarthritis Policy Model to project long-term clinical and economic benefits of the WE-CAN interventions. We considered three strategies: UC, UC + HE, and UC + (D + E). We derived cohort characteristics, weight, and pain reduction from the WE-CAN trial. Our outcomes included quality-adjusted life years (QALYs), cost, and incremental cost-effectiveness ratios (ICERs).

RESULTS

In a cohort with mean age 65 years, BMI 37 kg/m2, and Western Ontario and McMaster Universities Osteoarthritis Index pain score 38 (scale 0-100, 100 = worst), UC leads to 9.36 QALYs/person, compared with 9.44 QALYs for UC + HE and 9.49 QALYS for UC + (D + E). The corresponding lifetime costs are $147,102, $148,139, and $151,478. From the societal perspective, UC + HE leads to an ICER of $12,700/QALY; adding D + E to UC leads to an ICER of $61,700/QALY.

CONCLUSION

The community-based D + E program for persons with knee OA and BMI >27kg/m2 could be cost-effective for willingness-to-pay thresholds greater than $62,000/QALY. These findings suggest that incorporation of community-based D + E programs into OA care may be beneficial for public health.

Collegiate Dancers With Chronic Ankle Instability Possess Altered Strength and saut de chat Leap Landing Mechanics

INTRODUCTION

Ankle sprains are among the most common injuries in dancers. Following one or more severe sprains, some individuals will experience residual mechanical and functional deficits, otherwise known as chronic ankle instability (CAI). Dancers who suffer from CAI may have weaker musculature surrounding the ankle and altered landing mechanics. The purpose of this study was to compare ankle strength and saut de chat landing mechanics between dancers with and without CAI.

METHODS

Dancers with and without CAI, defined by the Identification of Functional Ankle Instability (IdFAI), participated in the study (CAI n = 8; IdFAI = 18.75 ± 5.50 points; age = 20 ± 1.5 years; training = 15.5 ± 3.5 years) (Control n = 8; IdFAI = 7.13 ± 3.40 points; age = 19 ± 0.6 years; training = 15.9 ± 2.5 years). Strength and leap landing mechanics were measured on the affected ankle for the CAI group and on the preferred landing leg of a leap for the control group. Concentric and eccentric ankle plantar flexion, and subtalar inversion and eversion strength were determined with dynamometry set at an angular velocity of 60°•s-1. Force plates and motion capture cameras were used to calculate lower extremity kinematic and kinetic data as participants performed 3 saut de chat leaps. Independent t-tests were calculated to determine differences between groups.

RESULTS

Compared to dancers without CAI, dancers with CAI had lower eccentric plantar flexor strength, landed with higher vertical ground reaction forces, and absorbed greater power at the knee-joint during landing.

CONCLUSION

Whether dancers who are weaker are more prone to injury or ankle-joint injury leads to muscular weakness is unknown. Dancers with CAI appear to lack control during leap landing while concomitantly shifting loads proximally away from the ankle-joint. We encourage dancers with and without CAI to engage in additional training that enhances ankle strength.

The osteoarthritis prevention study (TOPS) - A randomized controlled trial of diet and exercise to prevent Knee Osteoarthritis: Design and rationale

Background

Osteoarthritis (OA), the leading cause of disability among adults, has no cure and is associated with significant comorbidities. The premise of this randomized clinical trial is that, in a population at risk, a 48-month program of dietary weight loss and exercise will result in less incident structural knee OA compared to control.

Methods/design

The Osteoarthritis Prevention Study (TOPS) is a Phase III, assessor-blinded, 48-month, parallel 2 arm, multicenter randomized clinical trial designed to reduce the incidence of structural knee OA. The study objective is to assess the effects of a dietary weight loss, exercise, and weight-loss maintenance program in preventing the development of structural knee OA in females at risk for the disease. TOPS will recruit 1230 ambulatory, community dwelling females with obesity (Body Mass Index (BMI) ​≥ ​30 ​kg/m2) and aged ≥50 years with no radiographic (Kellgren-Lawrence grade ≤1) and no magnetic resonance imaging (MRI) evidence of OA in the eligible knee, with no or infrequent knee pain. Incident structural knee OA (defined as tibiofemoral and/or patellofemoral OA on MRI) assessed at 48-months from intervention initiation using the MRI Osteoarthritis Knee Score (MOAKS) is the primary outcome. Secondary outcomes include knee pain, 6-min walk distance, health-related quality of life, knee joint loading during gait, inflammatory biomarkers, and self-efficacy. Cost effectiveness and budgetary impact analyses will determine the value and affordability of this intervention.

Discussion

This study will assess the efficacy and cost effectiveness of a dietary weight loss, exercise, and weight-loss maintenance program designed to reduce incident knee OA.

Trial registration

ClinicalTrials.gov Identifier: NCT05946044.

The metabolome of individuals with knee osteoarthritis is influenced by 18-months of an exercise and weight loss intervention and sex: the IDEA trial

Objective

The Intensive Diet and Exercise for Arthritis (IDEA) trial was conducted to evaluate the effects of diet and exercise on osteoarthritis (OA), the most prevalent form of arthritis. Various risk factors, such as obesity and sex, contribute to the debilitating nature of OA. While diet and exercise are known to improve OA symptoms, cellular and molecular mechanisms underlying these interventions, as well as effects of participant sex, remain elusive.

Methods

Serum was obtained at three timepoints from IDEA participants assigned to groups of diet, exercise, or combined diet and exercise (n=10 per group). All serum metabolites were extracted and analyzed via liquid chromatography-mass spectrometry combined with metabolomic profiling. Extracted serum was pooled and fragmentation patterns were analyzed to identify metabolites that statistically differentially regulated between groups.

Results

Changes in metabolism across male and female IDEA participants after 18-months of diet, exercise, and combined diet and excise intervention mapped to lipid, amino acid, carbohydrate, vitamin, and matrix metabolism. The diverse metabolic landscape detected across IDEA participants shows that intervention type impacts the serum metabolome of individuals with OA in distinct patterns. Moreover, differences in the serum metabolome corresponded with participant sex.

Conclusions

These findings suggest that intensive weight loss among male and female subjects offers potential metabolic benefits for individuals with knee OA. This provides a deeper understanding of dysregulation occurring during OA development that may pave the way for improved interventions, treatments, and quality of life of those impacted by this disease.

Walk with ease for knee osteoarthritis: A cost-effectiveness analysis

Objective

The Walk With Ease (WWE) program was developed by the Arthritis Foundation to help people with arthritis learn to exercise safely and improve arthritis symptoms. We sought to establish the value of the WWE program.

Methods

We used the Osteoarthritis Policy (OAPol) Model, a widely published and validated computer simulation of knee osteoarthritis (OA), to assess the cost-effectiveness of WWE in knee OA. We derived model inputs using data from a workplace wellness initiative in Montana that offered WWE to state employees. Our primary outcomes were quality-adjusted life years (QALYs) and costs over a 2-year period, which we used to calculate the incremental cost-effectiveness ratio (ICER). The base case analysis was restricted to subjects who were inactive or insufficiently active (<180 ​min/week of PA) at baseline. We performed scenario and probabilistic sensitivity analyses to determine the impact of uncertainty in model parameters on our results.

Results

In the base case analysis, adding WWE to usual care resulted in an ICER of $47,900/QALY. When the program was offered without preselection by baseline activity level, the ICER for WWE ​+ ​usual care was estimated at $83,400/QALY. Results of the probabilistic sensitivity analysis indicated that WWE offered to inactive or insufficiently active individuals has a 52% chance of having an ICER <$50,000/QALY.

Conclusion

The WWE program offers good value for inactive/insufficiently active individuals. Payers may consider including such a program to increase physical activity in individuals with knee OA.

Cost-Effectiveness of Surgical Weight-Loss Interventions for Patients With Knee Osteoarthritis and Class III Obesity

OBJECTIVE

Class III obesity (body mass index [BMI] ≥40 kg/m2 ) is associated with worse knee pain and total knee replacement (TKR) outcomes. Because bariatric surgery yields sustainable weight loss for individuals with BMI ≥40 kg/m2 , our objective was to establish the value of Roux-en-Y gastric bypass (RYGB) and laparoscopic sleeve gastrectomy (LSG) in conjunction with usual care for knee osteoarthritis (OA) patients with BMI ≥40 kg/m2 .

