2015 ISAKOS Biennial Congress ePoster #1372
Oval Apertures of Femoral Tunnel on the Lateral Cortex Cause a Risk of Cortical Button Fixation Failure in ACL Reconstruction
Ken Okazaki, MD, PhD, Tokyo JAPAN
Yasutaka Tashiro, MD, PhD, Kitakyushu JAPAN
Hirokazu Matsubara, MD, Fukuoka JAPAN
Hideki Mizu-uchi, MD, PhD, Fukuoka City, Fukuoka JAPAN
Satoshi Hamai, MD, Fukuoka JAPAN
Yukihide Iwamoto, MD, PhD, Fukuoka, Fukuoka JAPAN
Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kyushu University, Fukuoka, JAPAN
FDA Status Cleared
Summary: The study investigated the effect of location of drilling entry point in outside-in technique on the oval shape of tunnel aperture on the lateral femoral cortex, which could cause a fixation failure of cortical button.
In outside-in femoral tunnel drilling technique in the anterior cruciate ligament (ACL) reconstruction, surgeon can set the location of drilling entry point to create the tunnels in his/her desired directions. Development of retrograde reaming systems for the outside-in drilling has enabled to use a cortical button on the lateral femoral cortex for the fixation of graft. However, if the aperture of the oval-shaped femoral tunnel on the lateral cortex becomes bigger than half the size of the cortical button, the risk of fixation failure increases. This study investigated the effect of the location of the entry point and diameter of the femoral tunnel on the length of the major axis of the tunnel aperture in ACL reconstruction using the outside-in technique.
Simulation of femoral tunnel drilling was performed on computed tomography (CT)-based 3-dimensional (3D) bone models obtained from 40 participants. The tunnel connected the center of the ACL footprint and various points on the lateral femoral surface. The diameter of the tunnel was set at 4.2 mm, 5.2 mm, or 6 mm, depending on the commercially available outside-in surgical systems. The length of the major axis of the oval-shaped aperture on the lateral femoral surface was measured. Results: When the tunnel was introduced at 2 cm from the lateral epicondyle in a 45 anteroproximal direction, the major axis was lengthened to 130.7%± 9.0% (P < .001) of the tunnel diameter, and it was more than 6.5 mm in 65% of participants in whom a 5.2-mm-diameter tunnel was drilled. When the entry point was 3 cm from the lateral epicondyle, 60% of participants had an oval-shaped aperture with a major axis of more than 6.5 mm, even though the diameter of the tunnel was only 4.2 mm. Conclusions: The risk of fixation failure of a cortical button increases if the entry point for drilling is 2 cm or further from the lateral epicondyle and the tunnel diameter is more than 5 mm.
Clinical Relevance: This study indicates the potential risk of cortical button fixation failure caused by an oval tunnel aperture on the lateral femoral surface in ACL reconstruction using the outside-in technique