A histopathologic differentiation of tissue types in human osteoarthritic cartilage.

A histopathologic system of classifying minced human hip and knee osteoarthritic cartilage often used in organ cultures was developed. The tissue types characterizing the cartilage fragments were correlated with characteristics noted in full thickness cartilage specimens from young normal, aged and osteoarthritic cartilage. In the minced tissue specimens 3 distinct tissue types (A, B, and C) were discerned. Tissue types A and B were seen in nonfibrillated discolored as well as fibrillated osteoarthritic cartilage. Type C tissue was derived principally from chondroosteophytic spurs. Each tissue type differed in the number and organization of chondrocytes and orthochromatic and metachromatic staining of the perilacunar region and interterritorial matrix. No A, B or C tissue types were seen in normal cartilage samples derived from patients below the age of 50. Cartilage from patients above this age contained elements of all 3 tissue types.