METHODS

We used the Osteoarthritis Policy model to assess long-term clinical benefits, costs, and cost-effectiveness of RYGB and LSG. We derived model inputs for efficacy, costs, and complications associated with these treatments from published data. Primary outcomes included quality-adjusted life-years (QALYs), lifetime costs, and incremental cost-effectiveness ratios (ICERs), all discounted at 3%/year. This analysis was conducted from a health care sector perspective. We performed sensitivity analyses to evaluate uncertainty in input parameters.

RESULTS

The usual care + RYGB strategy increased the quality-adjusted life expectancy by 1.35 years and lifetime costs by $7,209, compared to usual care alone (ICER = $5,300/QALY). The usual care + LSG strategy yielded less benefit than usual care + RYGB and was dominated. Relative to usual care alone, both usual care + RYGB and usual care + LSG reduced opioid use from 13% to 4%, and increased TKR usage from 30% to 50% and 41%, respectively. For cohorts with BMI between 38 and 41 kg/m2 , usual care + LSG dominated usual care + RYGB. In the probabilistic sensitivity analysis, at a willingness-to-pay threshold of $50,000/QALY, usual care + RYGB and usual care + LSG were cost-effective in 70% and 30% of iterations, respectively.

CONCLUSION

RYGB offers good value among knee OA patients with BMI ≥40 kg/m2 , while LSG may provide good value among those with BMI between 35 and 41 kg/m2 .

Effect of Baseline BMI and IL-6 Subgroup Membership on Gait Speed Response to Caloric Restriction in Older Adults with Obesity

BACKGROUND

Prior work shows caloric restriction (CR) can improve physical function among older adults living with obesity. However, the contribution of starting weight and inflammatory burden to CR-associated functional improvements is unclear. The primary purpose of this study was to determine if CR-associated gait speed change varied by body mass index (BMI) and plasma interleukin 6 (IL-6) at baseline and secondarily to determine the contribution of BMI change and IL-6 change to gait speed change.

DESIGN, SETTING, PARTICIPANTS

Data from eight randomized control trials were pooled, with 1184 participants randomized to CR (n=661) and No CR (n=523) conditions. All studies assessed outcomes before and five or six months after assignment to CR or No CR.

MEASUREMENTS

BMI and IL-6 were assessed at baseline using standard procedures. Gait speed was assessed with the six-minute walk test or 400m walk test. Baseline BMI/IL-6 subgroups were constructed using BMI≥35 kg/m2 and IL-6>2.5 pg/mL thresholds. Participants with BMI≥35 kg/m2 were grouped into class 2+ obesity and BMI<35 kg/m2 into class 1- obesity; IL-6>2.5 pg/mL were grouped into high IL-6, and <2.5 pg/mL as low IL-6 (class 2+ obesity/high IL-6: n=288, class 2+ obesity/low IL-6: n=143, class 1- obesity/high IL-6: n=354, or class 1- obesity/low IL-6: n=399). All analyses used adjusted general linear models.

RESULTS

Gait speed significantly improved with CR versus non-CR [mean difference: +0.02 m/s (95% CI: 0.01, 0.04)]. CR assignment significantly interacted with BMI/IL-6 subgroup membership (p=0.03). Greatest gait speed improvement was observed in the class 2+ obesity/high IL-6 subgroup [+0.07 m/s (0.03, 0.10)]. No other subgroups observed significant gait speed change. For each unit decrease in BMI, gait speed change increased by +0.02 m/s (p<0.001; R2=0.26), while log IL-6 change did not significantly affect gait speed change [+0.01 m/s (p=0.20)].

CONCLUSIONS

Only the class 2+ obesity/high IL-6 subgroup significantly improved gait speed in response to CR. Improvement in gait speed in this subgroup was driven by a larger decrease in BMI, but not IL-6, in response to CR. Individuals with class 2+ obesity and high IL-6 are most likely to show improved gait speed in response to CR, with improvement predominantly driven by reductions in BMI.

Effect of Diet and Exercise on Knee Pain in Patients With Osteoarthritis and Overweight or Obesity: A Randomized Clinical Trial

IMPORTANCE

Some weight loss and exercise programs that have been successful in academic center-based trials have not been evaluated in community settings.

OBJECTIVE

To determine whether adaptation of a diet and exercise intervention to community settings resulted in a statistically significant reduction in pain, compared with an attention control group, at 18-month follow-up.

DESIGN, SETTING, AND PARTICIPANTS

Assessor-blinded randomized clinical trial conducted in community settings in urban and rural counties in North Carolina. Patients were men and women aged 50 years or older with knee osteoarthritis and overweight or obesity (body mass index ≥27). Enrollment (N = 823) occurred between May 2016 and August 2019, with follow-up ending in April 2021.

INTERVENTIONS

Patients were randomly assigned to either a diet and exercise intervention (n = 414) or an attention control (n = 409) group for 18 months.

MAIN OUTCOMES AND MEASURES

The primary outcome was the between-group difference in the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) knee pain score (range, 0 [none] to 20 [severe]; minimum clinically important difference, 1.6) over 18 months, tested using a repeated-measures mixed linear model with adjustments for covariates. There were 7 secondary outcomes including body weight.

RESULTS

Among the 823 randomized patients (mean age, 64.6 years; 637 [77%] women), 658 (80%) completed the trial. At 18-month follow-up, the adjusted mean WOMAC pain score was 5.0 in the diet and exercise group (n = 329) compared with 5.5 in the attention control group (n = 316) (adjusted difference, -0.6; 95% CI, -1.0 to -0.1; P = .02). Of 7 secondary outcomes, 5 were significantly better in the intervention group compared with control. The mean change in unadjusted 18-month body weight for patients with available data was -7.7 kg (8%) in the diet and exercise group (n = 289) and -1.7 kg (2%) in the attention control group (n = 273) (mean difference, -6.0 kg; 95% CI, -7.3 kg to -4.7 kg). There were 169 serious adverse events; none were definitely related to the study. There were 729 adverse events; 32 (4%) were definitely related to the study, including 10 body injuries (9 in diet and exercise; 1 in attention control), 7 muscle strains (6 in diet and exercise; 1 in attention control), and 6 trip/fall events (all 6 in diet and exercise).

CONCLUSIONS AND RELEVANCE

Among patients with knee osteoarthritis and overweight or obesity, diet and exercise compared with an attention control led to a statistically significant but small difference in knee pain over 18 months. The magnitude of the difference in pain between groups is of uncertain clinical importance.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02577549.

Cost-Effectiveness of Weight-Loss Interventions Prior to Total Knee Replacement for Patients With Class III Obesity

OBJECTIVE

Class III obesity (body mass index >40 kg/m² ) is associated with higher complications following total knee replacement (TKR), and weight loss is recommended. We aimed to establish the cost-effectiveness of Roux-en-Y gastric bypass (RYGB), laparoscopic sleeve gastrectomy (LSG), and lifestyle nonsurgical weight loss (LNSWL) interventions in knee osteoarthritis patients with class III obesity considering TKR.

METHODS

Using the Osteoarthritis Policy model and data from published literature to derive model inputs for RYGB, LSG, LNSWL, and TKR, we assessed the long-term clinical benefits, costs, and cost-effectiveness of weight-loss interventions for patients with class III obesity considering TKR. We assessed the following strategies with a health care sector perspective: 1) no weight loss/no TKR, 2) immediate TKR, 3) LNSWL, 4) LSG, and 5) RYGB. Each weight-loss strategy was followed by annual TKR reevaluation. Primary outcomes were cost, quality-adjusted life expectancy (QALE), and incremental cost-effectiveness ratios (ICERs), discounted at 3% per year. We conducted deterministic and probabilistic sensitivity analyses to examine the robustness of conclusions to input uncertainty.

RESULTS

LSG increased QALE by 1.64 quality-adjusted life-years (QALYs) and lifetime medical costs by $17,347 compared to no intervention, leading to an ICER of $10,600/QALY. RYGB increased QALE by 0.22 and costs by $4,607 beyond LSG, resulting in an ICER of $20,500/QALY. Relative to immediate TKR, LSG and RYGB delayed and decreased TKR utilization. In the probabilistic sensitivity analysis, RYGB was cost-effective in 67% of iterations at a willingness-to-pay threshold of $50,000/QALY.

CONCLUSION

For patients with class III obesity considering TKR, RYGB provides good value while immediate TKR without weight loss is not economically efficient.

