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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. [ABSTRACT FROM AUTHOR]

People with lower-limb loss participate in less physical activity than able-bodied individuals, which increases the mortality risk and incidence of metabolic syndromes. This study evaluated the effect of lower-limb prosthesis osseointegration on physical activity, including daily steps and stepping cadence. Free-living walking activity was assessed from 14 patients scheduled to undergo prosthesis osseointegration at two time points (within 2 weeks prior to osseointegration surgery and 12-months following). Daily step count, stepping time, number of walking bouts, average step cadence per bout, maximum step cadence per bout, and time spent in bands of step cadence were compared before and after osseointegration. Twelve months after prosthesis osseointegration, participants increased daily steps, daily stepping time, average step cadence, and maximum cadence per walking bout compared to pre-osseointegration. Participants engaged in more daily steps, higher stepping cadence, and longer bouts at higher cadence one year following osseointegration compared to when using a socket prosthesis. As a novel intervention that is becoming more common, it is important to understand walking activity outcomes as these are critical for long-term health. People with lower-limb loss participate in less physical activity than able-bodied individuals, which increases the mortality risk and incidence of metabolic syndromes. Daily step count, walking bouts, and step cadence during free-living walking activity are promising measures to capture physical functional performance in patients with lower-limb amputation. This study shows that patients with osseointegrated prostheses increase their stepping activity, including daily steps, number of bouts, and stepping cadence compared to when using a socket prosthesis, which has positive implications on overall patient health. As a novel intervention that is becoming more common, it is important for clinicians, patients, and researchers to understand expectations for walking activity outcomes as a critical factor in long-term patient health after prosthesis osseointegration. [ABSTRACT FROM AUTHOR]

Purpose: Less physical activity has been associated with systemic biomarkers of cartilage breakdown after anterior cruciate ligament reconstruction (ACLR). However, previous research lacks analysis of deleterious cartilage compositional changes and objective physical activity after ACLR. The purpose of this study was to determine the association between physical activity quantified via accelerometer-based measures of daily steps and time in moderate-to-vigorous physical activity (MVPA), and T1rho magnetic resonance imaging (MRI) of the femoral articular cartilage, a marker of proteoglycan density in individuals with ACLR. Methods: Daily steps and MVPA were assessed over 7 d using an accelerometer worn on the hip in 26 individuals between 6 and 12 months after primary unilateral ACLR. Resting T1rho MRI was collected bilaterally, and T1rho MRI interlimb ratios (ILR: ACLR limb/contralateral limb) were calculated for lateral and medial femoral condyle regions of interest. We conducted univariate linear regression analyses to determine associations between T1rho MRI ILRs and daily steps and MVPA with and without controlling for sex. Results: Greater T1rho MRI ILR of the central lateral femoral condyle, indicative of less proteoglycan density in the ACLR limb, was associated with greater time in MVPA (R 2 = 0.178, P = 0.032). Sex-adjusted models showed significant interaction terms between daily steps and sex in the anterior (P = 0.025), central (P = 0.002), and posterior (P = 0.002) medial femoral condyle. Conclusions: Lesser physical activity may be a risk factor for maintaining cartilage health after ACLR; additionally, the relationship between physical activity and cartilage health may be different between males and females. [ABSTRACT FROM AUTHOR]

Individuals who undergo anterior cruciate ligament reconstruction (ACLR) are at higher risk of posttraumatic osteoarthritis. Altered joint tissue loading caused by aberrant gait biomechanics leads to deleterious changes in joint health linked to the onset of posttraumatic osteoarthritis. Knee braces have been used to modify joint tissue loading in individuals with joint injury, yet the effects of walking with a brace after ACLR on biomechanical, biochemical, and structural cartilage outcomes are unknown. To compare biomechanical, biochemical, and structural outcomes between braced and nonbraced walking in individuals with ACLR. Crossover study. Research laboratory. A total of 34 individuals with unilateral ACLR (18 females, 16 males; time since ACLR = 50.1 ± 36.8 months). Gait biomechanics were assessed during braced and unbraced conditions on separate days. Vertical ground reaction force, knee-flexion angle, and internal knee-extension moment waveforms were evaluated throughout the stance phase and compared between conditions. Percentage changes in serum cartilage oligomeric matrix protein (%ΔCOMP) and femoral cartilage cross-sectional area (%ΔCSA) measured via ultrasound were calculated after a 3000-step walking protocol. Braced walking increased the knee-flexion angle (largest difference = 3.56°; Cohen d effect size = 1.72) and knee-extension moment (largest difference = −0.48% body weight × height; Cohen d effect size = −1.14) compared with nonbraced walking but did not influence vertical ground reaction force. Whereas no difference (P =.20) in %ΔCOMP existed between the braced and nonbraced conditions in the entire cohort (n = 30 with complete blood data), a larger increase (P =.04) in %ΔCOMP was seen during nonbraced than braced walking in individuals who demonstrated increased COMP during nonbraced walking. No difference (P =.86) in %ΔCSA was present between the braced and nonbraced conditions. Braced walking may improve sagittal-plane gait biomechanics and %ΔCOMP in a subset of individuals who demonstrate a typical increased COMP response to load (ie, increase in COMP) after nonbraced walking. [ABSTRACT FROM AUTHOR]

