Minimal Detectable Difference Research Articles

Test-retest reliability of the Dyskinesia Impairment Scale: measuring dystonia and choreoathetosis in dyskinetic cerebral palsy.

To assess test-retest reliability of the Dyskinesia Impairment Scale (DIS) in children and young adults with dyskinetic cerebral palsy (CP). Dystonia and choreoathetosis were assessed in 15 participants with dyskinetic CP (13 males, 2 females; age range 5-22y, mean 14y, SD 4y) using the DIS in two separate sessions over 7 days. Exclusion criteria were changes in muscle relaxant medication within the previous 3 months, orthopaedic or neurosurgical interventions within the previous year, and spinal fusion. Intraclass correlation coefficient, confidence intervals (CI), standard error of measurement, and the minimal detectable difference (MDD) were determined for test-retest reliability. Intraclass correlation coefficients of the DIS, the dystonia subscale of the DIS, and the choreoathetosis subscale of the DIS were 0.98 (95% CI 0.94-0.99), 0.97 (95% CI 0.92-0.99), and 0.96 (95% CI 0.90-0.99). The standard error of measurement and MDD were 2.6% and 7.2%. The DIS is a reliable tool to assess dystonia and choreoathetosis; it remains stable over time in children and young adults with dyskinetic CP. These results add to the current evidence for good clinimetric properties of the DIS. The Dyskinesia Impairment Scale (DIS) shows stability in scoring dystonia and choreoathetosis. The total DIS score and dystonia and choreoathetosis subscales are clinically useful.

Psychometric Properties of the Hip–Return to Sport After Injury Scale (Short Form) for Evaluating Psychological Readiness to Return to Sports After Arthroscopic Hip Surgery

Background: Successful return to sports activity after surgery requires both physical and psychological readiness. The Hip–Return to Sport After Injury (Short Form) has been developed to assess psychological readiness to return to sports after hip injury and hip surgery, including hip arthroscopy. Purpose: To evaluate the reliability, validity, responsiveness, and interpretability of the scale for a cohort of patients after hip arthroscopy with a range of sports participation levels. Study Design: Cohort study (diagnosis); Level of evidence, 2. Methods: Invitations to participate were sent to 145 patients from 3 specialist surgeons. The study included 77 participants 1 to 24 months after hip arthroscopy (mean ± SD age, 35 ± 9 years; 62% women) and 33 healthy age-matched controls (age, 37 ± 7 years; 52% women). The scale was administered electronically on 3 occasions to patients: baseline (≥1 month postarthroscopy), 1 week later, and 6 months later. In addition to the scale, participants were asked about sports participation status and their global rating of postsurgical change. The scale was administered to healthy controls on 1 occasion. The minimal detectable difference, discriminant validity, floor and ceiling effects, responsiveness, and interpretability (minimally important change) were determined for the scale. Results: Among the postarthroscopy group, excellent test-retest reliability was found (intraclass correlation coefficient = 0.869; 95% CI, 0.756-0.932) with a minimal detectable difference of 26 points out of 100 at the individual level and 4 points out of 100 at the group level. At baseline discriminant validity was evident between those who had returned to sports (median = 69, n = 35) and those who had not returned to sports (median = 30, n = 42; Mann-Whitney U score = 232.5, z = −5.141, P < .001) and between the returned-to-sports postarthroscopy group and healthy controls (median = 96, n = 33; Mann-Whitney U score = 165.500, z = 5.666, P < .001). No floor or ceiling effects were evident. Responsiveness was demonstrated for the scale in relation to sports status. With sports status as an anchor, a minimally important change of 26 points was identified. Conclusion: Assessment of the Hip–Return to Sport After Injury (Short Form) supports its use as a reliable and valid measure of psychological readiness to return to sports in patients after hip arthroscopy.

Ultrasound Doppler Flow in Patients With Chronic Midportion Achilles Tendinopathy: Is Surface Area Quantification a Reliable Method?