Reduction of risk factors for ACL Re-injuries using an innovative biofeedback approach: A phase I randomized clinical trial

OBJECTIVES

Determine the safety and initial efficacy of a novel biofeedback intervention to improve landing mechanics in patients following anterior cruciate ligament reconstruction (ACLR).

METHODS

Forty patients post-ACLR (age: 16.9 ± 2.0 years) were randomly allocated to a biofeedback intervention or an attention control group. Patients in the biofeedback group completed 12 sessions over six-weeks that included bilateral unweighted squats with visual and tactile biofeedback. Patients in the control group completed a six-week educational program. Lower extremity mechanics were collected during a bilateral stop jump at baseline, six-weeks, and 12-weeks post-intervention. Linear mixed-effects models adjusted for sex and graft type determined the main effects of and interactions between group and time.

RESULTS

No group by time interaction existed for peak knee extension moment symmetry. A group by time interaction existed for peak vertical ground reaction force symmetry (p = 0.012), where patients in the biofeedback group had greater improvements in symmetry between baseline and post-intervention that were not maintained through the retention assessments.

CONCLUSION

This novel biofeedback program did not reduce risk factors for second ACL injuries. Future work could develop and test multidisciplinary interventions for reducing second ACL injury risk factors.

CLINICALTRIALS

GOV IDENTIFIER: (NCT03273673).

Estimating heterogeneity of physical function treatment response to caloric restriction among older adults with obesity

Clinical trials conventionally test aggregate mean differences and assume homogeneous variances across treatment groups. However, significant response heterogeneity may exist. The purpose of this study was to model treatment response variability using gait speed change among older adults participating in caloric restriction (CR) trials. Eight randomized controlled trials (RCTs) with five- or six-month assessments were pooled, including 749 participants randomized to CR and 594 participants randomized to non-CR (NoCR). Statistical models compared means and variances by CR assignment and exercise assignment or select subgroups, testing for treatment differences and interactions for mean changes and standard deviations. Continuous equivalents of dichotomized variables were also fit. Models used a Bayesian framework, and posterior estimates were presented as means and 95% Bayesian credible intervals (BCI). At baseline, participants were 67.7 (SD = 5.4) years, 69.8% female, and 79.2% white, with a BMI of 33.9 (4.4) kg/m². CR participants reduced body mass [CR: -7.7 (5.8) kg vs. NoCR: -0.9 (3.5) kg] and increased gait speed [CR: +0.10 (0.16) m/s vs. NoCR: +0.07 (0.15) m/s] more than NoCR participants. There were no treatment differences in gait speed change standard deviations [CR–NoCR: -0.002 m/s (95% BCI: -0.013, 0.009)]. Significant mean interactions between CR and exercise assignment [0.037 m/s (95% BCI: 0.004, 0.070)], BMI [0.034 m/s (95% BCI: 0.003, 0.066)], and IL-6 [0.041 m/s (95% BCI: 0.009, 0.073)] were observed, while variance interactions were observed between CR and exercise assignment [-0.458 m/s (95% BCI: -0.783, -0.138)], age [-0.557 m/s (95% BCI: -0.900, -0.221)], and gait speed [-0.530 m/s (95% BCI: -1.018, -0.062)] subgroups. Caloric restriction plus exercise yielded the greatest gait speed benefit among older adults with obesity. High BMI and IL-6 subgroups also improved gait speed in response to CR. Results provide a novel statistical framework for identifying treatment heterogeneity in RCTs.

Effects of adding a diet intervention to exercise on hip osteoarthritis pain: protocol for the ECHO randomized controlled trial

Background

Hip osteoarthritis (OA) is a leading cause of musculoskeletal pain. Exercise is a core recommended treatment. Despite some clinical guidelines also recommending weight loss for hip OA, there is no evidence from randomised controlled trials (RCT) to substantiate these recommendations. This superiority, 2-group, parallel RCT will compare a combined diet and exercise program to an exercise only program, over 6 months.

Methods

One hundred people with symptomatic and radiographic hip OA will be recruited from the community. Following baseline assessment, participants will be randomly allocated to either, i) diet and exercise or; ii) exercise only. Participants in the diet and exercise group will have six consultations with a dietitian and five consultations with a physiotherapist via videoconferencing over 6 months. The exercise only group will have five consultations with a physiotherapist via videoconferencing over 6 months. The exercise program for both groups will include prescription of strengthening exercise and a physical activity plan, advice about OA management and additional educational resources. The diet intervention includes prescription of a ketogenic very low-calorie diet with meal replacements and educational resources to support weight loss and healthy eating. Primary outcome is self-reported hip pain via an 11-point numeric rating scale (0 = ‘no pain’ and 10 = ‘worst pain possible’) at 6 months. Secondary outcomes include self-reported body weight (at 0, 6 and 12 months) and body mass index (at 0, 6 and 12 months), visceral fat (measured using dual energy x-ray absorptiometry at 0 and 6 months), pain, physical function, quality of life (all measured using subscales of the Hip Osteoarthritis Outcome Scale at 0, 6 and 12 months), and change in pain and physical activity (measured using 7-point global rating of change Likert scale at 6 and 12 months). Additional measures include adherence, adverse events and cost-effectiveness.

Discussion

This study will determine whether a diet intervention in addition to exercise provides greater hip pain-relief, compared to exercise alone. Findings will assist clinicians in providing evidence-based advice regarding the effect of a dietary intervention on hip OA pain.

Trial registration

ClinicalTrials.gov . Identifier: NCT04825483. Registered 31st March 2021.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-022-05128-9.

Predictors of Clinically Meaningful Gait Speed Response to Caloric Restriction among Older Adults Participating in Weight Loss Interventions

BACKGROUND

The purpose of this study was to examine whether select baseline characteristics influenced the likelihood of an overweight/obese, older adult experiencing a clinically meaningful gait speed response (±0.05 m/s) to caloric restriction (CR).

METHODS

Individual level data from 1188 older adults participating in eight, five/six-month, weight loss interventions were pooled, with treatment arms collapsed into CR (n=667) or no CR (NoCR; n=521) categories. Exercise assignment was equally distributed across groups (CR: 65.3% versus NoCR: 65.4%) and did not interact with CR (p=0.88). Poisson risk ratios (95% CI) were used to examine whether CR assignment baseline characteristic subgroups: age (≥65 years), sex (female/male), race (black/white), body mass index (BMI; ≥35 kg/m 2), comorbidity (diabetes, hypertension, cardiovascular disease) status (yes/no), gait speed (<1.0 m/s), or inflammatory burden (C-reactive protein ≥3 mg/L, interleukin-6 ≥2.5 pg/mL) to influence achievement of ±0.05 m/s fast-paced gait speed change. Main effects were also examined.

RESULTS

The study sample (69.5% female, 80.1% white) was 67.6±5.3 years old with a BMI of 33.8±4.4 kg/m 2. Average weight loss achieved in the CR versus NoCR group was -8.3±5.9% versus -1.1±3.8%; p<0.01. No main effect of CR was observed on the likelihood of achieving a clinically meaningful gait speed improvement [RR: 1.09 (95% CI: 0.93,1.27)] or gait speed decrement [RR: 0.77 (95% CI: 0.57,1.04)]. Interaction effects were non-significant across all subgroups.

CONCLUSION

The proportion of individuals experiencing a clinically meaningful gait speed change was similar for CR and NoCR conditions. This finding is consistent across several baseline subgroupings.

Changes in body weight and knee pain in adults with knee osteoarthritis 3.5 years after completing diet and exercise interventions

OBJECTIVE

To determine whether long-term diet (D) and exercise (E) interventions, alone or in combination (D+E), have beneficial effects for older adults with knee osteoarthritis 3.5-years after the interventions end.

METHODS

This is a secondary analysis of a subset (N = 94) of the first 184 participants who had successfully completed the Intensive Diet and Exercise in Arthritis (IDEA) trial (N = 399) and who consented to follow-up testing. Participants were older (age ≥ 55 years), overweight and obese adults with radiographic and symptomatic knee osteoarthritis in at least one knee who completed 1.5-year D+E (N=27), D (N=35), or E (N=32) interventions and returned for 5-year follow-up testing an average of 3.5-years later.

