Reliability of crural fascia and Achilles tendon excursion using ultrasound imaging : a pilot study

Abstract

BACKGROUND: There has been recent interest in the role of gliding and sliding of connective tissue, such as tendons and fascia, in joint dysfunction. To date there are few studies that have investigated Achilles tendon (AT) excursion in vivo, and none that have investigated crural fascia (CF) excursion. Quantifying CF and AT excursion could provide valuable baseline information in relation to aetiology, diagnosis and management of AT disorders such as AT tendinopathy, and AT ruptures. AIM: i) to establish the intra- and inter-session reliability of high-resolution-ultrasound imaging (USI) to quantify tissue excursion of the CF and AT; and ii) undertake a preliminary assessment of CF and AT excursion and explore the correlation with ankle dorsiflexion range of motion (ROM). METHODS: High-resolution, B-mode, USI and a cross-correlation algorithm were utilised to investigate longitudinal CF and AT excursion (n=10 participants, mean ±SD age=34.7 ±18.9 years), through total ankle ROM. Participants attended two data collection sessions. The reliability of extracting excursion measurements from cine-loops was analysed for the CF and AT. Intra-session and inter-session (intra-rater) reliability was analysed for AT excursion. RESULTS: Extraction reliability for the CF was ‘moderate’ (ICC = 0.56 (95%CI = -0.11 – 0.88), while the AT was ‘very good’ (ICC = 0.86, 95%CI = 0.53 – 0.96). AT excursion was 14.25 ± 4.86mm during active ROM and 12.26 ± 5.55 mm during passive ROM. ICCs for all intra-session AT excursion data were ‘very large’ or ‘nearly perfect’ (ICC=0.89, 95%CI = 0.57 – 0.97 for active ROM; and ICC=0.96, 95%CI = 0.84 – 0.99 for passive ROM). ICCs for inter-session AT excursion data were ‘very large’ (ICC=0.80, 95%CI =0.19 – 0.95 for active ROM; and ICC=0.88, 95%CI =0.53 – 0.97 for passive ROM). There was a ‘large’ statistically significant correlation between passive plantarflexion ROM and passive AT excursion (r=0.67, p=0.04). CONCLUSION: Frame-by-frame cross correlation analysis of AT excursion during active and passive movement in vivo is reliable. Establishing normative data for AT excursion in large samples is recommended, as it would provide a baseline to use in the assessment of AT excursion for post-surgery and post rehabilitation interventions. Future studies evaluating and comparing AT excursion in populations with AT pathology such as tendinopathy are of clinical value and may inform ideas about the aetiology and management of AT disorders.