Comparison of femoral and tibial pullout forces in bone-patellar tendon-bone anterior cruciate ligament reconstructions with a new interference fixation device.

Interference screws have become the standard method for fixing bone-patellar tendon-bone (BPTB) grafts. To avoid the inherent pitfalls and complications of interference screws, a 28-mm long and from 5 to 7 mm spreadable metal bolt with nontapping threads was developed for this study. The technical applicability and biomechanical characteristics of this new BPTB interference fixation device were investigated by dissection or tensile testing of 48 cadaveric knee specimens from young donors. No problems occurred with respect to bone plug anchoring during insertion of the spreading bolts. The clinically important linear load was 920+/-283 N for the femoral and 635+/-247 N for the tibial fixation site. Bone plug pullout was the mode of failure in all specimens. The results of this study indicate that the spreading bolt is a reasonable alternative to interference screws.