A 22-year-old man comes to the office due to intermittent right knee pain that has been increasing for the past 8 weeks. The pain began after the patient participated in a recreational soccer tournament, but he does not recall any significant injuries. He has intermittent, moderate pain associated with a sensation of "catching" in the knee while walking. At times, the patient is unable to completely extend the knee. Swelling also occurred at the joint several days after the pain began but slowly resolved. The symptoms affect the patient's daily routine, especially outdoor activities, which he has not participated in since the pain began. He has taken over-the-counter acetaminophen with inconsistent relief. On examination, gait is grossly normal. There is full range of motion of the knee with no erythema, warmth, or swelling. No ligamentous laxity is found with varus or valgus stress, or with anterior or posterior traction on the lower leg. With the knee held in internal and external rotation, flexion and extension at the knee elicit moderate pain and crepitus. X-ray of the knee is normal. Which of the following is the best next step in management of this patient?
Meniscal tears | |
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This patient most likely has a meniscal tear, which is commonly caused by a flexed knee twisting while the corresponding foot is planted. Because the level of pain at the time of injury varies, some patients (such as this one) may be unaware that an injury occurred. They may note intermittent knee pain, catching of the joint, and limitation in range of motion; tenderness of the involved joint line and abnormal knee motion may or may not be present on examination. Associated effusion often develops slowly (eg, over hours to days) and can resolve spontaneously.
Provocative tests such as the Thessaly test and/or McMurray test can confirm the diagnosis of meniscal injury. The McMurray test involves fully flexing and extending the patient's knee while the tibia is externally rotated (stresses medial meniscus) and internally rotated (stresses lateral meniscus). Pain and/or palpable locking, catching, or crepitus during the test suggests meniscal injury.
Young patients with suspected meniscal injury and effusions or mechanical symptoms (eg, catching, incomplete extension) lasting >3-4 weeks should be considered for confirmatory MRI, which can clearly visualize the internal structures (eg, menisci, ligaments) of the knee. If a meniscal tear is found, surgical consultation is recommended. In older patients, chronic tears due to cartilage degeneration and osteoarthritis are sometimes managed conservatively with rest and nonsteroidal anti-inflammatory drugs (Choice C).
(Choice A) Arthrocentesis is recommended to evaluate unexplained joint effusions. This patient's effusion has resolved, and arthrocentesis is unlikely to be useful.
(Choice B) Intraarticular glucocorticoid injections are recommended only in patients with degenerative meniscal injury due to underlying osteoarthritis.
(Choice E) Radionuclide bone scans are used to evaluate malignant, infectious, or inflammatory bone diseases. These scans can also identify occult fractures, but MRI is superior for imaging the internal structures (eg, menisci) of the knee and would also identify an occult fracture.
Educational objective:
Acute knee pain associated with catching, reduced extension, and positive provocative testing (eg, McMurray or Thessaly tests) suggests a meniscal tear. Persistent symptoms in young patients with suspected meniscal injury should be evaluated by MRI, and surgical consultation is advised for tears.