Development and application of an inside-to-out drill bit for anterior cruciate ligament reconstruction.

We report a novel drilling device for anterior cruciate ligament (ACL) reconstruction that has been developed. We invented a special inside-to-out drill bit that can make a bone socket in an inside-to-out fashion. A blade at the tip of a 4.5-mm diameter drill bit closes when the drill bit is in orthograde rotation, but the blade opens when the drill bit is in reverse rotation. The special drill bit is introduced into the joint through a 4.5-mm diameter bone tunnel rotating the bit in the orthograde direction. Then the drill bit is switched to reverse rotation and is pulled backward so that it bores the bone from the inside out. We have used this special drill bit in treating 31 ACL-injured knees and have experienced no problems or complications with the procedure.