[Illustration:  FIG. 134.—­Changes in the Skull resulting from Ostitis Deformans.

(Anatomical Museum, University of Edinburgh.)]

Clinical Features.—­The disease is usually met with in persons over fifty years of age.  It is insidious in its onset, and, the patient’s attention may be first attracted by the occurrence of vague pains in the back or limbs; by the enlargement and bending of such bones as the tibia or femur; or by a gradual increase in the size of the head, necessitating the wearing of larger hats.  When the condition is fully developed, the attitude and general appearance are eminently characteristic.  The height is diminished, and, owing to the curving of the lower limbs and spine, the arms appear unnaturally long; the head and upper part of the spine are bent forwards; the legs are held apart, slightly flexed at the knees, and are rotated out as well as curved; the whole appearance suggests that of one of the large anthropoid apes.  The muscles of the limbs may waste to such an extent as to leave the large, curved, misshapen bones covered only by the skin (Fig. 135).  In the majority of cases the bones of the lower extremities are much earlier and more severely affected than those of the upper extremity, but the capacity of walking is usually maintained even in the presence of great deformity.  In a case observed by Byrom Bramwell, the patient suffered from a succession of fractures over a period of years.

[Illustration:  FIG. 135.—­Cadaver, illustrating the alterations in the Lower Limbs resulting from Ostitis Deformans.]

The disease may last for an indefinite period, the general health remaining long unaffected.  In a considerable number of the recorded cases one of the bones became the seat of sarcoma.

#Osteomyelitis Fibrosa.#—­This comparatively rare disease, which was first described by Recklinghausen, presents many interesting features.  Because of its causing deformities of the bones and an undue liability to fracture, and being chiefly met with in adolescents, it is regarded by some authors as a juvenile form of Paget’s disease.  It may be diffused throughout the skeleton—­we have seen it in the skull and in the bones of the extremities—­or it may be confined to a single bone, usually the femur, or, what is more remarkable, the condition may affect a portion only of the shaft of a long bone and be sharply defined from the normal bone in contact with it.

[Illustration:  FIG. 136.—­Osteomyelitis Fibrosa affecting Femora in a man aet. 19.  The curving of the bones is due to multiple fractures.]