Double-bundle ACL reconstruction with lateral extra-articular tenodesis is effective in restoring knee stability in a chronic complex ACL-injured knee model: A cadaveric biomechanical study.

PURPOSE The purpose was to compare knee stability after intra-articular isolated double-bundle (DB) anterior cruciate ligament reconstruction (ACLR) and combined single-bundle (SB) and DB ACLRs with lateral extra-articular tenodesis (LET) in a chronic complex ACL-injured knee model. METHODS For 10 fresh-frozen cadaveric knees, we measured knee laxity in the following order: (1) intact knee, (2) ACL-sectioned knee, (3) complex ACL-injured knee model with additional sectioning of the anterolateral complex (ALC), medial meniscus posterior horn (MMPH), and lateral meniscus posterior horn (LMPH), (4) SB ACLR+LET, (5) DB ACLR, and (6) DB ACLR+LET. RESULTS Compared to the intact knee, significantly increased IR laxity persisted at 60o and 90o after DB ACLR (p = .002 and p = .003). SB ACLR+LET and DB ACLR+LET resulted in significant reductions in IR laxity at 90o (p = .003 and p = .037), representing an over-constraint of internal rotation. SB ACLR+LET resulted in persistently increased external rotation (ER) laxity at 30o, 60o, and 90o (p = .001, p < .001, and p < .001). DB ACLR persistently showed significant increase in anterior translation (ANT) laxity at 60o and 90o (p = .037 and p = .024). A greater increase in ER laxity was seen in SB ACLR+LET versus DB ACLR+LET at 30o, 60o, and 90o (p < .001, p < .001, and p < .001). CONCLUSIONS DB ACLR+LET restored intact knee stability in IR, ER, and ANT laxity at 0o, 30o, 60o, and 90o of knee flexion except over-constraining IR at 90o in the chronic complex ACL-injured knee model. CLINICAL RELEVANCE This cadaveric study provides some biomechanical evidence to support performing DB ACLR combined with LET to restore knee stability after a complex, chronic knee injury, involving ACL tear combined with ALC injury and irreparable tears of the MMPH and the LMPH.