Höfundar:
Haraldur Sigurðsson
Introduction: Achilles tendon (AT) injuries are frequently associated with changes in AT thickness. Healthy ATs have a uniform thickness while pathological thickening is non-uniform. Ultrasound is frequently used to measure AT thickness and differences of 1mm are clinically meaningful. Interrater reliability of ultrasound is generally insufficient to measure clinically meaningful changes in AT thickness. The aim of this study was to evaluate the interrater reliability of a structured ultrasound examination procedure.
Methods: Ten subjects with AT pathology were measured twice on non-consecutive days by 4 different ultrasound examiners. Examiners had different levels of experience ranging from 2 years to 4 sessions. Each examiner measured AT thickness on 10 cross sectional images captured at the thickest section with the narrowest width and the brightest tendon area. ICC was calculated from a random effects model for each measurement day. Confidence intervals (CI) were calculated with boothstrapping and the minimum detectable change was calculated.
Results: Interrater reliability (CI) was 0.90 (0.73 – 0.95) and 0.91 (0.76 – 0.96) for day one and day two respectively. The minimum detectable change was 1.15 (0.78 – 1.88) and 1.13 (0.79 – 1.86) for day one and day two respectively.
Conclusions: Despite very high inter rater ICC values the structured ultrasound examination procedure was not precise enough to detect 1mm changes in AT thickness. To track changes in AT thickness over time likely requires that the same ultrasound examiner perform all measurements.