QUADRICEPS MUSCLE-CONTRACTION PROTECTS THE ANTERIOR CRUCIATE LIGAMENTDURING ANTERIOR TIBIAL TRANSLATION

The proposed skiing injury mechanism that suggests a quadriceps muscle contraction can contribute to anterior cruciate ligament rupture was biomechanically investigated. The effect of quadriceps muscle force on a knee specimen loaded to anterior cruciate ligament failure during a nterior tibial translation was studied in a human cadaveric model. In both knees from six donors, average age 41 years (range, 31 to 65), th e joint capsule and ligaments, except the anterior cruciate ligament, were cut. The quadriceps tendon, patella, patellar tendon, and menisci were left intact. One knee from each pair was randomly selected to un dergo destructive testing of the anterior cruciate ligament by anterio r tibial translation at a displacement rate of 30 mm/sec with a simult aneously applied 889 N quadriceps muscle force. The knee flexion durin g testing was 30 degrees. As a control, the contralateral knee was loa ded correspondingly, but only 5 N of quadriceps muscle force was appli ed. The ultimate load for the knee to anterior cruciate ligament failu re when tested with 889 N quadriceps muscle force was 22% +/- 18% high er than that of knees tested with 5 N of force. The linear stiffness i ncreased by 43% +/- 30%. These results did not support the speculation that a quadriceps muscle contraction contributes to anterior cruciate ligament failure. In this model, the quadriceps muscle force protecte d the anterior cruciate ligament from injury during anterior tibial tr anslation.