ObjectivesUltrasound assessments of patients with chronic midportion Achilles tendinopathy include determining the degree of neovascularization using Doppler flow. A frequently used measure to quantify neovascularization is the modified Öhberg score. It is unknown whether the semiquantitative modified Öhberg score (0–4+) has higher reliability than a quantified measure of Doppler flow (0–100%). The purpose of this cross‐sectional study was to evaluate the interobserver reliability of the modified Öhberg score and a surface area quantification (SAQ) method for Doppler flow in patients with chronic midportion Achilles tendinopathy.MethodsTwo observers examined the degree of Doppler flow independently using SAQ and the modified Öhberg score during a single consultation. The intraclass correlation coefficient, standard error of measurement, and minimal detectable difference were determined to evaluate the reliability and measurement properties of the SAQ method and the modified Öhberg score.ResultsIn total, 28 consecutive patients with chronic midportion Achilles tendinopathy participated. The intraclass correlation coefficient for interobserver reliability of the SAQ method was 0.81 (95% confidence interval, 0.58–0.91), compared to 0.64 (95% confidence interval, 0.45–0.81) for the modified Öhberg score. The standard error of measurement and minimal detectable difference values for the SAQ method were 2.9% and 8.0%, respectively, and for the modified Öhberg score, they were 0.55 and 1.53 points.ConclusionsThe SAQ method shows good reliability to evaluate the degree of Doppler flow in patients with chronic midportion Achilles tendinopathy, and it overcomes the ceiling effect of the modified Öhberg score. Future research should focus on the relationship between the SAQ method and clinical outcomes and use this method to monitor treatment responses.

Translating Treatment Effects Between Rheumatoid Arthritis Activity Measures and American College of Rheumatology Responses in Direct Comparison Trials.

Direct comparison trials in rheumatoid arthritis (RA) increasingly use changes in continuous disease activity measures as endpoints. However, the between-arm differences in these scores that are clinically meaningful are uncertain. To aid interpretation of clinical trials that use the Disease Activity Score in 28 joints (DAS28) or Simplified Disease Activity Index (SDAI) as endpoints, we developed statistical equivalences between changes in these measures and American College of Rheumatology (ACR) responses. For superiority trials, we computed the minimal detectable difference in DAS28 changes and SDAI changes that correspond to the ACR criteria for 20% improvement (ACR20) and 50% improvement (ACR50) responses at the same type I and type II errors and same sample size. For noninferiority trials, we computed noninferiority margins that were statistically equivalent across measures. Standard deviations of the changes in the DAS28 and SDAI from a recent observational study were used as the basis of calculations in our examples. In the base scenario with type 1 error 0.05 and power 0.80, a trial with 300 subjects per arm would detect a 0.31-point difference in mean DAS28 change scores and 3.71-point difference in mean SDAI change scores as statistically equivalent to an absolute difference of 11% in ACR20 between treatment arms. We developed a web-based utility that provides equivalent differences among these measures for customized sample sizes, error rates, and standard deviations of the DAS28 and SDAI between-arm differences. The DAS28 and SDAI responses can be related to statistically equivalent changes in ACR responses, which can aid the interpretation of trials that use these measures.

Single-Trial Mechanisms Underlying Changes in Averaged P300 ERP Amplitude and Latency in Military Service Members After Combat Deployment.

Attenuation in P300 amplitude has been characterized in a wide range of neurological and psychiatric disorders such as dementia, schizophrenia, and posttraumatic stress disorder (PTSD). However, it is unclear whether the attenuation observed in the averaged event-related potential (ERP) is due to the reduction of neural resources available for cognitive processing, the decreased consistency of cognitive resource allocation, or the increased instability of cognitive processing speed. In this study, we investigated this problem by estimating single-trial P300 amplitude and latency using a modified Woody filter and examined the relation between amplitudes and latencies from the single-trial level to the averaged ERP level. ERPs were recorded from 30 military service members returning from combat deployment at two time points separated by 6 or 12 months. A conventional visual oddball task was used to elicit P300. We observed that the extent of changes in the within-subject average P300 amplitude over time was significantly correlated with the amount of change in three single-trial measures: (1) the latency variance of the single-trial P300 (r = −0.440, p = 0.0102); (2) the percentage of P300-absent trials (r = −0.488, p = 0.005); and (3) the consistent variation of the single-trial amplitude (r = 0.571, p = 0.0022). These findings suggest that there are multiple underlying mechanisms on the single-trial level that contribute to the changes in amplitudes seen at the averaged ERP level. The changes between the first and second assessments were quantified with the intraclass correlation coefficient, the standard error of measurement and the minimal detectable difference. The unique population, the small sample size and the large fraction of participants lost to follow up precludes generalizations of these measures of change to other populations.

Test-Retest Reliability and Response Stability of Gaze Stabilization, Postural Sway, and Dynamic Balance Tests in Persons with Multiple Sclerosis and Controls.

