Objectives: To assess the distribution of microvascular response on colour Doppler (CD) and power Doppler (PD) ultrasound (US) of the tendo Achilles (TA) in tendonopathy, and to look for any relationship between tendon morphology and symptoms.
Design and patients: A retrospective, observational study was carried out on consecutive ambulant US patients with suspected tendonopathy, presenting with pain or an Achilles mass. Exclusion criteria were: use of steroids, and previous or possible rupture or surgery in either tendon or arthropathy. Using a 5-12 MHz linear array probe (ATL HDI 3000) both TAs were scanned. Tendonopathy was defined as tendon swelling and/or hypoechogenicity of the TA. The site, number and distribution of microvascularity, on CD and PD, and the anteroposterior size were recorded, with the analysis masked.
Results: Fifty-two patients presented with TA pain and six also with swelling. There were 34 males and 18 females, aged from 11 to 78 years (mean 45 years). Fifty-five TAs that showed tendonopathy with hypoechogenic areas were all observed to be over 5.9 mm (mean 11.1 mm, range 5.9-20 mm), of which 45 were symptomatic with abnormal PD and 24 with abnormal CD flow. It was observed that the extent and completeness of vessel branching was more extensive on PD than CD. All TAs demonstrating tendonopathy were over 5.9 mm in adults and all TAs that showed PD flow were over 6.5 mm. All microvessels originated towards the TA from the ventral surface usually into tendonopathy, and were 16-fold more frequent around the margins. There were 49 TAs with normal spectral US, and with no PD flow, with a mean size of 4.5 mm (range 3.0-7.4 mm). For the right and left TAs independently analysed and taking the 40 patients with a paired asymptomatic and symptomatic tendon: (1) There was a highly significant difference in size (P<0.00001) using the paired t-test (parametric) between the asymptomatic tendon (mean 5.2+/-1.4 mm (1 SD)), and the contralateral morphologically abnormal and symptomatic side (mean 9.7+/-1.4 mm). (2) There was no linear Pearson correlation (0.25) between TA size and duration of symptoms (P=0.11) for symptomatic tendons. (3) There was a positive Spearman correlation (0.84) between the number of vessels and TA size (P<0.00001). (4) There was a significant difference in the number of PD vessels using the non-parametric Wilcoxon signed test (P<0.00001) between the symptomatic and asymptomatic groups.
Conclusions: (1) PD shows more tendon microvascularity than CD in TA tendonopathy. (2) All microvessels arise on the ventral side of the TA. (3) There is a non-linear relationship between tendonopathy, TA size and the amount of microvascularity, but not between PD and duration of symptoms. (4) Morphologically abnormal adult TAs were larger than 5.9 mm, and PD flow was only seen in TAs above 6.5 mm.