Accelerometer-based Physical Activity Monitoring in Patients with Knee Osteoarthritis: Objective and Ambulatory Assessment of Actual Physical Activity During Daily Life Circumstances

Causal association of leisure sedentary behavior with arthritis: A Mendelian randomization analysis

OBJECTIVES

This study aimed at exploring the potential causal effects of leisure sedentary behavior (LSB) on common types of arthritis.

METHOD

Two-sample Mendelian randomization (MR), including both univariable MR (UVMR) and multivariable MR (MVMR) analysis, was performed to explore the effects of LSB on the risk of several common types of arthritis, including osteoarthritis, rheumatoid arthritis (RA), and psoriatic arthritis (PsA). Genetic variants from genome-wide association studies (GWAS) of LSBs for time spent on television watching, computer use, and driving were obtained from the UK Biobank. Summarized GWAS data of OA [overall, OA of the hip (HOA), and OA of the knee (KOA)], RA [overall, seronegative RA (nRA) and seropositive RA], and PsA was also acquired from the FinnGen Biobank Analysis. Causal Analysis Using Summary Effect Estimates (CAUSE) were further applied to verify the causality.

RESULTS

UVMR results provided evidence for the causal relationship of time spent on watching TV with overall OA [odds ratio (OR) = 1.80, 95% confidence interval (CI) = 1.45-2.23], KOA (OR = 1.86, 95% CI = 1.45-2.39) and HOA (IVW-fixed: OR = 1.65, 95% CI =1.20-2.26). Similar associations were observed in the TV-overall RA and TV-pRA, and TV-PsA, but the CAUSE method results only supported the causal association of time spent TV watching with OA and KOA. Moreover, MVMR results showed indicated an independent causal effect of TV watching on OA (overall, KOA, and HOA).

CONCLUSION

This study demonstrated the genetic causal association of prolonged TV watching time with overall OA and KOA risks.

Day-to-day variability of knee pain and the relationship with physical activity in people with knee osteoarthritis: an observational, feasibility study using consumer smartwatches

OBJECTIVE

To assess the feasibility of using smartwatches in people with knee osteoarthritis (OA) to determine the day-to-day variability of pain and the relationship between daily pain and step count.

DESIGN

Observational, feasibility study.

SETTING

In July 2017, the study was advertised in newspapers, magazines and, on social media. Participants had to be living/willing to travel to Manchester. Recruitment was in September 2017 and data collection was completed in January 2018.

PARTICIPANTS

26 participants aged>50 years with self-diagnosed symptomatic knee OA were recruited.

OUTCOME MEASURES

Participants were provided with a consumer cellular smartwatch with a bespoke app that triggered a series of daily questions including two times per day questions about level of knee pain and one time per month question from the pain subscale of the Knee Injury and Osteoarthritis Outcome Score (KOOS) questionnaire. The smartwatch also recorded daily step counts.

RESULTS

Of the 25 participants, 13 were men and their mean age was 65 years (standard deviation (SD) 8 years). The smartwatch app was successful in simultaneously assessing and recording data on knee pain and step count in real time. Knee pain was categorised into sustained high/low or fluctuating levels, but there was considerable day-to-day variation within these categories. Levels of knee pain in general correlated with pain assessed by KOOS. Those with sustained high/low levels of pain had a similar daily step count average (mean 3754 (SD 2524)/4307 (SD 2992)), but those with fluctuating pain had much lower step count levels (mean 2064 (SD 1716)).

CONCLUSIONS

Smartwatches can be used to assess pain and physical activity in knee OA. Larger studies may help inform a better understanding of causal links between physical activity patterns and pain. In time, this could inform development of personalised physical activity recommendations for people with knee OA.

Abnormal Gait Pattern Examination Screening for Physical Activity Level after One Year in Patients with Knee Osteoarthritis

This study examined the relationship between abnormal gait pattern and physical activity level one year later in patients with knee osteoarthritis (KOA) and determined the clinical utility of the abnormal gait pattern examination. Initially, the patients' abnormal gait pattern was assessed using seven items, based on the scoring system reported in a previous study. The grading was based on a three-criteria system with 0: no abnormality, 1: moderately abnormal, and 2: severely abnormal. The patients were then classified into three groups according to physical activity level one year after gait pattern examination: low, intermediate, and high physical activity groups, respectively. Cut-off values for physical activity levels were calculated based on abnormal gait pattern examinations results. On follow-ups with 24 of the 46 subjects, age, abnormal gait pattern, and gait speed showed significant differences among the three groups according to the amount of physical activity. Effect size of abnormal gait pattern was higher than age and gait speed. Patients with KOA with physical activity < 2700 steps/day and <4400 steps/day at one year had abnormal gait pattern examination scores of ≥8 and ≥5, respectively. Abnormal gait pattern is associated with future physical activity. The results suggested that abnormal gait pattern examinations in patients with KOA could be used to screen for the possibility of physical activity being <4400 steps one year later.

Disability and physical activity in people with chronic disease receiving physiotherapy. A prospective cohort study

Chronic disease affects patients' disability and participation in activities of daily living. Longitudinal information on disability and physical activity is generally scarce in patients with chronic disease. The current study aimed to investigate if self-reported disability and physical activity changed in patients with chronic disease receiving physiotherapy. Furthermore, the aim was to assess if an improvement in self-reported disability was related to an increase in objectively measured physical activity and if an aggravation in self-reported disability was related to a decrease in physical activity. Seventy patients with either multiple sclerosis, Parkinson's disease, rheumatoid arthritis or stroke receiving free of charge physiotherapy were tested at baseline and 1 year later. Disability was measured with the self-reported modified Ranking Scale-9 Questionnaire and physical activity was objectively measured using tri-axial accelerometry. Neither self-reported disability nor physical activity changed among patients receiving 1 year of free of charge physiotherapy at group level. Furthermore, self-reported change of disability was not expressed with changes in objectively measured physical activity, indicating that the two measures represent two different constructs.

Accelerometer-Based Physical Activity Patterns and Associations With Outcomes Among Individuals With Osteoarthritis

BACKGROUND

This study examined patterns of physical activity and associations with pain, function, fatigue, and sleep disturbance among individuals with knee or hip osteoarthritis.

