Repair of Ramp Lesions of the Medial Meniscus With ACL Reconstruction Can Better Restore Knee Stability: A Cadaveric Study.

BACKGROUND: Ramp lesions of the medial meniscus have an impact on joint stability in anterior cruciate ligament (ACL)-deficient knees, but the impact of lesion length and repair is unclear.

PURPOSE/HYPOTHESIS: The purpose of this cadaveric study was to evaluate the effect of medial meniscal ramp lesion repair on the biomechanics of ACL-deficient knee joints. It was hypothesized that (1) ramp lesions will increase the anterior tibial translation (ATT), internal rotation (IR), and external rotation (ER) in ACL-deficient knee joints; (2) increasing the length of the ramp lesion will further increase the ATT, IR, and ER; and (3) repairing the ramp lesion will reduce the ATT, IR, and ER after ACL reconstruction.

STUDY DESIGN: Controlled laboratory study.

METHODS: Included were 9 fresh-frozen cadaveric specimens (4 left knees, 5 right knees; 6 males and 3 females; mean age, 60 years [range, 40-73 years]). The specimens were tested on a biomechanical rig. Two external loading conditions were applied: a 134-N anterior tibial load and 5-N·m internal/external tibial torque with the knee at full extension and at 15°, 30°, 60°, and 90° of flexion. ATT was tracked via a high-speed video camera. The following knee states were tested: intact; ACL-deficient; ACL-deficient combined with a 5-, 10-, 15-, or 20 mm-long ramp lesion of the medial meniscus; ACL reconstruction; and ACL reconstruction combined with ramp lesion repair. The ATT, IR, and ER at all knee angles were analyzed by 1-way analysis of variance.

RESULTS: The ATT, IR, and ER were significantly increased after cutting of the ACL ( P < .05). The ATT, IR, and ER continued to increase when ACL deficiency was combined with ramp lesions of 5 to 20 mm in length ( P < .05). The ATT, IR, and ER significantly decreased after ACL reconstruction and ACL reconstruction combined with ramp lesion repair ( P < .05).

CONCLUSION: The laxity of knees with ACL deficiency combined with a ramp lesion of the medial meniscus increased more obviously as the ramp lesion increased in length. In a cadaveric model, ACL reconstruction combined with ramp repair improved knee joint stability.