Ultrasonography versus magnetic resonance imaging in detecting and grading common extensor tendon tear in chronic lateral epicondylitis

OBJECTIVES To investigate the diagnostic performance and reliability of ultrasonography (US) in detecting and grading common extensor tendon (CET) tear in patients with chronic lateral epicondylitis (LE), using magnetic resonance imaging (MRI) as the reference standard. MATERIALS AND METHODS The study comprised fifty-eight chronic LE patients. Each patient underwent US and MRI. CET status was classified as: high-grade tear (≥50% thickness), low-grade tear (<50% thickness), suspected tear (possible but not evident tear), no tear. Additionally, the following dichotomous scale was used: confirmed or unconfirmed CET tear. Relative US parameters (versus MRI) for detecting CET tear included: sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy. The agreement between US and MRI findings was measured using the weighted Cohen kappa coefficient (κ). RESULTS US showed moderate agreement with MRI in detecting and grading CET tear (κ = 0.49). Sensitivity, specificity, and accuracy in CET tear detecting by US were 64.52%, 85.19%, and 72.73%, respectively. PPV and NPV of US were 83.33% and 67.65%, respectively. No patient with unconfirmed CET tear on US had high-grade CET tear on MRI. CONCLUSION Ultrasonography is a valuable imaging modality that can be used as a screening tool to exclude high-grade CET tear in chronic LE patients. Once a tear is evident on US, MRI should be considered to assess precisely the extent of tendon injury.