Reliability of sonographic measurements of the ulnar collateral ligament: a multi-rater prospective study.

Intrarater reliability estimates for operator 1 were 0.90-0.98 (mid-substance) and 0.91-0.99 (apex). Operator 2's values were 0.92-0.97 and 0.93-0.99, respectively. The standard error of measurement (SEM) ranged from 0.045-0.071 cm (mid-substance) and 0.023-0.067 cm (apex). The minimal detectable difference (MDD95) was 0.12-0.20 cm (mid-substance) and 0.07-0.19 cm (apex). Interrater reliability was 0.86-0.96 (mid-substance) and 0.79-0.98 (apex); most ICCs were >0.90. Measurement of UCL thickness at two locations demonstrated very good to excellent reliability with high precision. Using this protocol, two evaluators can obtain consistent UCL measurement at two positions. This finding has significant implications for the clinical evaluation of superficial tissue pathology of the same individual by two experienced practitioners.