Relationship between ultrasound detected tendon abnormalities, sensory system changes and clinical measures of pain and function in lateral epicondylalgia

Background: Local tendon pathology, sensory system changes and motor impairments are associated with lateral epicondylalgia. The aim of the study was to investigate the interrelationship between ultrasound detected tendon structural changes, sensory measures using quantitative sensory testing (QST), and self-reported pain and function in lateral epicondylalgia.

Methods: Both elbows of 120 adult patients with clinical diagnosis of unilateral lateral epicondylalgia were studied. Disease related clinical impairments were assessed using the Patient-Reported Tennis Elbow Evaluation (PRTEE), pain-free grip strength, pain visual analog scale (PVAS) and EuroQol (EQ-5D). Sensory system changes were evaluated using QST measures (i) pain-pressure threshold, (ii) heat and cold pain threshold, (iii) vibration sensation threshold. Ultrasound images were assessed by a trained examiner using a reliable ultrasound image grading system, and tendon pathology graded (thickening, hypoechogenicity, heterogenicity, neovascularity, enthesis changes). Univariate and multivariate linear regression analyses were used to determine the relationship between variables.

Results: Neovascularity (P = .027) was the most consistent predictor of cold hyperalgesia, and the final multivariate regression model indicated female gender, tendon hypoechogenicity and transverse tendon thickness were significant predictors of vibration sensation threshold. Heat pain threshold (P = .005) was the single best predictor of pain and disability measures with no other US or QST variables contributing to the model.

Conclusion: Generally, structural changes and sensory variables were not related, however neovascularity, hypoechogenicity and transverse tendon thickness may be related to sensory system changes in LE.