Comparison of three device generations of the StepWatch Activity Monitor: analysis of model version agreement in pediatric and adult independent ambulators.

Purpose: Devices such as the StepWatch Activity Monitor (SAM) have been available for 20 years and have been shown to accurately measure ambulatory activity. This study aimed to evaluate the agreement among the three generations of the StepWatch Activity Monitor (SW3, SW4, and SW5) with respect to stride count. Methods: A total of 36 participants (age range, 6-55 years) participated in this institutional review board-approved study. The participants concurrently wore three different SAM model devices on the same leg and performed a 6-min walk test (6MWT). A research staff member of the laboratory manually counted the number of strides for the first 2 min of the test (2MWT). Agreement among the device models was evaluated by calculating ANOVAs and interclass correlation coefficients (ICCs) and creating Bland-Altman plots. Results: There was no significant difference among the model versions during the 6MWT and 2MWT (p > 0.05). The ICC for the total stride count was 0.993 (95% CI = 0.988-0.996) during the 2MWT and 0.992 (95% CI = 0.986-0.996) during the 6MWT. There was a near-perfect agreement (ICC ≥ 0.990) of each model version to the manually counted strides during the 2MWT. The systematic bias of all three SAM model versions was <1 step. Conclusions: The results from the present study demonstrate that the stride counts among all three devices are comparable and relative to the manual stride count. All three SAM model versions had an ICC of >0.90. Researchers can safely incorporate historical data from previous SAM model versions with newer data collected with the latest SAM model version.

Investigating the association between self-reported physical function, temporo-spatial parameters, walking kinematics and community-based ambulatory activity: Analysis of post-operative hip preservation patients.

INTRODUCTION: Wearable sensors provide the ability to assess ambulatory activity in the community after hip preservation surgery (HPS). In combination with gait analysis and patient reported outcomes, more perspective on post-operative function is gained. The purpose of this study was to assess the relationship between self-reported function/activity, temporo-spatial parameters and walking kinematics to objectively measured ambulatory activity. METHODS: Forty-nine participants (38 Females; age range 16-38 years) who were five years or more post-surgery and the following diagnoses were included: Acetabular Dysplasia (n=34), Femoroacetabular Impingement (n=12) and Legg-Calvé Perthes disease (n=3). Participants underwent 3D gait analysis and gait deviations were quantified using the Gait Deviation Index (GDI) and Gait Profile Score (GPS). Temporo-spatial parameters were also calculated. Self-reported pain/function and activity level were assessed via the Harris Hip Score (HHS) and UCLA Activity Scale (UCLA). Participants wore a StepWatch Activity Monitor in their community and the Intensity/Duration of ambulatory bouts were analyzed. Spearman correlation coefficients were run to assess the following relationships: in-lab walking measures, self-reported function/activity vs.community ambulatory activity. RESULTS: There were no statistically significant correlations between HHS, UCLA or temporospatial parameters with ambulatory activity (p>0.05). Worsening gait deviations (GDI/GPS scores) correlated with daily total ambulatory time (ρ=0.284/-0.284, p<0.05), time spent in Short duration ambulatory bouts (ρ=-0.321/0.321, p<0.05) and the amount of time in Long duration ambulatory bouts (ρ=0.366/-0.366, p<0.05). The amount of time spent in Easy intensity/Short duration and Easy intensity/Long duration ambulatory bouts did have a weak correlation with the GDI and GPS (p<0.05). CONCLUSIONS: In HPS patients after long-term follow up, ambulatory activity in the community did not correlate with patient reported outcomes but there was a weak correlation with the presence of gait deviations. Incorporating wearable sensors to assess community ambulatory bout intensity/duration, provides additional quantifiable measures into the overall function of patients following HPS.

COVID-19 Stay-at-home mandates impacts daily ambulatory bout intensity and duration in elementary school-aged children: A wearable sensor based analysis.

