Validation of the 65 degrees Howell guide for anterior cruciate ligament reconstruction

To study in cadaver knees the position of the tibial tunnel in anterior cruciate ligament (ACL) reconstruction using the 65 degrees Howell guide (Arthrotek, Ontario, CA).

Controlled laboratory study in vitro.

Twenty-one fresh-frozen cadaver knees were used. The ACL was resected and its tibial attachment was demarcated. To drill the guidewire, we used the Howell 65 degrees tibial guide, which references off of the intercondylar roof in extension to avoid impingement. The intra-articular position of the wire was digitized with a digital camera and referred to a transverse axis passing through the over-the-back position and a sagittal axis passing through the lateral aspect of the medial spine. The percentage position of the wire within the ACL attachment was also calculated, taking the posterior and medial limits as the 0% positions.

All the wires were within the ACL attachment: 17 were in the ACL posterolateral bundle attachment and the other 4 in the anteromedial. The average distance of the wire from the transverse and sagittal axes was 12 mm (SD, 3 mm) anterior and 1 mm (SD, 1 mm) lateral, respectively. The wire was positioned at 38% (SD, 16%) of the length of the ACL attachment and at 40% (SD, 17%) of the width. Eighty percent of the wires were positioned at between 35% and 48% of the attachment length.

The 65 degrees Howell guide, which positions the tibial tunnel in extension to avoid roof impingement, ensures anatomic positioning of the graft on the tibial side and reproducibility can be expected.

This study proves that a commonly used drill guide succeeds in placing the ACL graft in the tibial anatomic attachment.