Case 05a - 26 year old female with history of Crohns, now with new knee pain
Case 5: 26 year old female with Crohn's disease and progressively worsening right knee pain.
- As it turns out, this patient had recently taken a course of high-dose steroids for a Crohn's flare, which precipitated this episode of knee pain. Steroid medications are a common cause of avascular necrosis and bone infarct.
- Bone infarcts have several important features: they are confined to the medullary space, they have serpiginous margins, and are often multifocal. The metaphyseal location is also typical.
- Other common causes of bone infarcts include trauma, sickle cell disease, radiation, connective tissues disorders, and alcohol use, although there are dozens of other causes.
- In additional to the multiple large femoral, tibial, and fibular bone infarcts, there are also subchondral areas of avascular necrosis, including a small lesion of the lateral femoral condyle and a larger lesion of the medial femoral condyle.
- Why aren't we calling these lesions subchondral fractures? While they look an awful like the preceding cases with hypointense fracture lines undercutting the cartilage, the pathophysiology differs. In this instance, the injury is caused by ischemia and not a mechanical force.
- These lesions also have a typical appearance on radiographs; again note the multiple, well-defined serpiginous lesions confined to the medullary space.
- Subchondral infarcts, synonymous with AVN, may lead to subchondral fractures which can collapse and disrupt the articular surface, leading to debilitating arthritis.
- Some orthopedists are trying stem cell injections in the area of subchondral infarcts to promote healing.
Accession: CL0034
Study description: MR OUTSIDE COMPARE
Case discussion: