Abstract
BACKGROUND: Magnetic resonance imaging (MRI) is a reliable diagnostic tool for anterior cruciate ligament (ACL) injuries. Nonetheless, the clinical relevance of morphological changes in the posterior cruciate ligament (PCL), such as the M-shaped PCL, following ACL injuries has not been well studied. This study aimed to investigate whether the presence of M-shaped PCL was associated with meniscal and ligamentous injuries in patients with ACL injuries. METHODS: From May 2018 to May 2023, a total of 281 patients diagnosed noncontact ACL injuries with arthroscopy were retrospectively reviewed. The preoperative MRI images were examined to identify the presence of M-shaped PCL. Thirty-five patients with an M-shaped PCL were included in the study group, while 70 patients with non-M-shaped PCL were matched using 1:2 ratio by age (within 2 years) and sex to the control group. Key anatomical factors of the femur and tibia, including femoral notch width (NW), bicondylar width (BCW), notch width index (NWI), medial tibial depth (MTD), static anterior tibial subluxation (SATS), medial tibial slope (MTS), lateral tibial slope (LTS), as well as the status of meniscal and ligamentous injuries including medial and lateral menisci (LM), medial and lateral collateral ligaments, and anterolateral ligament (ALL) were assessed using MRI. The Spearman correlation coefficients and multivariate logistic regression were applied to analyze potential predictors of M-shaped PCL. RESULTS: The mean age of all patients was 34.7 ± 10.2 years, and the male-to-female ratio was 3:4 in each group. The incidence of M-shaped PCL was 12.4%. The study group demonstrated a higher proportion of ALL injuries compared to the control group (54.3% vs 31.4%, respectively; p = 0.024). In all patients, the presence of M-shaped PCL independently predicted ALL injury (p = 0.021). In the M-shaped PCL group, ALL injury was associated with NW (ρ = 0.372; p = 0.028), BCW (ρ = 0.380; p = 0.024), and SATS (ρ = 0.437; p = 0.009). Additionally, LM lesions (p = 0.041), a larger NW (p = 0.038), and SATS (p = 0.019) independently predicted ALL injury. In the non-M-shaped PCL group, LTS was correlated with ALL injury (ρ = 0.375; p = 0.001), and a larger LTS independently predicted ALL injury (p = 0.005). CONCLUSION: In patients with ACL injuries, the presence of an M-shaped PCL was associated with ALL injury. For patients with M-shaped PCL, ALL injury was associated with LM lesions, a larger NW, and SATS.