INTER- AND INTRARATER RELIABILITY OF SLAP LESION CLASSIFICATION USING MRA

This study aims to assess the inter- and intra-rater reliability of MRa in the classification of SLAP lesions using the Snyder and Maffet classification scales. MR arthrograms were identified using the Picture Archiving and Communication System (PACS). In total, 273 shoulder arthrograms were reviewed, and 20 were selected with the desired pathology. Three orthopedic surgeons and three musculoskeletal radiologists were asked to classify the SLAP lesions into one of seven categories (Snyder & Maffet classification systems). Data was collected on two separate occasions at an interval of at least two months. Inter- and intra-rater reliability were calculated using Fleiss Kappa and Cohen's Kappa, respectively. Between all raters, there was poor inter-rater reliability for each round of data collection (κ = .177, κ = .124 for rounds 1 and 2, respectively). Between orthopedic surgeons, there was poor levels of agreement (κ = -.056, κ = .114), whereas, between radiologists, there was fair to moderate agreement (κ = 0.479, κ = 0.340). Within orthopedic raters, κ values ranged from -0.059 to 0.125, indicating, at best, poor intra-rater reliability. Within radiologists, κ values ranged from 0.545 to 0.553, indicating moderate agreement within raters. The analysis determined that none of the orthopedic values for inter or intra-rater reliability could be deemed statistically different from zero. Overall, classification using MRa resulted in significant disagreement between and within raters. Trained radiologists demonstrated higher overall levels of agreement than orthopedic surgeons. In summary, when using MRa to assess SLAP lesions, the Snyder classification demonstrates poor reliability by orthopedic surgeons and moderate reliability when used by musculoskeletal radiologists.