Description
【objective】
To investigate whether the instability of meniscal ramp lesion which is observed magnetic resonance imaging (MRI) in the 120-degree flexed knee position as the gap between the medial meniscus posterior horn (MMPH) and posterior meniscocapsular structure (PMS) is associated with preoperative anterior knee laxity.
【method】
Fifty patients who had a ramp lesion concomitant to anterior cruciate ligament (ACL) injury were include in this study. All patients underwent 3-Tesla MRI at 120º of knee flexion preoperatively. The gap distance of the ramp lesion on sagittal slices was measured, and a distance >1 mm was classified as unstable ramp lesion. Additionally, the joint effusion in the posteromedial recess was quantitatively evaluated by measuring the surface area of the joint fluid. Prior to surgery, the side-to-side difference (SSD) in anterior tibial translation (ATT) on stress radiographs at 20º of knee flexion was measured to evaluate anterior knee laxity. During ACL reconstruction, the length of the ramp lesion was measured by a scale from the posteromedial portal. These measurements were compared with stable and unstable group.
【result】
Twenty-nine of the 50 knees had unstable ramp lesion on MRI at knee flexion. The unstable group had significantly greater SSD in ATT and larger length of the ramp lesion than the stable group (ATT: 9.6 ± 3.6 mm versus 5.0 ± 2.7 mm, p<0.001; length: 15.7 ± 4.9 mm versus 11.7 ± 3.9 mm, p=0.002). The unstable group also had significantly more joint effusions than the stable group (p<0.001).
【conclusion】
Instability of the ramp lesion is related to greater anterior knee laxity, lesion size, and joint effusion.
