Purpose: In tendon research, using ultrasound (US), studies often refer to tendon thickness, structural abnormalities and neovascularisation. The reliability concerning these measurements and evaluations is seldom reported. The aim of this study was to assess the intra- and inter-observer reliability for quantitative measures (thickness) and qualitative evaluations (structure and neovascularisation) of symptomatic and asymptomatic Achilles and patellar tendons with US and colour Doppler using a modified Öhberg score.
Methods: Twenty-eight consecutive patients with symptomatic and asymptomatic Achilles (n = 27) and patellar tendons (n = 26) were included. Tendon anteroposterior thickness was measured. Tendon structure and neovascularisation were evaluated using a modified Öhberg score. US-images were evaluated twice by four independent observers.
Results: Mean thickness for Achilles and patellar tendons was 8.4 mm (±2.0) and 5.5 mm (±1.7), respectively. The reliability for measures of distance was high all over (ICC = 0.963-0.999). A moderate-strong correlation was found between observers concerning evaluation of neovascularisation (r = 0.767-0.992) and poor-moderate correlation concerning evaluation of structural changes (r = 0.379-0.837). Intra-observer reliability was moderate strong for evaluations of both tendon structure (k = 0.537-0.873) and neovascularisation (k = 0.639-0.864).
Conclusions: With a strict method for how to measure tendon thickness and set criteria for evaluating structural changes and amount and distribution of neovascularisation, US and colour Doppler is a reliable method for evaluating Achilles and patellar tendons. The modified, 4-graded, Öhberg score was found to be a reproducible instrument for assessment of tendon structure and neovascularisation.
Keywords: Echogenicity; Inter-observer reliability; Neovascularisation; Tendon structure; Öhberg score.