Differential Diagnosis

  • Achondroplasia
  • Aseptic necrosis
  • Meniscus tear
  • Osteochondritis dissecans of the medial femoral condyle
  • Punctate epiphyseal dysplasia

Figure 2.

Diagnosis
The image shows osteochondritis dissecans of the medial femoral condyle, which occurs most typically in patients between 9 and 18 years of age.

Learnings

  • Osteochondritis dissecans (OCD) of the medial femoral condyle is often the result of repetitive injury or growth disturbances
  • The knee, talar domes, and elbows are common locations, though it can occur in other locations
  • Typical OCD lesions appear as a semilunar bone fragment along the articular surface separated from the parent bone by a lucent zone
  • The OCD lesion is caused by loss of blood supply to the subarticular bone leading to a focal bone necrosis. Absorption of the necrotic bone deprives the support to over lying articular cartilage, which becomes prone to trauma, tears and fissures
  • Symptoms include pain, limited mobility of the joint and locking

Pearls for Urgent Care Management and Consideration for Transfer

  • Treatment and prognosis vary according to the age of the patient
  • In children with nondisplaced fractures, initial treatment includes limitation of activity with the use of crutches and restricted range of motion
  • Nonopioid pain medication and nonsteroidal anti-inflammatory drugs may control discomfort and swelling
  • Normal activity may be resumed upon healing of the OCD lesion, and when quadriceps strength has returned to within normal limits
  • If symptoms do not resolve in 6–12 months, surgical treatment may be required

Acknowledgment: Images courtesy of Teleradiology Specialists.

A 17-Year-Old Male with Knee Pain After a Fall
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