Description
【Objective】 Anterior tibial subluxation (ATS) in knee extension is seen in anterior cruciate ligament (ACL) injured knees. ATS in patients with ACL-deficient might include medial meniscus dysfunction and stretching of the posterior capsule. The purpose of this study was to investigate whether posterior displacement of meniscocapsular ligament in ramp lesions were related to ATS.
【Methods】Thirty-six ACL injury patients for whom an attendant ramp lesion was observed on preoperative MRI were included in this study. All subjects received 3-T MRI at 120º of knee flexion before surgery. The gap distance of the ramp lesion on sagittal slices was measured, and a distance greater than 1 mm was classified as gap positive. Also, the presence of effusion pooled in the posteromedial recess was evaluated. Before surgery the side-to-side difference (SSD) in anterior tibial translation on stress radiographs at 20º of knee flexion and in anterior tibial subluxation on lateral radiographs in full extension were measured to evaluate anterior knee laxity. ATS was measured the distance between a perpendicular line to femoral condyles and tibial condyles with respect to the medial tibial plateau to one decimal place. During ACL reconstruction, the length of the ramp lesion was measured using a scale from the posteromedial portal.
【Result】 Twenty-one of 36knees had ramp lesion gaps greater than 1 mm on MRI at 120º of knee flexion. Gap-positive group had significantly greater ATT and ATS, larger length of ramp lesion than gap-negative group (ATT 10.3 ± 3.8 mm versus 4.8 ± 2.4 mm: p < 0.01, ATS 2.5 ± 2.2 mm versus 1.2 ± 0.9 mm: p = 0.02, length; 15.5 ± 4.7 mm versus 12.2 ± 4.2 mm: p = 0.035). Gap-positive group had significantly more joint effusion than gap-negative group (p < 0.001).
【Conclusion】The ramp lesions gap was associated with joint effusion and greater anterior knee laxity, anterior tibial subluxation.