Psychometric properties of tests that assess the angular vestibulo-ocular reflex (aVOR) and vestibulospinal reflex function are currently unknown. This study investigated the test-retest reliability and response stability of gaze stabilization, postural sway, and dynamic balance measures in persons with multiple sclerosis (MS) and controls. Nineteen adults with MS and 14 controls performed passive horizontal head impulses, quiet standing, and dynamic balance tests on two separate occasions. Gaze stabilization measures included aVOR gain, number of compensatory saccades (CSs) per head rotation, CS latency, and gaze position error. Postural sway included sway amplitude and total sway path. Dynamic balance measure included the Functional Gait Assessment. Intraclass correlation coefficient, standard error of measurement (SEM, SEM%), and minimal detectable difference at 95% confidence level were calculated. Test-retest reliability for aVOR gain, CSs per head rotation, and gaze position error was moderate and for each postural sway and dynamic balance measure was good. Low error (SEM, SEM%) for aVOR gain, CS latency, postural sway, and dynamic balance variables and low minimal detectable difference values for aVOR gain and Functional Gait Assessment scores were seen, suggestive of acceptable response stability. These results support the utility of some of the gaze and postural measures for examination and treatment efficacy purposes in people with MS.

Translation, cultural adaptation, and psychometric testing of the Yoruba version of Fear-Avoidance Beliefs Questionnaire in patients with low-back pain

Purpose To translate, culturally adapt, and validate the Fear-Avoidance Beliefs Questionnaire into Yoruba language. Materials and Methods Translation and cultural adaptation of the Yoruba version of the Fear-Avoidance Beliefs Questionnaire was carried out following the Guillemin criteria. One hundred and thirty-one individuals with chronic low-back pain participated in the psychometric evaluation of the Yoruba language translation. Cronbach’s alpha (α), principal component analysis, intra-class correlation, Bland–Altman analysis, Spearman rank correlation coefficient, and minimal detectable difference were used for the analysis. Alpha level was set at p < 0.05. Results and Conclusion The mean age of the respondents was 53.6 ± 11.6 years. The internal consistency of the Yoruba language version of the Fear Avoidance Beliefs Questionnaire yielded a Cronbach’s alpha of 0.9. Principal component analysis yielded a three-factor structure including the “work”, “beliefs related to work”, and “physical activity” which accounted for 61.6% of variance in the Yoruba translation. Test–retest reliability of the Yoruba translation yielded an Intra class correlation coefficient 0.97 (0.95–0.98). The Yoruba Fear Avoidance Beliefs Questionnaire was poorly correlated with the Visual Analog Scale (r = 0.01) and Roland–Morris Disability Questionnaire (r = 0.3). The minimal detectable difference of the Yoruba translation was 7.0. The Yoruba Fear Avoidance Beliefs Questionnaire demonstrated excellent psychometric properties similar to existing versions and is appropriate for clinical use among Yoruba-speaking patients. IMPLICATIONS FOR REHABILITATION The Fear-Avoidance Beliefs Questionnaire is a culturally sensitive psychosocial outcome measure, necessitating its existence, and adaptation into different languages. The instrument was translated and culturally adapted into the Yoruba language following the Guillemin criteria. The Yoruba translation demonstrated excellent internal consistency, test–retest reliability and weak correlations with the Visual analog scale and Roland–Morris Disability Scale. The Yoruba version of the Fear-Avoidance Beliefs Questionnaire can be used to assess fear-avoidance beliefs among Yoruba speaking patients with low-back pain.

Minimal detectable difference of the finger and wrist range of motion: comparison of goniometry and 3D motion analysis

