Advancing ex-vivo meniscus tissue characterization: sensitivity and accuracy of shear modulus measurements via...

Non-invasive measurement of meniscal mechanical properties is critical for advancing both meniscal pathophysiology research and represents a critical advancement in musculoskeletal diagnostics. This study aimed to evaluate the accuracy and sensitivity of ultrasound-based stiffness measurements using Supersonic Shear Imaging (SSI) compared to low-strain and high-strain tensile testing and to assess the ability of SSI to detect meniscal degeneration. Sixty bovine menisci were analyzed across seven regions, covering including the tibial and femoral layers, as well as the circumferential region, using shear wave elastography (SWE) and tensile testing. To evaluate tissue degeneration, samples underwent mechanical testing both before and after being subjected to five freeze-thaw cycles. Shear stiffness values obtained from SSI were compared against tensile-derived parameters, including shear modulus at low strain, linear stiffness, and Young's modulus measured from stress-strain curves up to failure, assuming small-amplitude shear wave propagation. Depth-dependent effects in Region of Interest (ROI) selection were evaluated, and Different SSI transducers were assessed using various receiver tests. Our results demonstrate significant agreement between SSI measurements and mechanical properties: 88 % sensitivity for stiffness and Young's modulus in circumferential samples, and 91 % for shear modulus at 3 % strain in femoral and tibial regions. While intact samples showed strong positive correlations between stiffness measures, degenerated tissue exhibited inverse relationships. Our comprehensive transducer comparison and receiver tests yielded optimized protocols for ROI selection. Crucially, we identify for depth-dependent measurement artifacts, proposing the ROI selection guidelines specific to meniscal elastography. This depth-aware acquisition strategy, together with the observed sensitivity of SSI to degeneration (p < 0.001), supports its clinical utility in contexts where conventional ultrasound elastography is limited. Overall, these findings validate SSI as a sensitive technique for biomechanical assessment of the meniscus, with direct translational potential for diagnosing degeneration and monitoring post/pre surgical tissue remodeling.