The Inter-rater and Intrarater Reliability of the Femoral Tunnel O'Clock Grading System During ACL Reconstruction (SS-63)

Abstract

Introduction While the o'clock grading system is widely used to describe the placement of femoral tunnels during anterior cruciate ligament (ACL) reconstruction, the inter-rater and intrarater reliability of the system remains unknown. The purpose of this study is to determine the inter-rater and intrarater reliability of the o'clock grading system as used by 3 fellowship trained sports medicine surgeons. Methods Arthroscopic video was taken of the femoral tunnel placement during 20 consecutive ACL reconstructions performed by 2 different surgeons. All femoral tunnels were created using a medial portal technique. Video was taken using a 30 degree arthroscope placed in the lateral portal and demonstrated the femoral tunnel as well as the remainder of the femoral notch, the posterior cruciate ligament and the menisci for orientation. Three fellowship trained sports medicine surgeons were asked to review the videos and assign an o'clock position to the femoral tunnel from the 9 to the 3 o'clock position in half-hour increments. They were also asked to review the videos again 6 months later to determine the intrarater reliability. Inter-rater reliability was evaluated using the intraclass correlation coefficient (ICC) 2-way mixed effect model with absolute agreement. The Spearman rank-order correlation coefficient (rs) was applied to evaluate intrarater reliability. Results The inter-rater reliability as measured by the intraclass correlation coefficient (ICC) demonstrated poor agreement between the three surgeons (ICC = .204; 95% confidence interval, –.015 to .491; F=2.8; P=.004). The intrarater reliability at a 6-month interval was found to be moderate (rs = .43, P=.004). Conclusion The inter-rater reliability of the o'clock femoral tunnel grading system was found to be poor among fellowship trained sports medicine surgeons while the intrarater reliability was found to be moderate. The utility of the femoral tunnel o'clock grading system may be compromised by suboptimal inter-rater and intrarater reliability making it less useful as a tool of communication between surgeons.