BackgroundThe measurement of finger and wrist range of motion (ROM) is of great importance to clinicians when assessing functional outcomes of therapeutic interventions and surgical procedures. The purpose of the study was to assess the repeatability of ROM measurements of the hand joints with manual goniometer and 3D motion capture system and to calculate the minimal detectable difference for both methods.MethodsActive finger and wrist joints ROM of 20 healthy volunteers were assessed using a manual goniometer and 3D motion capture system. Minimal detectable difference (MDD) and standard error of measurement (SEM) were calculated for both measurement systems and compared within the same task. Maximal ROM of all joints was registered twice on two different days to evaluate the test-retest repeatability. The intraclass correlation coefficients (ICC) was calculated and examined to determine if reliability ≥ 0.70 existed.ResultsMDD for the 3D motion capture was between 5 and 12° except for the metacarpophalangeal joint (MCP) 1, interphalangeal joint (IP), and MCP5. SEM values lay between 2 and 4° for all joints except for the MCP5, IP, and MCP1. For the goniometric measurements, MDD and SEM were between 12–30° and 4–11°, respectively. The reliability criterion (ICC > 0.7) was achieved for the ROM measurement with the 3D motion capture system for 94% of the joints and in only 65% of the joints with the manual goniometer.ConclusionsJoint ROM assessed with 3D motion analysis showed higher test-retest agreement demonstrating overall better repeatability for this method. Because of the smaller measurement error, the 3D motion capture system has a smaller MDD. Only individual test-rest differences bigger than the MDD can be considered as real changes, and therefore, in an experimental situation, the use of a more precise measurement method can greatly reduce the number of subjects needed for a statistical significance. Goniometer measurements of some joints should be carefully interpreted, due to a low repeatability and reliability.Trial registrationThis study is approved by the Ethical Committee Zurich (Kek-ZH-Nr: 2015-0395).

Reliability and validity of pelvic floor muscle displacement measurements during voluntary contractions.

Understanding the functioning of pelvic floor muscles (PFM) is crucial in female PFM rehabilitation. The aim of this study was to determine the intra-session retest reliability and validity to evaluate the quantity of PFM displacement. This cross-sectional observational study examined the PFM displacement of 17 young healthy nulliparous women in the midsagittal plane. Three maximal voluntary contractions (MVCs) and five fast voluntary contractions (FVCs) were simultaneously examined with an electromagnetic tracking system (ETS) and transabdominal ultrasound (TAUS) and expressed in millimeters (mean, SD). To evaluate reliability and validity, the analysis of variance, intraclass coefficient (2,1), standard error of measurement (SEM), and minimal detectable difference (MDD) were calculated. Maximal voluntary contractions and FVCs in supine position measured by an ETS (TAUS) showed a displacement of MVC: 3.5 ± 1.9mm (7.8 ± 4.5mm), FVC: 3.5 ± 2.4mm (7.6 ± 5.3mm), and during standing of MVC: 5.2 ± 1.6mm (9.4 ± 3.8mm) and FVC: 4.8 ± 2.5mm (9.7 ± 4.1mm). Intraclass correlation for the ETS (TAUS) measurement varied between 0.79 and 0.89 (0.61 and 0.74), SEM 0.52 and 1.03mm (1.54 and 3.2mm), and MDD 1.54 and 3.2mm (6.64 and 7.53mm). The correlation between an ETS and TAUS varied between 0.53 and 0.67. For MVC and FVC, ETS measurements are highly reliable and TAUS measurements are moderately reliable for both contraction types. The correlation between the TAUS and ETS measurements is moderate. An ETS seems to be a reliable and valid measurement tool for evaluating PFM displacement during voluntary contractions. In future studies, the reproducibility and validity of ETS measurements need to be investigated in impact activities.

Psychometric properties of the Flemish version of the life balance inventory: a patient-reported outcome measure in the chronic stage after stroke

Purpose: To investigate test-retest reliability, measurement error, and convergent validity of the Flemish version of the Life Balance Inventory (Fl-LBI) in chronic community-dwelling stroke survivors.Methods: Stroke survivors living at home (>6 months post-stroke) were recruited. The Fl-LBI was administered twice (1st home-visit, 2nd postal), with a 1-week time interval.Results: Thirty-two stroke-survivors participated: median age 61 years (IQR: 54–67), median time since stroke 571 days (IQR: 433–734). Median total Fl-LBI score was 2.47(IQR: 2.18–2.80) out of 3 on the first occasion (n = 32) and 2.55(IQR: 2.35–2.77) on the second occasion (n = 29), 91% retention rate. The intraclass correlation coefficient [95% confidence interval] for total Fl-LBI score was 0.88 [0.77–0.94] and for subscale scores >0.74 [0.48–0.94] indicating moderate to good test-retest reliability. Standard error of measurement was 0.14 out of 3(7%) and minimal detectable difference 0.39(20%). Agreement for activity category scores ranged from moderate to excellent. Construct validity was supported by moderate associations between Fl-LBI and participation (rs = 0.46); mobility (rs = 0.36) and emotion (rs = 0.37) subscales of the Stroke Impact Scale.Conclusion: In a pilot sample, the FL-LBI has satisfactory test-retest reliability, acceptable measurement error and minimal detectable difference and acceptable convergent validity. It can be used in clinical practice and research to assess life balance in chronic community-dwelling stroke survivors.Implications for rehabilitationLife balance can be a useful concept in stroke rehabilitation; it corresponds to individuals’ perception of having a satisfying activity pattern tailored to their life circumstances.The Flemish version of the Life Balance Inventory can be used to evaluate life balance in community-dwelling chronic stroke.Satisfactory test-retest reliability and acceptable measurement error and minimal detectable difference were demonstrated in a pilot sample for the Flemish version of the Life Balance Inventory.

