The correlation between posterior cruciate ligament buckling sign and meniscofemoral ligaments: A radiological study

Objectives: This study aims to investigate the correlation between posterior cruciate ligament (PCL) buckling phenomena and the presence or absence of the anterior meniscofemoral ligament (aMFL). Patients and methods: Between January 2012 and January 2019, magnetic resonance imaging of a total of knee joints of 199 patients (163 males, 16 females; mean age: 31.5 +/- 5.3 years; range, 18 to 40 years) were reviewed retrospectively. The patients were divided into four groups. The first group included 32 patients with a ruptured anterior cruciate ligament (ACL) and absent aMFL. The second group included 67 patients with a ruptured ACL and apparent aMFL. The third group included 23 patients with an intact ACL and absent aMFL, and the fourth group included 77 patients with an intact ACL and apparent aMFL. The PCL angle was used to measure the buckling degree of the ligament, as calculated as the angle between two lines drawn through the tibial and femoral central portions of the PCL insertions. We assessed the buckling phenomena of the PCL in ACL-ruptured and ACL-intact knees and examined a possible correlation between the PCL buckling angle and the presence or absence of the aMFL of Humphrey. Results: In the ruptured ACL groups (Groups 1 and 2), the mean PCL buckling angle values were 133.88 +/- 6.32 and 104.83 +/- 7.34 degrees, respectively. A significant difference was detected between both groups (p=0.026). In the intact ACL groups (Groups 3 and 4), the mean PCL buckling angle values were 143.47 +/- 5.96 and 116.77 +/- 8.38 degrees, respectively. A significant difference was detected between both groups (p=0.039). No statistically significant difference was observed between Groups 1 and 3 (p=0.13) and between Groups 2 and 4 (p=0.088). Conclusion: The PCL buckling sign is not specific for ACL ruptures, and can be seen frequently in normal knee joints which it is strongly associated with the presence of aMFL of Humphrey.