METHODS

Participants (n = 54) were enrolled in a telephone-based physical activity coaching intervention trial; all data were collected at baseline. Self-reported measures of pain and function (WOMAC [Western Ontario and McMaster Universities Osteoarthritis Index] subscales), fatigue (10-point numeric rating scale), and PROMIS (Patient-Reported Outcomes Information System) Sleep Disturbance were collected via telephone. Accelerometers were mailed to participants and were worn for at least 3 days. Proportion of time participants spent in sedentary behavior during the morning (from wake until 12:00 pm), afternoon (12:00 pm until 5:59 pm) and evening (6:00 pm until sleep) each day was averaged across all days of wear. Pearson correlations assessed associations between activity and self-reported measures.

RESULTS

Participants spent a large proportion of time in sedentary behavior: 65.6% of mornings, 70.0% of afternoons, and 76.6% of evenings. Associations between proportion of time spent in sedentary behavior and reported outcomes were generally strongest in the afternoon, strongest for WOMAC function, and lowest for PROMIS Sleep Disturbance. In the evening hours, sedentary time was most strongly associated with fatigue.

CONCLUSIONS

Overall, findings stress the importance of reducing sedentary behavior among adults with osteoarthritis and suggest behavioral interventions may be strengthened by considering patients' within-day variation in symptoms and activity.

Reliability of activity monitors for physical activity assessment in patients with musculoskeletal disorders: A systematic review

BACKGROUND

Activity monitors have been introduced in the last years to objectively measure physical activity to help physicians in the management of musculoskeletal patients.

OBJECTIVE

This systematic review aimed at describing the assessment of physical activity by commercially available portable activity monitors in patients with musculoskeletal disorders.

METHODS

PubMed, Embase, PEDro, Web of Science, Scopus and CENTRAL databases were systematically searched from inception to June 11th, 2020. We considered as eligible observational studies with: musculoskeletal patients; physical activity measured by wearable sensors based on inertial measurement units; comparisons performed with other tools; outcomes consisting of number of steps/day, activity/inactivity time, or activity counts/day.

RESULTS

Out of 595 records, after removing duplicates, title/abstract and full text screening, 10 articles were included. We noticed a wide heterogeneity in the wearable devices, that resulted to be 10 different types. Patients included suffered from rheumatoid arthritis, osteoarthritis, juvenile idiopathic arthritis, polymyalgia rheumatica, and fibromyalgia. Only 3 studies compared portable activity trackers with objective measurement tools.

CONCLUSIONS

Taken together, this systematic review showed that activity monitors might be considered as useful to assess physical activity in patients with musculoskeletal disorders, albeit, to date, the high device heterogeneity and the different algorithms still prevent their standardization.

Should We Use Unilateral or Bilateral Tasks to Assess Maximal and Explosive Knee Extensor Strength in Patients with Knee Osteoarthritis? A Cross-Sectional Study

Deficits in maximal and explosive knee extensor strength, which are usually assessed with unilateral tasks, are substantial in patients with knee osteoarthritis (KOA). The aim of this study was to investigate the clinical relevance of unilateral vs. bilateral tasks for assessing knee extensor strength in patients with KOA. This was achieved primarily by comparing unilateral and bilateral inter-limb strength asymmetries and secondarily by examining the relationship between unilaterally and bilaterally measured strength, and performance-based and self-reported function. Twenty-four patients with unilateral KOA (mean age: 65 ± 7 years) performed isometric gradual and explosive maximal voluntary contractions to assess, respectively their maximal and explosive strength. Performance-based and self-reported function were also evaluated with standard functional tests and questionnaires, respectively. Inter-limb asymmetries of maximal and explosive strength did not differ significantly between unilateral (mean asymmetry: 26 ± 15%) and bilateral tasks (22 ± 21%). In the same way, the relationships between knee extensor strength-measured either unilaterally or bilaterally-and performance-based or self-reported function were not influenced by the type of task. In conclusion, it does not seem to make a difference in terms of clinical relevance whether maximal and explosive knee extensor strength are evaluated with unilateral or bilateral tasks in KOA patients.

Does Daily Physical Activity Differ Between Patients with Femoroacetabular Impingement Syndrome and Patients with Hip Dysplasia? A Cross-Sectional Study in 157 Patients and 60 Healthy Volunteers

BACKGROUND

The clinical presentation of femoroacetabular impingement syndrome (FAIS) and acetabular hip dysplasia (HD) are similar. However, the groups seem to differ regarding physical activity (PA) and sport.

PURPOSE

The aim was to compare PA between three groups; patients with FAIS, patients with HD, and healthy volunteers. A secondary purpose was to compare self-reported function in sport and recreation (sport/recreation) between patients with FAIS and HD.

STUDY DESIGN

This study is a cross-sectional study on 157 patients with FAIS or HD and 60 healthy controls.

METHODS

PA was measured with accelerometer-based sensors, and sport/recreation was measured with the Copenhagen Hip and Groin Outcome Score (HAGOS). Data on patients with FAIS or HD and healthy volunteers were collected in other studies and merged for comparison in this study.

RESULTS

Fifty-five patients with FAIS (20 males; mean age 36 years), 97 patients with HD (15 males; mean age 30 years) and 60 healthy volunteers (24 males; mean age 31 years) were included. Compared with patients with HD, patients with FAIS spent more time on very low intensity PA (mean 73 minutes (95% CI: 45;102)) and less time on low intensity PA per day (mean -21 minutes (95% CI: -37;-6)). Both groups spent less time on high intensity PA per day compared with healthy volunteers (p≤0.03). However, sport/recreation did not differ between the two groups (FAIS: median 34 points (IQR: 22;50) and HD: median 38 points (IQR: 25;53), p=0.16).

CONCLUSION

Patients with FAIS appear to be less physical active compared with patients with HD. However, both groups seem to perform less high intensity PA compared with healthy volunteers. This is interesting, as self-reported function in sport/recreation does not differ between patients with FAIS and HD. Thus, high intensity PA seems to be a key outcome in the management of patients with FAIS and HD.

LEVEL OF EVIDENCE

Level 2b.

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.

Alignment of Physical Activity in Older Couples Affected by Osteoarthritis: Investigation by Accelerometry and Questionnaire

This study examined whether an alignment of physical activity (PA) between osteoarthritis patients and their spouses, which was previously proven by accelerometry, might also be revealed by self-report. The PA of 28 cohabitating couples (58–83 years) was assessed by means of synchronous accelerometry (ActiGraph wGTX3-BT) and compared to their according self-reports in the German Physical Activity, Exercise, and Sport Questionnaire (BSA-F). Both methods were used to quantify the average weekly light PA, moderate to vigorous PA (MVPA), and total PA. Accelerometry revealed no differences in weekly light PA and total PA (p ≥ 0.187) between patients and spouses, whereas the patients’ spouses accumulated significantly more MVPA (p = 0.015). In contrast, the self-report did not reveal any differences between the two groups in terms of PA (p ≥ 0.572). Subsequent correlation analyses indicated that accelerometry data for mild PA and total PA were significantly correlated in couples (r ≥ 0.385, p ≤ 0.024), but MVPA was not (r = 0.257, p = 0.097). The self-reported PA data, on the other hand, did not indicate any significant correlation (r ≤ 0.046, p ≥ 0.409). The presented results give a first indication that an alignment of PA between osteoarthritis patients and their spouses is most likely to be detected by accelerometry, but not by self-report.

