title: Sonoelastography shows that Achilles tendons with insertional tendinopathy are harder than asymptomatic tendons.
abstract: OBJECTIVE
  To seek differences of Achilles tendon hardness between insertional tendinopathy (IT) and asymptomatic controls by using computer-assisted quantification on axial-strain sonoelastography (ASE).
  
  
  METHODS
  The study consisted of 37 non-athletic patients presenting with Achilles tendon pain in one or two tendons. Both tendons were examined clinically. Among the 74 tendons, 16 were diagnosed and categorized into an IT group and 29 into an asymptomatic group. The remaining 29 tendons were excluded due to non-insertional tendinopathy, ruptures, previous surgery or mixed disorders. The tendons in the IT and asymptomatic groups were examined with both ASE and conventional ultrasound. Computer-assisted quantification on ASE was conducted to extract parameters of tendon hardness, including the 20th percentile (H20), median (H50) and skewness (Hsk) of the hardness within tendon, as well as the ratio of the mean hardness within tendon to that outside tendon (Hratio).
  
  
  RESULTS
  The H20 (p = 0.003), H50 (p = 0.004) and Hratio (p = 0.002) were larger and Hsk (p = 0.001) was smaller at distal thirds of IT tendons than those of asymptomatic tendons. For differentiation between two groups, the Hsk achieved the best value (0.815) of area under the receiver operating characteristic curve, with a sensitivity of 81.3 %, a specificity of 86.2 % and an accuracy of 84.4 %.
  
  
  CONCLUSIONS
  Computer-assisted quantification on ASE shows that IT tendons are harder than asymptomatic tendons. It might act as a potentially useful technique for identification and risk stratification of IT patients and thus be valuable in day-by-day clinical practice for monitoring IT progression and for evaluating therapeutic effects.
  
  
  METHODS
  III.
authors.affiliation: Institute of Biomedical Engineering, Shanghai University, Shanghai, 200444, China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: Department of Ultrasound, Huashan Hospital, Fudan University, No. 12, Urumqi Middle Road, Shanghai, 200438, China. sunnei@msn.com.
authors.forename: Yehua
authors.initials: Y
authors.lastname: Cai
authors.affiliation: Department of Sports Medicine, Huashan Hospital, Fudan University, No. 12, Urumqi Middle Road, Shanghai, 200438, China. huayh_huashan@163.com.
authors.forename: Yinghui
authors.identifier: http://orcid.org/0000-0001-7041-643X
authors.initials: Y
authors.lastname: Hua
authors.affiliation: Institute of Biomedical Engineering, Shanghai University, Shanghai, 200444, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Shi
authors.affiliation: Department of Electronic Engineering, Fudan University, Shanghai, 200433, China.
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Ultrasound, Huashan Hospital, Fudan University, No. 12, Urumqi Middle Road, Shanghai, 200438, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Wang
mesh_terms: D000125:Achilles Tendon / Q000000981:diagnostic imaging* / Q000293:injuries; D000293:Adolescent; D000328:Adult; D058070:Asymptomatic Diseases; D003936:Diagnosis, Computer-Assisted; D054459:Elasticity Imaging Techniques / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012421:Rupture / Q000000981:diagnostic imaging; D012680:Sensitivity and Specificity; D052256:Tendinopathy / Q000000981:diagnostic imaging*; D055815:Young Adult
keywords: Achilles tendon; Computer-assisted quantification; Insertional tendinopathy; Sonoelastography; Tissue elasticity; Tissue hardness