2.0-mm Diameter Arthroscopy versus MRI in Predicting Appropriate Surgical Management of Intra-articular Shoulder Pathology: A Blinded, Prospective Study

Background: Small-bore needle arthroscopy (SNA) has emerged as a minimally invasive diagnostic tool in outpatient orthopaedics, allowing direct intra-articular visualization and serving as a potential alternative to magnetic resonance imaging (MRI). Purpose: To compare the diagnostic accuracy of a 2.0-mm needle arthroscope with MRI and determine which more accurately predicts appropriate surgical intervention in patients with glenohumeral pathology. Study Design: Cohort study (Diagnosis); Level of evidence, 2. Methods: In this institutional review board–approved, prospective, single-center, blinded study, 30 consecutive patients scheduled for shoulder arthroscopy between May and July 2020 were enrolled. All patients underwent preoperative MRI followed by 2 diagnostic arthroscopies using a 2.0-mm SNA and a standard 4.0-mm arthroscope. Deidentified arthroscopic recordings and MRIs were reviewed by 2 blinded, fellowship-trained orthopaedic sports medicine surgeons. The standard 4.0-mm arthroscope served as the gold standard. Diagnostic agreement and appropriate treatment recommendations—reflected by Current Procedural Terminology (CPT) codes—were assessed for both SNA and MRI. Results: The 2.0-mm diameter arthroscope demonstrated superior diagnostic accuracy compared with MRI for most intra-articular shoulder pathologies, with the exception of humeral head chondromalacia. SNA showed higher sensitivity, specificity, positive predictive value (PPV), and negative predictive value in evaluating the long head of the biceps (LHB), superior labrum, infraspinatus, subscapularis, and glenoid cartilage. The strongest diagnostic agreement with the standard 4.0-mm arthroscope was observed for LHB lesions (κ = 0.73), subscapularis tears (κ = 0.66), and articular-sided supraspinatus tears (κ = 0.62). For CPT 29827 (arthroscopic rotator cuff repair), SNA yielded a higher PPV (100% vs 83.3%). Conclusion: Small-bore needle arthroscopy using a 2.0-mm platform demonstrated high diagnostic performance in identifying glenohumeral pathology, particularly involving the LHB, subscapularis, and articular-sided supraspinatus. SNA outperformed MRI in predicting the appropriate surgical procedure and may serve as a reliable diagnostic alternative in the outpatient setting.