RESULTS

During the 3.5-years following the interventions, weight regain in D+E and D was 5.9 kg (7%) and 3.1 kg (4%), respectively, with a 1 kg (1%) weight loss in E. Compared to baseline, weight (D+E, -3.7 kg, P=.0007; D, -5.8 kg, P<.0001; E, -2.9 kg, P=.003) and WOMAC pain (D+E, -1.2, P=.03; D, -1.5, P=.001; E -1.6, P=.0008) were lower in each group at 5-year follow-up. The effect of group assignment at 5-year follow-up was significant for body weight, with D less than E (-3.5 kg, P=.04).

DISCUSSION

Older adults with knee osteoarthritis who completed 1.5-year diet or diet plus exercise interventions experienced partial weight regain 3.5 years later, yet relative to baseline, they preserved statistically significant changes in weight loss and reductions in knee pain.

Reduction of Risk Factors for ACL Re-injuries using an Innovative Biofeedback Approach: Rationale and Design

Nearly 1 in 60 adolescent athletes will suffer anterior cruciate ligament (ACL) injuries with 90% of these athletes electing to undergo an ACL reconstruction (ACLR) at an estimated annual cost of $3 billion. While ACLR and subsequent rehabilitation allow these athletes to return to sports, they have a 15-fold increased risk of second ACL injuries. The modification of post-operative rehabilitation to improve movement and loading symmetry using visual and tactile biofeedback could decrease the risk factors for sustaining a second ACL injury. Participants included 40 adolescent ACLR patients who were intending to return to full sport participation. This preliminary randomized controlled trial (RCT) examined the changes in knee extension moment symmetry, a known risk factor for second ACL injuries, during landing from a stop-jump task between the following time-points: pre-intervention, immediate post-intervention, and subsequent follow-up 6-weeks post-intervention. Participants met twice per week for six-weeks (12-session). The intervention included bilateral squat biofeedback (visual and tactile); the attention control group attended weekly educational sessions. This RCT enrolled and randomize 40 participants over a two-and-a-half-year period. All participants were greater than 4.5 months post-op from a primary, unilateral ACLR and were released to participate by their treating physician. The findings from this pilot biofeedback RCT will provide critical effect size estimates for use in subsequent larger clinical trials.

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

IMPORTANCE

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

OBJECTIVE

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

DESIGN, SETTING, AND PARTICIPANTS

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

INTERVENTIONS

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

MAIN OUTCOMES AND MEASURES

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

RESULTS

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

CONCLUSIONS AND RELEVANCE

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

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT01489462.

Quality-Adjusted Life-Years Lost Due to Physical Inactivity in a US Population With Osteoarthritis

OBJECTIVE

One-half of the 14 million persons in the US with knee osteoarthritis (OA) are not physically active, despite evidence that physical activity (PA) is associated with improved health. We undertook this study to estimate both the quality-adjusted life-year (QALY) losses in a US population with knee OA due to physical inactivity and the health benefits associated with higher PA levels.

METHODS

We used data from the Osteoarthritis Initiative and the Centers for Disease Control and Prevention to estimate the proportions of a US population with knee OA ages ≥45 years that are inactive, insufficiently active, and active, and the likelihood of a shift in their PA level. We used the OA Policy Model, a computer simulation of knee OA, to determine QALYs lost due to inactivity and to measure potential benefits of increased PA (comorbidities averted and QALYs saved).

RESULTS

Among 13.7 million persons with knee OA, a total of 7.5 million QALYs, or 0.55 QALYs per person, were lost due to inactivity or insufficient PA relative to activity over their remaining lifetimes. Black Hispanic women experienced the highest losses, at 0.76 QALYs per person. Women of all races/ethnicities had ~20% higher loss burdens than men. According to our model, if 20% of the inactive population were instead active, 95,920 cases of cancer, 222,413 of cardiovascular disease, and 214,725 of diabetes mellitus would potentially be averted, and 871,541 potential QALYs would be saved.

CONCLUSION

Physical inactivity leads to substantial QALY losses in a US population with knee OA. Increases in the activity levels in even a fraction of this population may have considerable collateral health benefits, potentially averting cases of cancer, cardiovascular disease, and diabetes mellitus.

Association of Sex or Race With the Effect of Weight Loss on Physical Function: A Secondary Analysis of 8 Randomized Clinical Trials

IMPORTANCE

Consideration of differential treatment effects among subgroups in clinical trial research is a topic of increasing interest. This is an especially salient issue for weight loss trials.

OBJECTIVE

To determine whether stratification by sex and race is associated with meaningful differences in physical function response to weight loss among older adults.

DESIGN, SETTING, AND PARTICIPANTS

This pooled analysis used individual-level data from 8 completed randomized clinical trials of weight loss conducted at Wake Forest University or Wake Forest School of Medicine, Winston-Salem, North Carolina. Data were housed within the Wake Forest Older Americans Independence Center data repository and provided complete exposure, outcome, and covariate information. Data were collected from November 1996 to March 30, 2017, and analyzed from August 15, 2019, to June 10, 2020.

EXPOSURES

Treatment arms within each study were collapsed into caloric restriction (CR [n = 734]) and non-CR (n = 583) categories based on whether caloric restriction was specified in the original study protocol.

MAIN OUTCOMES AND MEASURES

Objectively measured 6-month change in weight, fast-paced gait speed (meters per second), and Short Physical Performance Battery (SPPB) score.

RESULTS

A total of 1317 adults (mean [SD] age, 67.7 [5.4] years; 920 [69.9%] female; 275 [20.9%] Black) with overweight or obesity (mean [SD] body mass index [calculated as weight in kilograms divided by height in meters squared], 33.9 [4.4]) were included at baseline. Six-month weight change achieved among those randomized to CR was -7.7% (95% CI, -8.3% to -7.2%), with no difference noted by sex; however, White individuals lost more weight than Black individuals assigned to CR (-9.0% [95% CI, -9.6% to -8.4%] vs -6.0% [95% CI, -6.9% to 5.2%]; P < .001), and all CR groups lost a significantly greater amount from baseline compared with non-CR groups (Black participants in CR vs non-CR groups, -5.3% [95% CI, -6.4% to -4.1%; P < .001]; White participants in CR vs non-CR groups, -7.2% [95% CI, -7.8% to -6.6%; P < .001]). Women experienced greater weight loss-associated improvement in SPPB score (CR group, 0.35 [95% CI, 0.18-0.52]; non-CR group, 0.08 [95% CI, -0.11 to 0.27]) compared with men (CR group, 0.23 [95% CI, 0.00-0.46]; non-CR group, 0.34 [95% CI, 0.09-0.58]; P = .03). Black participants experienced greater weight loss-associated improvement in gait speed (CR group, 0.08 [95% CI, 0.05-0.10] m/s; non-CR group, 0.02 [95% CI, -0.01 to 0.05] m/s) compared with White participants (CR group, 0.07 [95% CI, 0.06-0.09] m/s; non-CR group, 0.06 [95% CI, 0.04-0.08] m/s; P = .02).

CONCLUSIONS AND RELEVANCE

The association of weight loss on physical function in older adults appears to differ by sex and race. These findings affirm the need to consider biological variables in clinical trial design.

Long-term clinical and economic outcomes of a short-term physical activity program in knee osteoarthritis patients

OBJECTIVE

Physical activity (PA) in the US knee osteoarthritis (OA) population is low, despite well-established health benefits. PA program implementation is often stymied by sustainability concerns. We sought to establish parameters that would make a short-term (3-year efficacy) PA program a cost-effective component of long-term OA care.

METHOD

Using a validated computer microsimulation (Osteoarthritis Policy Model), we examined the long-term clinical (e.g., comorbidities averted), quality of life (QoL), and economic impacts of a 3-year PA program, based upon the SPARKS (Studying Physical Activity Rewards after Knee Surgery) Trial, for inactive knee OA patients. We determined the cost, efficacy, and impact of PA on QoL and medical costs that would make a PA program a cost-effective addition to OA care.

RESULTS

Among the 14 million with knee OA in the US, >4 million are inactive. Participation of 10% in the modeled PA program could save 200 cases of cardiovascular disease, 400 cases of diabetes, and 6,800 quality-adjusted life-years (QALYs). The program had an incremental cost-effectiveness ratio (ICER) of $16,100/QALY. Tripling PA program cost ($860/year) raised the ICER to $108,300/QALY; varying QoL benefits from PA yielded ICERs of $8,800/QALY-$99,900/QALY; varying background cost savings from PA did not qualitatively impact ICERs. Offering the PA program to any adults with knee OA (not only inactive) yielded $31,000/QALY.

