Measurement properties of a test battery to assess postural orientation during functional tasks in patients undergoing anterior cruciate ligament injury rehabilitation

STUDY DESIGN: Cross-sectional study. BACKGROUND: Visual rating of postural orientation during functional tasks may be a valuable tool to track rehabilitation progress following anterior cruciate ligament (ACL) injury. A valid test battery assessing postural orientation as a separate construct is lacking. OBJECTIVES: To evaluate measurement properties of a test battery to assess postural orientation in patients with ACL injury. METHODS: The content validity of functional tasks was assessed by expert focus group discussions. Fifty-one patients (45% women) with ACL injury performed 9 functional tasks of varying difficulty. Interpretability, internal consistency, interrater reliability, and measurement error were assessed for segment-specific postural orientation errors (POEs), within-task POEs, and total POE score. Postural orientation errors were scored on video on an ordinal scale from 0 (no POEs) to 3 (major POEs). RESULTS: Stair ascent, deep squat, and crossover hop for distance were excluded in focus group discussions. Postural orientation errors in some tasks were excluded due to floor effects. The minisquat and drop jump were excluded due to poor internal consistency (α≤.184). Interrater reliability values for segment-specific POEs and within-task POEs yielded fair to almost perfect agreement (κ = 0.429-0.875) and almost perfect agreement for total POE score (intraclass correlation coefficient = 0.842), without systematic differences between raters. The smallest detectable changes were 0.7 and 5 points for groups and individuals, respectively. CONCLUSION: The final test battery (single-leg mini-squat, stair descent, forward lunge, singleleg hop for distance) of 4 POEs (foot pronation, medial knee-to-foot position, hip joint POEs, and trunk segment POEs) demonstrated good measurement properties in people with ACL injury.