A 22-year-old soccer player comes to the emergency department with knee pain. During her practice earlier that day she tried to run around another player on the right when she felt a popping sensation in her right knee followed by pain and rapid swelling. The patient has no other injury or blow to the knee. She has had no significant prior knee injuries. Her past medical history is unremarkable. On physical examination, the right knee is significantly swollen and tender. Ambulation appears awkward and she hesitates to bear weight on the right leg. Aspiration of the knee yields grossly bloody joint fluid. Which of the following is the most likely diagnosis?

Question

A 22-year-old soccer player comes to the emergency department with knee pain.  During her practice earlier that day she tried to run around another player on the right when she felt a popping sensation in her right knee followed by pain and rapid swelling.  The patient has no other injury or blow to the knee.  She has had no significant prior knee injuries.  Her past medical history is unremarkable.  On physical examination, the right knee is significantly swollen and tender.  Ambulation appears awkward and she hesitates to bear weight on the right leg.  Aspiration of the knee yields grossly bloody joint fluid.  Which of the following is the most likely diagnosis?

Quizplus · Accepted Answer

Explanation: 11ec2b69_c1d1_6a5f_8f63_490a5015983a_MD0005_00 Injuries to the anterior cruciate ligament (ACL) are common in young athletes, especially women who participate in noncontact sports requiring rapid direction changes or pivots on the lower extremity (eg, soccer, basketball, tennis). ACL tears can also occur in high-contact sports or injuries involving a blow to the knee or significant twisting force. Patients with partial- or full-thickness tears of the ACL complain of a "popping" sensation in the knee at the time of injury, followed by development of rapid-onset hemarthrosis and a feeling of joint instability with weight bearing. anterior cruciate ligament (ACL) Patients with an ACL tear will show laxity at the knee with the tibia able to be pulled forward relative to the femur. Two such maneuvers - the Lachman test and the anterior drawer test - are highly sensitive and specific for ACL injuries. The diagnosis is usually confirmed on magnetic resonance imaging. (Choice B) Medial collateral ligament (MCL) tears commonly occur following injuries in which the knee is struck from the lateral side with the foot planted. MCL injuries will usually show tenderness at the medial knee along the joint line, and there may be laxity when the lower leg is gently forced into abduction with the knee stationary (valgus stress test). However, MCL injuries are not typically associated with significant hemarthrosis unless there is a concurrent ACL injury. Medial collateral ligament (MCL) (Choice C) Patients with a meniscal tear may report a subacute or chronic locking or catching sensation in the knee but often do not appreciate the extent of the injury when it occurs. Effusions, when they occur, typically develop slowly and hemarthrosis is rare. (Choice D) Patellofemoral pain syndrome is associated with chronic overuse rather than acute trauma. Patients report pain over the anterior knee, which can be reproduced by extending the knee while compressing the patella (patellofemoral compression test). Although there may be some degree of swelling at the anterior knee, true knee effusions and hemarthrosis are not seen. Patellofemoral pain syndrome (Choice E) Rupture of a popliteal cyst (Baker cyst) may cause posterior knee pain. This is a common condition in older patients (associated with osteoarthritis of the knee) but is uncommon in young adults. Patients may have pain and swelling at the posterior knee and calf resembling deep venous thrombosis. Knee effusions and hemarthrosis are not seen. Educational objective: Patients with anterior cruciate ligament injuries complain of a "popping" sensation in the knee at the time of injury, followed by development of rapid-onset hemarthrosis and a feeling of joint instability with weight bearing. Examination findings include laxity of anterior motion of the tibia relative to the femur; the diagnosis is confirmed with magnetic resonance imaging. References: Anterior cruciate ligament rupture: differences between males and females. (http://www.ncbi.nlm.nih.gov/pubmed/23281470) Anterior cruciate ligament injuries: anatomy, physiology, biomechanics, and management. (http://www.ncbi.nlm.nih.gov/pubmed/22695402)

A 22-Year-Old Soccer Player Comes to the Emergency Department with Knee