Fig. 261
Rachitic changes in limbs. (Lexer.)
In fact rickets supplies the explanation for the great majority of these deformities; incomplete ossification and calcification of the bones accounting for the comparative ease with which they yield to pressure or other deforming influences. Rickety children always manifest a tendency to defective ossification at epiphyseal lines, and it is here that the change usually takes place. Nevertheless marked instances of curvature are seen in all the bones of the lower extremity. As deformity in any given direction becomes more pronounced the tendency to its exaggeration becomes greater. Finally these changes involve not only the bones proper but the ligaments and the other joint structures, which yield where pressure is abnormal and greatest, thus completely changing their shape and internal relations. Along with other changes in knock-knee there is a tendency to external rotation, perhaps even to spiral curvature of the tibia; the patella lies outside of its normal position, the tendons are more or less displaced, while, at the same time, there may be inflection of the feet as an effort at compensation ([Fig. 261]).
With the exception of spinal curvatures and torticollis there is perhaps no more conspicuous deformity than that produced by these abnormalities at the knee-joint. While at first gait is not seriously affected, it is in time, especially in cases of double knock-knee. When these knees are bent to a right angle the angular deformity disappears and all that remains is the rotation of the tibia. Hence it follows that all correction of these deformities, either slow or operative, should be applied to the fully extended leg. In advanced cases there is frequently a complication with flat-foot, which may or may not be painful. The condition is rarely produced by paralytic affections, and should be differentiated from mere atrophy of wasted and contracted legs. A form of knock-knee is occasionally seen in the adult, which is of traumatic origin and is due to improper care or neglect in the treatment of the injury.
Treatment.
—The treatment of this condition is either mechanical or operative. Mechanical treatment varies between the gentlest expedients and the use of more or less extensive and cumbersome apparatus. When a young and growing child begins to show evidence of either of these deformities it is usually sufficient to supply shoes which are reasonably stiff, and raise one or other border of the sole and heel, according as we wish to influence the growth of the limb, i. e., in knock-knee the inner border of the foot is to be raised, in bow-leg the outer. The consequence of even slight influence thus constantly maintained when the child is upon its feet is usually sufficient to rectify slight degrees of these deformities. When, however, the case is pronounced more radical measures should be applied. Massage has been recommended along with manipulation, but should be gently performed. The different forms of apparatus in use afford various methods of making pressure against that condyle which is too prominent. It is possible to make them efficient, but only when they are both well planned and well made in the first place and intelligently applied and watched. The special forms of apparatus sold in the instrument stores are of little value. Too often it happens that when efficient they cannot be tolerated, and that when tolerated they are inefficient. Much speedier and more satisfactory results are achieved by operative methods, so that, in general, they may be regarded as the more desirable.
Operative treatment consists in some modification either of osteoclasis or osteotomy.
Osteoclasis has to do with the forcible stretching, bending, or even breaking of those parts which show the greatest effects of the deformity or are known to be its primary seat. In young children with tender and still somewhat flexible bones this may be accomplished by the hands alone, the patient being under an anesthetic. Manual power failing a simple instrument known as the osteoclast, which affords a means of applying powerful pressure by the agency of a screw at just the desired point, is used. Pressure is then applied and carried to the necessary degree, even with partial or complete fracture of the bone at fault. In this way is inflicted a simple fracture which permits of the immediate redressing of the limb, with such overcorrection of the deformity as seems desirable. The limb thus treated is completely encased in a suitable plaster-of-Paris splint, and should be held in the desired position until the plaster is completely hardened and not likely to yield. Osteoclasis, though it often appears an exceedingly barbarous procedure, is one of the most beneficent when properly managed, and is rarely followed by an undesirable result.
Osteotomy is performed by the use of the chisel and mallet, the former being introduced through a small incision made in the skin, passed down to the bone with its cutting edge parallel to the bone axis until the bone itself is reached, after which it is turned at right angles to it and the mallet used until the chisel has been driven partly or completely through the shaft of the bone or the portion which it is intended to attack. The chisel should be partly withdrawn and its position changed if it is necessary to continue its use. Thus by a partial division of the bones of the young it is possible usually to so weaken them that, without undue force, and by manual power, they are fractured at the desired point. The operation should be done with the most complete aseptic protection. The procedure recommended by Macewen is now universally accepted. The incision is made at the inner side of the thigh just above the tubercle for the adductor magnus, and the osteotome (as the chisel especially made for this purpose is called) is passed through it, down to the bone, turned at right angles, and made to cut nearly through the shaft. Lest it become too firmly wedged it may be moved a little laterally after each blow of the hammer. The operation, if properly done, is practically bloodless; the small opening made for the chisel is sealed at the moment of its withdrawal, the deformity corrected with the least amount of handling or disturbance, and the plaster-of-Paris bandage immediately applied, with the leg in exactly the position which it is desired should be maintained. Such a dressing may be left for three or four weeks before being changed. One change is usually sufficient, and in from six to seven weeks the patient is allowed to slowly regain use of the member.