Measuring Daily Compliance With Physical Activity Tracking in Ambulatory Surgery Patients: Comparative Analysis of Five Compliance Criteria

BACKGROUND

Physical activity trackers such as the Fitbit can allow clinicians to monitor the recovery of their patients following surgery. An important issue when analyzing activity tracker data is to determine patients' daily compliance with wearing their assigned device, using an appropriate criterion to determine a valid day of wear. However, it is currently unclear as to how different criteria can affect the reported compliance of patients recovering from ambulatory surgery. Investigating this issue can help to inform the use of activity data by revealing factors that may impact compliance calculations.

OBJECTIVE

This study aimed to understand how using different criteria can affect the reported compliance with activity tracking in ambulatory surgery patients. It also aimed to investigate factors that explain variation between the outcomes of different compliance criteria.

METHODS

A total of 62 patients who were scheduled to undergo total knee arthroplasty (TKA, ie, knee replacement) volunteered to wear a commercial Fitbit Zip activity tracker over an 8-week perioperative period. Patients were asked to wear the Fitbit Zip daily, beginning 2 weeks prior to their surgery and ending 6 weeks after surgery. Of the 62 patients who enrolled in the study, 20 provided Fitbit data and underwent successful surgery. The Fitbit data were analyzed using 5 different daily compliance criteria, which consider patients as compliant with daily tracking if they either register >0 steps in a day, register >500 steps in a day, register at least one step in 10 different hours of the day, register >0 steps in 3 distinct time windows, or register >0 steps in 3 out of 4 six-hour time windows. The criteria were compared in terms of compliance outcomes produced for each patient. Data were explored using heatmaps and line graphs. Linear mixed models were used to identify factors that lead to variation between compliance outcomes across the sample.

RESULTS

The 5 compliance criteria produce different outcomes when applied to the patients' data, with an average 24% difference in reported compliance between the most lenient and strictest criteria. However, the extent to which each patient's reported compliance was impacted by different criteria was not uniform. Some individuals were relatively unaffected, whereas others varied by up to 72%. Wearing the activity tracker as a clip-on device, rather than on the wrist, was associated with greater differences between compliance outcomes at the individual level (P=.004, r=.616). This effect was statistically significant (P<.001) in the first 2 weeks after surgery. There was also a small but significant main effect of age on compliance in the first 2 weeks after surgery (P=.040). Gender and BMI were not associated with differences in individual compliance outcomes. Finally, the analysis revealed that surgery has an impact on patients' compliance, with noticeable reductions in activity following surgery. These reductions affect compliance calculations by discarding greater amounts of data under strict criteria.

CONCLUSIONS

This study suggests that different compliance criteria cannot be used interchangeably to analyze activity data provided by TKA patients. Surgery leads to a temporary reduction in patients' mobility, which affects their reported compliance when strict thresholds are used. Reductions in mobility suggest that the use of lenient compliance criteria, such as >0 steps or windowed approaches, can avoid unnecessary data exclusion over the perioperative period. Encouraging patients to wear the device at their wrist may improve data quality by increasing the likelihood of patients wearing their tracker and ensuring that activity is registered in the 2 weeks after surgery.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03518866; https://clinicaltrials.gov/ct2/show/NCT03518866.

Physical Activity Monitoring Using a Fitbit Device in Ischemic Stroke Patients: Prospective Cohort Feasibility Study

Background

Continuous tracking of ambulatory activity in real-world settings using step activity monitors has many potential uses. However, feasibility, accuracy, and correlation with performance measures in stroke patients have not been well-established.

Objective

The primary study objective was to determine adherence with wearing a consumer-grade step activity monitor, the Fitbit Charge HR, in home-going ischemic stroke patients during the first 90 days after hospital discharge. Secondary objectives were to (1) determine accuracy of step counts of the Fitbit Charge HR compared with a manual tally; (2) calculate correlations between the Fitbit step counts and the mobility performance scores at discharge and 30 days after stroke; (3) determine variability and change in weekly step counts over 90 days; and (4) evaluate patient experience with using the Fitbit Charge HR poststroke.

Methods

A total of 15 participants with recent mild ischemic stroke wore a Fitbit Charge HR for 90 days after discharge and completed 3 mobility performance tests from the National Institutes of Health Toolbox at discharge and Day 30: (1) Standing Balance Test, (2) 2-Minute Walk Endurance Test, and (3) 4-Meter Walk Gait Speed Test. Accuracy of step activity monitors was assessed by calculating differences in steps recorded on the step activity monitor and a manual tally during 2-minute walk tests.

Results

Participants had a mean age of 54 years and a median modified Rankin scale score of 1. Mean daily adherence with step activity monitor use was 83.6%. Mean daily step count in the first week after discharge was 4376. Daily step counts increased slightly during the first 30 days after discharge (average increase of 52.5 steps/day; 95% CI 32.2-71.8) and remained stable during the 30-90 day period after discharge. Mean step count difference between step activity monitor and manual tally was –4.8 steps (–1.8%). Intraclass correlation coefficients for step counts and 2-minute walk, standing balance, and 4-meter gait speed at discharge were 0.41 (95% CI –0.14 to 0.75), –0.12 (95% CI –0.67 to 0.64), and 0.17 (95% CI –0.46 to 0.66), respectively. Values were similarly poor at 30 days.

Conclusions

The use of consumer-grade Fitbit Charge HR in patients with recent mild stroke is feasible with reasonable adherence and accuracy. There was poor correlation between step counts and gait speed, balance, and endurance. Further research is needed to evaluate the association between step counts and other outcomes relevant to patients, including patient-reported outcomes and measures of physical function.

Five-year Evolution Patterns of Physical Activity and Sedentary Behavior in Patients with Lower-limb Osteoarthritis and Their Sociodemographic and Clinical Correlates

OBJECTIVE

The present study aimed to identify trajectories of physical activity (PA) components (frequency, duration, intensity, and type) and screen-based sedentary behavior (SB) as well as baseline predictors of each trajectory in patients with hip and/or knee osteoarthritis (OA).

