of life, and results from a wide
range of conditions.

In infancy it is a common result of _general debility_. The child need
not appear to be badly nourished, it may even be fat and look well,
but there is a want of muscular vigour such as should enable it to
hold itself erect in the sitting posture. It is to be noted that a
considerable degree of kyphosis may exist without interference with
the normal outlook in the erect posture, and, therefore, the question
of compensatory curvature does not arise. In the adolescent a degree
of kyphosis in the cervico-thoracic region is common, and is spoken of
as "round shoulders"; it is largely a matter of habit that requires
correction by the governess or nurse. Among agricultural labourers and
gardeners after middle life, and in the aged, this type of curvature
is of common occurrence and is evidently associated with their
occupation. An exaggerated form of the same cervico-thoracic kyphosis
is met with in patients suffering from progressive muscular atrophy,
poliomyelitis, osteitis deformans of Paget, acromegaly, and many
allied conditions in which either the muscular or the mental vigour is
deficient, and the patient adopts the cervico-thoracic kyphosis as the
attitude of rest.

Another type of diffuse kyphosis without compensatory curvature is met
with in _arthritis deformans_, in which the kyphosis is associated
with the disappearance of the intervertebral discs and ankylosis of
the vertebral bodies by bridges of new bone in the position of the
anterior common ligament.

_Partial or localised kyphosis_, on the other hand, is the result of
organic changes in the bodies of the vertebrae of the segment of spine
affected. It is most often met with in Pott's disease in which the
extent of the curve depends on the number of bodies affected, and its
degree on the amount of destruction that the bodies have undergone.
With the resumption of the erect posture, and in order that the eyes
should look directly forwards, a compensatory lordosis is acquired
above and below the segment that is the seat of kyphosis (Fig. 211). A
similar but less marked type of kyphosis may follow upon compression
fracture of the spine--in the condition known as traumatic
spondylitis; and as a result of other lesions, such as osteomalacia,
or malignant disease, in which the bodies undergo softening and yield,
so that the spinous processes project posteriorly.

SCOLIOSIS

#Scoliosis# or _lateral curva