Diagnostic accuracy of clinical tests after subacromial lidocaine injection and ultrasonography for evaluating supraspinatus tendon disorder.

Background: Accurate pathoanatomic diagnosis of the cause of shoulder pain cannot rely solely on clinical tests. Similarly, diagnosis based on imaging results alone is not reliable due to the high prevalence of asymptomatic pathology. This study aims to assess the diagnostic accuracy of clinical testing with lidocaine injection and ultrasonography as a screening method for detecting supraspinatus disorders compared with magnetic resonance imaging (MRI).

Methods: Patients with supraspinatus-related shoulder pain were collected from outpatient clinics. Clinical tests, ultrasonography, and subacromial lidocaine injections were performed, with tests repeated post-injection. The results were confirmed with MRI findings.

Results: Of 78 patients, the average age was 58±6 years, with 76.9% being normal weight females. Moderate shoulder pain was reported by 75.6% of participants, predominantly on the dominant right side (84.6%), with a significant correlation (P<0.05). The Hawkins-Kennedy test (0.73) and Neer sign (0.68) had the best sensitivity, while the drop arm test (0.93) showed the highest specificity for tendon pathology. For full-thickness tears, the Hawkins-Kennedy and empty can test (0.76) had the best sensitivity, and the drop arm test (0.82) had the best specificity. Lidocaine injection reduced sensitivity but increased specificity, with the drop arm test reaching 0.96. Supraspinatus ultrasonography was over 90% accurate compared with MRI, with a kappa value above 0.7.

Conclusions: Subacromial lidocaine injection reduces sensitivity but increases the specificity of clinical tests for supraspinatus tendon disorders. Ultrasonography can be used as a screening tool for supraspinatus tendon abnormalities. Level of evidence: IV.