Can Suture Repair of ACL Transection Restore Normal Anteroposterior Laxity of the Knee? An Ex Vivo Study

Recent work has suggested the transected anterior cruciate ligament (ACL) can heal and support reasonable loads if repaired with sutures and a bioactive scaffold; however, use of a traditional suture configuration results in knees with increased anterior-posterior (AP) laxity. The objective was to determine whether one of five different suture repair constructs when performed at two different joint positions would restore normal AP knee laxity. AP laxity of the porcine knee at 60 degrees of flexion was evaluated for five suture repair techniques. Femoral fixation for all repair techniques utilized a suture anchor. Primary repair was to either the tibial stump, one of three bony locations in the ACL footprint, or a hybrid bony fixation. All five repairs were tied with the knee in first 30 and then 60 of flexion for a total of 10 repair constructs. Suture repair to bony fixation points within the anterior half of the normal ACL footprint resulted in knee laxity values within 0.5 mm of the ACL-intact joint when the sutures were tied with the knee at 60 degrees flexion. Suture repair to the tibial stump, or with the knee at 30 of flexion, did not restore normal AP laxity of the knee. Three specific suture repair techniques for the transected porcine ACL restored the normal AP laxity of the knee at the time of surgery. Additional studies defining the changes in laxity with cyclic loading and in vivo healing are indicated. (C) 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26: 1500-1505, 2008