Symptom assessment in knee osteoarthritis needs to account for physical activity level

Maximal daily stepping cadence partially explains functional capacity of individuals with end-stage knee osteoarthritis

BACKGROUND

Individuals with end-stage knee osteoarthritis (OA) walk at a lower intensity (ie, slower step cadence) contributing to worse physical function. Previous literature reports daily step counts and sedentary time, with little information regarding stepping bouts or cadence. Determining relationships between daily higher stepping cadence duration and clinical outcomes can move the field toward optimal daily stepping prescription.

OBJECTIVE

To quantify daily physical activity patterns of individuals with end-stage knee OA and determine the contribution of high stepping cadence to explain functional capacity variability.

DESIGN

Cross-sectional analysis.

SETTING

Veterans Administration medical center.

PARTICIPANTS

U.S. military veterans (n = 104; age: 67.1 years [7.2]; mean [SD]; male [89.3%]) with end-stage knee OA were enrolled.

INTERVENTION

Not applicable.

MAIN OUTCOME MEASURE

Functional capacity (6-Minute Walk Test [6MWT]). Physical activity (activPAL wearable sensor; cadence and time sitting, standing, and stepping), pain (Western Ontario and McMaster Universities Osteoarthritis Index-pain subscale) sociodemographic variables, and comorbidities (body mass index and Functional Comorbidity Index) are the main explanatory variables.

RESULTS

Participants' wake time was mainly sitting (11.0 h/day) in ≥60-minute bouts (29.7% ± 12.7 of sitting time). Standing (3.4 hours/day) and stepping (1.4 h/day) primarily occurred in 0-5 minute bouts (standing: 87.7% ± 14.4 of standing time, stepping: 98.7% ± 12.7 of stepping time) and stepping cadence was predominantly incidental (1-19 spm; 52.9% ± 9.6 of total stepping time). Backward elimination model results indicated shorter medium-to-brisk cadence bout duration, older age, and higher pain significantly explained shorter 6MWT distance (AdjR2=0.24, p < .01).

CONCLUSIONS

Individuals with knee OA spend most of their waking hours sitting, while standing and stepping occurs in short bouts at very low stepping cadence. Decreased time in high stepping cadence is associated with lower functional capacity. Future studies should explore if increasing the daily time spent in higher step cadence can improve functional capacity in this population.

Effects of psychological distress on the general health to self-reported pain and function outcome relationship in knee arthroplasty: A causal mediation study

Objectives

We examined two potential causal pathways that could be intervention targets to enhance knee arthroplasty outcomes. Data from a no-effect trial of persons with moderate to high pain catastrophizing were used to determined whether pain catastrophizing, depressive symptoms causally mediate the effect of preoperative general health on postoperative knee pain and functional difficulty.

Methods

We used natural-effects models to conduct causal mediation analyses using the preoperative dichotomized EQ-5D-5L general health measure as the exposure, 2-month postoperative pain catastrophizing, depressive symptoms, and localized knee pain as potential mediators, and 12-month dichotomized Western Ontario and McMaster's University Osteoarthritis Index (WOMAC) Pain and Function scores reflecting good versus poor outcome as the outcomes.

Results

Estimates of the indirect (mediating) effect suggested that pain catastrophizing mediated the effect of preoperative general health on 12-month WOMAC pain score by increasing odds of a good outcome by 8% (natural indirect effect odds ratio ​= ​1.08, 95% CI: 0.88, 1.29). The direction of mediating effects and their magnitude were similar for depressive symptoms; Sensitivity analyses suggested similar magnitudes and mediating effects to those reported for the main analyses.

Conclusions

Our findings suggested that pain catastrophizing and depressive symptoms have a mediating role on the effect of baseline general health on self-reported pain and function outcomes. These findings support the continued treatment of pain catastrophizing and depressive symptoms as viable targets for interventions to potentially enhance pain and function outcomes for patients with moderate to high levels of psychological distress prior to surgery.