INTRODUCTION: SARS COVID-19 pandemic resulted in major changes to how daily life was conducted. Health officials instituted policies to decelerate the spread of the virus, resulting in changes in physical activity patterns of school-aged children. The aim of this study was to utilize a wearable activity monitor to assess ambulatory activity in elementary-school aged children in their home environment during a COVID-19 Stay-at-Home mandate. METHODS: This institutional review board approved research study was performed between April 3rd - May 1st of 2020 during which health officials issued several stay-at-home (shelter-in-place) orders. Participant recruitment was conducted using a convenience sample of 38 typically developing children. Participants wore a StepWatch Activity Monitor for one week and data were downloaded and analyzed to assess global ambulatory activity measures along with ambulatory bout intensity/duration. For comparison purposes, SAM data collected before the pandemic, of a group of 27 age-matched children from the same region of the United States, was included. Statistical analyses were performed comparing SAM variables between children abiding by a stay-at-home mandate (Stay-at-Home) versus the Historical cohort (alpha=0.05). RESULTS: Stay-at-Home cohort took on average 3737 fewer daily total steps compared to the Historical cohort (p<0.001). Daily Total Ambulatory Time (TAT), across all days was significantly lower in the Stay-at-Home cohort compared to the Historical cohort (mean difference: 81.9 minutes, p=0.001). The Stay-at-Home cohort spent a significantly higher percentage of TAT in Easy intensity ambulatory activity (mean difference: 2%, p<0.001) and therefore a significantly lower percentage of TAT in Moderate+ intensity (mean difference: 2%, p<0.001). CONCLUSIONS: The stay-at-home mandates resulted in lower PA levels in elementary school-aged children, beyond global measures to also bout intensity/duration. It appears that in-person school is a major contributor to achieving higher levels of PA and our study provides additional data for policymakers to consider for future decisions.

Investigating pelvic drop gait abnormality in adolescent hip pathology patients.

BACKGROUND: Trendelenburg gait describes contralateral pelvic drop during single leg stance (SLS) with occasional lateral trunk lean compensation over the stance limb. However, quantitative research on 'uncompensated Trendelenburg' gait (pelvic drop independent of lateral trunk lean) remains sparse among populations that commonly utilize this gait pattern, such as adolescent hip pathology patients. RESEARCH QUESTION: How prevalent is uncompensated Trendelenburg among various adolescent hip pathologies and how is it related to hip load, hip abduction strength, and self-reported hip pain? METHODS: Gait, strength, and pain data were collected among 152 pre-operative patients clinically diagnosed with acetabular hip dysplasia, femoroacetabular impingement, Legg-Calvé-Perthes, or slipped capital femoral epiphysis (SCFE). Patients with ≥ 5.4° of dynamic pelvic drop in SLS were divided into a 'pelvic drop' group and screened to exclude those with excessive ipsilateral trunk lean. They were then compared to the 'stable pelvis' patients using a Mann-Whitney test. RESULTS: Dysplasia patients represented the highest proportion of the pelvic drop group (46%). The pelvic drop group showed a significant increase in self-reported hip pain (p = 0.011), maximum hip abductor moment (p = 0.002), and peak coronal power absorption at the affected hip during SLS loading response, (p < 0.001) while showing no difference in abduction strength (p = 0.381). SIGNIFICANCE: Uncompensated Trendelenburg gait may lead to increased loading of the affected hip in adolescent hip pathology patients. Disadvantageous hip biomechanics can create increased abductor muscle demand among these pathological populations, with dysplasia patients showing the highest prevalence. Maximal abduction strength did not correlate with pelvic drop. Future work should aim to identify and quantify causal factors. Increased coronal hip power absorption during weight acceptance warrants clinical attention, as there may be a detrimental, over-reliance on passive hip structures to support load among a population that that is already predisposed to hip osteoarthritis.

Inclusive community playgrounds benefit typically developing children: An objective analysis of physical activity.