Better knee function is linked to psychological readiness to return to sport after anterior cruciate ligament reconstruction (ACLR). Individuals with ACLR participate in less physical activity than matched uninjured control individuals, yet the association between knee function and physical activity post–ACLR remains unclear. To determine the associations between (1) patient-reported knee function measured using the Knee Injury and Osteoarthritis Outcome Score Knee-Related Quality of Life (KOOS-QOL), daily steps, and minutes spent in moderate-to-vigorous physical activity (MVPA) of individuals with ACLR and (2) KOOS-QOL and daily steps and MVPA in individuals with ACLR who presented with (ie, symptomatic) or without (ie, asymptomatic) clinically meaningful knee-related symptoms. Cross-sectional study. Laboratory, free-living conditions. A total of 66 individuals with primary unilateral ACLR (36 women, 30 men; age = 22 ± 4 years, height = 1.71 ± 0.1 m, mass = 71.3 ± 12.6 kg, body mass index = 24.2 ± 2.9, time post–ACLR = 28 ± 33 months). We collected KOOS data and retrospectively stratified participants into those with (symptomatic group, n = 30) or without (asymptomatic group, n = 36) clinically meaningful knee-related symptoms based on previously defined KOOS cutoffs. We assessed daily steps and MVPA using accelerometers that participants wore on the right hip for 7 days. We conducted linear regressions to determine associations between KOOS-QOL and daily steps and MVPA. In the entire sample, no associations existed between KOOS-QOL and daily steps (ΔR2 = 0.01, P =.50) or MVPA (ΔR2 = 0.01, P =.36). In the symptomatic group, a greater KOOS-QOL was associated with more time in MVPA (ΔR2 = 0.12, P =.05). In the asymptomatic group, no associations were identified between the KOOS-QOL and daily steps and MVPA. Individuals with symptoms post–ACLR who spent more time in MVPA reported higher QOL. [ABSTRACT FROM AUTHOR]

Objective: To compare gait biomechanics 6 months following anterior cruciate ligament (ACL) reconstruction (ACLR) between patients with the highest and lowest concentrations of synovial fluid (SF) interleukin-6 (IL-6) and matrix metalloproteinase-3 (MMP-3), as well as compared to uninjured controls.Design: SF concentrations of IL-6 and MMP-3 were collected 7 ± 4 days post injury in 38 ACL injured patients (55% female, 21±4yrs, 25.3 ± 5.2BMI). ACL injured individuals were stratified into the lowest and highest quartiles based on IL-6 (IL-6Lowest and IL-6Highest) and MMP-3 (MMP-3Lowest and MMP-3Highest) concentrations. Gait biomechanics were collected on the injured limb 6 months post-ACLR and in 38 uninjured controls (50% female, 21±3yrs, 23.8 ± 2.8BMI). Functional analyses of variance were used to compare vertical ground reaction force (vGRF), knee flexion angle (KFA), and internal knee extension moment (KEM) waveforms throughout stance phase of gait to determine the proportions of stance differing between limbs and groups.Results: Compared to uninjured controls, IL-6High and MMP-3High ACL subgroups demonstrated lesser vGRF (largest differences: IL-6, 7.88%BW; MMP-3, 11.05%BW) during early-stance and greater vGRF (largest differences: IL-6, 6.21%BW; MMP-3, 5.85%BW) in mid-stance, lesser KFA (largest differences: IL-6, 3.11°; MMP-3, 3.72°) and lesser KEM (largest differences: IL-6, 0.96%BW•m; MMP-3, 1.07%BW•m) in early-stance, as well as greater KFA in mid-stance (largest differences: IL-6, 1.5°; MMP-3, 2.95°).Conclusions: High SF concentrations of a proinflammatory cytokine and a degradative enzyme early post-ACL injury are associated with aberrant gait biomechanics in the injured limb at 6 months post-ACLR (i.e., lesser vGRF, KFA and KEM) linked to posttraumatic osteoarthritis development. [ABSTRACT FROM AUTHOR]

