Topographical and histological examination of osteophytes taken from arthrotic femoral heads.

Until now it is not known whether osteophytes of the femoral head develop because of pathological joint alterations or arise from normal remodeling processes secondary to osteoarthrosis. Firstly, we analysed the topographical localization of osteophytes. We then compared the extracellular matrix components of macroscopically normal cartilage from the margin of osteophytes with osteophytic cartilage from weight bearing and non-weight bearing zones by histochemical staining of low and heavily sulfated glycosaminoglycans. For examination 65 femoral heads were taken during endoprosthetic hip surgery. Osteophytes from different locations and macroscopically normal cartilage from the margin of osteophytes were excised, decalcified and embedded in paraplast. A lateral or medial localization of osteophytes (47 cases) was more common than a ventral or dorsal position (18 cases). Histochemical staining for low and heavily sulfated glycosaminoglycans from normal cartilage at the rim of osteophytes was stronger in the unmineralized cartilaginous zones compared to the mineralized cartilaginous zone. Weight bearing zones of osteophytic cartilage, on the other hand, showed an even distribution of the two differently sulfated glycosaminoglycans. Surprisingly, non-weight bearing zones of osteophytic cartilage showed a weaker staining for low and especially for heavily sulfated glycosaminoglycans in the superficial cartilage layer than in the deep cartilage layer. Altogether, osteophytic cartilage can be regarded as a reparative phenomenon for two reasons: Firstly, osteophytes arise very often at the weight bearing lateral and medial femoral head. Secondly, despite local differences in osteophytic cartilage, the same types of glycosaminoglycans are synthesized as in normal cartilage at the margin of osteophytes.