Purpose: Limited research is available on the physical activity levels of children while playing on an inclusive playground, specifically designed to accommodate children with physical disabilities. The aims of this study were to objectively measure ambulatory activity and heart rate (HR) of children during unstructured play on an inclusive community playground. Methods: Typically developing children at least 4 years of age were recruited to play freely upon entering the playground. Participants wore a StepWatch4 Activity Monitor and a Polar V800 Sport Watch. Ambulatory measures included total steps, percentage of recommended steps, total ambulatory time (TAT), bout intensity levels/duration periods. Time spent in HR zones and moderate-to-vigorous physical activity (MVPA) was determined. Results: 95 children (48 males; Avg. age: 7 ± 2 years.) were included in this study. Children played for 31.8 ± 14.7 min., were ambulatory for 25.9 ± 12.0 min., took 1826 ± 824 steps, and accumulated 17 ± 8% of the recommended daily step count. Ambulatory bout intensity was predominantly lower intensity and bout durations varied in length. 99% of the play time was spent at a moderate HR or higher. Significant correlations were found between ambulatory and HR measures (ρ range from 0.23 to 0.99, p < 0.05), and 7-10 yo children spent a significantly higher percentage of TAT at higher intensity ambulation (p < 0.05). Conclusions: Typically developing children can achieve moderate or higher intensity exercise and HR on an inclusive playground. Both typically developing children and those with disabilities, would benefit from a setting where they can interact and participate in parallel play with their peers.

Validation of Accelerometry Data to Identify Movement Patterns During Agility Testing.

Purpose: The purpose of this study was to develop an algorithm for the detection and timing of foot contact/off timing for each lateral repetition and assess the validity/reliability of the calculated timings. Methods: Participants performed a modified Edgren Side Step Test in which they moved laterally along a 4-m path as quickly as possible while wearing an accelerometer on each ankle. Time of completion of each attempt was recorded using a stopwatch and digital video was obtained. Accelerometer-based (ACC) events were determined for the start of the test (START), foot contact at the end-line (FC) and the lifting of the foot when transitioning to the other direction (FO). Based on these ACC events the Overall, Split (ST) and Lag (LT) times were determined and compared to either the stopwatch or video-based timings (p < 0.05). The ACC event criterion was then applied by independent reviewers to assess inter/intra-rater reliability of identifying the events. Results: There was no significant difference in ACC (12.37 ± 2.19 s) based Overall Time compared to the Stopwatch (12.42 ± 2.25 s, p = 0.34). Bland-Altman plots for ST and LT revealed very good agreement between the ACC time to the Video (ST: Bias = 0.11 s, LOA -0.57 to 0.79; LT: Bias = -0.11 s, LOA -0.43 to 0.22). Intra and inter-rater reliability was moderate to excellent for all reviewer identified events. Conclusions: This study demonstrates methodology to identify ACC based timings during an agility test. The inclusion of an accelerometer supplements standard timing options with the added benefit of assessing sided split and lag times.

The relationship of coronal trunk motion on the hip abductor moment impulse in pre-operative hip pathology patients during walking.

BACKGROUND: Compensatory mechanisms for hip pain, pathology, and weakness include excessive trunk lean towards the stance limb, counteracting pelvic drop to maintain stability during single leg stance. Trunk lean shifts the center of mass towards the hip joint center to decrease the moment arm and reduce hip abductor demand. The purpose of this study was to evaluate whether adolescent patients with symptomatic hip pain demonstrate excessive trunk lean and the effect on the hip abductor moment impulse. METHODS: Self-selected speed walking data collected through an approved study were reviewed on pre-operative patients clinically diagnosed with a hip deformity. Instrumented motion analysis was performed to analyze trunk kinematics and the hip abductor moment impulse. FINDINGS: There was a weak, but significant correlation between hip abductor moment impulse and trunk lean. Patients diagnosed with Acetabular Dysplasia demonstrated an increased trunk lean and a decreased hip abductor moment impulse (r = - 0.311, p = 0.001). Of those who presented with excessive trunk lean, 62% of these patients had a normal hip abductor moment impulse. There was no correlation between hip abductor moment impulse and hip abductor strength. INTERPRETATION: Excessive trunk lean was not seen uniformly across adolescent patients with symptomatic hip deformities, despite pain being reported in 80% of patients. Furthermore, a majority of those that presented with excessive trunk lean did not present with a reduced moment, suggesting that although the amount of lean was greater than normal, it was not enough to significantly reduce the demand on the hip musculature.

Clinically derived biomechanical criteria for the Trendelenburg test.

