Diagnosis of cruciate knee ligament rupture: 1. Clear history of trauma. 2, Pain, swelling soon after the injury, and inability to bear weight. 3.Positive drawer test and positive Lachman test. 4.X-ray shows that there may be intercondylar spine avulsion, and drawer position film shows tibial anterior displacement of more than 5 mm. Treatment of knee cruciate ligament rupture: 1. partial rupture (positive drawer test or Lachman test) with straight splinting for 4 weeks. 2. Complete rupture (positive for both drawer test and Lachman test) within 2 weeks for emergency surgery. 3, old rupture has instability first muscle exercises, if there is no significant improvement then the cruciate ligament must be reconstructed.