Osgood Schlatter lesion: histologic features of slipped anterior tibial tubercle.

No study reports the histological features of the various zone of the anterior tubercle of the tibia in the different stages of the Osgood-Schlatter (O-S) lesion. For this reason we carried on an histological study. Specimens were taken from 13 patients with O-S lesion prior to surgery. In 4 cases in the apophyseal stage lesions were present in an altered fibrocartilage anterior to the ossification centre. In 9 cases in the epiphyseal stage varying degrees of reparative tissues were observed in the bed of the fragment of the secondary ossification centre. In 3 of them a zone of lesion was observed within the fibrocartilage anterior to the ossification centre. These results suggest that the slippage of the patellar tendon insertion may be progressive and caused by pathological fibrocartilage.