METHODS

We included 878 patients with a 5-year follow-up from the KHOALA cohort. PA and SB were measured by the Modifiable Activity Questionnaire. We used group-based trajectory analysis to identify the trajectories of PA components and screen-based SB, and multivariable logistic regression to determine predictors of the identified trajectories.

RESULTS

Two groups of trajectories were identified for each PA component and 3 for SB. High and decreasing PA duration was associated with female sex (OR 0.3, 95% CI 0.1-0.5) as was low and stable, more so than high and decreasing prevalence of weight-bearing activities (OR 0.6, 95% CI 0.4-0.9). Patients with impaired patient-reported outcome measures and obese patients often featured low versus high and decreasing prevalence of weight-bearing activities. Predictors of moderate and high versus low and slightly increasing screen-based SB trajectories were male sex, age < 60 years, single status (OR 1.5, 95% CI 1.1-2.1), obesity (OR 2.1, 95% CI 1.4-3.1), smoking (OR 2.0, 95% CI 1.1-3.7), and less physical jobs. Predictors of moderate and high versus low screen-based SB trajectories were all sociodemographic: male sex, age < 60 years, single status, obesity, smoking, and less physical jobs.

CONCLUSION

Sociodemographic and clinical predictors of trajectories vary between PA components; they are associated mainly with PA frequency and type. No clinical characteristics were associated with screen-based SB.

Systematic review on the application of wearable inertial sensors to quantify everyday life motor activity in people with mobility impairments

BACKGROUND

Recent advances in wearable sensor technologies enable objective and long-term monitoring of motor activities in a patient's habitual environment. People with mobility impairments require appropriate data processing algorithms that deal with their altered movement patterns and determine clinically meaningful outcome measures. Over the years, a large variety of algorithms have been published and this review provides an overview of their outcome measures, the concepts of the algorithms, the type and placement of required sensors as well as the investigated patient populations and measurement properties.

METHODS

A systematic search was conducted in MEDLINE, EMBASE, and SCOPUS in October 2019. The search strategy was designed to identify studies that (1) involved people with mobility impairments, (2) used wearable inertial sensors, (3) provided a description of the underlying algorithm, and (4) quantified an aspect of everyday life motor activity. The two review authors independently screened the search hits for eligibility and conducted the data extraction for the narrative review.

RESULTS

Ninety-five studies were included in this review. They covered a large variety of outcome measures and algorithms which can be grouped into four categories: (1) maintaining and changing a body position, (2) walking and moving, (3) moving around using a wheelchair, and (4) activities that involve the upper extremity. The validity or reproducibility of these outcomes measures was investigated in fourteen different patient populations. Most of the studies evaluated the algorithm's accuracy to detect certain activities in unlabeled raw data. The type and placement of required sensor technologies depends on the activity and outcome measure and are thoroughly described in this review. The usability of the applied sensor setups was rarely reported.

CONCLUSION

This systematic review provides a comprehensive overview of applications of wearable inertial sensors to quantify everyday life motor activity in people with mobility impairments. It summarizes the state-of-the-art, it provides quick access to the relevant literature, and it enables the identification of gaps for the evaluation of existing and the development of new algorithms.

Daily pain catastrophizing predicts less physical activity and more sedentary behavior in older adults with osteoarthritis

Musculoskeletal disorders such as knee osteoarthritis (OA) are the primary cause of chronic pain in older adults. Recommended self-management strategies for knee OA include staying physically active in the face of pain, but many patients avoid activities they are capable of doing. The overall purpose of this study was to examine the extent to which daily pain catastrophizing, a maladaptive coping strategy, could influence OA patients' physical activity and sedentary behavior. The current study used data from 143 older knee OA patients who completed electronic daily diaries for 22 days and wore an accelerometer to capture physical activity and sedentary behavior. At the beginning of each day, patients reported their pain catastrophizing regarding the day ahead. Results from multilevel models demonstrated that on mornings when patients catastrophized more than usual about their pain in the day ahead, they spent more time in sedentary behavior and engaged in fewer minutes of moderate to vigorous physical activity that day. Cross-day lagged analyses further showed that the effect of morning pain catastrophizing on subsequent sedentary behavior extended to the next day. More time spent in sedentary behavior, in turn, contributed to greater pain catastrophizing the next morning. These findings support the mechanistic role of daily pain catastrophizing in the avoidance of physical activity for older OA patients, and suggest that effective interventions for pain catastrophizing may also reduce sedentary behavior and enhance physical activity, with longer-term benefits for pain management, physical function, and overall health.

Quality, but not quantity of physical activity is associated with metal ion concentrations in unilateral hip resurfacing

Little is known about the influence of physical activity (PA) on metal ion concentrations in subjects with metal-on-metal hip arthroplasty. Implant wear is thought to be a function of use and thus of patient activity levels. It is hypothesized that daily habitual PA of patients with hip resurfacing arthroplasty (HRA) is associated with metal ion concentrations. Therefore a study was conducted in patients with a unilateral HRA at 10-years follow-up. Blood metal ion concentrations were determined. An acceleration-based activity monitor was used to measure PA in daily life. The cohort consisted of 12 males (75%) and 4 females (25%) with a median age at surgery of 55.5 ± 9.7 years [43.0-67.9] and a median follow-up of 9.9 ± 1.0 years [9.1-10.9]. The median cobalt and chromium ion concentrations were 25 ± 13 and 38 ± 28 nmol/L. A significant association between sit-stand transfers and high-intensity peaks with cobalt ion concentrations were found. Regarding PA and metal ion concentrations as a proxy of wear in HRA, specific activities like transfers or qualitative aspects of activity behavior like intensity, seem to matter more than the quantity of low-intensity activities like walking or cycling. This suggests that patients may safely engage in such activities to achieve important general health benefits and quality of life.

Daily Sedentary Behavior Predicts Pain and Affect in Knee Arthritis

BACKGROUND

Sedentary behavior (SB), which has been linked with numerous adverse health outcomes, is prevalent among adults with osteoarthritis (OA). The associations between SB and daily physical and psychological health outcomes for OA patients, however, have received little attention.

PURPOSE

Using accelerometer and self-report data, the current study examined how the amount of time OA patients spent in SB was associated with their pain and affect in daily life, independent of physical activity.

