Usefulness of clinical tests for the diagnosis of infraspinatus tendon tears

Reference

Sgroi M, Loitsch T, Reichel H, Kappe T. Diagnostic value of clinical tests for infraspinatus tendon tears. Arthroscopy 2019;35(5):1339-1347.

Synopsis

There are at least 6 established clinical tests for infraspinatus tendon tears: the Hornblower's sign, the drop sign, the Patte sign, the external rotation lag sign, the RERT, and the infraspinatus scapular retraction test. These investigators identified 115 consecutive adults who presented with shoulder pain and were scheduled for shoulder arthroscopy. Of these, 91 who met inclusion criteria (no history of shoulder surgery and no evidence of shoulder instability, adhesive capsulitis, or calcific tendinitis) underwent examination by a single expert in sports medicine, followed by arthroscopy of the shoulder with specific examination of the articular and bursal side of the infraspinatus tendon. The initial examiner was unaware of the diagnosis for each individual patient and the surgeons performing the operations were masked to the results of the clinical tests. A total of 19 full thickness tears, 8 partial thickness tears, and 64 intact infraspinatus tendons were found at surgery. Only the drop sign (positive likelihood ratio [LR+] = 2.25; negative likelihood ratio [LR-] = 0.71) and the RERT (LR+ = 1.73; LR- = 0.34) as isolated tests accurately diagnosed the infraspinatus tendon tears, with muscle weakness instead of pain being considered when interpreting the RERT. The combination of the RERT and the Patte sign (LR+ = 1.29; LR- = 0.49) showed the highest correlation with intraoperative findings. None of the tests in isolation or combination accurately discriminated between partial thickness and full thickness tears. The authors describe the 3 useful tests as follows: (1) The drop sign: the arm is passively elevated to 90 degrees with the examiner supporting the elbow with one hand while rotating the arm to maximal external rotation with the other hand. The patient is asked to hold this position for 10 seconds. The result is considered positive if the arm drops back to internal rotation by more than 5 degrees; (2) The RERT: with the arm at zero degrees of abduction, the elbow at 90 degrees of flexion, and the shoulder at a neutral rotation, the patient is asked to externally rotate the arm against the examiner's resistance, with muscle weakness (not pain alone) considered a positive result; and (3) The Patte sign: with the arm at 90 degrees of elevation and 90 degrees of external rotation, and with the elbow at 90 degrees of flexion, the patients is asked to externally rotate the arm against the examiner's resistance. Either pain or weakness is considered a positive test result.