The spine is often bent. In an infant the cervical curve is increased so that the head is supported with difficulty and falls backwards upon the shoulders, producing a very characteristic attitude. Also, the weight of the head and shoulders, as the child sits bending forwards, causes a pro jection backwards of the dorsal and lumbar spines, which is sometimes so sharp as to give the appearance of vertebral caries. The deformity, how ever, subsides completely when the child is taken up under the arms and the spine is drawn upon by the weight of the limbs and pelvis. If the pa tient is able to walk, there_ is an increase in the lumbar and dorsal curves. The curvature may be lateral. If the child is carried habitually on his nurse's left arm, the trunk sways over to the right ; if on the right arm, the body leans to the left. In all these cases the deformity is due to weak ness of the ligaments and muscles.
The bones forming the pelvis may be also deformed, and sometimes, like the chest, are greatly distorted. The shape assumed by this frame work is very various, for as it is due in all cases to compression of the yielding bones, it will be determined partly by the age at which the dis ease begins, and the degree to which ossification has advanced. It is therefore different, according to the usual attitude of the child, and to the circumstance of his being able or not to walk about. Its most ordinary shr-Pa 's an irregular triangle. Distortion of the pelvis is of great impor Lance in its influence upon child-bearing in the adult female ; but even in early life it may have. grave consequences. The operation of lithotomy in the ydung subject has been attended with serious difficulties, and even been followed by Mal results, on account of this deformity.
In the bones of the limbs the articular ends are nodular from en largement, but the shafts themselves have often an unnatural shape. In the arm the humerus is often curved at the insertion of the deltoid muscle by the weight of the forearm and hand when the arm is raised. The ra dius and Om are curved outwards and twisted, for a rickety child often rests his hands on the bed or floor to assist his feeble spine in supporting the weight of his trunk. In the femur the head of the bone may be bent at an angle with the, shaft. The body of the bone is curved forwards if the child cannot walk ; for as he sits on his mother's lap the weight of the leg drags upon the lower part of the thigh. If he can walk, the curve is
an exaggeration of the natural curve—forwards and outwards. The tibia is curved outwards if the child is unable to walk, so that when the patient is held upright the knees are widely apart. The deformity is due in this case to the position commonly assumed by the infant, who is addicted to sitting cross-legged on his bed, so as to make pressure upon the outside of his ankle.. In children who can walk an abrupt curve, having its convexity forwards and outwards, is seen in the lower third of the bone. The lower limbs are not distorted in the infant so frequently as the arms. If the child cannot stand, these extremities, although small and feeble, are often perfectly straight. In cases where the deformity of the long bones is ex treme, the shaft is not only bent but broken, for a partial (" green-stick ") fracture is generally present. The same thing is often seen in the clavicles which have their normal curves very greatly exaggerated.
Besides the softening and deformity of the bones there is another con sequence of the disease which is of great importance. This is the arrest of growth and development of bone which can be noticed in all cases of severe rickets. Rickety children are short for their age, and remain under sized after the disease has passed away. The arrest of growth is most marked in the bones of the jaws, of the lower limbs, and of the pelvis. As it affects the pelvis, this feature is of especial importance on account of its influence upon parturition in after life ; for if the capacity of the pelvic framework be not only diminished by distortion, but also relatively small from arrest of development and growth, the difficulties in the way of suc cessful delivery may be insuperable.
The weakness in the lower limbs, which is a marked feature in rickets, is due not alone to feebleness of the muscles combined with the general debility of the child. There is also great weakness and looseness of the ligaments of the joints. This weakness is more pronounced in cases where the disease begins after the end of the second year. In such cases of late rickets softening and deformity of bone are less common features of the disease, while the looseness of the joints from marked relaxation of the ligaments may reach a very high degree. In such cases, too, the disease having begun after the completion of dentition, the teeth are often white and sound.