This manuscript describes the method to test the concurrent validity of kinematic measures recorded by the smartphone application in comparison to a 3D motion capture system in the sagittal plane. This protocol will enable clinicians to set up smartphones for video capture of human movement.
A subscription to JoVE is required to view this content. Sign in or start your free trial.
Method Article
Video Movement Analysis Using Smartphones (ViMAS): A Pilot Study
In This Article
Summary
Abstract
The use of smartphones in clinical practice is steadily increasing with the availability of low cost/freely available "apps" that could be used to assess human gait. The primary aim of this manuscript is to test the concurrent validity of kinematic measures recorded by a smartphone application in comparison to a 3D motion capture system in the sagittal plane. The secondary aim was to develop a protocol for clinicians on the set up of the smartphone camera for video movement analysis.
The sagittal plane knee angle was measured during heel strike and toe off events using the smart phone app and a 3D motion-capture system in 32 healthy subjects. Three trials were performed at near (2-m) and far (4-m) smartphone camera distances. The order of the distances was randomized. Regression analysis was performed to estimate the height of the camera based on either the subject's height or leg length.
Absolute measurement errors were least during toe off (3.12 ± 5.44 degrees) compared to heel strike (5.81 ± 5.26 degrees). There were significant (p < 0.05) but moderate agreements between the application and 3D motion capture measures of knee angles. There were also no significant (p > 0.05) differences between the absolute measurement errors between the two camera positions. The measurement errors averaged between 3 - 5 degrees during toe off and heel strike events of the gait cycle.
The use of smartphone apps can be a useful tool in the clinic for performing gait or human movement analysis. Further studies are needed to establish the accuracy in measuring movements of the upper extremity and trunk.
Introduction
Assessment of human gait is a key component of the physical therapy evaluation and clinical decision-making process.1 Gait assessment is a frequently used clinical tool to assess gait deficits in patients with neurological and musculoskeletal deficits. Reassessment of gait can then provide the clinician with information about the efficacy of an intervention in achieving the goals they had set at their initial evaluation. There is a nationally recognized need in the United States for physical therapists to utilize standardized outcome measurements when evaluating patients.2 This need stems from the rapidly changing landsc....
Access restricted. Please log in or start a trial to view this content.
Protocol
This protocol was approved by the Institutional Review Board of Wayne State University.
1. Experimental Preparation
- Position cameras to capture the entire 6-m walkway. Use a total of 4 3D motion captures cameras to capture walking over a 6-m walkway.
- Place each of the cameras at the 4 corners of the 6 m walkway. Orient each of the cameras at the diagonal ends of the walkway to face each other.
- Collect height, weight and leg length measures of each participant.
- Measure mass in kilograms.
- Measure leg length (in meters) from greater trochanter to medial malleoli of both leg....
Access restricted. Please log in or start a trial to view this content.
Results
All 32 subjects completed the 6 walking trials; however, data from 6 of the participants were not included in the data analysis due to technical problems resulting in poor marker visibility. The absolute measurement errors of knee angles were least during toe off events (3.12 ± 5.44 degrees) compared to heel strike (5.81 ± 5.26 degrees) (Table 1b). There were no statistically significant agreements (P > 0.05) between the smartphone application and 3D motion capture mea.......
Access restricted. Please log in or start a trial to view this content.
Discussion
The purpose of this validation study was to determine the validity of a freely available smartphone application in order to be clinically used as an objective and cost effective means of using smartphone technology for kinematic gait analysis in the clinical setting. Existing validation studies that examined kinematic measures with a smartphone application are limited and have not assessed dynamic kinematic measures recorded during gait in the sagittal plane. This validation study is the first to have examined kinematic .......
Access restricted. Please log in or start a trial to view this content.
Disclosures
No relevant financial relationship exists with Hudl Technique (Ubersense). Adams Physical Therapy Clinic, Novi, MI were our clinical collaborators on this study.
Acknowledgements
The authors wish to thank all the participants who generously gave their time to participate in this study.
....Access restricted. Please log in or start a trial to view this content.
Materials
| Name | Company | Catalog Number | Comments |
|---|---|---|---|
| Hudl Technique App | Hudl | Online app | Freely downladable app from adroid /apple store |
| Optotrak Certus 3D motion capture system | Northern Digital inc | Optotrak certus System | http://www.ndigital.com/msci/products/optotrak-certus/ |
| Smartphone | Apple | Iphone 5 | www.apple.com |
References
- Brunnekreef, J. J., van Uden, C. J., van Moorsel, S., Kooloos, J. G. Reliability of videotaped observational gait analysis in patients with orthopedic impairments. BMC Musculoskelet Disord. 6 (17), (2005).
- Jette, D. U., Halbert, J., Iverson, C., Miceli, E., Shah, P.
Access restricted. Please log in or start a trial to view this content.
Reprints and Permissions
