Quantifying frontal plane knee motion during single limb squats: reliability and validity of 2-dimensional measures
Craig R Gwynne1, Sarah A Curran1
1Cardiff School of Health Sciences, Llandaff Campus, Cardiff Metropolitan University, Wales, UK.
International Journal of Sports Physical Therapy
|December 26, 2014
Summary
Two-dimensional (2-D) analysis offers a reliable and valid method for assessing frontal plane knee alignment during squats, serving as a practical alternative to three-dimensional (3-D) motion analysis for identifying movement abnormalities.
Area of Science:
- Biomechanics
- Kinesiology
- Clinical Assessment
Background:
- Abnormal lower limb kinematics during dynamic tasks can contribute to knee conditions like patellofemoral joint (PFJt) pain.
- Accurate assessment of movement patterns is crucial for identifying at-risk individuals.
Purpose of the Study:
- To evaluate the reliability, validity, and measurement error of a clinical two-dimensional (2-D) method for quantifying frontal plane knee alignment.
- To compare 2-D assessment with established three-dimensional (3-D) motion analysis.
Main Methods:
- Nine male and nine female subjects performed single limb squats.
- Frontal plane knee alignment was measured using both 3-D motion analysis and 2-D digital video cameras.
- Statistical analyses included Pearson's correlation, intraclass correlation coefficients (ICCs), and standard error of measurement (SEM).
Main Results:
- 2-D analysis showed good correlation with 3-D measures (r = 0.64 to 0.78).
- Within-session ICC was 0.86, and between-session ICC was 0.74, indicating good reliability.
- SEM scores ranged from 2° to 4°, signifying acceptable measurement error.
Conclusions:
- 2-D measurement of lower limb alignment demonstrates good consistency and validity compared to 3-D methods.
- 2-D analysis is a clinically useful and accurate alternative to 3-D motion analysis for identifying movement patterns associated with PFJt pain.