CONCLUSION

A PA program with 3-year efficacy in the knee OA population carried favorable long-term clinical and economic benefits. These results offer justification for policymakers and payers considering a PA intervention incorporated into knee OA care.

The effect of weight loss on the progression of meniscal extrusion and size in knee osteoarthritis: a post-hoc analysis of the Intensive Diet and Exercise for Arthritis (IDEA) trial

OBJECTIVE

Weight loss has beneficial effects on clinical outcomes in knee osteoarthritis (OA), but the mechanism is still unclear. Since meniscus extrusion is associated with knee pain, this study assessed whether weight loss by diet and/or exercise is associated with less progression in meniscus extrusion measures over time.

DESIGN

The Intensive Diet and Exercise for Arthritis trial (IDEA) was a prospective, single-blind, randomized-controlled trial including overweight and obese older adults with knee pain and radiographic OA. Participants were randomized to 18-month interventions: exercise only, diet only or diet + exercise. In a random subsample of 105 participants, MRIs were obtained at baseline and follow-up. The medial and lateral menisci were segmented and quantitative position and size measures were obtained, along with semiquantitative extrusion measures. Linear and log-binomial regression were used to examine the association between change in weight and change in meniscus measures. Between-group differences were analyzed using an analysis of covariance.

RESULTS

Weight loss was associated with less progression over time of medial meniscus extrusion as measured by the maximum (β: -24.59 μm, 95%CI: -41.86, -7.33) and mean (β: -19.08 μm, 95%CI: -36.47, -1.70) extrusion distances. No relationships with weight loss were observed for lateral meniscus position, medial or lateral meniscus size or semiquantitative measures. Change in meniscus position and size did not differ significantly between groups.

CONCLUSIONS

Weight loss was associated with beneficial modifications of medial meniscus extrusion over 18 months. This may be one of the mechanisms by which weight loss translates into a clinical benefit.

CLINICAL TRIAL REGISTRATION

NCT00381290.

Cost-Effectiveness of Diet and Exercise for Overweight and Obese Patients With Knee Osteoarthritis

OBJECTIVE

The Intensive Diet and Exercise for Arthritis (IDEA) trial showed that an intensive diet and exercise (D+E) program led to a mean 10.6-kg weight reduction and 51% pain reduction in patients with knee osteoarthritis (OA). The aim of the current study was to investigate the cost-effectiveness of adding this D+E program to treatment in overweight and obese (body mass index >27 kg/m² ) patients with knee OA.

METHODS

We used the Osteoarthritis Policy Model to estimate quality-adjusted life-years (QALYs) and lifetime costs for overweight and obese patients with knee OA, with and without the D+E program. We evaluated cost-effectiveness with the incremental cost-effectiveness ratio (ICER), a ratio of the differences in lifetime cost and QALYs between treatment strategies. We considered 3 cost-effectiveness thresholds: $50,000/QALY, $100,000/QALY, and $200,000/QALY. Analyses were conducted from health care sector and societal perspectives and used a lifetime horizon. Costs and QALYs were discounted at 3% per year. D+E characteristics were derived from the IDEA trial. Deterministic and probabilistic sensitivity analyses (PSAs) were used to evaluate parameter uncertainty and the effect of extending the duration of the D+E program.

RESULTS

In the base case, D+E led to 0.054 QALYs gained per person and cost $1,845 from the health care sector perspective and $1,624 from the societal perspective. This resulted in ICERs of $34,100/QALY and $30,000/QALY. In the health care sector perspective PSA, D+E had 58% and 100% likelihoods of being cost-effective with thresholds of $50,000/QALY and $100,000/QALY, respectively.

CONCLUSION

Adding D+E to usual care for overweight and obese patients with knee OA is cost-effective and should be implemented in clinical practice.

Budget Impact of Funding an Intensive Diet and Exercise Program for Overweight and Obese Patients With Knee Osteoarthritis

Objective

Diet and exercise (D+E) for knee osteoarthritis (OA) is effective and cost‐effective. However, cost‐effectiveness does not imply affordability; the impact of knee OA–specific D+E programs on insurer budgets is unknown.

Methods

We estimated changes in undiscounted medical expenditures (2016 US dollars) with and without a D+E program. We accounted for both additional program outlays and potential savings from reduced use of other knee OA treatments and from reduced incidence of comorbidities. We adopted the perspective of a representative commercial insurance plan covering 200 000 individuals aged 25 to 64 years and a representative Medicare Advantage plan covering 200 000 Medicare‐eligible individuals aged 65 years and older. We used the Osteoarthritis Policy Model, a validated microsimulation model of knee OA, to model D+E efficacy (measured by pain and weight reduction), adherence, and price based on the Intensive Diet and Exercise for Arthritis (IDEA) trial. In sensitivity analyses, we varied time horizon, D+E efficacy, and D+E price.

Results

Over 3 years, the D+E program increased spending by $752 200 ($0.10 per member per month [PMPM]) in the commercial plan and by $6.0 million ($0.84 PMPM) in the Medicare plan. Over 3 years, the D+E program reduced opioid use by 6% and 5% and reduced total knee replacements by 5% and 4% in the commercial and Medicare plans, respectively. Expenses were higher in the Medicare plan because it had more patients with knee OA than the commercial plan.

Conclusion

Although there is no established threshold to define affordability, a D+E program for knee OA would likely produce expenditures comparable with outlays for other health‐promotion interventions.

Exercise prescription for weight management in obese adults at risk for osteoarthritis: synthesis from a systematic review

BACKGROUND

The aim of this systematic review was to identify principles of exercise interventions associated with improved physical function, weight management or musculoskeletal pain relief among young and middle-aged adults with obesity and propose an evidence-based exercise prescription that could assist in secondary prevention of osteoarthritis.

METHODS

A structured electronic review was conducted using MEDLINE, PubMed, and SPORTDiscus. The search string included 1) "obes*" AND "exercise" AND "interven*" AND "musculoskeletal pain OR knee pain OR hip pain". Studies 1) were randomized controlled trials of humans, with a non-exercise control, 2) included participants aged 18-50 years, and 3) had outcomes that included physical function, musculoskeletal pain, and/or body composition. Studies were excluded if participants had peri-menopausal status, cancer, or obesity-related co-morbidities. A recommended exercise prescription was developed based on common principles used in the included exercise interventions with greatest change in function or pain.

RESULTS

Seven studies were included. Similarities in exercise intensity (40-80% VO_2max), frequency (three times per week), duration (30-60 min), and exercise mode (treadmill, cross-trainer, stationary bike, aquatic exercise) were observed in exercise interventions that resulted in improved physical function and/or pain, compared to non-exercise control groups.

CONCLUSION

Common principles in exercise prescription for improvements in weight management, physical function and pain relief among otherwise healthy people with obesity. Exercise prescription including moderate intensity exercise for 30-60 min, three times per week can be considered an effective treatment for weight management and obesity-related musculoskeletal symptoms. Exercise should be recommended to at-risk individuals as part of secondary prevention of osteoarthritis.

The effects of intensive dietary weight loss and exercise on gait in overweight and obese adults with knee osteoarthritis. The Intensive Diet and Exercise for Arthritis (IDEA) trial

The Intensive Diet and Exercise for Arthritis (IDEA) trial was an 18-month randomized controlled trial that enrolled 454 overweight and obese older adults with symptomatic and radiographic knee osteoarthritis (OA). Participants were randomized to either exercise (E), intensive diet-induced weight loss (D), or intensive diet-induced weight loss plus exercise (D + E) interventions. We previously reported that the clinical benefits of D + E were significantly greater than with either intervention alone (e.g., greater pain reduction, and better function, mobility, and health-related quality of life). We now test the hypothesis that D + E has greater overall benefit on gait mechanics compared to either intervention alone. Knee joint loading was analyzed using inverse dynamics and musculoskeletal modeling. Analysis of covariance determined the interventions' effects on gait. The D + E group walked significantly faster at 18-month follow-up (1.35 m s^-1) than E (1.29 m s^-1, p = 0.0004) and D (1.31 m s^-1, p = 0.0007). Tibiofemoral compressive impulse was significantly lower (p = 0.0007) in D (1069 N s) and D + E (1054 N s) compared to E (1130 N s). D had significantly lower peak hip external rotation moment (p = 0.01), hip abduction moment (p = 0.0003), and peak hip power production (p = 0.016) compared with E. Peak ankle plantar flexion moment was significantly less (p < 0.0001) in the two diet groups compared with E. There also was a significant dose-response to weight loss; participants that lost >10% of baseline body weight had significantly (p = 0.0001) lower resultant knee forces and lower muscle (quadriceps, hamstring, and gastrocnemius) forces than participants that had less weight loss. Compared to E, D produces significant load reductions at the hip, knee, and ankle; combining D with E attenuates these reductions, but most remain significantly better than with E alone.

