Shear wave elastography imaging in a porcine tendinopathy model.

objectiveTo quantify the effect of structural damage in an ex vivo animal tendinopathy model using shear wave elastography (SWE). MATERIALS AND

methodsSixteen porcine flexor tendons were injected with a 0.05 mL bolus of 1.5% collagenase solution to induce focal structural damage without surfacing tears. Control tendons were injected with saline (n = 16). Eight tendons from each group were incubated at 37 °C for 3.5 h while the remaining 8 from each group were incubated for 7 h. Tendons were mechanically stretched to 0% and 1% strain. Simultaneously, SWE was acquired proximal to, at, and distal to the injection site using a clinical ultrasound scanner.

resultsThere were significant differences in SWS (saline > collagenase) at 1% strain and 7-h incubation for all three locations (PROX p = 0.0031, ROI p = 0.001, DIST p = 0.0043). There were also significant differences at 0% strain and 7 h, but only at (p = 0.0005), and distal to (p = 0.0035), the injection site. No statistically significant differences were observed for 3.5-h incubation, at 0% or 1% strain.

conclusionsCollagenase-mediated structural damage does appear to convey decreased tissue elasticity on SWE when ex vivo tendons are incubated for 7 h. These findings suggest that SWE may be a useful tool for predicting ultimate tissue strength in tendinopathic tissues. Pull-to-failure testing should be performed in the future and are expected to show that tendons with decreased SWS, and, therefore, decreased elasticity, rupture at lower pulls forces.