METHODS

Over 22 days, 143 older adults (mean age = 65 years) with knee OA wore an accelerometer to measure SB and physical activity, and also reported their pain and affect three times a day using a handheld computer. Multilevel analyses were conducted to examine the prospective within-person associations between SB and subsequent pain or affect within the same day and across days, independent of physical activity.

RESULTS

The time spent in SB daily predicted less pain but worse affect at the end of that day, above and beyond the effects of physical activity, as well as demographics and individual differences in general health and depression. Moreover, cross-day lagged analyses indicated that time spent in SB on 1 day predicted higher negative affect the next morning. Finally, the average level of SB was also associated with worse average affect at the between-person level.

CONCLUSIONS

SB may be related to less pain in the short term but detract from patients' emotional well-being. Future intervention should aim to reduce daily SB to improve OA patients' emotional well-being.

Association of Pain and Steps Per Day in Persons With Mild-to-Moderate, Symptomatic Knee Osteoarthritis: A Mixed-Effects Models Analysis of Multiple Measurements Over Three Years

OBJECTIVE

Pain is a consistently reported barrier to physical activity by persons with knee osteoarthritis (OA). Nonetheless, few studies of knee OA have investigated the association of pain with daily walking levels. The current study assessed the relationship of 2 distinct measures of knee pain with objectively measured physical activity in adults with knee OA.

METHODS

This was a longitudinal, observational investigation of 59 individuals (48 women; mean ± SD age 61.1 ± 6.4 years, mean ± SD body mass index 28.1 ± 5.6 kg/m² ) with clinical knee OA. Data were collected every 3 months for up to 3 years. Physical activity was characterized as the average steps per day taken over at least 3 days, mea-sured by accelerometry. Pain was measured using 2 patient-administered questionnaires: the pain subscale of the Knee Injury and Osteoarthritis Outcome Score (KOOS-pain) and the P4 pain scale (P4-pain). Mixed-effects models determined the association between pain and physical activity levels (over covariates) among adults with knee OA (α = 0.05).

RESULTS

All covariates (age [β = -3.65, P < 0.001], body mass index [β = -3.06, P < 0.001], season [spring/fall β = -6.91, P = 0.002; winter β = -14.92, P < 0.001]) were predictors of physical activity. Neither the inverted KOOS-pain (β = 0.04, P = 0.717) nor P4-pain (β = -0.37, P = 0.264) was associated with physical activity.

CONCLUSION

Knee pain is not associated with daily walking levels in persons with mild-to-moderate, symptomatic knee OA. While pain management remains an important target of interventions, strategies to increase steps per day in this population should focus on overcoming potentially more crucial barriers to activity participation.

Despite patient-reported outcomes improve, patients with femoroacetabular impingement syndrome do not increase their objectively measured sport and physical activity level 1 year after hip arthroscopic surgery. Results from the HAFAI cohort

PURPOSE

Patients with femoroacetabular impingement syndrome (FAIS) are young and middle-aged persons living physically active lives including sports activities. However, measurements of the physical activity level before and after hip arthroscopic surgery in patients with FAIS using both self-reported and objective accelerometer-based measures are lacking. Furthermore, comparing patients with a reference group of persons reporting no hip problems and conducting subgroup analyses investigating changes in physical activity level and self-reported outcomes according to pre-surgery activity level may further highlight the activity pattern for patients.

METHODS

Sixty patients with FAIS eligible for hip arthroscopic surgery were consecutively included in a prospective cohort study (HAFAI cohort) together with 30 reference persons reporting no hip problems. Participants completed the Copenhagen Hip and Groin Outcome Score (HAGOS) together with questions regarding their sports activities. Furthermore, participants wore a three-axial accelerometer for five consecutive days during waking hours. The accelerometer-based data were analysed and presented as total activity and type, frequency and duration of activities.

RESULTS

Patients experienced significant and clinically relevant changes in all HAGOS scores. 88% of patients participated in some kind of sports activity 1 year after surgery. Overall, objectively measured physical activity did not change from before to 1 year after surgery. However, subgroup analyses of the most sedentary patients preoperatively revealed significant changes towards a more active pattern. Compared to reference persons, patients performed less bicycling and running.

CONCLUSION

Despite clinically relevant changes in self-reported outcomes, patients did not increase their overall physical activity level 1 year after surgery. Physical activity levels were lower in patients than in the reference group and patients continued bicycling and running less compared with the reference group.

LEVEL OF EVIDENCE

II.

Use of accelerometer-based activity monitoring in orthopaedics: benefits, impact and practical considerations

Studies of the effectiveness of orthopaedic interventions do not generally measure physical activity (PA). Applying accelerometer-based activity monitoring in orthopaedic studies will add relevant information to the generally examined physical function and pain assessment.Accelerometer-based activity monitoring is practically feasible in orthopaedic patient populations, since current day activity sensors have battery time and memory to measure continuously for several weeks without requiring technical expertise.The ongoing development in sensor technology has made it possible to combine functional tests with activity monitoring.For clinicians, the application of accelerometer-based activity monitoring can provide a measure of PA and can be used for clinical comparisons before and after interventions.In orthopaedic rehabilitation, accelerometer-based activity monitoring may be used to help patients reach their targets for PA and to coach patients towards a more active lifestyle through direct feedback. Cite this article: EFORT Open Rev 2019;4:678-685. DOI: 10.1302/2058-5241.4.180041.

What does digitalization hold for the creation of real-world evidence?

Health-related information is increasingly being collected and stored digitally. These data, either structured or unstructured, are becoming the ubiquitous assets that might enable us to comprehensively map out a patient's health journey from an asymptomatic state of wellness to disease onset and its trajectory. These new data could provide rich real-world evidence for better clinical care and research, if they can be accessed, linked and analyzed-all of which are possible. In this review, these opportunities will be explored through a case vignette of a patient with OA, followed by discussion on how this digitalized real-world evidence could best be utilized, as well as the challenges of data access, quality and maintaining public trust.

