BACKGROUND: Lateral meniscus (LM) posterior root tear (PRT) is often associated with anterior cruciate ligament (ACL) injury and can result in rotational instability, joint overloading, and degenerative changes in the knee. Improved rotational stability and kinematics have been reported after LMPRT repair. However, it is unclear what repair technique can achieve the greatest reduction in LM extrusion (LME). HYPOTHESIS: We hypothesized that transtibial pullout repair would decrease LME to a greater extent than other repair techniques. PATIENTS AND METHODS: Seventeen patients with ACL injury and complete LMPRT were evaluated. Nine underwent ACL reconstruction (ACLR) and transtibial pullout repair, and eight underwent ACLR and other repairs such as inside-out suturing. Double-bundle ACLR was performed using hamstring tendons, and LMPRT pullout repair was performed through the bone tunnel for the posterolateral bundle. Magnetic resonance imaging was performed immediately preoperatively and at>6 months postoperatively, and LME was measured from coronal images only. RESULTS: A significantly greater decrease in the value of LME from pre- to postoperative measurement was observed in the transtibial pullout repair group (-0.5±0.7mm) than in the other-repair group (1.0±0.9mm, p<0.01). Pre- and postoperative LME measurements were not significantly different between the two groups. DISCUSSION: The most important finding of this study was that transtibial pullout repair resulted in a greater decrease in LME than other repair techniques in patients with ACL injury and LMPRT. This technique might be useful for restoring hoop tension by decreasing LME. LEVEL OF EVIDENCE: III, comparative retrospective study.