Reliability of the Cutting Alignment Scoring Tool (CAST) to Assess Trunk and Limb Alignment During a 45-Degree Side-Step Cut.
Lauren S Butler, Eryn K Milian, Amie DeVerna and 8 others
PMID 33842027WHAT IT FOUND
The CAST tool showed good agreement between and within raters for assessing 45-degree side-step cuts in adolescents.
Cut width was almost perfectly agreed upon, trunk lean was moderate, but knee valgus scores had only fair agreement.
Key findings
01The CAST tool demonstrated good cumulative inter-rater reliability (ICC 0.808) and good cumulative intra-rater reliability (ICC 0.753) among sports medicine providers.
02Rater agreement varied by variable: almost perfect for cut width (k=0.949), moderate for trunk lean (k=0.632), and fair for dynamic (k=0.462) and static (k=0.533) knee valgus.
03Inter-rater reliability improved from moderate in the first session to excellent in the second session, potentially due to a learning effect after a peer-to-peer discussion.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The study only evaluated reliability, not validity; it is unknown if CAST scores actually predict ACL injury risk. A two-hour peer-to-peer discussion occurred before the reliability sessions, which may have artificially inflated reliability scores due to a learning effect. The sample was small (8 athletes, 10 videos), limiting generalizability. The CAST only assesses frontal plane movements, ignoring sagittal and transverse plane mechanics relevant to ACL injury. Reliability was tested only among sports medicine providers, not coaches, who often perform these screenings. The cutting task was planned, whereas unplanned cuts (more common in sport) produce different joint loads.
Declared interests
No funding was received, and the authors declared no financial conflicts of interest.
The easy way to misread this
Do not assume the CAST predicts ACL injury risk. This study only showed that raters can agree on what they see (reliability), not that what they see accurately identifies athletes at risk for tearing their ACL (validity).