Myotonometry as a measure to detect myofascial trigger points: an inter-rater reliability study

Objective: Several diagnostic methods have been used in the identification of mechanical properties of skeletal muscle, including myofascial trigger points (MTrPs), however, they are not suitable for daily clinical use. Myotonometry offers an easy noninvasive alternative to assess these muscle properties. Nevertheless, previous research has not yet studied the mechanical properties of MTrPs by myotonometry. The purposes of this study were (1) to analyze the differences in the mechanical properties between latent MTrPs and their taut bands by myotonometry, (2) to investigate the inter-rater reproducibility of myotonometric measurements, and (3) to examine the association between myotonometry and passive isokinetic dynamometry. Approach: Fifty individuals (58% male; age 24.6 ± 7.9 years) with a latent medial MTrP of the right soleus muscle participated. The mechanical properties of this MTrP area of soleus muscle and its taut band area were measured using a myotonometer (MyotonPRO). Additionally, passive resistive torque and extensibility of triceps surae muscle were assessed using a Kin-Com dynamometer. Main results: Statistical analysis indicated higher values for the stiffness parameter in the taut band with respect to the MTrP (P < 0.05). The inter-rater reliability of the myotonometric measurements was good for all variables (ICC3,1 > 0.75). The standard error of measurement (SEM) and minimal detectable difference (MDD) indicated a small measurement error for frequency and stiffness variables (SEM% < 10%; MDD95% < 20%). Significant fair correlations between myotonometric parameters and passive isokinetic parameters ranged from −0.29 to 0.48 (P < 0.05). Significance: The myotonometer was demonstrated to be a reliable tool and was able to quantify differences in the mechanical properties of myofascial tissues. The potential of this method for the assessment of myofascial pain syndromes requires further investigation.

Measurement of bend sprinting kinematics with three-dimensional motion capture: a test–retest reliability study

ABSTRACT Sprint velocity decreases on the bend when compared with the straight, therefore understanding technique during bend sprinting could have important implications for aiding race performance. Few bend sprinting studies have used optoelectronic cameras to investigate kinematic variables. Limited published evidence regarding the reliability of marker sets in conditions representative of elite bend sprinting makes model selection difficult. Therefore, a test-retest protocol was conducted to establish the reliability and minimum detectable difference of a lower limb and trunk marker set during bend sprinting (radius: 36.5 m). Six participants completed five, 60 m trials at maximum effort, with data collected at 38–45 m. This was repeated 2–7 days later. Spatio-temporal (e.g., contact time) and kinematic variables (e.g., peak joint angles) were evaluated. Intra-class correlation coefficients (ICC) were used to determine the between- and within-day reliability. Between-day reliability (ICC 3, k) was fair to excellent for all variables. Compared to between-day, within-day reliability demonstrated stronger agreement for the majority of variables. Thus, same-day data collection is preferable. It has been established that the marker set is reliable for future use. In addition, the minimal detectable difference was calculated which serves as useful reference for future research in bend sprinting

High-frequency ultrasound of the skin in systemic sclerosis: an exploratory study to examine correlation with disease activity and to define the minimally detectable difference