Applications of Wearable Technology in a Real-Life Setting in People with Knee Osteoarthritis: A Systematic Scoping Review

With the growing number of people affected by osteoarthritis, wearable technology may enable the provision of care outside a traditional clinical setting and thus transform how healthcare is delivered for this patient group. Here, we mapped the available empirical evidence on the utilization of wearable technology in a real-world setting in people with knee osteoarthritis. From an analysis of 68 studies, we found that the use of accelerometers for physical activity assessment is the most prevalent mode of use of wearable technology in this population. We identify low technical complexity and cost, ability to connect with a healthcare professional, and consistency in the analysis of the data as the most critical facilitators for the feasibility of using wearable technology in a real-world setting. To fully realize the clinical potential of wearable technology for people with knee osteoarthritis, this review highlights the need for more research employing wearables for information sharing and treatment, increased inter-study consistency through standardization and improved reporting, and increased representation of vulnerable populations.

Evaluation of a lower-extremity robotic exoskeleton for people with knee osteoarthritis

A multi-site study was conducted to evaluate the efficacy of the Keeogo™ exoskeleton as a mobility assist device for use in the clinic and at home in people with knee osteoarthritis (KOA). Twenty-four participants were randomized in a two-stage cross-over design that evaluated the immediate effects of using the exoskeleton in the clinic and the cumulative effects of training and home use. Immediate effects were quantified by comparing 1) physical performance with|without (W|WO) the device during a battery of mobility tests, and 2) physical activity levels at home (actigraphy) for one month, two weeks W|WO the device. Cumulative effects were quantified as change in physical performance W and WO over time. WOMAC and other self-report scales were measured and usability assessed. There were no immediate effects on physical performance or physical activity at home; however, there were cumulative effects as indicated by improved stair time (p = .001) as well as improved WOMAC pain (p = .004) and function (p = .003). There was a direct relationship between improved physical function and improved WOMAC pain (r = -.677, p < .001) and stiffness (r = .537, p = .007). Weight and battery life were identified as important to usability. A full-scale RCT with more participants, longer study period, and better usage monitoring is warranted.

The relationship of radiographic findings with pain, function, and quality of life in patients with knee osteoarthritis

PURPOSE

The aim of the study was to investigate the relationship between pain, function and quality of life with radiographic findings in patients with knee osteoarthritis (OA).

METHODS

A total of 86 patients diagnosed with knee OA were included in the study. Demographic, physical, and pathological information was collected. Visual analog scale (VAS) was used to determine pain levels. The evaluation of radiographic findings was conducted by Kellgren-Lawrence (K&L) rating scale. The Turkish version of the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) questionnaire was used to evaluate the patient's disability and functional status. The objective functional status was assessed using the commonly used physical performance test, the Timed up and Go Test (TUG). The Turkish version of the Short Form 36 (SF-36) questionnaire was used for quality of life assessment. The "Spearman rank correlation coefficient" was used to investigate the relationship between pain, function and quality of life with radiographic findings.

RESULTS

The mean age of the participants was 61.08 ± 9.27 years. There was a strong correlation between VAS at activity and K&L (p < 0.05). There was a negative correlation between Physical Function (PF) (p < 0.05) and General Health (GH) (p < 0.05) subscore of the SF-36 with K&L. In addition, K&L and TUG were positively correlated (p < 0.05).

CONCLUSION

Radiographic findings were associated with pain in activity and functional status based on physical performance, but not with clinical results based on Patient Reported Outcome Measures (PROMs). As the patient's radiographic findings worsened, the level of pain increased and functionality decreased.

The Relationship Between Daily Physical Activity and Pain in Individuals with Knee Osteoarthritis

Objective

Investigate the association between physical activity and pain severity in individuals with knee osteoarthritis.

Design

Cross-sectional; systematic review with meta-analyses.

Methods

Thirty-one participants with knee osteoarthritis underwent assessment of symptoms via self-report questionnaires and quantitative sensory testing. Following testing, physical activity and symptoms were monitored for seven days using accelerometers and logbooks. Cross-correlation analyses were performed on fluctuations in symptoms and physical activity across the week to detect the relative timing of the strongest association between pain and activity. These data were complemented by meta-analyses of studies that examined correlations between pain from knee osteoarthritis and physical activity or fitness.

Results

Pain severity at baseline correlated with moderate to vigorous physical activity (r2 = 0.161–0.212, P &lt; 0.05), whereby participants who were more physically active had less pain. Conversely, the peak of the cross-correlation analyses was most often positive and lagging, which indicated that pain was increased subsequent to periods of increased activity. These superficially discrepant findings were supported by the results of a meta-analysis of 13 studies and 9,363 participants, which identified significant heterogeneity for associations between physical activity and pain (I2 = 91%). Stronger inverse associations were found between fitness and pain.

