Spontaneous osteonecrosis of the knee (SONK) - tibial

Case contributed by Ali Abougazia


Marked knee pain. No history of major traumatic incident.

Patient Data

Age: 65 years
Gender: Female

Medial tibial condyle subchondral low signal fracture line is seen with surrounding bone marrow edema.

Posterior horn of medial meniscus intrameniscal transverse intermediate to high signal on T1/PD is seen reaching both articular surfaces with blunting of its apex.

Degenerative joint disease.

Joint effusion.

Patchy areas of intermediate signal on all sequences is noted in femoral, and to less extent the tibial, shafts.

Case Discussion

Spontaneous osteonecrosis of the knee (SONK) associated with degenerative joint disease and posterior horn of medial meniscus degenerative tear.

The absence of trauma in history is typical for SONK, since the insult is usually repititive microtauma on osteoporotic bone, especially in old females.

The femoral and tibial marrow signal abnormality is mostly yellow to red marrow reconversion.

How to use cases

You can use Radiopaedia cases in a variety of ways to help you learn and teach.

Creating your own cases is easy.

Updating… Please wait.

 Unable to process the form. Check for errors and try again.

 Thank you for updating your details.