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In bacterial diseases originating in the marrow, if the epiphysial junction is directly involved in the destructive process, its bone-forming functions may be retarded or abolished, and the subsequent growth of the bone be seriously interfered with.
In the limbs, the prominent features are the deficient growth in length of the long bones, the enlargements at the epiphysial junctions, and the bending, and occasional greenstick fracture, of the shafts.
These changes are well brought out in skiagrams; instead of the well-defined narrow line which represents the epiphysial cartilage, there is an ill-defined, blurred zone of considerable depth. In the shafts of the long bones, owing to the excessive absorption of bone, the cortex becomes porous, the spongy bone is rarefied, and the bones readily bend or break under mechanical influences.
They are believed to occur more frequently in those who have suffered from rickets. They have no malignant tendencies and tend to undergo ossification concurrently with the epiphysial cartilage from which they take origin, and constitute what are known as cartilaginous exostoses. These are sometimes met with in a multiple form, and may occur in several generations of the same family.
When a cartilaginous tumour takes on active growth, it must be treated as malignant. The chondromas that are met with at the ends of the long bones in children and young adults form a group by themselves. They are usually related to the epiphysial cartilage, and it was suggested by Virchow that they take origin from islands of cartilage which have not been used up in the process of ossification.
The function of the epiphysial cartilage is to provide for the growth of the shaft in length. While all epiphysial cartilages contribute to this result, certain of them functionate more actively and for a longer period than others. Those at the knee, for example, contribute more to the length of limb than do those at the hip or ankle, and they are also the last to unite.
While a considerable number of syphilitic children grow up without showing any trace of their syphilitic inheritance, the majority retain throughout life one or more of the following characteristics, which may therefore be described as permanent signs of the inherited disease: Dwarfing of stature from interference with growth at the epiphysial junctions; the forehead low and vertical, and the parietal and frontal eminences unduly prominent; the bridge of the nose sunken and rounded; radiating scars at the angles of the mouth; perforation or destruction of the hard palate; Hutchinson's teeth; opacities of the cornea from antecedent keratitis; alterations in the fundus oculi from choroiditis; deafness; depressed scars or nodes on the bones from previous gummata; "sabre-blade" or other deformity of the tibiæ.
The new bone may be so abundant that it forms a thick crust on the surface, and in the flat bones of the skull this may be heaped up in the form of bosses or ridges resembling those ascribed to inherited syphilis. In the epiphysial cartilages and at the ossifying junctions, all the processes concerned in ossification, excepting the deposition of lime salts, occur to an exaggerated degree.
The epiphysial cartilage usually continues its bone-forming functions, but when it has been seriously damaged or displaced, the further growth of the bone in length may be interfered with. Sometimes the separated and displaced epiphysis dies and constitutes a sequestrum. The adjacent joint may become filled at an early stage with a serous effusion, which may be sterile.
So long as growth continues there intervenes between the shaft and each of the epiphyses a disc of actively growing cartilage the epiphysial cartilage; and at the junction of this cartilage with the shaft is a zone of young, vascular, spongy bone known as the metaphysis or epiphysial junction.
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