Improving Regions of Deviation Gait Symmetry Analysis With Pointwise t Tests

Abstract

The regions of deviation method has been proposed as a technique for identifying regions of the gait cycle where joint motion deviates from normal (Shorter et al., 2008). The original statistical analysis distinguished only peak values during stance and swing. In the current article, we extend the approach by examining deviations from normal throughout the entire gait cycle using pointwise t tests. These methods were demonstrated on hind-limb joint angles of 21 Labrador Retrievers without and with cranial cruciate ligament disease. Results were compared with peak difference analysis previously performed on these subjects. All points in the gait cycle where symmetry deviations were significantly affected by cranial cruciate ligament disease (via pointwise t tests) were defined as regions of deviation from symmetry. Discriminant function analysis was used to consider single subjects and validate that these regions were truly areas of difference between groups. Regions of deviation encompassed previously determined significant peak differences, while extending analysis to additional areas of asymmetry. Discriminant function analysis suggested that the region of deviation method is a viable approach for distinguishing motion pattern differences. This enhanced method may help researchers better understand the mechanisms behind lameness and compensation.

Evidence for a Time-Invariant Phase Variable in Human Ankle Control

“…Point-wise analysis is an accepted method for finding statistical deviations from normal in continuous trajectories [46], e.g., for the ankle angle. Each subject performed a large number of trials for each condition to obtain within-subject means close to the true values, which helped justify our small subject sample size: n  = 9 for the 2-degree experiment and n  = 7 (three repeats) for the follow-up 5-degree experiment.…”

Inverse Dynamics Analysis of the Pelvic Limbs in Labrador Retrievers With and Without Cranial Cruciate Ligament Disease

“…Kinetics and kinematics were determined for each selected trial. For trials with minimal overlap of the pelvic limb and contralateral thoracic limb at ground contact, the interpolating method was used to identify the start of the gait cycle and remove additional GRF because of the thoracic limb 19 . Trotting velocity and acceleration during each trial were calculated based on the displacement of the sacrococcygeal marker during 1 pelvic limb stride.…”

Smoothing spline analysis of variance models: A new tool for the analysis of cyclic biomechanical data

“…The Regions of Deviation (ROD) approach (DiBerardino et al, 2012;Shorter et al, 2008) is a pointwise analysis technique that attempts to determine which time points exhibit significant mean differences between biomechanical signals from different experimental conditions. To test for significant differences, the ROD approach performs a t test at each time point of interest.…”

“…Both the average data and cycle-to-cycle variability can be used to characterize behavior (Hausdorff et al, 2001;James, 2004;O'Connor et al, 2012;Romei et al, 2004;Huang and Kuo, 2014). However, current methods tend to reduce continuous time series data to discrete points for statistical comparison (DiBerardino et al, 2012;Shorter et al, 2008), which ignores the functional nature of the biomechanical data.…”