BackgroundThickened skin is a major clinical feature in patients with systemic sclerosis (SSc). We investigated changes of skin thickness in patients with SSc using both high frequency ultrasound (HFU) and the modified Rodnan skin score (mRSS) to evaluate the feasibility of application of HFU in skin involvement and the relationship between HFU and clinical profiles.MethodsWe recruited 31 consecutive patients with SSc and 31 age-matched and sex-matched healthy controls in this prospective, cross-sectional study. Skin thickness was measured by an 18-MHz ultrasonic probe at five different skin sites. Total skin thickness (TST) and skin thickness using categorical mRSS scores were recorded and compared to HFU. The European Scleroderma Trial and Research (EUSTAR) group Disease Activity Index (EUSTAR-DAI) and other clinical manifestations were assessed and analyzed.ResultsTST in patients with SSc was thicker than in healthy controls (P < 0.001), and correlated positively with total mRSS and the EUSTAR-DAI and correlated negatively with disease duration (P < 0.05). Patients with higher TST had higher EUSTAR-DAI, mRSS, C-reactive protein (CRP) and lower diffusing capacity of the lung for carbon monoxide (DLCO) (P < 0.05). Even in patients who on clinical assessment were assigned an mRSS that suggested the skin thickness was normal. This was also true to mRSS locally of 1 and 2 (P < 0.01). The area under the receiver operator characteristic (ROC) curve was 0.831 and yielded sensitivity of 77.4% and specificity of 87.1% at the predicted probability of 7.4 mm as the optimal cutoff point to access skin thickness.ConclusionsIn the study, HFU was able to measure skin thickness, it correlated quantitatively with a valid measure of SSc activity, and a minimal detectable difference was identified.

Measure of activity performance of the hand (MAP-Hand) questionnaire: linguistic validation, cultural adaptation and psychometric testing in people with rheumatoid arthritis in the UK

BackgroundDeveloped in the Norway, the Measure of Activity Performance of the Hand (MAP-Hand) assesses 18 activities performed using the hands. It was developed for people with rheumatoid arthritis (RA) using patient generated items, which are scored on a 0–3 scale and summarised into a total score range (0 to 54). This study reports the development and psychometric testing of the British English MAP-Hand in a UK population of people with RA.MethodsRecruitment took place in the National Health Service (NHS) through 17 Rheumatology outpatient clinics. Phase 1 (cross-cultural adaptation) involved: forward translation to British English; synthesis; expert panel review and cognitive debriefing interviews with people with RA. Phase 2 (psychometric testing) involved postal completion of the MAP-Hand, Health Assessment Questionnaire (HAQ), Upper Limb HAQ (ULHAQ), Short-Form 36 (SF-36v2) and Disabilities of the Arm Shoulder Hand (DASH) to measure internal consistency (Cronbach’s alpha); concurrent validity (Spearman’s correlations) and Minimal Detectable Difference (MDC95). The MAP-Hand was repeated three-weeks later to assess test-retest reliability (linear weighted kappa and Intra-Class Correlations (ICC (2,1)). Unidimensionality (internal construct validity) was assessed using (i) Confirmatory Factor Analysis (CFA) (ii) Mokken scaling and (iii) Rasch model. The RUMM2030 software was used, applying the Rasch partial credit model.ResultsIn Phase 1, 31 participants considered all items relevant. In Phase 2, 340 people completed Test-1 and 273 (80%) completed Test-2 questionnaires. Internal consistency was excellent (α = 0.96). Test-retest reliability was good (ICC (2,1) = 0.96 (95% CI 0.94, 0.97)). The MAP-Hand correlated strongly with HAQ20 (rs = .88), ULHAQ (rs = .91), SF-36v2 Physical Functioning (PF) Score (rs = −.80) and DASH (rs = .93), indicating strong concurrent validity. CFA failed to support unidimensionality (Chi-Square 236.0 (df 120; p < 0.001)). However, Mokken scaling suggested a probabilistic ordering. There was differential item functioning (DIF) for gender. Four testlets were formed, resulting in much improved fit and unidimensionality. Following this, testlets were further merged in pairs where opposite bias existed. This resulted in perfect fit to the model.ConclusionsThe British English version of the MAP-Hand has good validity and reliability in people with RA and can be used in both research and clinical practice.

Diffusion tensor MRI of the healthy brachial plexus.

IntroductionDiffusion Tensor MRI (DT-MRI) is a promising tool for the evaluation of brachial plexus pathology. Therefore, we introduce and evaluate a fast DT-MRI protocol (8min33s scanning with 5–10 min postprocessing time) for the brachial plexus.Materials and methodsThirty healthy volunteers within three age-groups (18–35, 36–55, and > 56) received DT-MRI of the brachial-plexus twice. Means of fractional-anisotropy (FA), mean-diffusivity (MD), axial-diffusivity (AD), and radial-diffusivity (RD) for the individual roots and trunks were evaluated. A stepwise forward approach was applied to test for correlations with age, sex, body-mass-index (BMI), bodysurface, height, and bodyweight. Within-subject, intra-rater, and inter-rater repeatability were assessed using Bland-Altman analysis, coefficient of variation (CV), intraclass-correlation (ICC), and minimal detectable difference (MDD).ResultsNo differences between sides and root levels were found. MD, AD, and RD correlated (P < 0.05) with bodyweight. Within-subject quantification proved repeatable with CVs for FA, MD, AD, and RD of 16%, 12%, 11%, and 14%, respectively.DiscussionThe DT-MRI protocol was fast and repeatable. Found correlations should be considered in future studies of brachial plexus pathology.

