Normal Range of Patellar Tendon Elasticity Using the Sharewave Elastography Technique: An In Vivo Study in Normal Volunteers.

In-vivo investigation of tendon mechanical properties in healthy subjects using Shear Wave Elastography (SWE) techniques is a relatively new field of study. This work aims to evaluate the elastic properties of the patellar tendon in various knee range of flexion. Twenty healthy adult subjects were enrolled in the study. Shear wave speed (SWS) in the patellar tendon was measured in three different positions: Knee extended, knee semi-flexed (30°), and knee flexed (90°). Mean shear modulus was 50.9 +- 33.1 kPa in knee extension position, 137.5 +- 50.7 kPa in 30° flexion position, and 226.5 +- 60.3 kPa in 90° flexion position. The lowest shear modulus was obtained at rest with the knee in a fully extended position. These results are in agreement with those previously reported on Achilles tendon and triceps muscles. Shear modulus values obtained in our study could be considered as baseline values for further investigations in adults.