Supplemental digital content is available in the text. Purpose: History of an anterior cruciate ligament reconstruction (ACLR) and high body mass index (BMI) are strong independent risk factors for knee osteoarthritis (KOA) onset. The combination of these risk factors may further negatively affect joint loading and KOA risk. We sought to determine the combined influence of BMI and ACLR on walking speed and gait biomechanics that are hypothesized to influence KOA onset. Methods: Walking speed and gait biomechanics (peak vertical ground reaction force [vGRF], peak vGRF instantaneous loading rate [vGRF-LR], peak knee flexion angle, knee flexion excursion [KFE], peak internal knee extension moment [KEM], and peak internal knee abduction moment [KAM]) were collected in 196 individuals with unilateral ACLR and 106 uninjured controls. KFE was measured throughout stance phase, whereas all other gait biomechanics were analyzed during the first 50% of stance phase. A 2 × 2 ANOVA was performed to evaluate the interaction between BMI and ACLR and main effects for both BMI and ACLR on walking speed and gait biomechanics between four cohorts (high BMI ACLR, normal BMI ACLR, high BMI controls, and normal BMI controls). Results: History of an ACLR and high BMI influenced slower walking speed (F 1,298 = 7.34, P = 0.007), and history of an ACLR and normal BMI influenced greater peak vGRF-LR (F 1,298 = 6.56, P = 0.011). When evaluating main effects, individuals with an ACLR demonstrated lesser KFE (F 1,298 = 7.85, P = 0.005) and lesser peak KEM (F 1,298 = 6.31, P = 0.013), and individuals with high BMI demonstrated lesser peak KAM (F 1,297 = 5.83, P = 0.016). Conclusion: BMI and history of ACLR together influence walking speed and peak vGRF-LR. History of an ACLR influences KFE and peak KEM, whereas BMI influences peak KAM. BMI may need to be considered when designing interventions aimed at restoring gait biomechanics post-ACLR. [ABSTRACT FROM AUTHOR]

Objectives: To evaluate changes in the femoral cartilage cross‐sectional area (CSA) measured with ultrasound (US) between baseline and 1000, 2000, 3000, 4000, and 5000 steps of walking on a treadmill. Methods: Forty‐one healthy individuals completed a single testing session. Participants rested with their knees extended on a plinth for 45 minutes to unload the femoral cartilage. Ultrasound was used to acquire images of the femoral cartilage before the treadmill‐walking protocol. After the baseline US acquisition, participants walked on a treadmill at their preferred overground walking speed for 1000 steps, after which additional US images of the femoral cartilage were acquired. This process was repeated after 2000, 3000, 4000, and 5000 steps. A 1‐way repeated‐measures analysis of variance compared the CSA across the 6 step counts. An analysis of variance with repeated measures on time and Bonferroni corrected planned comparisons (.05/5) were used to evaluate differences in the femoral cartilage at each step count compared to baseline. Results: The study included 20 male and 21 female participants (mean age ± SD, 21.5 ± 2.8 years; mean body mass index, 24.3 ± 3.4 kg/m2). The CSAs were significantly greater at the 2000‐step (1.27 ± 1.75 mm2; P <.001), 4000‐step (0.89 ± 1.17 mm2; P <.001), and 5000‐step (2.10 ± 1.73 mm2; P <.001) points compared to baseline. The CSA was significantly less at the 3000‐step point (1.05 ± 1.29 mm2; P <.001) compared to baseline. Conclusions: Changes in the CSA after walking may be dependent on the number of steps. The participants had a significant decrease in the CSA after 3000 steps of normal walking and a significant increase in the CSA after 2000, 4000, and 5000 steps of normal walking. [ABSTRACT FROM AUTHOR]

