An Investigation of the Asymptomatic Limb in Unilateral Lateral Epicondylalgia.

INTRODUCTION: Musculoskeletal ultrasound (MSUS) imaging is used to investigate features of tendinosis. Recent studies have reported tendon pathology not only in the symptomatic tendon but also in the contralateral asymptomatic tendon of animals and humans with unilateral Achilles tendinopathy. This study assessed the symptomatic and contralateral asymptomatic tendon in unilateral lateral epicondylalgia (LE) for features of tendinosis and compared with a pain-free control.

METHODS: Twenty-nine participants with clinically diagnosed unilateral LE and 32 pain-free controls (matched for age, sex, and arm dominance) underwent a blinded bilateral MSUS examination of the common extensor tendon using a standardized protocol. Grayscale features, including tendon thickening, hypoechoic region, fibrillar disruption and calcification, as well as neovascularity, were scored using separate ordinal scales. Tendon thickness and hypoechoic volume were also measured.

RESULTS: The contralateral asymptomatic tendon did not differ from the tendons of the pain-free controls. The symptomatic tendon of participants with LE revealed a significantly greater score for the following: tendon thickening (mean difference, 0.76 (95% confidence interval, 0.22-1.30)), hypoechoic changes (0.58 (0.05-1.11)), fibrillar disruption (0.97 (0.52-1.42)), and neovascularity (1.53 (0.9-2.2)) than controls. Hypoechoic volume was greater in the symptomatic arm (33.0 mm3 (8.4-57.6)), than that in the controls.

DISCUSSION: Unlike Achilles tendinopathy, MSUS examination did not reveal features of tendinosis in the contralateral asymptomatic limb beyond those present in tendons of pain-free controls.