Common causes of injuries are direct blows to the flexed knee, such as the knee hitting the dashboard in a car accident or falling hard on the knee, both instances displacing the tibia<unk>  to the femur. An additional test of<unk>  injury is the<unk>  sag test, where, in contrast to the drawer test, no active force is applied. Rather, the person lies supine with the leg held by another person so that the hip is flexed to 90 degrees and the knee 90 degrees. The main parameter in this test is step-off, which is the shortest distance from the femur to a hypothetical line that tangents the surface of the tibia from the tibial tuberosity and upwards. Normally, the step-off is approximately 1 cm, but is decreased (Grade I) or even absent (Grade II) or inverse (Grade III) in injuries to the<unk> . The<unk>  drawer test is one of the tests used by doctors and physiotherapists to detect injury to the<unk> . Patients who are suspected to have a<unk>  injury should always be evaluated for other knee injuries that often occur in combination with an<unk>  injuries. These include cartilage/meniscus injuries, bone bruises, ACL tears, fractures, posterolateral injuries and collateral ligament injuries. There are four different grades of classification in which medical doctors classify a<unk>  injury: :Grade I, the<unk>  has a slight tear. :Grade II, the<unk>  ligament is minimally torn and becomes loose. :Grade III, the<unk>  is torn completely and the knee can now be categorized as unstable. :Grade IV, the ligament is damaged along with another ligament housed in the knee (i.e. ACL). With these grades of<unk>  injuries, there are different treatments available for such injuries. The<unk>  is located within the knee Mechanism In this medial view of the flexed knee, the lateral femoral condyle has been removed to reveal the structure of the<unk> . Because the anterolateral bundle is stretched and the posteromedial bundle relaxed during flexion, excessive flexion in the form of hyperflexion causes tensile stress, shown in red, on the anterolateral bundle of the ACL that leads to ACL injury. In this position, the<unk>  functions to prevent movement of the tibia in the<unk>  direction and to prevent the tilting or shifting of the patella. However, the respective laxity of the two sections makes the<unk>  susceptible to injury during hyperflexion, hyperextension, and in a mechanism known as a dashboard injury. Because ligaments are viscoelastic) they can handle higher amounts of stress only when the load is increased slowly. When hyperflexion and hyperextension occur suddenly in combination with this viscoelastic behavior, the<unk>  deforms or tears. In the third and most common mechanism, the dashboard injury mechanism, the knee experiences impact in a<unk>  direction during knee flexion toward the space above the tibia. These mechanisms occur in excessive external tibial rotation and during falls that induce a combination of extension and adduction of the tibia, which is referred to as varus-extension stress, or that occur while the knee is flexed. Treatment It is possible for the<unk>  to heal on its own. Even if the<unk>  does not heal normally, it is unusual for surgery to be required. Treatment is usually physiotherapy to strengthen the muscles around the knee; usually they provide adequate stability even without a functional<unk> . Only if there are ongoing symptoms down the track, or if there are other injuries in the knee (eg posterolateral corner injury) will ligament reconstruction be required. Ligament reconstruction is used to replace the torn<unk>  with a new ligament, which is usually a graft taken from the hamstring or Achilles tendon from a host cadaver. An arthroscope allows a complete evaluation of the entire knee joint, including the knee cap (patella), the cartilage surfaces, the meniscus, the ligaments (ACL &<unk> , and the joint lining. Then, the new ligament is attached to the bone of the thigh and lower leg with screws to hold it in place. Surgery to repair the<unk>  is controversial due to its placement and technical difficulty. It is possible for the<unk>  to heal on its own without surgery when it is a Grade I or Grade II injury.<unk>  injuries that are diagnosed in these categories can have their recovery times reduced by performing certain rehabilitative exercises. Fernandez and Pugh(2012) found that following a<unk>  grade II diagnosis, a multimodal treatment that spanned the course of 8 weeks consisting of chiropractic lumbopelvic manipulation, physiotherapy, and implementing an exercise program that emphasized eccentric muscle contraction (lunges, 1-leg squats, and trunk stabilization proved to be an effective way to recover from the<unk>  injury. For Grades III and IV, operative surgery is recommended or is usually needed. Grafts is the method when addressing<unk>  injuries that are in need of operative surgery. With grafts, there are different methods such as the tibial inlay or tunnel method.
Posterior cruciate ligament
Osborne's ligament
Median arcuate ligament
Discoid meniscus
Achilles tendon
Ligamenta flava
Pivot joint
Epiphyseal plate