Conclusions

Associations between physical activity and pain in people with knee osteoarthritis are variable and dynamic. These results reflect the beneficial impact of an active lifestyle and accompanying higher fitness. Yet, the side effect of acute periods of physical activity to transiently exacerbate pain may influence the behavior of some people to avoid activity because of pain.

Composite measures of physical activity and pain associate better with functional assessments than pain alone in knee osteoarthritis

INTRODUCTION

Recent research showed that physical activity (PA)-adjusted pain measures were more strongly associated with radiographic osteoarthritis (OA) severity than an unadjusted pain measure. This exploratory study examined whether PA-adjusted pain measures were more closely associated with other key OA-related measures, compared to unadjusted pain scores.

METHOD

Participants were 122 Veterans (mean age = 61.2 years, 88.5% male) with knee OA. Baseline Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain scores were adjusted for accelerometer-derived daily: (1) step counts, (2) minutes of any activity, (3) minutes of moderate or greater intensity activity, (4) minutes of light intensity activity, and (5) energy expenditure. Partial correlations, adjusted for age, sex, and body mass index, estimated associations of unadjusted and PA-adjusted WOMAC pain scores with functional assessments (6-minute walk test, 8-foot walk test, chair stand test, satisfaction with physical function), fatigue (Brief Fatigue Inventory), and anxiety/depressive symptoms (single item).

RESULTS

Significant (p < 0.05) associations were found in 29 of 36 of models. For the four function-related assessments, step count and energy expenditure-adjusted WOMAC pain scores had stronger associations (partial rs = 0.24-0.48) than WOMAC pain score (partial rs = 0.19-0.25). For fatigue and anxiety/depressive symptoms, WOMAC pain score had stronger, positive associations than most PA-adjusted pain scores. Of the PA-adjusted measures, the strongest associations overall were observed for step count and energy expenditure.

CONCLUSION

PA-adjusted pain scores may have particular value for OA studies involving functional assessments, whereas unadjusted WOMAC pain scores are more closely associated with psychological symptoms. This has implications for measurement in clinical OA studies.

TRIAL REGISTRATION

NCT01058304 KEY POINTS: • Among patents with osteoarthritis, physical activity-adjusted pain measures (particularly those adjusted for step count and energy expenditure) were more strongly associated with measures of physical function, compared to unadjusted pain scores, whereas unadjusted pain score was more strongly associated with a measure of psychological symptoms. • In clinical osteoarthritis research, the most appropriate or sensitive symptom measure (pain vs. physical activity-adjusted pain) may depend on the type of intervention or outcome being studied.

Validation of a new symptom outcome for knee osteoarthritis: the Ambulation Adjusted Score for Knee pain

OBJECTIVE

Validation of a symptom measure for early knee OA may help identify new treatments and modifiable risk factors. Symptom measures that consider pain in the context of activity level may provide better discrimination than pain alone. Therefore, we aimed to compare sensitivity to change for radiographic progression between Ambulation Adjusted Score for Knee pain (AASK), which accounts for self-reported ambulation, and Western Ontario McMaster Osteoarthritis (WOMAC) knee pain score.

DESIGN

Participants were assessed annually up to 48 months using WOMAC, Physical Activity Scale for the Elderly (PASE) ambulation, and knee radiographs. AASK was defined as ((WOMAC pain) + 1)/((average daily hours of walking) + 1). Radiographs were scored for Kellgren-Lawrence (KL) grade. Linear regression, stratified by OA status, evaluated relationships between changes in AASK and WOMAC pain and KL grade over time.

RESULTS

For 4191 people (8030 knees), the mean age was 61.2 (+ 9.2) years old and BMI was 28.6 (+ 4.8) kg/m2; 58% female. Over 40% of knees had WOMAC pain scores of 0; by design, no knees had AASK scores of 0. Annual changes in AASK were more sensitive to changes in KL than changes in WOMAC in those without baseline OA (0.20 and 0.16 change per unit KL change, p = 0.005 and 0.070 respectively), but performed similarly in knees with OA.

CONCLUSION

AASK is simple to assess using existing validated questionnaires. AASK performs well in individuals with and without OA and should be considered in clinical trials and observational studies of early knee OA.

