Inter- and Intrarater Reliability of the Femoral Tunnel Clock-Face Grading System During Anterior Cruciate Ligament Reconstruction

Abstract

To determine the inter- and intrarater reliability of the clock-face grading system as used by 3 fellowship-trained sports medicine surgeons. Arthroscopic video was taken of the femoral tunnel placement during 20 consecutive anterior cruciate ligament (ACL) reconstructions performed by 2 surgeons. All femoral tunnels were created using a medial portal technique. The video was taken using a 30° arthroscope placed in the lateral portal and showed 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 positions in "half-hour" increments. They were also asked to review the videos again 6months later to determine 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 (r) was applied to evaluate intrarater reliability. The inter-rater reliability as measured by the ICC revealed poor agreement between the 3 surgeons (ICC= 0.204, 95% confidence interval=-0.015 to 0.491, F=2.8, P= .004). The intrarater reliability at a 6-month interval was found to be moderate (r's= .43, P= .004). The inter-rater reliability of the clock-face femoral tunnel grading system was found to be poor among fellowship-trained sports medicine surgeons whereas the intrarater reliability was found to be moderate. The utility of the femoral tunnel clock-face grading system may be compromised by suboptimal inter- and intrarater reliability, making it less useful as a tool of communication between surgeons. Level IV, case series with poor reference standard.