Viscoelasticity in Achilles tendonopathy: quantitative assessment by using real-time shear-wave elastography

Area of Science:

• Musculoskeletal imaging
• Biomechanics
• Medical ultrasonography

Background:

• Achilles tendon (AT) injuries are common, affecting athletes and the general population.
• Accurate assessment of AT viscoelastic properties is crucial for diagnosing tendonopathy.
• Real-time shear-wave elastography (SWE) offers a non-invasive method to evaluate tissue stiffness.

Purpose of the Study:

• To compare the viscoelastic properties of normal and pathologic Achilles tendons (ATs) using real-time shear-wave elastography (SWE).
• To investigate the diagnostic performance of SWE in identifying tendonopathy in the midportion of the AT.

Main Methods:

• Prospective assessment of 180 normal ATs and 30 ATs from patients with tendonopathy using B-mode ultrasonography (US) and SWE.
• Acquisition of SWE data (axial and sagittal mean velocity, relative anisotropic coefficient) in relaxed and stretched ankle positions.
• Evaluation of AT morphology, cross-sectional area, and identification of tears or signal-void areas.

Main Results:

• Tendons with tendonopathy exhibited significantly lower mean velocity compared to normal tendons across various SWE measurements (P < .001).
• Tendon softening, indicative of tendonopathy, was identified with high specificity (81.8%-91.5%) using defined mean velocity thresholds.
• Partial-thickness tears were detected as signal-void areas in 100% of cases using SWE.

Conclusions:

• SWE successfully confirms and quantifies pathologic tendon softening in the midportion of the AT in patients with tendonopathy.
• SWE did not reveal significant modifications in the viscoelastic anisotropy of the AT.
• While SWE demonstrates high specificity for tendon softening, its sensitivity for detecting AT abnormalities was relatively low.