[Osteochondritis dissecans - an easy classification in MRI].

AIM: For the diagnosis of osteochondritis dissecans (OD) MRI is used besides X-ray. However, there is no consensus about the necessity of MRI or the interpretation of MRI. The aim of this prospective study was to find a diagnostic concept for OD which is simple and practicale for daily routine.

METHOD: In 90 patients with OD of the knee or ankle MRI (T1- and T2-w SE) was carried out before arthroscopy. According to the interface between the osteochondral fragment and the parent bone, MRI was classified in 2 stages ("stable" or "unstable") and compared with the arthroscopic findings.

RESULTS

With the 2-stage classification of MRI, a prediction of the stability of the osteochondral fragment was possible in 92 %. Out of the 90 patients 7 (8 %) differed regarding preoperative stability in MRI compared to stability in arthroscopy. Incorrect diagnosis in MRI was only found among the patients with unstable fragments.

CONCLUSION

The chosen 2-stage classification in MRI is well suitable for the planning of stage-related therapy.