Optimization and Validation of an Adjustable Activity Classification Algorithm for Assessment of Physical Behavior in Elderly

Due to a lack of transparency in both algorithm and validation methodology, it is difficult for researchers and clinicians to select the appropriate tracker for their application. The aim of this work is to transparently present an adjustable physical activity classification algorithm that discriminates between dynamic, standing, and sedentary behavior. By means of easily adjustable parameters, the algorithm performance can be optimized for applications using different target populations and locations for tracker wear. Concerning an elderly target population with a tracker worn on the upper leg, the algorithm is optimized and validated under simulated free-living conditions. The fixed activity protocol (FAP) is performed by 20 participants; the simulated free-living protocol (SFP) involves another 20. Data segmentation window size and amount of physical activity threshold are optimized. The sensor orientation threshold does not vary. The validation of the algorithm is performed on 10 participants who perform the FAP and on 10 participants who perform the SFP. Percentage error (PE) and absolute percentage error (APE) are used to assess the algorithm performance. Standing and sedentary behavior are classified within acceptable limits (±10% error) both under fixed and simulated free-living conditions. Dynamic behavior is within acceptable limits under fixed conditions but has some limitations under simulated free-living conditions. We propose that this approach should be adopted by developers of activity trackers to facilitate the activity tracker selection process for researchers and clinicians. Furthermore, we are convinced that the adjustable algorithm potentially could contribute to the fast realization of new applications.

Metal ion concentrations after metal-on-metal hip arthroplasty are not correlated with habitual physical activity levels

INTRODUCTION

Metal-on-metal (MoM) hip arthroplasties have shown high clinical failure rates with many patients at risk for a revision and under surveillance for high metal ion concentrations. Implant wear releasing such ions is assumed to be a function of use, i.e. the patient's physical activity. This study aimed to assess whether habitual physical activity levels of MoM patients are correlated with metal ion concentrations and are higher in patients with high (at risk) than in patients with low (safe) metal ion concentrations.

METHODS

A cohort study was conducted of patients with any type of MoM hip prosthesis. Metal ion concentrations were determined using ICP-MS. Habitual physical activity of subjects was measured in daily living using an acceleration-based activity monitor. Outcome consisted of quantitative and qualitative activity parameters.

RESULTS

In total, 62 patients were included. Mean age at surgery was 60.8 ± 9.3 years and follow-up was 6.3 ± 1.4 years. Cobalt concentrations were highly elevated overall (112.4 ± 137.9 nmol/L) and significantly more in bilateral (184.8 ± 106.5 nmol/L) than in unilateral cases (87.8 ± 139.4 nmol/L). No correlations were found between physical activity parameters and metal ion concentrations. Subgroup analysis of patients with low versus high cobalt concentration showed no significant differences in habitual physical activity.

DISCUSSION

No correlation was found between physical activity levels and metal ion concentrations. Implant use by normal habitual activities of daily living seems not to influence metal ion concentrations.

Relative difference among 27 functional measures in patients with knee osteoarthritis: an exploratory cross-sectional case-control study

Background

To raise the effectiveness of interventions, clinicians should evaluate important biopsychosocial aspects of the patient’s situation. There is limited knowledge of which factors according to the International Classification of Function, Disability, and Health (ICF) are most deviant between patients with knee osteoarthritis (KOA) and healthy individuals. To assist in measures’ selection, we aimed to quantify the differences between patients with KOA and healthy controls on various measures across the ICF dimensions of body function, activity, and participation.

Methods

We performed an exploratory cross-sectional case-control study. In total, 28 patients with mild-to-moderate KOA (mean age 61 years, 64% women) referred by general physicians to a hospital’s osteoarthritis-school, and 31 healthy participants (mean age 55 years, 52% women), volunteered. We compared between-group differences on 27 physical and self-reported measures derived from treatment guidelines, trial recommendations, and trial/outcome reviews. Independent t-test, Chi-square, and Mann-Whitney U test evaluated the significance for continuous parametric, dichotomous, and ordinal data, respectively. For parametric data, effect sizes were calculated as Cohen’s d. For non-parametric data, ds were estimated by p-values and sample sizes according to statistical formulas. Finally, all ds were ranked and interpreted after Hopkins’ scale. An age-adjusted sensitivity-analysis on parametric data validated those conclusions.

Results

Very large differences between patients and controls were found on the Pain numeric rating scale¹, the Knee Injury and Osteoarthritis Scale (KOOS, all subscales)², as well as the Örebro Musculoskeletal psychosocial scale³ (P < 0.0001). Large differences were found on the Timed 10-steps-up-and-down stair climb test⁴ and Accelerometer registered vigorous-intensity physical activity in daily life⁵ (P < 0.001). Respectively, these measures clustered on ICF as follows: ¹body function, ²all three ICF-dimensions, ³body function and participation, ⁴activity, and ⁵participation.

Limitations

The limited sample excluded elderly patients with severe obesity.

Conclusions

Very large differences across all ICF dimensions were indicated for the KOOS and Örebro questionnaires together for patients aged 45–70 with KOA. Clinicians are suggested to use them as means of selecting supplementary measures with appropriate discriminative characteristics and clear links to effective therapy. Confirmative studies are needed to further validate these explorative and partly age-unadjusted conclusions.

Using Physical Activity Trackers in Arthritis Self-Management: A Qualitative Study of Patient and Rehabilitation Professional Perspectives

OBJECTIVE

To compare and contrast the perspectives of patients with arthritis and those of rehabilitation professionals regarding starting and sustaining use of physical activity trackers (PATs).

METHODS

We conducted focus group sessions with patients, physiotherapists, and occupational therapists in Ontario, Alberta, or British Columbia, Canada. To be eligible, patients must have self-reported a diagnosis of inflammatory or osteoarthritis. Rehabilitation professionals reported that at least 40% of their caseload was dedicated to arthritis care. Participants had any level of experience with PATs. A thematic analytic approach was used.

RESULTS

The following 3 themes were identified: 1) anticipating sharing objective measures of physical activity. Participants agreed that use of PATs had the potential to improve consultations between patients with arthritis and rehabilitation professionals but were uncertain how to achieve this potential; 2) perceived or experienced barriers to start or continue using a PAT. Participants shared doubts about whether existing PATs would meet specific needs of patients with arthritis and expressed concerns about possible negative impacts; and 3) bolstering motivation? Although there was agreement that use of PATs could bolster the motivation of patients who were already active, patients and rehabilitation professionals had different opinions regarding whether use of PATs alone would motivate patients to start increasing activity levels.

CONCLUSION

Our study highlights similarities and differences between the perspectives of patients and rehabilitation professionals regarding the potential value and risks of integrating PATs into arthritis self-management. Despite agreement about the potential of PATs, participants were uncertain how to effectively incorporate these tools to enhance patient-clinician consultations and had differing views about whether use of PATs would support a patient's motivation to be active.

Feedback From Activity Trackers Improves Daily Step Count After Knee and Hip Arthroplasty: A Randomized Controlled Trial

BACKGROUND

Commercial wrist-worn activity monitors have the potential to accurately assess activity levels and are being increasingly adopted in the general population. The aim of this study was to determine if feedback from a commercial activity monitor improves activity levels over the first 6 weeks after total hip arthroplasty (THA) or total knee arthroplasty (TKA).

