Reliable sagittal plane kinematic gait assessments are feasible using low-cost webcam technology.
Robert J Saner, Edward P Washabaugh, Chandramouli Krishnan
PMID 28482201WHAT IT FOUND
In 21 healthy adults, a low-cost webcam system gave good to excellent repeatability for sagittal-plane hip and knee measurements across speeds, except stance-phase knee excursion at 1 mph when using actual toe-off events.
Key findings
01In 21 healthy adults tested twice about one week apart, the system showed good to excellent reliability for hip and knee parameters across tested speeds when using the 60:40 stance-to-swing approach (ICC 0.75 to 0.93), but lacked sufficient reliability for stance-phase knee excursion at 1 mph when using actual toe-off events.
02Minimal detectable change scores, a measure of the smallest change likely to be real, were typically 3° to 5° for hip parameters and 4° to 8° for knee parameters.
03Bland-Altman plots showed good agreement between sessions and no systematic bias for hip and knee parameters.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
21 healthy adults only, so reliability in patients with gait problems is not shown. The study tested sagittal-plane hip and knee measurements during treadmill walking, not overground walking or patient outcomes. Stance-phase knee excursion at 1 mph lacked sufficient reliability when actual toe-off events were used. The paper reports measurement repeatability, not whether the system improves clinical decisions or rehabilitation.
The easy way to misread this
Do not conclude that this webcam system is validated for clinical gait assessment in patients. It was tested in 21 healthy adults, and stance-phase knee excursion at 1 mph lacked sufficient reliability when actual toe-off events were used.