US National Health and Nutrition Examination Survey Arthritis Initiatives, Methodologies and Data

The US National Health and Nutrition Examination Survey (NHANES) has collected population-based, nationally representative examination, laboratory, and radiographic data for arthritis and musculoskeletal diseases for more than 50 years. The resulting body of data and publications are substantial, yet much data remain unpublished. This review provides a basic understanding of the design and capabilities of the NHANES survey, reviewing the major accomplishments in the area of arthritis and musculoskeletal diseases. Currently available US National Health and Nutrition Examination Survey arthritis-related datasets are identified. Guidelines for using these data, and opportunities for data analysis and designing future studies are presented.

Efficacy of duloxetine by prior NSAID use in the treatment of chronic osteoarthritis knee pain: A post hoc subgroup analysis of a randomized, placebo-controlled, phase 3 study in Japan

BACKGROUND

A previously conducted placebo-controlled, randomized, phase 3 study of 353 Japanese patients with knee osteoarthritis (OA) showed significant improvements for duloxetine vs placebo in pain and health-related quality of life (HRQoL) (ClinicalTrials.gov Identifier: NCT02248480). Reported here are post hoc subgroup analyses evaluating the efficacy of duloxetine according to the pattern of prior nonsteroidal anti-inflammatory drug (NSAID) use.

METHODS

Patients with knee OA pain received once-daily duloxetine or placebo for 14 weeks. Pain was evaluated using the Brief Pain Inventory (BPI) and HRQoL was evaluated using the Western Ontario McMaster Universities Osteoarthritis Index (WOMAC). Patients were divided into four subgroups based on their prior NSAID use: (i) no prior NSAID use; (ii) low-frequency NSAID use (<14 days/month); (iii) high-frequency transdermal NSAID use (transdermal NSAIDs only; ≥14 days/month for the 3 months before study entry); and (iv) high-frequency other NSAID use (eg, oral NSAIDs only, both oral and transdermal NSAIDs; ≥14 days/month for the 3 months before study entry).

RESULTS

In each of the four prior NSAID use subgroups, there were greater reductions in BPI average pain severity score for duloxetine vs placebo at all timepoints during the 14-week treatment period; the treatment*prior NSAID use interaction was not statistically significant. In each subgroup, the proportion of patients achieving a ≥50% reduction in BPI average pain severity score was higher for duloxetine vs placebo. In each subgroup, there were greater reductions in WOMAC total score for duloxetine vs placebo at all timepoints; the treatment*prior NSAID use interaction was not statistically significant. In each subgroup, there were greater reductions at Week 14 in WOMAC pain, stiffness, physical function, and total scores for duloxetine vs placebo.

CONCLUSIONS

Duloxetine was consistently effective with respect to pain relief and HRQoL in Japanese patients with knee OA pain, regardless of the pattern of prior NSAID use.

Emerging Treatment Models in Rheumatology: Challenges for Osteoarthritis Trials

At a time when advancing understanding of osteoarthritis (OA) has created opportunities for new treatments, development of treatments has remained considerably behind advances in other rheumatic diseases. We describe elements of trial design and measurements that have inhibited success and offer suggestions that may help break the log jam. Among the problems with trials that include pain as an outcome measure are reliance on a single, non-optimal pain outcome, overestimation of likely effects of treatments on pain, and failure to identify patient subgroups most likely to respond to specific treatments. With regard to the use of structure modification as an outcome measure, demonstrating structure modification is often highly challenging, even with the use of magnetic resonance imaging. Many OA patients have advanced disease that is unlikely to respond to treatments that prevent cartilage loss. Further, prevention of cartilage loss and reduction of pain correlate weakly at best, and in at least some patients, reduction in pain may actually increase joint damage, making it impossible to demonstrate dual treatment effects on structure and pain in such scenarios. For structure outcomes, treatment effects on pain-sensitive structures such as bone and synovium may be more achievable than preventing cartilage loss. We suggest that changes in trial design related to some of these issues may increase the chances that new exciting and effective OA treatments will become available.

Financial Incentives and Health Coaching to Improve Physical Activity Following Total Knee Replacement: A Randomized Controlled Trial

OBJECTIVE

Most persons who undergo total knee replacement (TKR) do not increase their physical activity following surgery. We assessed whether financial incentives and health coaching would improve physical activity in persons undergoing TKR.

