COXA VARA Etiology.—Judging by its crane-like shape, the neck of the femur is destined to bear the main weight of the body (J. Wolff). The structure is correspondingly strengthened to pre vent depression. The angle formed F.. N.
by the femoral neck varies in dif ferent races from 10S° to HO°, but always more than 90°. It remains rectangular in quadrupeds and in bipeds walking with the body bent forward, in birds and in anthropoids.
Nor did the forerunners of our ' race enjoy the present erectness of the neck of the femur. Such erect ness, combined with an increased anti torsion, must be looked upon as a result of adaption to the erect gait.
(Sec Congenital dislocation of the hip, — Fig. 96.) a b If the structure of the femoral neck be weakened in any manner, either by softening processes (rachitis) or by external force (fracture), a shrinking of the femoral neck takes °logical or better biological curvatures of the bones place as a result of the subsequent of the thigh and leg.
action of gravity and the traction of the trochanter muscles of the pelvis. Hofmeister has termed this condition coxa vara.
There are a few cases of congenital coin rare on record (Hon) which must be considered as atavistic relapses (vara congenita).
The rachitic coxa rare of younger children is characterized by a deformity of both femoral diaphyses (flon) occurring at the same time and in the same manner (Fig. OS).
The later developing coxa vara statica pertains principally to later childhood and adolescence, resulting in a depression of the femoral neck alone. The strong femoral bone, now less burdened, does not follow the distortion any longer. The main cause in this case is a shifting of the epiphyseal junction between the neck and head (Kocher).
The coxa vara traumatica may be the result of a faulty opposition and reduction of a fractured femoral neck (see Fracture of the neck of the femur).
The symptoms consist of an impairment of gait, similar to that in dislocation of the hip, and of ilmping and waddling of the bilateral type (Trendelenhurg), and are elicited by disturbances of the muscular me chanism due to the elevation of the trochanter above Roser-Maton's line (see Dislocation). However, the uncertain step, one of the main
symptoms of dislocation, is missing.
Combined with the depression is a detorsion of the neck, both result ing in a modification of the range of motion.
Abduction of the leg is prohibited on account of the shortening of the adductors, and even more as a result of the obstruction coming from the elevated trochanter itself. The &torsion produces an outward rota tion. Inward rotation is, therefore, restricted. Flexion is possible only when outward rotation takes place at the same I hne.
But aside from these restrictions, the motions are not limited. Moreover, the inactive gluteal and abductor muscles become atrophic.
Subjectively, the patient complains of pain in the hip which appears to be like that in flat-foot, and probably results from the dispropor tionate strain on certain groups of muscles and ligaments. The affected leg is limited in motion, tires quickly, and presents in a gradually increas ing degree the above-mentioned disturbances of locomotion.
The diagnosis is not difficult when careful attention is given to the history.
In cases existing since birth, the affection must not be mistaken for congenital dislocation of the hip. A firmer gait, palpation of the head in its normal position below the artery, and, finally, a Röntgen picture permit of an exact diagnosis in patients with symptoms which are otherwise similar.
Coexisting raehitis may manifest itself by accompanying symp toms. The existence of former fractures is given in the history. Only eoxa vara statica, which develops later, calls for an exact differential diagnosis to avoid mistaking it for hip disease.
Pain, tenderness, and limitation of range of motion may indicate coxitis. flowerer, outward rotation is unrestrained, and in this position flexion and extension are painless. In difficult cases the Röntgen pic ture must decide whether a depression of the femoral neck has taken place or not.