Abstract
The purpose of this study is to identify the optimal amount of knee flexion required to drill the femoral tunnel in ACL reconstruction using the transtibial technique in order to ensure the correct alignment between the femoral tunnel and the interference screw.
Methods: Twenty (10 × 2) fresh-frozen cadaveric knees were used. The native ACL was resected and its tibial attachment was identified. The angle of the tibial tunnel was set at 55° using an Arthrex tibial guide. The extra-articular tibial tunnel entry point was located at the anterior border of the superficial MCL. The intra-articular exit point of the guide wire was digitized with a digital camera and referenced to anatomical landmarks (the anterior border of the PCL, the lateral aspect of the medial spine and the anterior horn of the lateral meniscus). The femoral tunnels were made using the transtibial technique and a 5mm femoral guide to insert guidewires at 70, 80, and 90 degrees of knee flexion (groups a, b, c respectively). The angles of divergence between the longitudinal axis of the femoral tunnel and the interference screw (placed through an anteromedial portal at 120° of knee flexion) were then measured.
Results: The degrees of divergence were: 5° ± 2° for group a, 12° ± 4 for group b, and 15° ± 3° for group c.
Conclusions: Optimal femoral tunnel and interference screw alignment is achieved using the transtibial technique when the femoral tunnel is drilled with the knee in 70 degrees of flexion and the screw is inserted at 120 degrees of knee flexion.
This study identifies a mathematical formula for the optimal amount of knee flexion required to drill the femoral tunnel in ACL reconstruction using the transtibial technique in order to ensure the correct alignement between the femoral tunnel and the interference screw.
Correspondence should be addressed to Ms Larissa Welti, Scientific Secretary, EFORT Central Office, Technoparkstrasse 1, CH-8005 Zürich, Switzerland