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

OBJECTIVE

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

DESIGN

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

RESULTS

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

CONCLUSIONS

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

Effect of intensive diet and exercise on self-efficacy in overweight and obese adults with knee osteoarthritis: The IDEA randomized clinical trial

Physical activity decreases the risk of osteoarthritis (OA)-related disability; however, pain and lack of confidence represent barriers for older adults with knee OA. The purpose of this study was to examine (a) the baseline associations among self-efficacy and physical activity, function, and pain; (b) longitudinal changes in self-efficacy; and (c) whether self-efficacy mediates treatment effects on clinical outcomes. The Intensive Diet and Exercise for Arthritis (IDEA) trial was a single-blind, randomized controlled 18-month study including 454 overweight/obese older adults (M age = 66 years) with knee OA. Participants were randomized to one of three interventions: exercise (E), diet-induced weight loss (D), or both (D+E). Self-efficacy for gait, balance, and walking duration were assessed at baseline, 6 months, and 18 months. Baseline associations were tested using Pearson correlations, and group least squares means were compared using mixed linear models at follow-up. Participants with higher self-efficacy reported significantly better physical function and less knee pain at baseline, walked farther (6-min walk), and were more physically active (all |r| > 0.12, all p < .01). Significant differences between groups were detected for all self-efficacy measures at 18 months; the D+E group reported significantly (all p < .005) higher self-efficacy for gait, walking duration, and balance compared with the D- or E-only groups. Self-efficacy significantly (p < .05) mediated treatment effects on physical function and pain at 18 months. A combined intervention of diet-induced weight loss and exercise is the treatment of choice to maximize self-efficacy, improve physical function, and reduce pain in overweight/obese adults with knee OA.

Long-Term Effects of Randomization to a Weight Loss Intervention in Older Adults: A Pilot Study

Randomized, controlled trials (RCTs) show intentional weight loss improves body composition and physical function in older adults; however, the long-term benefits (and risks) are unknown. We conducted a pilot study to assess the feasibility of recalling prior RCT participants to examine the long-term effects of intentional weight loss on body composition and physical function. A weighted, random sample of 60 older adults who were randomized to caloric restriction plus exercise (CR + EX) or exercise (EX) only in 5 prior RCTs (mean age at randomization, 67.3 years; 69% women, 80% white) were invited to participate. Follow-up was obtained on 89% (42 clinic visits, 10 phone interviews, 1 death) an average of 3.5 years (range, 2.2-5.8 years) after RCT completion. Despite greater weight, fat and lean mass loss during the RCT (mean difference in change (95% CI): -4.19 (-7.52, -0.86), -2.75 (-5.10, -0.40), and -2.32 (-3.69, -0.95) kg, respectively) in those randomized to CR + EX, long-term changes in weight (2.05 (-2.35, 6.45) kg) and body composition (1.80 (-1.56, 5.17) and 0.03 (-2.20, 2.26) kg for fat and lean mass, respectively) from baseline and physical function at long-term follow-up (mean difference in 400-m walk and SPPB (95% CI): 23.2 (-19.3, 65.6) sec and -0.03 (-1.02, 0.96) points, respectively) were similar in CR + EX and EX only. Although improvements in weight and body composition following intentional weight loss may not be sustained long-term, physical function does not appear to be negatively impacted. A larger study is needed to confirm these results.

Intentional Weight Loss in Overweight and Obese Patients With Knee Osteoarthritis: Is More Better?

OBJECTIVE

To determine the dose response effect of weight loss on clinical and mechanistic outcomes in overweight and obese adults with knee osteoarthritis (OA).

METHODS

This is a secondary analysis of the diet-induced weight loss only (D) and diet-induced weight loss plus exercise (D + E) groups in the Intensive Diet and Exercise for Arthritis randomized controlled clinical trial. The 240 participants were overweight and obese older community-dwelling adults with pain and radiographic knee OA. Participants were assigned to 1 of 4 groups according to weight loss achieved over an 18-month period: <5% (<5% group), 5-10% (≥5% group), 10-20% (≥10% group), and >20% (≥20% group).

RESULTS

There were significant dose responses to weight loss for pain (P = 0.01), function (P = 0.0006), 6-minute walk distance (P < 0.0001), physical (P = 0.0004) and mental (P = 0.03) health-related quality of life (HRQoL), knee joint compressive force (P < 0.0001), and interleukin-6 (P = 0.002). Greater weight loss resulted in superior clinical and mechanstic outcomes, with the highest weight loss group (≥20% group) distinguishing itself on all measures compared with the <5% and ≥5% groups; the ≥20% group had 25% less pain and better function compared with the ≥10% group and significantly (P = 0.006) better physical HRQoL.

CONCLUSION

Long-term weight loss of 10-19.9% of baseline body weight has substantial clinical and mechanistic benefits compared with less weight loss. The value of an additional 10% weight loss includes significantly improved physical HRQoL and a clinically important reduction of pain and improvement in function.

Alterations in quadriceps muscle cellular and molecular properties in adults with moderate knee osteoarthritis

OBJECTIVE

Quadriceps muscle weakness is common in knee osteoarthritis (OA). While pain, disuse, and atrophy are commonly cited causes for muscle weakness in OA, emerging evidence suggests changes in muscle quality also occur. Alterations in muscle quality are not well understood, but likely include both cellular and morphologic adaptions. The purpose of this study was to conduct the first cellular-level analysis of the vastus lateralis in adults with moderate knee OA.

METHODS

Vastus lateralis biopsies were obtained from 24 subjects with moderate knee OA and 15 healthy controls. Quadriceps strength, muscle fiber cross sectional area (CSA), fiber type distribution, extracellular matrix (ECM) content, satellite cell abundance, and profibrotic gene expression were assessed.

RESULTS

Relative to controls, quadriceps strength was significantly lower in OA subjects (OA 62.23, 50.67-73.8 Nm vs 91.46, 75.91-107.0 Nm, P = 0.003) despite no difference in fiber CSA. OA subjects had significantly fewer Type I fibers (OA 41.51, 35.56-47.47% vs 53.07, 44.86-61.29%, P = 0.022) and more hybrid IIa/x fibers (OA 24.61, 20.61-28.61% vs 16.4, 11.60-21.20%, P = 0.009). Significantly greater ECM content, lower satellite cell density, and higher profibrotic gene expression was observed with OA, and muscle collagen content was inversely correlated to strength and satellite cell (SC) density.

CONCLUSION

Lower quadriceps function with moderate OA may not result from fiber size impairments, but is associated with ECM expansion. Impaired satellite cell density, high profibrotic gene expression, and a slow-to-fast fiber type transition may contribute to reduced muscle quality in OA. These findings can help guide therapeutic interventions to enhance muscle function with OA.

A 2-Year Prospective Cohort Study of Overuse Running Injuries: The Runners and Injury Longitudinal Study (TRAILS)

BACKGROUND

The National Center for Injury Prevention and Control, noting flaws in previous running injury research, called for more rigorous prospective designs and comprehensive analyses to define the origin of running injuries.

PURPOSE

To determine the risk factors that differentiate recreational runners who remain uninjured from those diagnosed with an overuse running injury during a 2-year observational period.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

Inclusion criteria were running a minimum of 5 miles per week and being injury free for at least the past 6 months. Data were collected at baseline on training, medical and injury histories, demographics, anthropometrics, strength, gait biomechanics, and psychosocial variables. Injuries occurring over the 2-year observation period were diagnosed by an orthopaedic surgeon on the basis of predetermined definitions.

