Analysis of sagittal thoracolumbar spine and hip joint movements during sit-to-stand using a 2D image analysis freeware.
Yuki Yamanaka, Tomohito Mizuno, Toshie Nagare and 1 others
PMID 36118663WHAT IT FOUND
Free 2D video software matches 3D motion capture for overall trunk angles and hip-spine coordination during sit-to-stand, but individual spine and hip angles differ before standing up.
It reliably detects the altered movement patterns in late pregnancy that total trunk angle misses.
Key findings
01Agreement between 2D free software and 3D motion analysis was high for trunk angles (CMC 0.97) and relative phase angles (CMC 0.98), but lower for thoracolumbar angles (CMC 0.85).
02Mean angle differences between the two methods were substantial for the thoracolumbar spine (6.7°) and hip (4.9°) before lift-off, but small for the spine (0.5°) after lift-off.
03In a pregnant participant, relative phase angles revealed reduced thoracolumbar flexion and delayed hip extension, changes not fully captured by trunk lean angle alone.
STILL TO COME
How it was doneWhat they foundWhat it means for PTsWhat it means for OTs
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What it does not show
The study included only seven healthy young men and one pregnant woman, so the validity of the software is not proven for older adults, people with pathologies, or diverse body types. The spine was treated as a single rigid segment, so the software cannot distinguish between thoracic and lumbar movement, which may be clinically important. The 2D software showed significant angle differences compared to the 3D system before lift-off, meaning early-phase spinal and hip angles are less reliable. The pregnancy data is from a single case, so it describes one person's pattern rather than a general rule for pregnancy-related movement changes.
Declared interests
The authors have no conflicts of interest to declare.
The easy way to misread this
Do not assume this software is accurate for every angle. While it matches 3D systems for overall trunk movement and coordination, it showed substantial differences for specific thoracolumbar and hip angles before the patient stands up. Also, do not generalize the pregnancy findings to all patients; they come from a single case.