The Effect of Different Sagittal Angles of the Tibial Guide on Aperture Widening of the Tibial Tunnel during Modified Transtibial Anterior Cruciate Ligament Reconstruction: A Randomized In Vivo Study

PURPOSE: The effect of sagittal plane angle of the tibial tunnel on the severity of tibial intra-articular aperture expansion caused by iatrogenic re-reaming in anterior cruciate ligament (ACL) reconstruction using a modified transtibial technique is unknown. The purpose of this study was to compare the severity of intra-articular aperture widening at different angles (40°, 45°, and 50°) of the tibial guide (TG). MATERIALS AND METHODS: Ninety-seven patients who underwent modified transtibial ACL reconstruction were randomly allocated to TG 40°, 45°, and 50° groups. Intra-articular tibial aperture width (TW) and tibial tunnel length (TTL) were measured intraoperatively using an arthroscopic ruler and a depth gauge. RESULTS: The TG 50° group had significantly greater tibial aperture widening than the TG 40° group. There was a significant difference among TG 40°, 45°, and 50° groups and the percentage of knees with TTL <35 mm was 8%, 9% and 3%, respectively. There were 2 females with TTL <35 mm in TG 40° and 45° groups each. The average mediolateral length of the tibial plateau was 75 mm. CONCLUSIONS: This study shows that the TG angle of 40° would reduce the severity of intra-articular aperture widening of the tibial tunnel compared to 45° or 50° in modified transtibial ACL reconstruction.