The Diagnostic Accuracy of Clinical Tests in Identifying Structural Change in Achilles Tendinopathy: A Pilot Study

Abstract

Background: With the development of a consensus agreement on the essential clinical diagnostic criteria for Achilles tendinopathy (AT), there is scope to investigate the diagnostic accuracy of clinical tests, their relationship to structural changes observed on ultrasound imaging (USI), and the potential role of USI in the clinical diagnosis of AT. Objectives. To evaluate the relationship between clinical tests and tendon structure via USI. Methods: A pilot cross-sectional study of 23 individuals (14 male, and 9 female) with unilateral, symptomatic AT were recruited from physiotherapy clinics. Assessment included subjective measures and patient-reported outcome measures (pain with loading, stiffness, self-reported function, Victorian Institute of Sport Assessment-Achilles [VISA-A], Pain Catastrophizing Scale, and 12-Item Short Form Survey). Objective tests included palpation, arc sign, Royal London Hospital Test, single-leg heel raise, and hopping. USI subcategorized tendon structure as normal or abnormal. Diagnostic accuracy (positivity rates, sensitivity, specificity, positive predictive value [PPV], negative predictive value [NPV]), receiver operating characteristic analysis, area under the curve (AUC), and effect sizes were calculated. Results: Stiffness and pain on palpation demonstrated high positivity rates (82.6%). Hopping pain demonstrated high positivity rates (78.3%). Pain on palpation and pain during hopping had high sensitivity (0.94) and PPV (0.84) for detecting structural abnormalities. VISA-A and self-reported function had excellent AUC (0.89) for detecting structural change. No test distinguished the degree of structural change. Conclusions: Pain on palpation and hopping pain are promising indicators of structural tendon pathology. Patient-reported outcome measures may aid in imaging decisions. Further studies are needed to validate findings. Level of Evidence: Level IV.