Ultrasound elastography of lateral epicondylosis: clinical feasibility of quantitative elastographic measurements

The objective of our study was to investigate the clinical feasibility of ultrasound elastography for assessing patients with lateral epicondylosis and to establish an objective and quantitative method of elastographic measurement in the affected tendon. A total of 97 symptomatic and 89 asymptomatic common extensor tendons from both elbows of 79 consecutive patients with lateral epicondylosis and 14 healthy participants were prospectively examined by gray-scale sonography, color Doppler sonography, and compression-based elastography. Real-time color-coded elastography was performed and quantified with two regions of interest: the adjacent subcutis (S1) for a reference area and the common extensor tendon (S2) for the target area. The mean strain ratio (S1/S2) was used for quantitative comparisons. The difference in the mean strain ratio between symptomatic and asymptomatic tendons was assessed with conditional regression analysis. In symptomatic elbows, 87 of 97 tendons (89.7%) showed intratendinous hypoechogenicity, 86 of 97 (88.7%) showed swelling, and 70 of 97 tendons (72.2%) showed intratendinous hyperemia. Color-coded elastography revealed a soft area on 73 of 97 tendons (75.3%). The mean strain ratio was 1.45 (SD, 0.45) for symptomatic tendons and 2.07 (SD, 0.70) for asymptomatic tendons. The mean strain ratio of the symptomatic tendons was significantly lower than that of asymptomatic tendons (p < 0.001), indicating that the symptomatic tendons were softer. Our results revealed that patients with lateral epicondylosis had significantly lower strain ratios in their common extensor tendon origins. Ultrasound elastography using quantitative strain ratio measurements could be a promising supplementary method to evaluate tendon abnormalities in lateral epicondylosis.