RESULTS

Of the 300 runners who entered the study, 199 (66%) sustained at least 1 injury, including 73% of women and 62% of men. Of the injured runners, 111 (56%) sustained injuries more than once. In bivariate analyses, significant ( P ≤ .05) factors at baseline that predicted injury were as follows: Short Form Health Survey-12 mental component score (lower mental health-related quality of life), Positive and Negative Affect Scale negative affect score (more negative emotions), sex (higher percentage of women were injured), and knee stiffness (greater stiffness was associated with injury); subsequently, knee stiffness was the lone significant predictor of injury (odds ratio = 1.18) in a multivariable analysis. Flexibility, quadriceps angle, arch height, rearfoot motion, strength, footwear, and previous injury were not significant risk factors for injury.

CONCLUSION

The results of this study indicate the following: (1) among recreational runners, women sustain injuries at a higher rate than men; (2) greater knee stiffness, more common in runners with higher body weights (≥80 kg), significantly increases the odds of sustaining an overuse running injury; and (3) contrary to several long-held beliefs, flexibility, arch height, quadriceps angle, rearfoot motion, lower extremity strength, weekly mileage, footwear, and previous injury are not significant etiologic factors across all overuse running injuries.

Does frontal knee kinematics predict treatment outcomes? Exploratory analyses from the Intensive Diet and Exercise for Arthritis (IDEA) trial

BACKGROUND

Pain is a cardinal symptom of knee osteoarthritis (OA) and although conservative treatments such as exercise and diet related interventions can reduce pain, effects are modest and can be improved. Frontal plane knee joint motion has been associated with knee pain, and is suggested as a patient-specific characteristic on which to tailor interventions.

RESEARCH QUESTION

Does the association between baseline frontal plane knee joint kinematics and pain-relief differ among overweight and obese people with knee OA who underwent an intervention from the Intensive Diet and Exercise for Arthritis (IDEA) clinical trial: diet-only, exercise-only, and combined diet and exercise intervention?

METHODS

323 participants with knee OA were included in the analysis (77% females; 66 ± 6 years; 33.5 ± 3.7 kg/m²). At baseline, frontal plane knee joint kinematics during walking were measured using 3-dimensional gait analysis and characterised as peak varus-valgus knee angle, peak varus-valgus excursion, and peak varus angular velocity. Pain was assessed at baseline and 18-month follow-up using the Western Ontario and McMaster Universities Osteoarthritis Index pain subscale. Linear regressions were performed unadjusted and adjusted for covariates to determine if the associations between baseline frontal plane knee joint kinematics and 18-month change in pain differed according to intervention.

RESULTS

The interaction terms between the intervention and measures of frontal plane knee joint kinematics were not statistically significant (all P ≥ 0.05).

SIGNIFICANCE

We found no evidence to suggest that 18-months of either exercise, diet, or a combination of diet and exercise could be more effective than the other to improve pain based on frontal plane measures of knee kinematics.

Subgrouping and TargetEd Exercise pRogrammes for knee and hip OsteoArthritis (STEER OA): a systematic review update and individual participant data meta-analysis protocol

INTRODUCTION

Knee and hip osteoarthritis (OA) is a leading cause of disability worldwide. Therapeutic exercise is a recommended core treatment for people with knee and hip OA, however, the observed effect sizes for reducing pain and improving physical function are small to moderate. This may be due to insufficient targeting of exercise to subgroups of people who are most likely to respond and/or suboptimal content of exercise programmes. This study aims to identify: (1) subgroups of people with knee and hip OA that do/do not respond to therapeutic exercise and to different types of exercise and (2) mediators of the effect of therapeutic exercise for reducing pain and improving physical function. This will enable optimal targeting and refining the content of future exercise interventions.

METHODS AND ANALYSIS

Systematic review and individual participant data meta-analyses. A previous comprehensive systematic review will be updated to identify randomised controlled trials that compare the effects of therapeutic exercise for people with knee and hip OA on pain and physical function to a non-exercise control. Lead authors of eligible trials will be invited to share individual participant data. Trial-level and participant-level characteristics (for baseline variables and outcomes) of included studies will be summarised. Meta-analyses will use a two-stage approach, where effect estimates are obtained for each trial and then synthesised using a random effects model (to account for heterogeneity). All analyses will be on an intention-to-treat principle and all summary meta-analysis estimates will be reported as standardised mean differences with 95% CI.

ETHICS AND DISSEMINATION

Research ethical or governance approval is exempt as no new data are being collected and no identifiable participant information will be shared. Findings will be disseminated via national and international conferences, publication in peer-reviewed journals and summaries posted on websites accessed by the public and clinicians.

PROSPERO REGISTRATION NUMBER

CRD42017054049.

Is There a Dose-Response Relationship Between Weight Loss and Symptom Improvement in Persons With Knee Osteoarthritis?

OBJECTIVE

We examined the dose-response relationship between weight reduction and pain/functional improvement in persons with symptomatic knee osteoarthritis (KOA) participating in a community-based weight loss program.

METHODS

Consecutive participants with KOA and enrolled in the 18-week Osteoarthritis Healthy Weight for Life weight-loss program were selected. In this completer-type analysis, participants were assessed at baseline, 6 weeks, and 18 weeks for body weight and Knee Injury and Osteoarthritis Outcome Score (KOOS) subscales. The dose-response relationship between weight-change categories (>10%, 7.6-10%, 5.1-7.5%, 2.6-5.0%, and <2.5% of body weight loss) and change in KOOS scores was assessed by repeated-measures analysis of variance, controlling for sex and age, body mass index (BMI), and KOOS. The Western Ontario McMaster Universities Osteoarthritis Index function score derived from the KOOS was used to assess a meaningful clinical functional improvement.

RESULTS

A total of 1,383 persons (71% females) were enrolled. Mean ± SD age, height, and weight were 64 ± 8.7 years, 1.66 ± 0.09 meters, and 95.1 ± 17.2 kg, respectively. Mean ± SD BMI was 34.4 ± 5.2 kg/m(2) with 82% of participants obese at baseline. A total of 1,304 persons (94%) achieved a >2.5% reduction in body weight. There was a significant dose-response relationship between all KOOS subscales and percentage of weight change across all weight-change categories. Participants required ≥7.7% (95% confidence interval 5.2, 13.3) body weight loss to achieve a minimal clinically important improvement in function.

CONCLUSION

There is a significant dose-response relationship between percentage of weight loss and symptomatic improvement. This study confirms the feasibility of weight loss as a therapeutic intervention in KOA in a community-based setting.

Impact of Diet and/or Exercise Intervention on Infrapatellar Fat Pad Morphology: Secondary Analysis from the Intensive Diet and Exercise for Arthritis (IDEA) Trial

OBJECTIVES

The infrapatellar fat pad (IPFP) represents intra-articular adipose tissue that may contribute to intra-articular inflammation and pain by secretion of proinflammatory cytokines. Here we examined the impact of weight loss by diet and/or exercise interventions on the IPFP volume.

METHODS

Intensive Diet and Exercise for Arthritis (IDEA) was a single-blinded, single-center, 18-month, prospective, randomized controlled trial that enrolled 454 overweight and obese older adults with knee pain and radiographic osteoarthritis. Participants were randomized to 1 of 3 groups: exercise-only control (E), diet-induced weight loss (D), and diet-induced weight loss + exercise (D+E). In a subsample (n = 106; E: n = 36, D: n = 35, and D+E: n = 35), magnetic resonance images were acquired at baseline and at the 18-month follow-up, from which we analyzed IPFP volume, surface areas, and thickness in this secondary analysis.

RESULTS

The average weight loss amounted to 1.0% in the E group, 10.5% in the D group, and 13.0% in the D+E group. A significant (p < 0.01) reduction in IPFP volume was observed in the E (2.1%), D (4.0%), and D+E (5.2%) groups. The IPFP volume loss in the D+E group was significantly greater than that in the E group (p < 0.05) when not adjusting for parallel comparisons. Across intervention groups, there were significant correlations between IPFP volume change, individual weight loss (r = 0.40), and change in total body fat mass (dual-energy X-ray absorptiometry; r = 0.44, n = 88) and in subcutaneous thigh fat area (computed tomography; r = 0.32, n = 82).

CONCLUSIONS

As a potential link between obesity and knee osteoarthritis, the IPFP was sensitive to intervention by diet and/or exercise, and its reduction was correlated with changes in weight and body fat.