BACKGROUND: The Trendelenburg test has been used to assess hip abductor muscle function. A standardized evaluation of the test requires an assessment of both pelvis and trunk coronal plane alignment as the patient stands on one leg for 30 s. Coronal plane biomechanics using motion analysis allows for development of objective criteria to grade the test response. The aim of this study was to develop biomechanical criteria of the pelvis and trunk coronal plane kinematics. METHODS: The video of 39 subjects with acetabular hip dysplasia performing the test while instrumented with a full-body modified Plug-In-Gait marker set for three-dimensional kinematic analysis, were evaluated by two orthopedic surgeons and one senior level biomechanist. Reviewers as a group assessed whether the subject had a positive test and noted the reason using guidelines outlined in the literature. Coronal plane trunk and pelvic angles of all subjects were analyzed and Receiver Operating Characteristic curves were used to determine optimal kinematic cutoff values for each positive Trendelenburg test reason. FINDINGS: There were 26/39 patients who reviewers identified as having a positive test. Area under the curve of the receiver operating characteristic curve for trunk and pelvis mean/minimum were greater than 0.75. The curve was used to identify the optimal cut-offs of trunk lean and pelvic obliquity mean/minimum. INTERPRETATION: The biomechanical criteria developed includes clinically derived coronal plane kinematic cut-offs of the pelvic and trunk angles. The criteria can be used within a motion capture setting for the standardization of the grading of the test response.

Compensatory sagittal plane ankle gait mechanics: Are they present in patients with a weak or stiff hip?

INTRODUCTION: Simulations suggest that subjects with reduced hip range of motion (ROM) and/or weakness can achieve more normal walking mechanics through compensations at the ankle. The aims of this study were to assess whether subjects with reduced hip ROM (Stiff hip) or hip flexor weakness (Weak hip) exhibit ankle compensations during walking and investigate redistribution of power in the lower extremity joints. METHODS: Retrospective gait data were reviewed (IRB-approved hip registry). Preoperative kinematic/kinetic walking data were collected in patients with: adolescent hip dysplasia (AHD), femoral acetabular impingement (FAI), and Legg-Calvé Perthes disease (Perthes). AHD patients with significantly weak hip flexors on their affected side were included (Weak hip group). The Gait Profile Score (GPS) was calculated on the affected side of the FAI and Perthes groups to identify patients who had a Stiff hip. Patients who had undergone a hip arthrodesis (Fusion) were also included (Stiff hip group). Ankle kinematics/kinetics were compared to healthy participants (Control). The total positive work of sagittal plane hip, knee and ankle power were compared along with the distribution of power. RESULTS: Patients in the Weak/Stiff hip groups did not walk with greater ankle plantarflexion, peak push-off power or positive ankle work on their affected sides compared to Control. Ankle work contribution (percentage of total positive work) on the affected or unaffected sides was greater in the Perthes and Hip Fusion patients compared to Control. Significant gait abnormalities on the unaffected side were observed. CONCLUSIONS: Patients with a weak or stiff hip did exhibit altered ankle mechanics during walking. Greater percent ankle work contribution appeared to correspond with hip stiffness. In patients with hip pathology the redistribution of power among the lower extremity joints can highlight the importance of preserving ankle function.

Functional Outcomes Following Treatment for Clubfoot: Ten-Year Follow-up.

