Upper extremity 3-dimensional reachable workspace analysis in dystrophinopathy using Kinect

Abstract

Introduction: An innovative upper extremity 3-dimensional (3D) reachable workspace outcome measure acquired using the Kinect sensor is applied toward Duchenne/Becker muscular dystrophy (DMD/BMD). The validity, sensitivity, and clinical meaningfulness of this novel outcome measure are examined.

Methods: Upper extremity function assessment (Brooke scale and NeuroQOL questionnaire) and Kinect-based reachable workspace analyses were conducted in 43 individuals with dystrophinopathy (30 DMD and 13 BMD, aged 7-60 years) and 46 controls (aged 6-68 years).

Results: The reachable workspace measure reliably captured a wide range of upper extremity impairments encountered in both pediatric and adult, as well as ambulatory and non-ambulatory individuals with dystrophinopathy. Reduced reachable workspaces were noted for the dystrophinopathy cohort compared with controls, and they correlated with Brooke grades. In addition, progressive reduction in reachable workspace correlated directly with worsening ability to perform activities of daily living, as self-reported on the NeuroQOL.

Conclusion: This study demonstrates the utility and potential of the novel sensor-acquired reachable workspace outcome measure in dystrophinopathy.

Keywords: Becker; Duchenne; Kinect; reachable workspace; upper extremity.

Fig. 1. Correlation of measured arm lengths

Correlation between actual evaluator-measured arm lengths and Kinect-acquired arm lengths for the BMD/DMD and control cohorts.

Fig. 2. Intuitive graphical visualization of 3D reachable workspace

(A) Overall schematic of the process to detect an individual’s upper extremity motion via Kinect sensor and visualization of the reachable workspace output. The example shows the reachable workspace quadrants as enumerated1–4 in the left upper extremity perspective. (B) A 7-year old healthy control’s reachable workspace viewed from different directions, along with reachable workspaces of individuals with DMD and progressively worsening upper extremity function as classified by Brooke grades 1–5. (C) Reachable workspace from 3 individuals with BMD and Brooke grades 1–3.

Fig. 3. Difference in reachable workspace between control and dystrophinopathy cohorts

(A) Mean RSAs by quadrant presented in a 2D reachable workspace plot format for the DMD cohort (solid line) and age-matched control cohort (dashed line); (B) BMD cohort (solid line) and age-matched control cohort (dashed line), and (C) combined BMD/DMD cohort (solid line) and all control subjects (dashed line). Plots shown in the right side perspective (*P<0.05).

Fig. 4. Progressive reductions in total and quadrant reachable workspace corresponding to disease severity in dystrophinopathy

(A) Mean reachable workspace RSA by quadrants presented in a reachable workspace plot format, shown in right side perspective. Controls are shown as a dashed line; BMD/DMD patients with Brooke grade 1 are shown with a dark blue line, 2 in red, 3 in green, 4 in purple, and 5 in orange. (B) a bar graph for controls and dystrophinopathy subjects by Brooke grade demonstrating reductions in total and quadrant RSAs corresponding to worsening disease severity as categorized by Brooke grades 1–5 (*P<0.05).

Fig. 5. Reduction in reachable workspace with non-loading vs. loading conditions (500- and 1,000-gram wrist weights)

Progressive change in reachable workspace of an individual with DMD (age 9 years) and Brooke grade 1 demonstrates the sensitivity of the reachable workspace outcome measure to detect incremental changes in upper extremity reachability; shown in left upper extremity perspective.

Fig. 6. Bar graph showing the reduction in mean total RSA (Δ mean total RSA = mean total RSA with 500 g loading - mean total RSA with no loading) for DMD, BMD (Brooke grades 1 and 2) and control groups

(A) Respective Δ mean total RSAs are shown with standard error bars. (B) Graph showing reduction in mean total RSAs with both 500- and 1000-gram wrist weights for those with Brooke grade 1: BMD (n=10), DMD (n=12), and healthy control cohorts (n=92).

Fig. 7. Relationship between self-reported function on the NeuroQOL upper extremity function questionnaire and reachable workspace (RSA) in DMD

(A) A correlation of mean total RSA and mean scores from the total 20-item questions of the NeuroQOL or with the 8-questions that deal primarily with proximal upper extremity function. (B) Box-and-whiskers plot show the relationship between mean total RSA and self-reported degree of difficulty (none, some/little, or unable/much) experienced by individuals with DMD in performing various activities. (C) An ROC curve to determine the optimal RSA cut-off value for identification of individuals who have no difficulty performing proximal upper extremity associated ADL tasks is shown and is represented by the dashed line in (B). (D) An ROC curve to determine the optimal RSA cut-off value for identification of individuals who are unable to perform the listed proximal upper extremity-associated ADL tasks is shown and is represented by the dotted line in (B).