METHODS

One hundred sixty-three consecutive subjects undergoing primary TKA or THA were randomized into 2 groups. Subjects received an activity tracker with the step display obscured 2 weeks before surgery and completed patient-reported outcome measures (PROMs). On day 1 after surgery, participants were randomized to either the "feedback (FB) group" or the "no feedback (NFB) group." The FB group was able to view their daily step count and was given a daily step goal. Participants in the NFB group wore the device with the display obscured for 2 weeks after surgery, after which time they were also able to see their daily step count but did not receive a formal step goal. The mean daily steps at 1, 2, 6 weeks, and 6 months were monitored. At 6 months after surgery, subjects repeated PROMs and daily step count collection.

RESULTS

Of the 163 subjects, 95 underwent THA and 68 underwent TKA. FB subjects had a significantly higher (P < .03) mean daily step count by 43% in week 1, 33% in week 2, 21% in week 6, and 17% at 6 months, compared with NFB. The FB subjects were 1.7 times more likely to achieve a mean 7000 steps per day than the NFB subjects at 6 weeks after surgery (P = .02). There was no significant difference between the groups in PROMs at 6 months. Ninety percent of FB and 83% of NFB participants reported that they were satisfied with the results of the surgery (P = .08). At 6 months after surgery, 70% of subjects had a greater mean daily step count compared with their preoperative level.

CONCLUSION

Subjects who received feedback from a commercial activity tracker with a daily step goal had significantly higher activity levels after hip and knee arthroplasty over 6 weeks and 6 months, compared with subjects who did not receive feedback in a randomized controlled trial. Commercial activity trackers may be a useful and effective adjunct after arthroplasty.

Use of Physical Activity Monitors in Rheumatic Populations

PURPOSE OF REVIEW

The purpose of this review paper is to provide an overview of the recent research using physical activity monitors in rheumatic populations including those with osteoarthritis, rheumatoid arthritis, systemic lupus erythematosus, and fibromyalgia.

RECENT FINDINGS

Recent research demonstrates increased use of physical activity monitors in these populations, especially in those with osteoarthritis. Results from cross-sectional, longitudinal, and intervention studies highlight that physical activity levels are below recommended guidelines, yet evidence suggests benefits such as improving pain, fatigue, function, and overall well-being. While the use of physical activity monitors in rheumatic populations is increasing, more research is needed to better understand physical activity levels in these populations, the effects of activity on relevant clinical outcomes, and how monitors can be used to help more individuals reach physical activity guidelines.

Are patients with knee osteoarthritis and patients with knee joint replacement as physically active as healthy persons?

Background

It is well documented that patients with knee osteoarthritis (KOA) suffer from reduced physical function and that function of the affected knee is improved after knee joint replacement (KJR). However, it remains uncertain whether patients with KOA are less physically active than healthy people and whether patients increase their level of physical activity after surgery to a level comparable with that of healthy people. The aim of this study was to examine whether patients with KOA are less physically active than healthy participants and whether patients who have undergone KJR show an increased activity and achieve the same level of physical activity as healthy participants 5 years postoperatively.

Methods

Fifty-four patients with KOA (29 women; mean age 62 ± 8.6; mean body mass index (BMI) 27 ± 5), 52 patients who had KJR due to KOA 5 years earlier (26 women; mean age 66 ± 7.2; mean BMI 30 ± 5) and 171 healthy participants (76 women, mean age 64 ± 9.7, mean BMI 26 ± 5) were included in this cross-sectional study. The level of physical activity was measured over a mean period of 5.5 days with a triaxial accelerometer mounted on the thigh. Number of daily steps, number of daily short walking bouts of <10 s duration and number of daily transfers from sitting to standing position were recorded. Data were analysed using two sample t tests and were adjusted for age, gender and BMI.

Results

Patients with KOA did not differ significantly from healthy participants regarding daily steps (+321, p = 0.50) or daily transfers from sitting to standing (+1.9, p = 0.52) but performed significantly less daily short walking bouts <10 s (-11.9, p = 0.02). Patients after KJR did not differ significantly from healthy participants regarding daily steps (-281, p = 0.60) of transfers from sitting to standing position (-3.2, p = 0.32) but performed significantly less daily short walking bouts <10 s (-21.7, p = 0.001).

Conclusion

Patients with KOA and KJR showed no significant reduction in number of daily step counts and transfers from sitting to standing position when compared with matched healthy controls. However, the number of short walking bouts was reduced in patients with KOA and by twice as much in patients with KJR. This indicates that KOA and treatment with KJR hardly affect health-related general activity but do affect specific physical activity behaviour potentially indicative of KOA or post-KJR functional limitations.

The translational potential of this article

Activity monitoring with an accelerometer-based method gives insights into health-related general activity levels such as total daily steps and specific parameters such as short walking bouts, which may serve as an objective outcome measure in clinical practice.

Objective assessment of physical activity and sedentary behaviour in knee osteoarthritis patients - beyond daily steps and total sedentary time

BACKGROUND

Knee osteoarthritis patients may become physically inactive due to pain and functional limitations. Whether physical activity exerts a protective or harmful effect depends on the frequency, intensity, time and type (F.I.T.T.). The F.I.T.T. dimensions should therefore be assessed during daily life, which so far has hardly been feasible. Furthermore, physical activity should be assessed within subgroups of patients, as they might experience different activity limitations. Therefore, this study aimed to objectively describe physical activity, by assessing the F.I.T.T. dimensions, and sedentary behaviour of knee osteoarthritis patients during daily life. An additional goal was to determine whether activity events, based on different types and durations of physical activity, were able to discriminate between subgroups of KOA patients based on risk factors.

METHODS

Clinically diagnosed knee osteoarthritis patients (according to American College of Rheumatology criteria) were monitored for 1 week with a tri-axial accelerometer. Furthermore, they performed three functional tests and completed the Knee Osteoarthritis Outcome Score. Physical activity levels were described for knee osteoarthritis patients and compared between subgroups.

RESULTS

Sixty-one patients performed 7303 mean level steps, 319 ascending and 312 descending steps and 601 bicycle crank revolutions per day. Most waking hours were spent sedentary (61%), with 4.6 bouts of long duration (> 30 min). Specific events, particularly ascending and descending stairs/slopes, brief walking and sedentary bouts and prolonged walking bouts, varied between subgroups.