BACKGROUND: The purpose of this study was to assess function, at the age of 10 years, of children initially treated nonoperatively for clubfoot with either the Ponseti or French physiotherapy program and to compare outcomes in feet that had undergone only nonoperative treatment with those that required subsequent surgery. METHODS: Gait analysis, isokinetic ankle strength, parent-reported outcomes, and daily step activity data were collected when patients who had been treated for idiopathic clubfoot reached the age of 10 years. Patients who had undergone only nonoperative treatment were compared with those who subsequently underwent extra-articular surgery or intra-articular surgery (posterior release or posteromedial release). The clubfoot groups were compared with age-matched controls. RESULTS: Of 263 treated clubfeet in 175 patients, 148 had only been treated nonoperatively, 29 underwent extra-articular surgery, and 86 underwent intra-articular surgery (posterior release in 42 and posteromedial release in 44). Significant abnormalities were found in ankle kinetics and isokinetic ankle strength in the feet treated with intra-articular surgery compared with the nonoperatively treated feet (p < 0.017). Compared with controls (n = 40 feet), all groups showed reduced ankle plantar flexion during gait, resulting in a deficit of 9% to 14% for dynamic range of motion, 13% to 20% for ankle moment, and 13% to 23% for power (p < 0.013). Within the intra-articular group, feet that underwent posteromedial release had decreased plantar flexion strength (15%; p = 0.008), dorsiflexion strength (6%; p = 0.048), and parent-reported global function scores (p = 0.032) compared with the posterior release group. The patients with clubfoot took 10% fewer steps (p = 0.015) and had 11% less total ambulatory time (p = 0.001) than the controls. CONCLUSIONS: Examination of patients when they had reached the age of 10 years showed better ankle power and isokinetic strength for clubfeet treated without surgery compared with those that underwent intra-articular surgery for residual deformity or recurrence. Compared with controls, both nonoperatively and surgically treated clubfeet had significant limitations in ankle plantar flexion resulting in decreased range of motion, moment, and power. Gastrocnemius-soleus complex strength was decreased after both nonoperative and surgical treatment of clubfeet. Although activity was diminished in the clubfoot population, no differences in function were perceived by the patients' parents. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Automated event detection algorithm for two squatting protocols.

INTRODUCTION: Squatting biomechanics assessed using motion analysis relies on the identification of specific events: start of descent, transition between descent/ascent and end of ascent. Automated identification reduces the time needed to process trials while allowing consistency across studies. The purpose of this study was to develop criteria for the identification of events and apply them to two squatting protocols in pathological patient and typically developing (TD) groups. METHODS: Thirty-four subjects with hip dysplasia and 41 TD subjects were enrolled in this study. While instrumented with a full-body Plug-In-Gait marker set, participants performed two squatting protocols: a hold squat, where subjects paused for a count of three at their lowest squat depth, and a traditional squat, where the descent phase was immediately followed by the ascent phase. Reviewers analyzed the kinematic/kinetic waveforms of a subset of trials to develop criteria for events. Sagittal plane knee and vertical center of mass velocities were used to identify events and absolute vs. relative thresholds of the peak knee velocity were compared. These criteria were incorporated into an automatic event detection code. RESULTS: Using a relative threshold algorithm, events were automatically identified in 244 of 259 total trials (94%). For the trials requiring manual placement of events (n=15 trials), there was perfect inter-rater reliability between research personnel. CONCLUSIONS: The criteria developed for the automatic detection of squatting events was highly successful for both protocols in each participant group and was also highly reliable for research personnel to follow in the few instances where manual placement was necessary.

Interval setting selection affects ambulatory activity outputs in children with cerebral palsy.

INTRODUCTION: Accelerometer based devices have been widely used to assess the ambulatory activity of children with and without functional disabilities. Many researchers who utilize the StepWatch Activity Monitor (SAM) collect at a 60second (60sec) interval setting. The purpose of this study was to assess the effect of SAM interval settings on ambulatory activity outputs in children with cerebral palsy (CP) and typically developing youth. METHODS: Participants wore a SAM which recorded the number of strides every 10seconds (10s) for one week. Raw 10s data was downsampled to combine strides into 60sec intervals. Strides were ensembled into walking bouts with the Intensity/Duration calculated as a percentage of Total Ambulatory Time (TAT). RESULTS: Twenty-eight children with CP (14 boys; avg. 12 yrs. 4 mths.; GMFCS Level I n=4, Level II n=19, Level III n=5) completed testing and 28 age matched typically developing youth (14 boys; avg. 12 yrs. 6 mths.) were included. Using the 10sec interval, ∼80% of walking bouts in both groups were less than or equal to 60s. Data recorded at 60sec intervals had higher daily TAT but fewer walking bouts. In children with CP, daily steps were higher using the 60sec interval. At the Easy intensity, the 60sec interval reported an increased volume of Long duration walking, and it rarely identified any Moderate+ intensity activity. CONCLUSIONS: 60sec interval data overestimated low intensity and long duration ambulatory activity. It is imperative that investigators choose a finer interval setting (10sec) to maximize the detection of gait transitions and rest periods which are critical in describing community ambulation of patients with cerebral palsy.

