Tibiofemoral compression force differences using laxity- and force-based initial graft tensioning techniques in the anterior cruciate ligament-reconstructed cadaveric knee.

Purpose: Our purpose was to document the tibiofemoral (TF) compression forces produced during clinical initial graft tension protocols.

Methods: An image analysis system was used to track the position of the tibia relative to the femur in 11 cadaveric knees. TF compression forces were quantified by use of thin-film pressure sensors. Before anterior cruciate ligament (ACL) reconstructions were performed with patellar tendon grafts, measurements of TF compression force were obtained from the ACL-intact knee with knee flexion. ACL reconstructions were then performed by use of "force-based" and "laxity-based" graft tension approaches. Within each approach, high- and low-tension conditions were compared with the ACL-intact condition over the range of knee flexion angles.

Results: The TF compression forces for all initial graft tension conditions were significantly greater than those of the normal knee when the knee was in full extension (0 degrees ). The TF compression forces produced with the laxity-based approach were greater than those produced with the force-based approach. However, the laxity-based approach was necessary to restore normal laxity at the time of surgery.

Conclusions: The results of this study show that initial graft tension conditions influence TF compressive forces at the time of surgery and that clinically relevant initial graft tension conditions produce different TF compressive forces.

Clinical Relevance: This study showed that the TF compression forces were greater in the ACL-reconstructed knee for all of the initial graft tension conditions when compared with the ACL-intact knee and that clinically relevant initial graft tension conditions produce different TF compressive forces.