Synovial Fluid Volume at the Time of Arthroscopic Rotator Cuff Repair Correlates With Tear Size

Background Inflammatory biomarkers are increased in the synovium and tendon of rotator cuff tears. Several studies demonstrate an associated increase in these markers and size of the tear, with implications of chondral destruction leading to rotator cuff tear arthropathy and glenohumeral arthritis. Methods This is a prospective study of 105 patients undergoing arthroscopic rotator cuff repair in which intra-articular synovial fluid was aspirated just prior to arthroscopy. Adult patients with a partial or full-thickness rotator cuff tear undergoing arthroscopic repair were included, and those with inflammatory arthritis, active infection, open cuff repair, intraoperative findings of osteoarthritis, or those undergoing revision cuff repair were excluded. Results The average patient age was 58 years (range 33-74 years), with 59 (56.2%) males. The mean aspirate volume of partial tears was 0.76 ± 0.43 mL, small tears 1.46 ± 1.88 mL, medium tears 3.04 ± 2.21 mL, and large tears 6.60 ± 3.23 mL. Full-thickness versus partial tears had significantly more synovial fluid (3.64 vs. 0.76 mL, respectively, p < 0.0001). An aspiration volume of 1.5 mL or greater resulted in 91.3% specificity and 96.8% positive predictive value for a full-thickness tear. Smoking (p = 0.017), tear size (p < 0.0001), and tears of the infraspinatus (p = 0.048) were significantly correlated with synovial fluid volume. Age, body mass index, chronicity of tear, sex, subscapularis involvement, supraspinatus involvement, and teres minor involvement had no association to synovial fluid volume. Conclusion Preoperative aspiration of the glenohumeral joint to identify the volume of synovial fluid can aid to identify full-thickness rotator cuff tears, and increased fluid volume should alert the clinician of a large tear.