Male Sex, Revision Surgery, Low Volume of Anterior Cruciate Ligament Remnant, and Significant Instability Are Risk Factors for Posterior Root Tear of the Lateral Meniscus in Patients Undergoing Anterior Cruciate Ligament Reconstruction

Purpose: To determine the incidence of lateral meniscus posterior root tears (LMPRTs) in patients undergoing anterior cruciate ligament (ACL) reconstruction and identify associated risk factors.

Methods: We conducted a retrospective, multicenter study using data from the Francophone Arthroscopic Society's registry. The study included all the patients in the registry who underwent ACL reconstruction surgery between June 2020 and June 2023; we excluded incomplete data. We compared delay from injury to surgery between LMPRTs group and no-LMPRTs group. Variables investigated as potential risk factors for LMPRTs included age, sex, nature of surgery (primary or revision), pivot shift test result, side-to-side laxity under anesthesia, presence of ACL remnant, occurrence of medial meniscal tear, and presence of collateral ligament injury. Risk factors were analyzed using a logistic regression model.

Results: Among the 5,359 patients analyzed, LMPRTs occurred in 7.0% (n = 375) of cases during ACL reconstruction. Mean age at surgery was 29.3 ± 10.3 years old [11-77]. Concerning delay to surgery, the mean time was 8.4 ± 23.1 weeks [0.0-347.2] in the no-LMPRTs group and 6.5 ± 10.2 weeks [0.2-61.6] in the LMPRTs group (P = .109). Univariate analysis revealed that male sex (P < .001), revision surgery (P < .001), medial meniscal injury (P = .007), ACL remnant (0% vs >70%, <10% vs >70%, 10%-30% vs >70%, >30%-50% vs >70%, >50%-70% vs >70%; P < .001), and greater pivot shift grade (P = .011) were significantly associated with a presence of LMPRTs. Age, side-to-side laxity, and collateral ligament injury were not found to be significant risk factors. In multivariate analysis, male sex, revision surgery, pivot shift test result, and a low volume of ACL remnant remained significant. Side-to-side laxity was also a significant factor in multivariate analysis.

Conclusions: This study identified male sex, revision surgery, low volume of ACL remnant, side-to-side laxity, and greater grade of pivot shift as significant risk factors for LMPRTs during ACL reconstruction.

Level of evidence: Level III, retrospective comparative case series.