[Illustration:  FIG. 137.—­Radiogram of Upper End of Femur showing appearances in Osteomyelitis Fibrosa.]

The X-ray appearances vary with the stage of the malady, not estimated in time, for the condition is chronic and may become stationary, but according to whether it is progressive or undergoing repair.  The shadow of the bone presents a poor contrast to the soft parts, and no trace of its original architecture; in extreme cases the shadow of the femur resembles an unevenly filled sausage (Fig. 137); there is no cortical layer, the interior shows no trabecular structure, and some of the many clear areas are probably cysts.  The condition extends right up to the articular cartilage, or, in the case of adolescent bones, up to the epiphysial cartilage.

Prognosis.—­The condition does not appear to affect the general health.  The future is concerned with the local conditions, and, especially in the case of the femur, with its liability to fracture; so far as we know there is no time limit to this.

Treatment is confined to protecting the affected bone—­usually the femur—­from injury.  Operative treatment may be required for lameness due to a badly united fracture.

#Neuropathic Atrophy of Bone.#—­The conditions included under this heading occur in association with diseases of the nervous system.

Most importance attaches to the fragility of the bones met with in general paralysis of the insane, locomotor ataxia, and other chronic diseases of the brain and spinal cord.  The bones are liable to be fractured by forces which would be insufficient to break a healthy bone.  In locomotor ataxia the fractures affect especially the bones of the lower extremity, and may occur before there are any definite nerve symptoms, but they are more often met with in the ataxic stage, when the abrupt and uncontrolled movements of the limbs may play a part in their causation.  They may be unattended with pain, and may fail to unite; when repair does take place, it is sometimes attended with an excessive formation of callus.  Joint lesions of the nature of Charcot’s disease may occur simultaneously with the alterations in the bones.  In syringomyelia pathological fracture is not so frequent as in locomotor ataxia; it is more likely to occur in the bones of the upper extremity, and especially in the humerus.  In some cases of epilepsy the bones break when the patient falls in a fit, and there is usually an exaggerated amount of comminution.

In these affections the bones present no histological or chemical alterations, and the X-ray shadow does not differ from the normal.  It is maintained, therefore, that the disposition to fracture does not depend upon a fragility of the bone, but on the loss of the muscular sense and of common sensation in the bones, as a result of which there is an inability properly to throw the muscles into action and dispose the limbs so as to place them under the most favourable conditions to meet external violence.