Biomechanical comparison of single-bundle versus double-bundle anterior cruciate ligament reconstruction: a meta-analysis

BACKGROUND: Of the many issues regarding surgical techniques related to anterior cruciate ligament reconstruction (ACLR), single-bundle (SB) or double-bundle (DB) ACLR is one of the most debated topics. However, it is unclear which of the techniques yields better outcomes after ACLR for ACL injury. The purpose of this meta-analysis was to compare the benefits of SB versus DB ACLR in terms of biomechanical outcomes. METHODS: The electronic databases MEDLINE, Embase, the Cochrane Central Register of Controlled Trials, Web of Science, and Scopus were searched for relevant articles comparing the outcomes of SB-ACLR versus DB-ACLR that were published until November 2019. RESULTS: Seventeen biomechanical studies were included. The anterior laxity measured using the anterior drawer test showed significantly better results in DB-ACLR when compared with SB-ACLR. In addition, outcomes of the anterior tibial translation test under a simulated pivot shift presented with better results at low flexion and 30° in DB-ACLR, compared with SB-ACLR. However, there were no significant biomechanical differences between the groups in internal rotation. CONCLUSIONS: The present study demonstrated that both techniques for ACLR are associated with restoration of normal knee kinematics. DB-ACLR is superior to SB-ACLR in terms of restoration of anteroposterior stability. However, which technique yields better improvement in internal rotation laxity, and internal rotation laxity under a simulated pivot shift at a specific angle, remains unclear. LEVEL OF EVIDENCE: This is a level II meta-analysis.