Weight-loss and exercise for communities with arthritis in North Carolina (we-can): design and rationale of a pragmatic, assessor-blinded, randomized controlled trial

BACKGROUND

Recently, we determined that in a rigorously monitored environment an intensive diet-induced weight loss of 10% combined with exercise was significantly more effective at reducing pain in men and women with symptomatic knee osteoarthritis (OA) than either intervention alone. Compared to previous long-term weight loss and exercise trials of knee OA, our intensive diet-induced weight loss and exercise intervention was twice as effective at reducing pain intensity. Whether these results can be generalized to less intensively monitored cohorts is unknown. Thus, the policy relevant and clinically important question is: Can we adapt this successful solution to a pervasive public health problem in real-world clinical and community settings? This study aims to develop a systematic, practical, cost-effective diet-induced weight loss and exercise intervention implemented in community settings and to determine its effectiveness in reducing pain and improving other clinical outcomes in persons with knee OA.

METHODS/DESIGN

This is a Phase III, pragmatic, assessor-blinded, randomized controlled trial. Participants will include 820 ambulatory, community-dwelling, overweight and obese (BMI ≥ 27 kg/m2) men and women aged ≥ 50 years who meet the American College of Rheumatology clinical criteria for knee OA. The primary aim is to determine whether a community-based 18-month diet-induced weight loss and exercise intervention based on social cognitive theory and implemented in three North Carolina counties with diverse residential (from urban to rural) and socioeconomic composition significantly decreases knee pain in overweight and obese adults with knee OA relative to a nutrition and health attention control group. Secondary aims will determine whether this intervention improves self-reported function, health-related quality of life, mobility, and is cost-effective.

DISCUSSION

Many physicians who treat people with knee OA have no practical means to implement weight loss and exercise treatments as recommended by numerous OA treatment guidelines. This study will establish the effectiveness of a community program that will serve as a blueprint and exemplar for clinicians and public health officials in urban and rural communities to implement a diet-induced weight loss and exercise program designed to reduce knee pain and improve other clinical outcomes in overweight and obese adults with knee OA.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT02577549 October 12, 2015.

Nutrient Intake During Diet-Induced Weight Loss and Exercise Interventions in a Randomized Trial in Older Overweight and Obese Adults

OBJECTIVES

Dietary restriction in obese older adults undergoing weight loss may exacerbate nutrient deficiencies common in this group; the nutritional health of older adults is a factor in their quality of life, disability, and mortality. This study examined the effect of an 18-month weight loss program based in social cognitive theory incorporating partial meal replacements, on nutrient intake in older overweight and obese adults.

DESIGN

The following analysis is from the Intensive Diet and Exercise for Arthritis (IDEA) trial, a single-blind, randomized controlled trial. Individuals were randomized into one of three 18-month interventions: exercise (E); intensive diet-induced weight loss (D); or intensive diet-induced weight loss plus exercise (D+E).

SETTING

The study setting was at a university research facility.

PARTICIPANTS

Overweight and obese older adults (n=388; BMI=33.7±3.8 kg/m2; 65.8±6.1 years) were recruited.

INTERVENTIONS

The D and D+E interventions (group mean goal of ≥10% loss by 18-months) utilized partial meal replacements (2 meal replacement shakes/day for 6-months). Exercise training for E and D+E was 3 days/week, 60 minutes/day.

MEASUREMENTS

Three day food records were collected at baseline, 6-months, and 18-months and analyzed for total energy and macro- and micronutrient intake. Comparisons of dietary intake among treatment groups were performed at 6 and 18 months using mixed linear models.

RESULTS

Weight loss at 18-months was 11.3±8.3% (D), 10.3±6.8% (D+E), and 1.2±4.2% (E). Meal replacements were used by more than 60% (6-months) and 50% (18-months) of D and D+E participants, compared to ≤15% for E. Both D and D+E consumed less energy and fat, and more carbohydrates and selected micronutrients than E during follow-up. More than 50% of all participants consumed less than the recommended intake of particular vitamins and minerals.

CONCLUSIONS

The diet intervention improved intakes of several nutrients. However, inadequate intake of several vitamins and minerals of concern for older adults suggests they need further guidance to assure adequate intake.

Number of Persons With Symptomatic Knee Osteoarthritis in the US: Impact of Race and Ethnicity, Age, Sex, and Obesity

OBJECTIVE

The prevalence of symptomatic knee osteoarthritis (OA) has been increasing over the past several decades in the US, concurrent with an aging population and the growing obesity epidemic. We quantify the impact of these factors on the number of persons with symptomatic knee OA in the early decades of the 21st century.

METHODS

We calculated the prevalence of clinically diagnosed symptomatic knee OA from the National Health Interview Survey 2007-2008 and derived the proportion with advanced disease (defined as Kellgren/Lawrence grade 3 or 4) using the Osteoarthritis Policy Model, a validated simulation model of knee OA. Incorporating contemporary obesity rates and population estimates, we calculated the number of persons living with symptomatic knee OA.

RESULTS

We estimate that approximately 14 million persons had symptomatic knee OA, with advanced OA comprising more than half of those cases. This includes more than 3 million persons of racial/ethnic minorities (African American, Hispanic, and other). Adults younger than 45 years of age represented nearly 2 million cases of symptomatic knee OA and individuals between 45 and 65 years of age comprised 6 million more cases.

CONCLUSION

More than half of all persons with symptomatic knee OA are younger than 65 years of age. As many of these younger persons will live for 3 decades or more, there is substantially more time for greater disability to occur, and policymakers should anticipate health care utilization for knee OA to increase in the upcoming decades. These data emphasize the need for the deployment of innovative prevention and treatment strategies for knee OA, especially among younger persons.

Relationship of Objectively-Measured Habitual Physical Activity to Chronic Inflammation and Fatigue in Middle-Aged and Older Adults

BACKGROUND

Habitual (non-exercise) physical activity (PA) declines with age, and aging-related increases in inflammation and fatigue may be important contributors to variability in PA.

METHODS

This study examined the association of objectively-measured PA (accelerometry over 7 days) with inflammation (plasma interleukin-6 and C-reactive protein) and with self-reported fatigue (SF-36 Vitality) at baseline and 18 months after a diet-induced weight loss, exercise, or diet-induced weight loss plus exercise intervention in 167 overweight/obese, middle-aged, and older adults.

RESULTS

At baseline, individuals with higher plasma interleukin-6, as well as those who reported feeling less energetic (more fatigued), took less steps per day and had lower PA energy expenditure and minutes of light and moderate-vigorous PA (p < .05 for all). At the 18-month follow-up, inflammation was lower in both weight loss groups, fatigue was reduced in all three groups with larger decreases in the combined group, and mean levels of habitual PA were not changed in any group. In longitudinal analyses with all groups combined, we found that participants reporting larger increases in vitality (eg, declines in fatigue) had greater increases in PA (p < .05 for all). Also, changes in steps/d and physical activity energy expenditure were indirectly associated with changes in interleukin-6 (β [SEM] for steps/d = -565 [253]; β [SEM] for physical activity energy expenditure = -22.4 [10.17]; p < .05).

CONCLUSIONS

Levels of habitual PA are lower in middle-aged and older adults with higher levels of chronic inflammation and greater self-reported fatigue. In addition, participants who experienced greater declines in inflammation during the interventions had greater declines in fatigue and larger increases in PA.

Are unilateral and bilateral knee osteoarthritis patients unique subsets of knee osteoarthritis? A biomechanical perspective

OBJECTIVE

To compare the gait of adults with unilateral and bilateral symptomatic and radiographic knee osteoarthritis (OA) to determine whether these subgroups can be treated similarly in the clinic and when recruiting for randomized clinical trials, and to use these data to generate future hypotheses regarding gait in these subsets of knee OA patients.

METHODS

Cross-sectional investigation of patients with unilateral and bilateral knee OA on gait mechanics using 136 older adults (age ≥55 yrs; 27 kg m(-2) ≥ BMI ≤ 41 kg m(-2); 82% female) with radiographic knee OA. Comparisons were made between the most affected side of the bilateral group (Bi) and the affected side of the unilateral group (Uni), and between symmetry indices of each group.

RESULTS

There were no significant differences in any temporal, kinematic, or kinetic measures between the Uni and Bi cohorts. Comparison of symmetry indices between groups also revealed no significant differences.

CONCLUSION

The similarity in lower extremity mechanics between unilateral and bilateral knee OA patients is sufficiently robust to consider both subsets as a single cohort. We hypothesize that biomechanical adaptations to knee OA are at least partially systemic in origin and not based solely on the physiological characteristics of an affected knee joint.