Examination of the correlation between the knee extension angles in the sitting and supine positions measured using ImageJ software: a prospective cross-sectional study.
Tomoharu Nakayama, Fuka Nakajima, Hiroshi Yamasaki and 1 others
PMID 37405184WHAT IT FOUND
Sitting knee extension angles measured with a smartphone photo and ImageJ closely matched supine angles in healthy adults.
With pelvic tilt control, sitting may serve as an alternative measurement position.
Key findings
01In 25 healthy adults, the mean knee extension angle was 131.5 ± 11.2° sitting and 132.1 ± 12.2° supine, and the two measurements correlated (r=0.85, p<0.01).
02Agreement analysis showed no fixed or proportional bias, with a mean bias of 0.6° (95% CI -1.2 to 2.3) and a minimal detectable change of 12.3°.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The study included only healthy adults, so it does not show that the sitting method works in older adults, facility residents, people with disease, or people with spinal deformity. The paper states that each position was measured once for validation, not multiple times and averaged. The angle was not available on the spot because the photo had to be imported into a computer. The sitting method required a 10° metal plate, a smartphone photo, and careful control of pelvic tilt and trick motion.
Declared interests
The study received no funding from public, commercial, or not-for-profit sources, and the authors declared no conflicts of interest.
The easy way to misread this
Do not conclude that sitting knee extension measurement with ImageJ is validated for older adults or facility residents. It was tested only in healthy adults, and each position was measured once.