METHODS

We designed a factorial randomized controlled trial among persons undergoing TKR for osteoarthritis. Subjects underwent normal perioperative procedures, including postoperative physical therapy, and were assigned to 1 of 4 arms: attention control, telephonic health coaching (THC), financial incentives (FI), or THC + FI. We objectively measured step counts and minutes of physical activity using a commercial accelerometer (Fitbit Zip) and compared the changes from pre-TKR to 6 months post-TKR across the 4 study arms.

RESULTS

Of the 202 randomized subjects, 150 (74%) provided both pre-TKR and 6 months post-TKR accelerometer data. Among completers, the mean ± SE daily step count at 6 months ranged from 5,619 ± 381 in the THC arm to 7,152 ± 407 in the THC + FI arm (adjusting for baseline values). Daily step count 6 months post-TKR increased by 680 (95% confidence interval [95% CI] -94, 1,454) in the control arm, 274 (95% CI -473, 1,021) in the THC arm, 826 (95% CI 89, 1,563) in the FI arm, and 1,808 (95% CI 1,010, 2,606) in the THC + FI arm. Weekly physical activity increased by mean ± SE 14 ± 10, 14 ± 10, 16 ± 10, and 39 ± 11 minutes in the control, THC, FI, and THC + FI arms, respectively.

CONCLUSION

A dual THC + FI intervention led to substantial improvements in step count and physical activity following TKR.

Could Activity Modifications Indicate Physical Decline Among Adults With Symptomatic Knee Osteoarthritis?

OBJECTIVES

Mobility activity modifications indicate early functional losses that act as precursors to future declines among community-dwelling older adults. However, there is scarce evidence on whether activity modifications indicate poorer physical health among adults with symptomatic osteoarthritis, a major cause of disability. Our purpose was to investigate whether patient-reported mobility activity modifications indicated poorer physical health among adults with symptomatic knee osteoarthritis.

DESIGN

Secondary cross-sectional analysis of randomized trial data was performed. Preclinical Disability Questionnaire was used to group participants into the following three categories: difficulty, modified, and no difficulty walking/stair climbing. Kruskal Wallis and χ tests were used to compare clinical factors across groups.

RESULTS

Among 121 participants (median age = 60 yrs; 73% female; 60% white), less than 10% had modified walking/stair climbing. Compared with those with no walking difficulty, participants with modified walking had significantly less balance (P = 0.01) and global health (P = 0.01) as well as greater knee pain (P = 0.05) and physical disability (P = 0.04). Those with modified stair climbing had significantly smaller walking distances (P = 0.03) compared with those with no difficulty stair climbing.

CONCLUSIONS

Activity modifications may signal early impairments in physical health among people with symptomatic knee osteoarthritis. If confirmed, patient-reported activity modifications may enhance symptom evaluation in osteoarthritis and enable a better understanding of the disablement process.

The Use of Functional Data Analysis to Evaluate Activity in a Spontaneous Model of Degenerative Joint Disease Associated Pain in Cats

Introduction and objectives

Accelerometry is used as an objective measure of physical activity in humans and veterinary species. In cats, one important use of accelerometry is in the study of therapeutics designed to treat degenerative joint disease (DJD) associated pain, where it serves as the most widely applied objective outcome measure. These analyses have commonly used summary measures, calculating the mean activity per-minute over days and comparing between treatment periods. While this technique has been effective, information about the pattern of activity in cats is lost. In this study, functional data analysis was applied to activity data from client-owned cats with (n = 83) and without (n = 15) DJD. Functional data analysis retains information about the pattern of activity over the 24-hour day, providing insight into activity over time. We hypothesized that 1) cats without DJD would have higher activity counts and intensity of activity than cats with DJD; 2) that activity counts and intensity of activity in cats with DJD would be inversely correlated with total radiographic DJD burden and total orthopedic pain score; and 3) that activity counts and intensity would have a different pattern on weekends versus weekdays.

Results and conclusions

Results showed marked inter-cat variability in activity. Cats exhibited a bimodal pattern of activity with a sharp peak in the morning and broader peak in the evening. Results further showed that this pattern was different on weekends than weekdays, with the morning peak being shifted to the right (later). Cats with DJD showed different patterns of activity from cats without DJD, though activity and intensity were not always lower; instead both the peaks and troughs of activity were less extreme than those of the cats without DJD. Functional data analysis provides insight into the pattern of activity in cats, and an alternative method for analyzing accelerometry data that incorporates fluctuations in activity across the day.

