Meniscus and ligament knee injuries


Knee ligaments

Knee anatomy
  • Anterior Cruciate Ligament
    • Limits anterior translation of tibia
    • 75% of all hemarthroses are caused by disruption of ACL
  • Posterior Cruciate Ligament
    • Limits posterior translation of tibia
    • Isolated injuries are rare
  • Medial Collateral Ligament
    • Provide restraint against valgus (outward) stress
  • Lateral Collateral Ligament
    • Provide restraint against varus (inward) stress

Clinical Features

  • History of locking episodes suggests a meniscal tear
  • A sensation of popping at the time of injury suggests ligamentous injury, probably complete rupture of a ligament (third-degree tear)
  • Episodes of giving way are consistent with some degree of knee instability and may indicate patellar subluxation or ligamentous rupture
  • Rapid onset (within two hours) of a large, tense effusion suggests rupture of the anterior cruciate ligament or fracture of the tibial plateau with resultant hemarthrosis, whereas slower onset (24 to 36 hours) of a mild to moderate effusion is consistent with meniscal injury or ligamentous sprain. Recurrent knee effusion after activity is consistent with meniscal injury.

ACL Injury

  • Hearing/feeling a "pop" during injury with ensuing knee instability is pathognomonic
  • Lever Sign or Lelli’s test (highest sensitivity at 94[1]-100%[2]). Demonstrated to be effective and 100% sensitive in a small ED study, especially compared to traditional methods[3].
    • Place a fist under the proximal third of the calf, opposite from tibial tuberosity
    • Apply moderate force to the anterior quadriceps
    • Heel should raise off table if there is not a complete rupture of ACL
Lever Test
  • Anterior Drawer Sign
    • Pt supine, knee flexed 90', attempt to displace tibia from femur in a forward direction
    • Displacement of >6mm compared w/ opposite knee indicates injury
  • Lachman Test
    • Pt supine, knee flexed 30', femur held w/ one hand, prox tibia pulled up w/ other hand
    • Displacement >5mm or soft end-point indicates injury
  • Pivot Shift Test
  • Segond Fracture
    • Pathognomonic for ACL tear but rare


  • Posterior Drawer Sign
    • Patient supine, knee flexed 90', attempt to displace tibia from femur in backward direction


  • Symptoms
    • "Locking" of joint or sensation of popping, clicking, or snapping
  • Signs
    • Effusions that occur after activity
    • Joint-line tenderness
  • Tests
    • McMurray, grind test only 50% Sn

Differential Diagnosis

Knee diagnoses

Acute knee injury



Segond Avulsion Fracture (ACL tear)

Ottawa knee rules

Ottawa knee rules points of tenderness

X-ray is only required in patients who have an acute injury and one or more of the following:

  • Age >55
  • Isolated tenderness of the patella
  • Tenderness at the fibular head
  • Inability flex to 90 degrees
  • Inability to walk 4 steps BOTH immediately after the injury and in the ED

Knee x-rays

  • Anteroposterior and lateral views
    • Consider sunrise if pain over patella

Diagnosis of Ligamentous and/or Meniscus Injury

  • Normally clinically diagnosed initially or referred for re-exam in 4-5 days after decrease of swelling
    • Primary medical doctor or orthopedics may later use MRI for definitive diagnosis


  • Knee brace, ice, elevation, ambulation as soon as comfortable
    • Full knee immobilization generally not indicated for single ligament injuries


  • Discharge with orthopedic surgery follow-up

See Also


  1. Deveci A, Cankaya D, Yilmaz S, Özdemir G, Arslantaş E, Bozkurt M. The arthroscopical and radiological correlation of lever sign test for the diagnosis of anterior cruciate ligament rupture. SpringerPlus. 2015; 4:830. doi:10.1186/s40064-015-1628-9.
  2. Lelli A, Di Turi RP, Spenciner DB, et al. Knee Surg Sports Traumatol Arthrosc. 2016; 24:2794.
  3. Mcquivey, K. S., Christopher, Z. K., Chung, A. S., Makovicka, J., Guettler, J., & Levasseur, K. (2019). Implementing the Lever Sign in the Emergency Department: Does it Assist in Acute Anterior Cruciate Ligament Rupture Diagnosis? A Pilot Study. The Journal of Emergency Medicine, 57(6), 805–811. doi: 10.1016/j.jemermed.2019.09.003