The Journal of Bone and Joint Surgery, Vol 65, Issue 6 797-807, Copyright © 1983 by Journal of Bone and Joint Surgery, Inc
Legg-Calve-Perthes disease. Histochemical and ultrastructural observations of the epiphyseal cartilage and physis
IV Ponseti, JA Maynard, SL Weinstein, EG Ippolito and JG Pous
Biopsy specimens of the lateral aspect of the femoral head and neck were
obtained from five children with Legg-Calve-Perthes disease and were
studied using histochemistry and electron microscopy. Beneath the normal
articular cartilage there was a thick zone of hyaline (epiphyseal)
cartilage containing sharply demarcated areas of hypercellular and
fibrillated cartilage with prominent blood vessels. The fibrillated
cartilage was strongly positive to alcian blue, weakly positive to periodic
acid-Schiff, and positive to aniline blue. The interterritorial matrix in
the hypercellular areas was weakly positive to both alcian blue and
periodic acid-Schiff. Ultrastructural examination of these areas revealed
many irregularly oriented large collagen fibrils and variable amounts of
proteoglycan granules. These results suggest that in the fibrillar areas
there are: (1) a high proteoglycan content, (2) a decrease in structural
glycoproteins, and (3) a different size of collagen fibrils from that of
normal epiphyseal cartilage. The hypercellular areas had a decrease in
proteoglycans, glycoproteins, and collagen. The lateral physeal margin was
often irregular, with a marked reduction of collagen and proteoglycan
granules, and contained numerous large lipid inclusions. CLINICAL
RELEVANCE: The abnormal areas in the epiphyseal cartilage of patients with
Legg-Calve-Perthes disease have different histochemical and structural
properties from normal cartilage and from fibrocartilage. This suggests
that the disease could be a localized expression of a generalized,
transient disorder of epiphyseal cartilage that is responsible for delayed
skeletal maturation. The cartilage lesions are similar to those seen in the
vertebral plates in patients with juvenile kyphosis. Whether the epiphyseal
cartilage abnormalities are primary or are secondary to ischemia remains
uncertain; however, it appears that the collapse and necrosis of the
femoral head could result from the breakdown and disorganization of the
matrix of the epiphyseal cartilage, followed by abnormal ossification.