Abstract
Background. The purpose of this study was to evaluate the reliability and validity of using US imaging for measuring Achilles tendon insertion area to the calcaneus.
Methods. Sixteen cadaveric tendons were used to compare the agreement between Achilles tendon insertion length measurements from US images with actual measurements after dissection. In addition, test-retest reliability was performed on six healthy subjects for tendon insertion length (IL), before calcaneal bone cross-sectional area (CSA) and tendon insertion angle (IA). The reliability and validity of the measurements was analyzed with intra-class correlation coefficient (ICC) and standard error of measurement (SEM).
Results. There were significant differences and poor to good agreement between US measurements and Anthropometric measurements. Using cadaveric tendons images, the measurements agreement between the observers were good to excellent for IL, bone- to-insertion length and width before calcaneal bone (ICC2,4 =.784, .935, .952). Test-retest reliability was excellent for US measurements for tendon IL (ICC2,4=.977,SEM=0.53mm), bone to IL (ICC2,4=96, SEM=0.44mm), width before calcaneal bone (ICC2,4=.946, SEM=0.51mm), GSA (ICC2,4 =.918, SEM=5.93mm(2)), and IA (ICC2,4 =.933, SEM=1.9 degrees) on healthy tendons.
Conclusions. US imaging was found to be reliable and valid to determine IL, width, and GSA of the Achilles tendon. The use of US imaging to determine Achilles tendon insertional size may be beneficial for evaluating the structural changes on disease development and progression.