CONCLUSIONS

From this sample of KOA patients, the most common form of activity was level walking, although cycling and stair climbing activities occurred frequently, highlighting the relevance of distinguishing between these types of PA. The total active time encompassed a small portion of their waking hours, as they spent most of their time sedentary, which was exacerbated by frequently occurring prolonged bouts. In this study, event-based parameters, such as stair climbing or short bouts of walking or sedentary time, were found more capable of discriminating between subgroups of KOA patients compared to overall levels of PA and sedentary time. Thereby, subtle limitations in physical behaviour of KOA-subgroups were revealed, which might ultimately be targeted in rehabilitation programs.

TRIAL REGISTRATION

German Clinical Trials Registry under ' DRKS00008735 ' at 02.12.2015.

Sedentary Behavior, Cadence, and Physical Activity Outcomes after Knee Arthroplasty

PURPOSE

This study comprehensively examined sedentary behavior and physical activity patterns in people with severe knee osteoarthritis awaiting total knee arthroplasty (TKA) and in individuals after TKA.

METHODS

Preoperative (n = 32, mean ± SD = 69.9 ± 5.3 yr) and 1-yr postoperative participants with TKA (n = 38, 67.9 ± 7.3 yr) wore ActiGraph GT3X+ activity monitors for 6.8 ± 0.6 d. Total sedentary time, time in long sedentary bouts (≥30 min), and physical activity outcomes (steps, time in moderate-to-vigorous physical activity [MVPA], cadence) were examined.

RESULTS

There were no differences between pre- and postoperative groups for total sedentary time (9.3 ± 1.4 vs 9.2 ± 1.4 h·d, P = 0.62) and number of long sedentary bouts per day (median [interquartile range] = 3.4 [1.9] vs 3.1 [2.0], P = 0.37). Daily steps, peak 30-min cadence, and peak 1-min cadence values were greater in people after TKA compared with those awaiting surgery (5935 [3316] vs 3724 [2338], 55.6 [31.0] vs 35.9 [19.3], and 91.5 ± 20.6 vs 70.0 ± 23.7, respectively, all P < 0.01). There were no differences in lifestyle MVPA between groups. The number of bouts of Freedson MVPA was greater in postoperative participants, but the differences were not substantial (one bout per week).

CONCLUSION

Patients report less knee pain and improved function after TKA; however, sedentary behavior does not differ and physical activity is only marginally increased compared with those awaiting surgery. After TKA, daily walking at slow, moderate, and brisk paces and engagement in MVPA do not match levels seen in healthy older adults, which, when combined with high levels of sedentary behavior, leaves patients at increased risk for physical disability and cardiovascular disease.

Measurement of physical activity in the pre- and early post-operative period after total knee arthroplasty for Osteoarthritis using a Fitbit Flex device

Total knee arthroplasty (TKA) is a standard treatment for patients with end stage knee Osteoarthritis (OA) to reduce pain and restore function. The aim of this study was to assess pre- and early post-operative physical activity (PA) with Fitbit Flex devices for patients with OA undergoing TKA and determine any benchmarks for expected post-operative activity. Significant correlations of pre-operative step count, post-operative step count, Body Mass Index (BMI) and Short Form 12 Physical Component Summaries (SF-12 PCS) were found. Mean step counts varied by 3,203 steps per day between obese and healthy weight patients, and 3,786 steps per day between those with higher and lower SF-12 PCS scores, suggesting the need for benchmarks for recovery that vary by patient pre-operative factors. A backwards stepwise regression model developed to provide patient specific step count predictions at 6 weeks had an R² of 0.754, providing a robust patient specific benchmark for post-operative recovery, while population means from BMI and SF-12 subgroups provide a clinically practical alternative.

Physical activity after outpatient surgery and enhanced recovery for total knee arthroplasty

PURPOSE AND HYPOTHESIS

The purpose of this study was to 'objectively' measure improvement of physical activity with the use of an activity monitor between patients who followed an enhanced recovery- or outpatient surgery pathway after total knee arthroplasty (TKA). It was hypothesized that both pathways will have comparable physical activity after TKA at 6-week follow-up.

METHODS

This prospective observational comparative case study was designed to investigate activity parameters (e.g. physical activity, number of steps, sit-stand transfers) of two different pathways after 6 weeks with the use of a non-invasive triaxial accelerometer activity monitor. This study included 20 patients with a mean age of 65.5 years (SD 6.1) undergoing TKA who were allocated to follow one of the two pathways: enhanced recovery (n = 10) or outpatient surgery (n = 10). Patients were monitored for 4 days pre-, 4 days during and 4 days after 5 weeks postoperatively. Patient-reported outcome measures (PROMs) and range of knee motion were obtained pre- and 6 weeks postoperatively.

RESULTS

The activity parameters recovered steeply during the first 4 postoperative days and continued to improve within both pathways (n.s.). Preoperative and during the first 4 days and 5 weeks postoperative, activity parameters were comparable (n.s.) between both pathways but did not reach preoperative levels of physical activity and range of motion (n.s.). PROMs improved within each pathway, and no difference between both pathways was observed (n.s.).

CONCLUSIONS

This study demonstrates that the early physical activity parameters of patients after TKA, following the outpatient surgery pathway, were similar to patients who followed the standard enhanced recovery pathway. The activity monitor is an added value for a more detailed and objective analysis of the physical performance in patients after TKA.

LEVEL OF EVIDENCE

III.

Evaluating physical function and activity in the elderly patient using wearable motion sensors

Wearable sensors, in particular inertial measurement units (IMUs) allow the objective, valid, discriminative and responsive assessment of physical function during functional tests such as gait, stair climbing or sit-to-stand.

Applied to various body segments, precise capture of time-to-task achievement, spatiotemporal gait and kinematic parameters of demanding tests or specific to an affected limb are the most used measures.

In activity monitoring (AM), accelerometry has mainly been used to derive energy expenditure or general health related parameters such as total step counts.

In orthopaedics and the elderly, counting specific events such as stairs or high intensity activities were clinimetrically most powerful; as were qualitative parameters at the ‘micro-level’ of activity such as step frequency or sit-stand duration.

Low cost and ease of use allow routine clinical application but with many options for sensors, algorithms, test and parameter definitions, choice and comparability remain difficult, calling for consensus or standardisation.

Cite this article: Grimm B, Bolink S. Evaluating physical function and activity in the elderly patient using wearable motion sensors. EFORT Open Rev 2016;1:112–120. DOI: 10.1302/2058-5241.1.160022.