Abstract
This study was undertaken to identify factors predisposing to cartilaginous degeneration in the patella. The test samples used were 67 patellae from males and 48 from females, totalling 115, their ages ranging from 39 to 93, averaging 65, 59 pieces from right legs and 56 pieces from left legs. The degeneration of cartilage was classified into rough surface, velvet formation, cartilage defect and peripheral hypertrophy. The cartilage surface was divided into 7 sections. The findings were classified according to sex, age, laterality and patellar morphology. 20 patellae were embedded in polyester resin and sliced. Then, the maximum thickness of cartilage on the medial and lateral facets was measured and the thickness of cartilage measured were contoured. The thickness of cartilage was studied for a relationship with the morphology of the subcartilaginous bone, and the findings were classified on this relationship. The following results were obtained; 1) In the macroscopic study, rough surface accounted for 97% of specimens, velvet formation 22%, cartilage defect 32% and peripheral hypertrophy 26%. The incidence of cartilaginous degeneration was not correlated with sex or laterality, but showed a correlation with aging. The frequency of cartilaginous degeneration was low for patellae which had little difference in size between the medial facet and lateral facet. 2) The mean maximum thickness of cartilage was 3.24±0.67mm on the medial facets and 3.68+ 0.38mm on the lateral facets. Based on the relationship between the thickness of cartilage and the morphology of the subcartilaginous bone, the patellae were classified into central, lateral and peripheral types. 3) With respect to classification by the thickness of cartilage and subcartilaginous morphology, the frequency of cartilaginous degeneration was low for the central type specimens, velvet formation and catilage defect accounted for 48% of the lateral type specimens and peripheral hypertrophy 41% of the peripheral type specimens. Of the factors which were examined in this study, aging, patellar morphology, thickness of cartilage and subcartilaginous morphology were considered responsible for cartilaginous degeneration in the patella.
