REPRODUCIBILITY OF TENDON AND APONEUROSIS DISPLACEMENT USING AN AUTOMATED TRACKING SYSTEM.

Abstract

Ultrasonography of tendinous displacement during isometric contraction requires subsequent measurement of separate images, which may be associated with human error and bias. Automated techniques that reduce ôthe human factorö can potentially provide more accurate and reliable diplacement data. PURPOSE: To evaluate intra-observer and interobserver reliability of tendinous displacement using a newly developed automated tracking system. METHODS: Separate real-time US video sequences from graded isometric contractions (n = 6) were obtained at the level of the triceps surae aponeurosis and the Achilles tendon, respectively. Two observers (Observer 1 and Observer 2) performed the analyses independently. In the first frame of each video sequence the observers placed nine tracking markers on 1) muscle fascicle/aponeurosis cross points, and 2) on Achilles intratendinous marker (thin needle). Thereafter automated displacement measurement was performed by a computerized tracking algorithm. Each sequence was measured four times followed by one attempt to reproduce the highest deformation value. Results are shown as mean sem and coefficient of variation (CV) for duplicate measures of the aponeurosis and the tendon trial. Results are based on the two highest highest values. RESULTS: There were no systematic differences within or between observer data. Displacement of the aponeurosis was 12.21 ± 1.69 mm, 12.25 ± 1.69 mm, CV = 0.6% for Observer 1, and 12.07 ± 1.63 mm, 12.00 ± 1.62 mm, CV= 1.3% for Observer 2. Displacement of the tendon was 4.89 ± 0.74 mm, 4.82 ± 0.74 mm, CV = 1.9% for Observer 1, and 4.82 ± 0.73 mm, 4.80 ± 0.72 mm, CV = 0.3% for Observer 2. Between observers data yielded r2 = 0.99 and CV = 1.5% for the aponeurosis, and r2 = 0.99 and CV = 0.6% for the tendon. CONCLUSION: Repeated measurements of tendinous displacement using automated tracking yield highly reproducible results both within and between observers for both aponeurosis and Achilles tendon displacement.