Correlations between Biomechanical and Acoustoelastographic Variables in the Equine DDFT

Introduction: Tendinous lesions are common in horses with the DDFT commonly injured. Acoustoelastograghy (AEG) is a new ultrasonographic technique that evaluates tissue strain based on changes in tissue length when an external force is applied. The purpose of this study was to evaluate AEG and biomechanical properties of the DDFT. Due to the differences in weight distribution between forelimb and hindlimb and the morphological change between the proximal (cylindrical) and distal (ribbon-like) appearance of the DDFT, we hypothesized that differences would exist in AEG parameters among these limbs and locations.

Materials and Methods: Eight horses were sedated and subsequently euthanatized for reasons unrelated to the study. Cineloops of DDFTs transitioning through the loading phase of the limb were made in vivo and then after harvesting tendons ex vivo. Software was then used to determine the strain of the tendons via AEG.

Results: A two-way ANOVA with limb and location as factors was performed along with linear regression. A p-value < 0.05 was considered significant. For maximal strain, there were significant differences between proximal and distal regions (p < 0.001) but no significant differences were identified between fore and hindlimbs.

Discussion/Conclusion: During loading movements in vivo, the DDFT is subjected to translation and strain underneath the skin in relation to the transducer; ex vivo, the transducer only identifies pure strain. These data indicate that biomechanical function of the DDFT changes from the proximal and distal regions and the caution should be used when making inferences between ex vivo and in vivo data.

Acknowledgement: Supported by a grant from the Surgical Translation and Research Laboratory, UF.

No conflict of interest has been declared by the author(s).