[The articular cartilage of the patella in scanning electron microscopy]

The authors have studied 50 samples of patellar cartilage, normal and pathological, obtained by biopsy, using a scanning electron-microscope. The normal cartilage shows characteristic regular wave-like undulations. The size of these waves varied between 5,000 and 7,000 nm and the undulations were linked by regularly-spaced fibrillary bridges. In a case with an osteochondral fracture, the fracture site was covered by peripheral cartilage, as had previously been shown by Ghadially. Eighteen cases of patellar chondropathy were divisible into three groups: group I (four cases) showed fibrillary chondropathy, of cerebriform appearance and without fibres. Group II (12 cases) showed a fibrillary chondropathy with loss of geometrical regularity and a staghorn appearance. Group III (two cases) showed an oedematous chondropathy with destruction of fibres. In group II, the presence of bundles of fibres with microfractures indicates a potential for progress to frank arthrosis.