Quantifying Mechanical Properties of the Patellar and Achilles Tendons Using Ultrasound Shear Wave Elastography: A Pilot Study

(1) <b>Background</b>: Patellar and Achilles tendon injuries have become increasingly prevalent, particularly among active populations and athletes, leading to significant functional impairments. While B-Mode ultrasound has been useful in the diagnosis of these injuries, its capacity to assess tendon mechanical properties, such as stiffness, is limited. Shear wave elastography (SWE) offers a promising alternative by measuring tissue stiffness, which may enhance the evaluation of tendon health. Previous studies have established that SWE can differentiate healthy tendons from those with pathological changes. However, reference values for specific tendon types, including the patellar and Achilles tendons, remain limited. This study aims to provide preliminary baseline SWE values for these tendons in a healthy cohort. (2) <b>Methods</b>: In this cross-sectional study, healthy volunteers aged 18-65, with no history of lower extremity injury, were assessed using a Samsung RS85 Prestige ultrasound system with a 14L-2 MHz transducer. SWE measurements were obtained from the patellar tendon at a single location and from the Achilles tendon at both the midportion and insertional sites. All assessments followed a standardized protocol to ensure consistency and minimize variability. (3) <b>Results</b>: A total of 54 healthy adult participants were included. The mean SWE value for the patellar tendon was 96.3 (SD = 10.9 kPa), with males showing significantly higher stiffness than females (99.3 kPa vs. 93.8 kPa, <i>p</i> = 0.009). A higher BMI was associated with lower stiffness in the patellar tendon. The mean SWE values for the Achilles tendon were 101.7 (SD = 16.2 kPa) at the insertion and 145.6 (SD = 18.8 kPa) at the midportion. (4) <b>Conclusions</b>: This study provides SWE values for the patellar and Achilles tendons in healthy individuals, which can serve as a foundation for future research and clinical applications. These values may help in the comparison of healthy and pathological tendons, particularly in the context of tendinopathies, tendon tears, and treatment monitoring. While shear wave elasticity shows promise as a tool for diagnosing and monitoring tendon injuries and degeneration, more research is required to establish its precise reliability and validity in clinical practice.