Differences in Knee and Hip Adduction and Hip Muscle Activation in Runners With and Without Iliotibial Band Syndrome

BackgroundIliotibial band syndrome has been associated with altered hip and knee kinematics in runners. Previous studies have recommended further research on neuromuscular factors at the hip. The frontal plane hip muscles have been a strong focus in strength comparison but not for electromyography investigation. ObjectiveTo compare hip surface electromyography, and frontal plane hip and knee kinematics, in runners with and without iliotibial band syndrome. DesignObservational cross-sectional study. SettingBiomechanics research laboratory within a university. ParticipantsThirty subjects were recruited consisting of 15 injured runners with iliotibial band syndrome and 15 gender-, age-, and body mass index–matched controls. In each group, 8 were male runners and 7 were female runners. Inclusion criteria for the injured group were pain within 2 months related to iliotibial band syndrome and a positive Noble compression test. Participants were excluded if they reported other lower extremity diagnoses within the last year or active lower extremity or low back pain not related to iliotibial band syndrome. Controls were excluded if they reported a history of iliotibial band syndrome. Convenience sampling was used based on referrals from local running clinics and orthopedic clinics. MethodsThree-dimensional motion capture was performed with 10 high-speed cameras synchronized with wireless surface electromyography during a 30-minute run. The first data point was at 3 minutes, using a constant speed of 2.74 meters per second. A second data point was at 30 minutes, using a self-selected pace by the participant to allow for a challenging run until completion at 30 minutes. Main Outcome MeasurementsMotion capture was reported as peak kinematic values from heel strike to peak knee flexion for hip adduction and knee adduction. Surface electromyography was reported as a percentage of maximal voluntary contraction for the gluteus maximus, gluteus medius and tensor fascia latae muscles. ResultsInjured runners demonstrated increased knee adduction compared with control runners at 30 minutes (P = .002, control = –1.48°, injured = 3.74°). Tensor fasciae latae muscle activation in injured runners was increased compared with control runners at 3 minutes (P = .017, control = 7% maximal voluntary isometric contraction, injured = 11% maximal voluntary isometric contraction). ConclusionThe results of this study suggest that lateral knee pain in runners localized to the distal iliotibial band is associated with increased knee adduction at 30 minutes. Increased tensor fasciae latae muscle activation at 3 minutes is noted, but more investigation is needed to better understand the clinical meaning. These findings are consistent with but not conclusive evidence supporting the theory that neuromuscular factors of the hip muscles may contribute to increased knee adduction in runners with iliotibial band syndrome. We advise caution using these findings to support treatments intended to modify tensor fasciae latae activation, given the small differences of 4% in muscle activation. Increased knee adduction in runners at 30 minutes was over 5° and beyond the minimal detectable difference. Additional research is needed to confirm whether the degree of knee adduction changes earlier versus later in a run and whether fatigue is a clinically relevant factor. Level of EvidenceIII

Abstract P366: Repeatability of Cardio-Ankle Vascular Index in Morbidly Obese Individuals