Reduced knee adduction moments for management of knee osteoarthritis:: A three month phase I/II randomized controlled trial

Wedged insoles are believed to be of clinical benefit to individuals with knee osteoarthritis by reducing the knee adduction moment (KAM) during gait. However, previous clinical trials have not specifically controlled for KAM reduction at baseline, thus it is unknown if reduced KAMs actually confer a clinical benefit. Forty-eight participants with medial knee osteoarthritis were randomly assigned to either a control group where no footwear intervention was given, or a wedged insole group where KAM reduction was confirmed at baseline. KAMs, Knee Injury and Osteoarthritis Outcome Score (KOOS) and Physical Activity Scale for the Elderly (PASE) scores were measured at baseline. KOOS and PASE surveys were re-administered at three months follow-up. The wedged insole group did not experience a statistically significant or clinically meaningful change in KOOS pain over three months (p=0.173). Furthermore, there was no association between change in KAM magnitude and change in KOOS pain over three months within the wedged insole group (R²=0.02, p=0.595). Improvement in KOOS pain for the wedged insole group was associated with worse baseline pain, and a change in PASE score over the three month study (R²=0.57, p=0.007). As an exploratory comparison, there was no significant difference in change in KOOS pain (p=0.49) between the insole and control group over three months. These results suggest that reduced KAMs do not appear to provide any clinical benefit compared to no intervention over a follow-up period of three months. ClinicalTrials.gov ID Number: NCT02067208.

Resilience does not explain the dissociation between chronic pain and physical activity in South Africans living with HIV

Pain burden is high in people living with HIV (PLWH), but the effect of this pain on functionality is equivocal. Resilience, the ability to cope with adversity, may promote adaptation to pain, so we hypothesised that higher resilience would correlate with less pain-related impairment of activity. We recruited 197 black South African PLWH, 99 with chronic pain (CP) and 98 patients without. We measured pain intensity and interference using the Brief Pain Inventory, and resilience using the Resilience Scale. Participants were generally highly resilient. Greater resilience correlated with better health-related quality of life, but not with pain intensity or interference. We also measured physical activity objectively, by actigraphy, in a subset of patients (37 with chronic pain and 31 without chronic pain), who wore accelerometers for two weeks. There was no difference in duration or intensity of activity between those with and without pain, and activity was not associated with resilience. In this sample, pain was not associated with altered physical activity. Resilience did not explain differences in pain intensity or pain interference but was associated with improved quality of life. Financial stresses and the fear of HIV stigma may have driven patients to conceal pain and to suppress its expected impairment of activity.

Association between activity limitations and pain in patients scheduled for total knee arthroplasty

Background

Historically, persons scheduled for total knee arthroplasty (TKA) have reported severe pain with low demand activities such as walking, but recent data suggests that TKA recipients may have less preoperative pain. Little is known about people who elect TKA with low levels of preoperative pain. To better understand current TKA utilization, we evaluated the association between preoperative pain and difficulty performing high demand activities, such as kneeling and squatting, among TKA recipients.

Methods

We used baseline data from a randomized control trial designed to improve physical activity following TKA. Prior to TKA, participants were categorized according to Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) Pain scores: Low (0–25), Medium (26–40), and High (41–100). Within each group, limitations in both low demand and high demand activities were assessed.

Results

The sample consisted of 202 persons with a mean age of 65 (SD 8) years; 21 %, 34 %, and 45 % were categorized in the Low, Medium, and High Pain groups, respectively. Of the Low Pain group, 60 % reported at least one of the following functional limitations: limited flexion, limp, limited walking distance, and limitations in work or housework. While only 12 % of the Low Pain group reported at least moderate pain with walking on a flat surface, nearly all endorsed at least moderate difficulty with squatting and kneeling.

Conclusions

A substantial number of persons scheduled for TKA report Low WOMAC Pain (≤25) prior to surgery. Persons with Low WOMAC Pain scheduled for TKA frequently report substantial difficulty with high demand activities such as kneeling and squatting. Studies of TKA appropriateness and effectiveness for patients with low WOMAC Pain should include measures of these activities.

Trial registration

Identifier NCT01970631; Registered 23 October 2013.