Ulnar collateral ligament: differentiation of displaced and nondisplaced tears with US and MR imaging

To compare the usefulness of ultrasound (US) and magnetic resonance (MR) imaging in the differentiation of displaced and nondisplaced tears of the ulnar collateral ligament (UCL).

Seventeen patients (eight female and nine male, aged 14-70 years) with clinically diagnosed tears underwent examination with US and MR imaging. T1-weighted, spin-echo (SE) and T2-weighted, turbo SE sequences were used. MR and US findings were compared with those of surgery. Normal UCLs in 21 volunteers were also examined with MR imaging.

The results of US were correct in 15 patients, but displaced and nondisplaced ruptures were misinterpreted in two patients (sensitivity, 88%; specificity, 83% for displaced, 91% for nondisplaced). Sensitivity and specificity were both 100% for MR imaging. The T2-weighted sequence was more useful because the normal UCL is rarely homogeneously hypointense.

MR imaging is better than US, but both methods are useful in the evaluation of the torn UCL.