A New Test for the Advanced Diagnosis of Lateral Elbow Tendinopathy with Concomitant Intrasubstance Tear: Failure to Resist Extension Effort (the Free Test)

BACKGROUND: Lateral elbow tendinopathy (LET) is one of the most common causes of musculoskeletal pain. The diagnosis is based on the clinical history and different physical maneuvers. Ultrasound (US) is a complementary diagnostic method to detect degenerative tendon changes and intrasubstance tears (IST). To date, there is no available physical maneuver to identify an IST in patients with LET. AIM: To evaluate the diagnostic accuracy of an index test to detect an IST confirmed by ultrasound in patients with LET. METHODS: A diagnostic retrospective study was performed. Patients who presented medical records with LET were recruited. Two orthopaedic surgeons developed the physical maneuver. The index test was considered positive when the position failed to resist the wrist extension maximum effort. Clinical findings were associated with confirmation of IST by US. Data were calculated using diagnostic accuracy, sensitivity, and specificity with 95% confidence intervals. RESULTS: Thirty-nine patients (39 elbows) were analyzed, 25 (64%) women and 14 (36%) men, with an average age of 47.7 years. The index test’s sensitivity was 0.86 (95% CI, 0.67–0.96). Accuracy was 0.79 (95% CI, 0.64–0.91), and the specificity was 0.64 (95% CI, 0.31–0.89). CONCLUSION: The index test presented very good sensitivity and good accuracy in patients with LET with US diagnostic confirmation of IST. LEVEL OF EVIDENCE: Diagnostic study, Level III.