The reliability of commonly used arthroscopic classifications of ligamentum teres pathology

The importance of the ligamentum teres (LT) in the hip is increasingly being recognized. However, the incidence of LT tears in the literature is extremely variable. Although classification systems exist their reliability in classifying LT pathology arthroscopically has not been well defined. To determine the inter- and intra-observer reliability of two existing classifications systems for the diagnosis of LT pathology at hip arthroscopy. Second, to identify key pathological findings currently not included. Four experienced hip-arthroscopists reviewed 40 standardized arthroscopic videos. Arthroscopic findings of the LT were classified using the Gray and Villar (G&V) and descriptive classification (DC). Reviewers were asked to record other relevant pathology encountered. Inter- and intra-observer reliability was defined using Fleiss-Kappa and Cohen-Kappa statistics. Both classifications demonstrated fair inter-observer reliability. The intra-observer reliability for G&V was moderate-to-substantial and for DC was slight-to-moderate. An absolute agreement rate of 10% (G&V) and 37.5% (DC) was found. Differentiation between normal, and partial or low-grade tears was a common source of disagreement. The prevalence of LT pathology was 90%. Synovitis was the most common diagnostic finding that was not included in either classification system used in this study. Arthroscopic classification of LT pathology using the G&V and the DC demonstrated only fair inter-observer reliability. The major discrepancy in interpretation was between normal, and partial or low-grade tears. The presence of synovitis was not in either classification but was considered an important arthroscopic finding. Thorough arthroscopic scrutiny reveals the prevalence of LT pathology is higher than previously reported.