Background: Wearable physiological monitoring devices are promising tools for remote monitoring and early detection of potential health changes of interest. The widespread adoption of such an approach across communities and over long periods of time will require an automated data platform for collecting, processing, and analyzing relevant health information., Objective: In this study, we explore prospective monitoring of individual health through an automated data collection, metrics extraction, and health anomaly analysis pipeline in free-living conditions over a continuous monitoring period of several months with a focus on viral respiratory infections, such as influenza or COVID-19., Methods: A total of 59 participants provided smartwatch data and health symptom and illness reports daily over an 8-month window. Physiological and activity data from photoplethysmography sensors, including high-resolution interbeat interval (IBI) and step counts, were uploaded directly from Garmin Fenix 6 smartwatches and processed automatically in the cloud using a stand-alone, open-source analytical engine. Health risk scores were computed based on a deviation in heart rate and heart rate variability metrics from each individual's activity-matched baseline values, and scores exceeding a predefined threshold were checked for corresponding symptoms or illness reports. Conversely, reports of viral respiratory illnesses in health survey responses were also checked for corresponding changes in health risk scores to qualitatively assess the risk score as an indicator of acute respiratory health anomalies., Results: The median average percentage of sensor data provided per day indicating smartwatch wear compliance was 70%, and survey responses indicating health reporting compliance was 46%. A total of 29 elevated health risk scores were detected, of which 12 (41%) had concurrent survey data and indicated a health symptom or illness. A total of 21 influenza or COVID-19 illnesses were reported by study participants; 9 (43%) of these reports had concurrent smartwatch data, of which 6 (67%) had an increase in health risk score., Conclusions: We demonstrate a protocol for data collection, extraction of heart rate and heart rate variability metrics, and prospective analysis that is compatible with near real-time health assessment using wearable sensors for continuous monitoring. The modular platform for data collection and analysis allows for a choice of different wearable sensors and algorithms. Here, we demonstrate its implementation in the collection of high-fidelity IBI data from Garmin Fenix 6 smartwatches worn by individuals in free-living conditions, and the prospective, near real-time analysis of the data, culminating in the calculation of health risk scores. To our knowledge, this study demonstrates for the first time the feasibility of measuring high-resolution heart IBI and step count using smartwatches in near real time for respiratory illness detection over a long-term monitoring period in free-living conditions., (©Pooja Gaur, Dorota S Temple, Meghan Hegarty-Craver, Matthew D Boyce, Jonathan R Holt, Michael F Wenger, Edward A Preble, Randall P Eckhoff, Michelle S McCombs, Hope C Davis-Wilson, Howard J Walls, David E Dausch. Originally published in JMIR Formative Research (https://formative.jmir.org), 07.08.2024.)

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 ( Adj R 2 =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., (© 2023 American Academy of Physical Medicine and Rehabilitation.)

Background: People with lower-limb amputation (LLA) are routinely prescribed a socket prosthesis; however, many socket prosthesis users experience severe complications with the fit of their prosthesis including residual limb wounds and pain. Osseointegration is a procedure that creates a direct connection between the bone and prosthetic limb through a bone-anchored prosthesis, eliminating the need for a socket interface. It is offered as a secondary procedure to people with LLA who experience significant complications with socket prostheses., Objectives: To evaluate change in disability and function 1 year postosseointegration compared with preosseointegration in people with LLA., Study Design: Single group, pretest, and post-test., Methods: Twelve participants (9 transfemoral and 3 transtibial amputations, age: 44 ± 10 years, 7 female participants, 14 ± 12 years since amputation) with unilateral LLA underwent osseointegration with press-fit implants. Disability was measured with the World Health Organization Disability Assessment Schedule 2.0, and function was measured with both Prosthetic Limb Users Mobility Survey and the Activities-Specific Balance Confidence Scale. Questionnaires were administered preosseointegration and 1 year postosseointegration. Paired t tests assessed change in outcomes between time points., Results: Postosseointegration, participants demonstrated reduced disability measured with World Health Organization Disability Assessment Schedule 2.0 (%Δ = -52.6, p = 0.01), improved mobility measured with Prosthetic Limb Users Mobility Survey (%Δ = 21.8, P < 0.01), and improved balance confidence measured with the Activities-Specific Balance Confidence Scale (%Δ = 28.4, P < 0.01)., Conclusions: Participants report less disability and greater function in their prosthesis postosseointegration. Osseointegration is a novel procedure for people experiencing complications with their socket prosthesis, and this study is the first to show improvements in disability postosseointegration., (Copyright © 2022 International Society for Prosthetics and Orthotics.)