The effect of pretwisting the ACL autograft on knee laxity.

This study was undertaken to determine whether pretwisting the bone-patellar tendon-bone autograft during primary anterior cruciate ligament (ACL) reconstruction had any effect on knee laxity. Patients were assigned to have twisted or nontwisted autografts based on the date of ACL reconstruction. The control group was comprised of 60 patients without graft twist, and the twist group was comprised of 60 patients who had 90 degrees of external twist applied to the graft prior to tibial fixation to reproduce the anatomic external twist of the native ACL. The average patient age was 28.8 years for the control group and 28.3 years for the twist group. Males accounted for 68% of the control patients and 73% of the twist patients. Meniscal tears were present in 45% of control and 52% of twist patients. Reconstructions were performed using an endoscopic, single-incision technique with interference screw fixation in the femur. Follow-up examination with KT-2000 arthrometry was performed when patients were within 10% of strength of the uninjured leg by isokinetic testing. KT-2000 testing at 30 lb revealed a mean side-to-side difference for reconstructed versus noninvolved knees of 1.06 for control patients and 1.08 for twist patients. The difference between the two groups was not statistically significant. All but three control and two twist patients had a Lachman and an anterior drawer examination graded as 0 to 1+. This difference also was not statistically significant. There were no clinical failures in either group. Furthermore, there was no statistically significant difference between groups clinically or by arthrometry when comparing tibial fixation with an interference fit screw versus suture fixation to a unicortical post. These results indicate that pretwisting the patellar tendon autograft in ACL reconstruction has no significant short-term effect on knee laxity as determined by instrumented testing or clinical examination.