title: Within-assessor reliability and minimal detectable change of gait kinematics in a young obese demographic.
abstract: Three-dimensional gait analysis (3DGA) in obese populations is a difficult task due to a great amount of subcutaneous fat. This makes it more challenging to identify anatomical landmarks, thus leading to inconsistent marker placement. Therefore, the purpose of this study was to investigate the test-retest reliability for kinematic measurements of obese children and adolescents.
  
  
  
  Nine males and two females with an age-based BMI above the 97th percentile (age: 14.6±2.6years, BMI: 33.4±4.4kg/m2) were administered to two 3DGA sessions. To quantify reliability of discrete parameters the intraclass correlation coefficient (ICC2,k), standard error of measurement (SEM) and minimal detectable change (MDC) were calculated. To quantify waveform similarity, the coefficient of multiple correlation (CMC) and the linear fit method (LFM) were used.
  
  
  
  From 28 kinematic parameters, 23 showed acceptable ICCs (≥0.70) and the remaining parameters demonstrated moderate values. These were peak hip extension during stance (0.58), mean pelvis rotation (0.60), mean anterior pelvic tilt (0.64), peak knee flexion during swing (0.67) and peak hip abduction during swing (0.69). The SEM was below 5° for all parameters. The MDC for the sagittal, frontal, and transversal plane were on average 7.5°±2.2, 4.6°±1.3 and 6.0°±0.9 respectively. Both the LFM and CMC showed, in general, moderate to good reliability except for pelvis tilt and hip rotation.
  
  
  
  Data demonstrated acceptable error margins especially for the sagittal and frontal plane. Low reliability for the pelvis tilt indicates that great effort is necessary to position the pelvic markers consistently during repeated sessions.
authors.affiliation: St. Pölten University of Applied Sciences, Department of Physiotherapy, Austria. Electronic address: brian.horsak@fhstp.ac.at.
authors.forename: Brian
authors.initials: B
authors.lastname: Horsak
authors.affiliation: Orthopedic Hospital Vienna-Speising, Laboratory of Gait and Movement Analysis, Austria.
authors.forename: Barbara
authors.initials: B
authors.lastname: Pobatschnig
authors.affiliation: University of Vienna, Department of Biomechanics, Kinesiology and Applied Computer Science, Austria.
authors.forename: Arnold
authors.initials: A
authors.lastname: Baca
authors.affiliation: Medical University of Vienna, Department of Pediatrics and Adolescent Medicine, Austria.
authors.forename: Susanne
authors.initials: S
authors.lastname: Greber-Platzer
authors.affiliation: Medical University of Vienna, Department of Pediatrics and Adolescent Medicine, Austria.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Kreissl
authors.affiliation: Danube University Krems, Centre for Regenerative Medicine and Orthopedics, Austria.
authors.forename: Stefan
authors.initials: S
authors.lastname: Nehrer
authors.affiliation: St. Pölten University of Applied Sciences, Department of Physiotherapy, Austria.
authors.forename: Barbara
authors.initials: B
authors.lastname: Wondrasch
authors.affiliation: Medical University of Vienna, Department of Physical Medicine and Rehabilitation, Austria.
authors.forename: Richard
authors.initials: R
authors.lastname: Crevenna
authors.affiliation: Medical University of Vienna, Department of Physical Medicine and Rehabilitation, Austria.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Keilani
authors.affiliation: Orthopedic Hospital Vienna-Speising, Laboratory of Gait and Movement Analysis, Austria.
authors.forename: Andreas
authors.initials: A
authors.lastname: Kranzl
mesh_terms: D000293:Adolescent; D000886:Anthropometry / Q000379:methods; D001696:Biomechanical Phenomena; D002648:Child; D005260:Female; D005684:Gait / Q000502:physiology*; D006801:Humans; D035002:Lower Extremity / Q000502:physiology; D008297:Male; D009069:Movement Disorders / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology; D063766:Pediatric Obesity / Q000150:complications / Q000503:physiopathology*; D015203:Reproducibility of Results
keywords: Gait analysis; Intra-rater reliability; Obesity; Repeatability; Test-retest