Dr. Pomeranz's Ultimate Guide to :

MRI of the Knee

Osteochondritis Dissecans (OCD)


A contour change sharply demarcated that involves the chondro-osseous surface and appears to be chronic in nature may be characterized as an osteochondral defect; one subset of osteochondral defect that occurs in young patients is osteochondritis dissecans, which can be graded when there is history of trauma.1




Osteochondritis Dissecans(OCD): Sites of Predilection

Medial Femoral Condyle1

  • Classic [69%]: Lateral aspect of medial femoral condyle on the non-weight-bearing surface
  • Inferocentral [10%]: Weight-bearing surface of the medial femoral condylar apex
  • Extended classic [6%]: Weight-bearing and non-weight-bearing surface of the medial femoral condyle

Lateral Femoral Condyle

  • Inferocentral [13%]: Apex of the lateral femoral condyle
  • Anterior [2%]: Anteropatellar portion of the femur




Osteochondritis Dissecans(OCD): Classification


Description 1


In situ bone fragment without evidence of displacement


In situ bone fragment without migration but migrated irregular cartilaginous fragment


In situ bone fragment with migrated irregular cartilaginous fragment


Migrated bone and cartilage fragment




Osteochondritis Dissecans(OCD): MRI Assessment

Signal intensity of osteochondritis dissecans or loose bodies: 1

  • [65%]: T1 and T2: Hypointense
  • [30%]: T1: Hyperintense centrally with hypointense rim
  • [5%]: T1: Hypointense or hyperintense / T2: Hyperintense




Osteochondritis Dissecans (OCD): Example

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This 17-year-old male has patellar pain in his right knee. The cause of his pain is somewhat unusual. What is the most common locale of patellofemoral osteochondritis dissecans? What is the best treatment in a juvenile? What is the underlying cause?


sagittal t2  coronal stir  sagittal t1

 Image 1 - Sagittal T2                  Image 2 - Coronal STIR              Image 3 - Sagittal T1

sagittal t2  axial t2

 Image 4 - Sagittal T2                 Image 5 - Axial T2


The unusual finding is stage 2 osteochondritis dissecans (OCD). Take note of the approximately 12 x 5 x 9 mm area of the patella just deep to the articular surface surrounded by thin linear hypointensity (arrow, image 5) suggesting fibrous attachment. A “puffy” appearance to the lesion (image 5) suggests a blister has formed in the overlying cartilage. There is no evidence of dislodgement at this time.

The most common location of patellofemoral OCD is the anterolateral femoral trochlear ridge. The best treatment in a juvenile is rest, especially if the growth plates are open. Most will heal. Sometimes lateral retinacular release is effective. The underlying cause of OCD is most likely repetitive friction microtrauma from an underlying femoral or patellofemoral dysplasia that devitalizes the superficial capsular blood supply to the bone.





Osteochondritis Dissecans (OCD): Appendix


Spontaneous Osteonecrosis Versus Osteochondritis Dissecans 


Spontaneous Osteonecrosis

Osteochondritis Dissecans

Age of onset

Middle aged and elderly



Pain, tenderness, swelling,

restricted motion

Variable; may be lacking

Typical location

Weight-bearing surface of medial femoral condyle

Non-weight-bearing surface of the medial femoral condyle

Probable pathogenesis

Trauma, related to meniscal tear; or chondral deficiency and capsular vascular devitalization

Trauma from friction and bone dysplasia


Degenerative joint disease; intra-articular osteocartilaginous bodies, fractures compartment collapse and failure

Intra-articular osteocartilaginous bodies



Osteochondritis Dissecans(OCD): References

  1. Pomeranz SJ. Gamuts & Pearls in MRI & Orthopedics. Ohio, The Merten Company, 1997.
  2. Resnick D. Diagnosis of bone and joint disorders [vol 5, 3rd ed]. Philadelphia, W.B.Saunders Co. 1995: 3539.