Background: The AHA 2016 Statement for arterial stiffness evaluation introduced several novel parameters. Cardio-ankle vascular index (CAVI) is one of them and has a unique property of being largely independent of blood pressure (BP) at the time of examination. The repeatability of CAVI has been confirmed in healthy population but not in morbidly obese individuals. Methods: We investigated 76 participants (mean age 44 years, and mean BMI 48 kg/m 2 [ranged from 36-70]) in the BARI-Heart Study, who underwent 2 standardized visits (1-10 months apart) before bariatric surgery. CAVI was measured twice 5-minute apart at each visit using oscillometric device VaSera VS-1500 (Fukuda Denshi, Tokyo, Japan) at a supine position. We calculated intra-class correlation coefficient (ICC), minimal detectable change (MDC 95 ) and minimal detectable difference (MDD) using a nested random-effects analysis of variance model for CAVI. As a contrast, we also calculated these repeatability statistics for brachial and ankle BP measured using the same device when CAVI was measured. Results: At the first visit, average CAVI was 6.2 (SD 1.1) and average brachial systolic and diastolic BP was 146 mmHg (SD 13) and 86 mmHg (SD 7). For short-term repeatability in 5 minutes at the first visit, the ICCs were very high for both CAVI and brachial and ankle BPs (all with ICC ≥ 0.82 bilaterally). When we observed longer term repeatability over several months, the ICCs were fair for BPs (ranged from 0.42-0.57) but remained very high for CAVI with ≥0.72 for both sides. The MDC 95 between repeated measures within an individual across two visits was 1.6-1.7 for CAVI and 15-35 mmHg for BP parameters. In this scenario, the MDD for two independent samples of 100 per group was ~0.5 for CAVI and 4-8 mmHg for BP parameters. Conclusion: The short- and longer-term repeatability of CAVI was overall good even among morbidly obese individuals. Our results suggest that a longitudinal change of CAVI by 1.6-1.7 indicates a change beyond the measurement error.

Reliability of the individual components of the Canadian Armed Forces Physical Employment Standard.

This investigation recruited 24 participants from both the Canadian Armed Forces (CAF) and civilian populations to complete 4 separate trials at "best effort" of each of the 4 components in the CAF Physical Employment Standard named the FORCE Evaluation: Fitness for Operational Requirements of CAF Employment. Analyses were performed to examine the level of variability and reliability within each component. The results demonstrate that candidates should be provided with at least 1 retest if they have recently completed at least 2 previous best effort attempts as per the protocol. In addition, the minimal detectable difference is given for each of the 4 components in seconds which identifies the threshold for subsequent action, either retest or remedial training, for those unable to meet the minimum standard. These results will educate the delivery of this employment standard, function as a method of accommodation, in addition to providing direction for physical training programs.

Statistical Primer for Athletic Trainers: The Essentials of Understanding Measures of Reliability and Minimal Important Change.

To describe the concepts of measurement reliability and minimal important change. All measurements have some magnitude of error. Because clinical practice involves measurement, clinicians need to understand measurement reliability. The reliability of an instrument is integral in determining if a change in patient status is meaningful. Measurement reliability is the extent to which a test result is consistent and free of error. Three perspectives of reliability-relative reliability, systematic bias, and absolute reliability-are often reported. However, absolute reliability statistics, such as the minimal detectable difference, are most relevant to clinicians because they provide an expected error estimate. The minimal important difference is the smallest change in a treatment outcome that the patient would identify as important. Clinicians should use absolute reliability characteristics, preferably the minimal detectable difference, to determine the extent of error around a patient's measurement. The minimal detectable difference, coupled with an appropriately estimated minimal important difference, can assist the practitioner in identifying clinically meaningful changes in patients.

Reliability, Validity, and Sensitivity of a Novel Smartphone-Based Eccentric Hamstring Strength Test in Professional Football Players.

To evaluate the test-retest reliability, sensitivity, and concurrent validity of a smartphone-based method for assessing eccentric hamstring strength among male professional football players. A total of 25 healthy male professional football players performed the Chinese University of Hong Kong (CUHK) Nordic break-point test, hamstring fatigue protocol, and isokinetic hamstring strength test. The CUHK Nordic break-point test is based on a Nordic hamstring exercise. The Nordic break-point angle was defined as the maximum point where the participant could no longer support the weight of his body against gravity. The criterion for the sensitivity test was the presprinting and postsprinting difference of the Nordic break-point angle with a hamstring fatigue protocol. The hamstring fatigue protocol consists of 12 repetitions of the 30-m sprint with 30-s recoveries between sprints. Hamstring peak torque of the isokinetic hamstring strength test was used as the criterion for validity. A high test-retest reliability (intraclass correlation coefficient = .94; 95% confidence interval, .82-.98) was found in the Nordic break-point angle measurements. The Nordic break-point angle significantly correlated with isokinetic hamstring peak torques at eccentric action of 30°/s (r = .88, r2 = .77, P < .001). The minimal detectable difference was 8.03°. The sensitivity of the measure was good enough that a significance difference (effect size = 0.70, P < .001) was found between presprinting and postsprinting values. The CUHK Nordic break-point test is a simple, portable, quick smartphone-based method to provide reliable and accurate eccentric hamstring strength measures among male professional football players.