Laura Slane PhD, Presenter: Nothing to Disclose

Ryan J. DeWall PhD, Abstract Co-Author: Nothing to Disclose

Jack Martin, Abstract Co-Author: Nothing to Disclose

Kenneth S. Lee MD, Abstract Co-Author: Research Consultant, SuperSonic Imagine Speakers Bureau, Medical Technology Management Institute

Darryl Thelen, Abstract Co-Author: Nothing to Disclose

Middle-aged adults exhibit increased incidence of Achilles tendon and calf muscle strain injuries. Age-related changes in tendon compliance are hypothesized to be a contributing factor, but assessing tissue compliance in vivo remains challenging. Supersonic Shear Imaging is an ultrasound elastography approach that noninvasively evaluates tissue compliance by measuring shear wave propagation speed (SWS). The purpose of this study was to compare spatial variations in SWS within the Achilles tendons of young and middle-aged adults.

We recruited ten healthy young (27±4 yrs) and middle-aged adults (49±4 yrs). SWS images were collected from regions of the Achilles tendon, including the free tendon, the soleus aponeurosis and the medial gastrocnemius aponeurosis, at three ankle angles: resting (R), dorsiflexed (R-15 deg) and plantarflexed (R+15 deg). SWS data were evaluated post-hoc at regions of interest defined within tendon boundaries.

Achilles tendon SWS varied significantly with imaging location, with the greatest speeds measured in the free tendon. Ankle posture had a significant effect on SWS, with speed progressively increasing with ankle dorsiflexion along the entire tendon length. A significant, inverse relationship between resting gastrocnemius aponeurosis SWS and age (R2=0.34, p<0.01) was observed, but there were no age-effects in the free tendon or soleus aponeurosis. A similar relationship existed in the gastrocnemius aponeurosis in the dorsiflexed posture (R2=0.55, p<0.01).

We observed age-related changes in Achilles tendon SWS to be location dependent, with evidence of a significant increase in compliance in the gastrocnemius aponeurosis of middle-aged adults. Our results suggest that Achilles tendon compliance increases in a distal-to-proximal fashion, with greater compliance at the muscle-tendon junction. Middle-aged adults seem to exhibit greater tendon compliance near the muscle-tendon junction, which could give rise to localized tissue stain concentrations and hence injury risk.

These results demonstrate the potential for Supersonic Shear Imaging to quantitatively characterize spatial variations in tendon elasticity that may be affected by aging, injury and disease processes.

Slane, L, DeWall, R, Martin, J, Lee, K, Thelen, D, Supersonic Shear Imaging Identifies Potential Evidence of Localized Changes in Achilles Tendon Compliance in Middle-aged Adults.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14004941.html