Exercise Tolerance in Children With Early Onset Scoliosis: Growing Rod Treatment "Graduates".

STUDY DESIGN: Prospectively enrolled early-onset scoliosis (EOS) patients undergoing growing rod treatment, who have had no surgery for >1 year and/or have received definitive fusion (growing rod "graduates"). OBJECTIVES: To assess oxygen consumption during exercise and determine if a diminished conventional pulmonary function test (PFT) correlates with metabolic, pulmonary, and cardiovascular measures during exercise. SUMMARY OF BACKGROUND DATA: Based on clinical impression and sequential PFT values, EOS patients who have undergone extensive treatment are thought to have limited capacity during exercise. The use of PFTs in this population has been a primary outcome measure of respiratory capacity; however, PFTs are dependent on effort, and thus subjective. This led us to find a new assessment of outcome, to better understand their pulmonary capacity. METHODS: Patients underwent oxygen consumption (VO2) testing while walking at self-selected speed over-ground and during a graded exercise test. Maximal VO2 was predicted in those who completed the test to 85% of maximal heart rate (HR). Statistical analysis included Mann-Whitney U test and Spearman correlation coefficient (α = 0.05). RESULTS: 12 patients participated. Over-ground walking showed that EOS graduates chose to walk at the same speed, but at a higher VO2 Cost (0.28 mL/kg/m) than controls (0.22 mL/kg/m; p < .001). Treadmill exercise testing showed 9 of 12 subjects able to complete the 85% of predicted maximum protocol. The EOS group had lower VO2 during the final stage (27.9 mL/kg/min) compared to controls (34.2 mL/kg/min; p = .021); however, their heart rate reached the same values. Subjects completing the protocol had lower predicted VO2 max (38.5 mL/kg/min) compared with controls (45.0 mL/kg/min), but this was not significant. CONCLUSIONS: Although PFT data suggest clinically relevant pulmonary compromise in EOS patients, the current study shows that these children are able to keep up with their peers in daily activities and also have the capacity to exercise. LEVEL OF EVIDENCE: Level II, therapeutic.

A comparison of the use of tympanic, axillary, and rectal thermometers in infants.

This study examined the relationship between three instruments used in measuring tympanic, axillary, and rectal temperatures in infants less than 1 year of age. Temperatures were measured by Oto-temp Pedi Q tympanic thermometers, Becton Dickinson axillary thermometer, and rectal thermometers. A convenience sample of 5 infants less than 90 day and 54 greater than 90 days with fever, as well as 34 infants less than 90 days and 27 infants greater than 90 days without fever were studied. Correlations of infants less than 90 days and greater 90 days of age, as well as differences between infant temperature with and without fevers as variables, were examined. Results indicated a strong statistical relationship between Oto-Temp Pedi Q, Becton Dickinson axillary temperatures, and rectal temperatures, but not strong enough to base critical clinical decisions. Age and presence or absence of fever significantly affected the relationships between thermometers.

Supralingual temperatures compared to tympanic and rectal temperatures.

OBJECTIVE: To evaluate the validity, reliability, sensitivity, and specificity of the PaciTemp supralingual digital pacifier thermometer as compared to the Thermoscan Instant tympanic and glass-mercury rectal thermometers. METHOD: Eighty-one children under the age of 2 years had temperatures taken sequentially at three body sites: supralingual, tympanic, and rectal. Corrections were calculated between the readings of the three types of thermometers. Percentage of agreement was done to examine sensitivity and specificity. RESULTS: Using the glass-mercury measurement as the standard, both the supralingual and tympanic measurements showed an overall specificity of 62.8% and sensitivity of 63.3%. Correlation between rectal and supralingual was 0.62, and correlation between rectal and tympanic was 0.71. CONCLUSIONS: The Paci-Temp provides temperature readings that are similar to the tympanic method as compared to the rectal method. Further research on at-home thermometers is needed.