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Core biopsy specimens of the proximal femoral growth plate from three patients with slipped capital femoral epiphysis were studied by light and electron microscopy. In the resting zone, the cartilage matrix was composed of large, densely packed collagen fibrils. The cartilage matrix in the zones of chondrocyte hypertrophy where the slippage occurred contained only scattered fine collagen fibrils in a homogeneous ground substance. The change in composition of cartilage matrix in the distal region of the epiphyseal plate may predispose that region to slippage.

Cartilage from patients with pseudoachondroplasia is characterized by unique inclusions in the cisternae of the endoplasmic reticulum and proteoglycan abnormalities have been suggested in this form of dwarfism. To elucidate the nature of the proteoglycan defect, we determined the amount of the individual glycosaminoglycans present in iliac-crest cartilage of three patients and extracted the proteoglycan monomers from one of the samples. Sections of iliac-crest cartilage and proximal fibular growth plates were examined by electron microscopy and also stained with hematoxylin and eosin, safranin O-fast green, and alcian blue in the presence of increasing concentrations of magnesium chloride (zero to one molar). The chondrocytes of the iliac crest and fibular physes were arranged in clusters more than in columns and contained characteristic endoplasmic reticulum inclusions, which were particularly large in the hypertrophic cells. The cartilage stained very poorly with hematoxylin and eosin and with safranin O-fast green. The alcian-blue stain was abolished from perilacunar areas and from longitudinal septa by magnesium chloride concentrations that were lower than those required by normal tissue. The proteoglycans of iliac-crest cartilage were found to be significantly enriched in keratan sulphate and had a below-normal ratio of chondroitin-4-sulphate to chondroitin-6-sulphate, although the amount of the two isomeric chondroitin sulphates combined was within normal limits. The urinary excretion of glycosaminoglycan by the three patients was normal. Pseudoachondroplasia appears to be a generalized cartilage disorder involving abnormalities of proteoglycans, probably related to the core protein or to enzymes that are responsible for the formation of the glycosaminoglycan chains.(ABSTRACT TRUNCATED AT 250 WORDS)

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.

Although previous studies failed to demonstrate elastic fibers in intervertebral discs, electron microscopy of twenty human intervertebral discs obtained at autopsy and operation revealed characteristic elastic fibers in both the annulus fibrosus and the nucleus pulposus. Their contribution to the mechanical properties of the intervertebral disc remains to be determined.

An estimated 70,000 to 100,000 anterior cruciate ligament reconstructions are performed each year in the United States. With the increasing number of anterior cruciate ligament surgeries being performed, a concomitant increase in intraoperative complications can be expected. Complications include those associated with tunnel placement, notchplasty, graft fixation and advancement, suture laceration, graft laceration, guidewire insertion and removal, intra-articular hardware, posterior cruciate ligament laceration, compartment syndrome, and vascular injury.