The validity of 2-dimensional measurement of trunk angle during dynamic tasks

Injury screening methods that use three-dimensional (3D) motion analysis accurately predict the risk of injuries, yet are expensive. There is great need for valid, cost-effective techniques that can be used in large-scale assessments. Utilizing two-dimensional (2D) measures of lateral trunk motion may identify athletes at risk for lower extremity injury. The purpose of this research was to determine the strength of the relationships between 2D and 3D calculations of lateral trunk angle for female athletes performing a single-leg cross drop landing.

Twenty-one high-school female volleyball players performed a single-leg cross drop landing onto a force plate. The 3D angular trunk motion was calculated, and four different 2D measures of lateral trunk angle were calculated for both left and right landing leg. A one-way multivariate analysis of variance was used to compare 2D measures to the 3D measurements, and Pearson correlations were used to determine the strength of these relationships.

The angle formed by the medial shoulder joint center, medial ASIS, and vertical line (LTA4) was similar to the 3D measures of lateral trunk angle during landing (r-values ≥ 0.62; p-values ≤ 0.003; mean differences, -1.0° to 1.2°).

Given the recent focus on the role of the trunk in lower extremity injury, using the 2D LTA4 assessment may expand existing assessments into a composite model that can more accurately assess female athletes at risk for injury than models that do not include trunk analysis.

Existing models that enable clinicians to effectively identify female athletes at risk for lower extremity injury may be enhanced by including accurate assessments of lateral trunk motion.