ht 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.

#Osteogenesis Imperfecta#, #Fragilitas Ossium#, or #Congenital
Osteopsathyrosis#.--These terms are used to describe a condition in
which an und