Purpose: To compare the postoperative rotatory knee laxity between ACL-reconstructed knees with different meniscus treatments using an electromagnetic pivot-shift measurement.
Methods: Forty-six patients with unilateral ACL reconstructions were enrolled (21 males/25 females, 25 ± 12 y.o.). Concomitant meniscus tears, if any, were repaired whenever possible during primary ACL reconstruction. At 1 year postoperatively, pivot-shift test was performed under anaesthesia during screw removal surgery and quantitatively evaluated by tibial acceleration using an electromagnetic system. The acceleration was compared between ACL-reconstructed knees with different meniscal treatments: intact, repaired and unrepaired.
Results: A concomitant meniscus tear was found in 28 knees preoperatively: lateral tears in 11 knees, medial tears in 11 knees and both medial and lateral tears in 6 knees. Postoperatively, 19 ACL-reconstructed knees had a repaired meniscus for either medial, lateral or bilateral menisci tears, and 18 knees had intact menisci pre- and post-operatively. Meanwhile, nine lateral meniscus tears were irreparable and treated by partial meniscectomy or left in situ. ACL-reconstructed knees with unrepaired lateral menisci had significantly larger pivot-shift acceleration (0.9 ± 0.7 m/s2) than those with intact menisci (0.5 ± 0.2 m/s2, p < 0.05), whereas rotatory knee laxity was similar between the knees with fully repaired menisci (0.6 ± 0.3 m/s2) and intact menisci (n.s.).
Conclusion: An unrepaired lateral meniscus tear in an ACL-reconstructed knee could lead to remaining pivot-shift postoperatively. A concomitant meniscus tear should be repaired during ACL reconstruction to restore normal rotational laxity.
Level of evidence: Therapeutic Study, Level III.
Keywords: Anterior cruciate ligament reconstruction; Meniscus repair; Pivot-shift test; Quantitative measurement; Rotatory knee laxity.