Aim To evaluate the association between tendon structure and clinical severity. Looking specifically at location of pathology, comparing ventral versus dorsal tendinopathy.

Methods Patients were recruited from a tertiary tendinopathy center between Jan 2015 – June 2016. Inclusion criteria included patients with midportion Achilles tendinopathy, aged between 1870. Patients with insertional Achilles tendinopathy or other suspected etiology were excluded. Patients were assessed using ultrasound tissue characterization (UTC) scanning. UTC software was used to analyse a 2 cm block 24 cm from the calcaneum for percentage of echo type I, II, III and IV. With percentage echo type I+II used as the primary outcome. A doctor also categorised patients into predominately dorsal or ventral pathology based on UTC imaging. VISAA and VAS scores were used for clinical outcome measures. Statistics were undertaken using SPSS, data was not normally distributed

Results Overall 33 tendons with mid portion Achilles tendinopathy were analysed, the overall percentage echo type I+II showed no correlation to either VISAA (p=0.745, r=0.0600) or VAS (p=0.157, r=0.248). When divided into dorsal and ventral Achilles tendinopathy there was a significant difference between baseline VISAA scores with a lower VISAA score 35 (SD±19) in dorsal group compared with the ventral group 60 (SD±17.1) (p=0.009). There was also a higher VAS score in the dorsal group (mean = 6, SD±2.28) at baseline compared with ventral (mean = 5, SD±3.07), although this was not significant (p=0.416).

Conclusions This highlights the possibility of using UTC to subcategories patients into ventral and dorsal which seems to correlate to increased clinical severity in the dorsal group. This is perhaps due to increased tension and stretching acting through this part of the tendon on loading and thus more nociceptive stimulation and greater dysfunction of the tendon. This could be used to help determine differing rehabilitation interventions in future with differing intensities for the two groups. It further highlights as previous studies^1,2 have that there is no direct correlation between overall structure and clinical severity.