A 12-year-old girl is brought to the emergency department following a sports injury involving the right lower extremity. The patient was playing soccer when she jumped and turned to the right to avoid being kicked by another player. She landed on her right foot with her foot internally rotated and her knee extended. Since the injury, the patient has been able to bear weight but says the knee feels unstable and she is afraid that it may give way, causing her to fall. Physical examination shows swelling of the right knee. Stability testing shows excessive anterior translation of the tibia relative to the femur. Which of the following ligaments is most likely injured?

Question

A 12-year-old girl is brought to the emergency department following a sports injury involving the right lower extremity.  The patient was playing soccer when she jumped and turned to the right to avoid being kicked by another player.  She landed on her right foot with her foot internally rotated and her knee extended.  Since the injury, the patient has been able to bear weight but says the knee feels unstable and she is afraid that it may give way, causing her to fall.  Physical examination shows swelling of the right knee.  Stability testing shows excessive anterior translation of the tibia relative to the femur.  Which of the following ligaments is most likely injured?

Quizplus · Accepted Answer

11ec160b_35e6_76c1_9249_f7f2b222a935_MD0001_00 The anterior cruciate ligament (ACL) originates on the lateral femoral condyle and courses anteriorly and medially to insert on the anterior intercondylar area of the tibia. The primary function of the ACL is to prevent anterior motion of the tibia with respect to the femur, although it also plays a role in stabilizing the knee against rotatory and varus/valgus forces. The ACL is most commonly ruptured in noncontact sports that involve sudden changes in direction or excessive internal rotation or lateral (valgus) bending forces when landing from a jump. The middle geniculate artery provides the primary blood supply to the ACL, and injuries are characterized by rapid-onset hemarthrosis and knee swelling. In addition to the effusion, examination typically shows anterior laxity of the tibia relative to the femur (eg, Lachman test, anterior drawer test). (Choices B and F) The tibial (medial) collateral ligament is most commonly injured by impacts to the lateral knee. The fibular (lateral) collateral ligament is only rarely injured but may be injured by a forceful blow to the medial knee while the leg is extended. Injury to these ligaments is characterized by laxity of valgus or varus stress, respectively. (Choice C) The oblique popliteal ligament is a wide, fibrous band that connects the posterior distal femur to the posterior proximal tibia. It has small openings for nerves, vessels, and muscle insertions. Injury would allow laxity of knee hyperextension. (Choice D) The patellar ligament (tendon) is a very robust structure that represents the inferior projection of the quadriceps femoris tendon. Injury causes impaired knee extension. (Choice E) The posterior cruciate ligament extends from the medial condyle of the femur to the posterior head of the tibia. Injury causes laxity of posterior movement of the tibia with respect to the femur (eg, posterior drawer test). Educational objective: The anterior cruciate ligament (ACL) can be damaged by sudden changes in direction or awkward landings (eg, excessive internal rotation or valgus stress) during sports activity. ACL tears are typically associated with rapid-onset hemarthrosis. Physical examination shows anterior laxity of the tibia relative to the femur (eg, Lachman test, anterior drawer test).

A 12-Year-Old Girl Is Brought to the Emergency Department Following