Sonographic examination of the common extensor tendon of the forearm at three different locations in the normal asymptomatic population

Abstract

The aim is to examine the common extensor tendon (CET) thicknesses at three locations in the normal population with ultrasound (US), to determine changes related to dominancy, age, gender, body mass index and to evaluate structural changes in normal tendons. The study included 100 normal volunteers (200 elbows). CET was examined at three landmark locations bilaterally (humeral, articular and radial) and if present, other structural abnormalities such as tendinosis (focal or diffuse tendon echogenicity changes), tears, bone changes (enthesophytes, spurs, irregularities), tendon calcification, effusion and neovascularization were noted. Common extensor tendon was thicker on the dominant side at all three locations (humeral 4.60 versus 4.22 mm, articular 3.55 versus 3.23 mm, radial 3.17 versus 2.88 mm, p < 0.001) and gradually tapered from proximal to distal, moderate relation with age and BMI was present, most pronounced at the humeral location. Bone changes (spurs, irregularities) correlated positively with age and CET thickened in the dominant arm after 42.5 years of age which was also a cut-off age for bone changes (p < 0.05). Asymptomatic tendinosis (12%) within the normal population was significantly related to the dominancy (p = 0.032) but was not influenced by age, gender, BMI, bone degeneration or tendon thickening. When interpreting CET thickness, caution should be placed on tendon measurement points in addition to variables such as age, gender, BMI, dominancy and bone changes. Structural tendon changes (tendinosis) may be encountered in the symptom free (healthy), normal population and, not tendon thickening but dominancy is a feature of this asymptomatic tendinosis.