Orthopedics - Oleksa A.P. 2006

Congenital and acquired deformities of the lower extremity
Lower limb axis deviations
Varus deformity of the leg bones

Varus curvature of the lower leg can be either congenital or acquired.

Congenital varus deformity of both BONES OF THE lower leg is rare; according to Pais, it occurs 100 times less frequently than congenital hip dislocation (B. Boychev, 1968). This deformity is most often left-sided (in nearly 95% of cases) and predominantly affects boys. It is believed that this congenital anomaly may be hereditary.

Typically, the bones of the lower leg are bowed in their lower third presenting as varus and antecurvation with medial torsion (Fig. 188), although crura recurvata posterior et valga and other variants also occur.

The lower leg may exhibit a smooth curvature or, at times, a sharper angulation that creates FOOT hyperextension. Patients complain of cosmetic defects and gait disturbances. Radiologically, bowing of the Tibia or both bones of the lower leg is revealed at the same level in the lower third of the diaphysis. At this site, the bone is sclerotic, often thinner, and typically deformed, featuring a thickened cortical layer on the concave side and a narrowed medullary canal.

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Fig. 188. Radiographs of congenital varus deformity of the lower leg bones: at three months of age (a) and three years of age (b).

Many orthopedists (M.P. Novachenko, R.R. Vreden, Potel, and others) believe that this congenital defect is caused by delayed and arrested Ossification of the tibia, which supposedly precedes The Development of an unformed congenital pseudarthrosis.

While congenital bowing of the lower leg bones is generally unilateral and very rare, acquired deformities are extremely common—particularly During the first years of a child's life—and are almost always bilateral. Unilateral curvature may result from the malunion of a bone fracture, among other causes.

Most commonly, bilateral varus curvature of the lower limbs develops As a result of Rickets, in which increased bone flexibility and pliability under body weight and Muscle contraction lead to such deformity (Fig. 189).

Clinically, three forms of rachitic bowing of the lower leg are distinguished:

1) crura vara totalis — total curvature in the frontal plane;

2) crura vara inflexa — bowed deformation of both bones of the leg in the distal metaphysis;

3) crura vara anteflexa — deformation of this area of both leg bones in the frontal and sagittal planes, i.e., laterally and anteriorly.

Treatment. The treatment of rachitic curvature of the leg bones caused by hypovitaminosis is primarily based on the administration of vitamin D, fish oil, quartz irradiation, fresh air exposure, and A balanced diet. Children are advised to limit limb weight-bearing during treatment and are prescribed corrective plaster or plastic splints during rest periods.

If rickets treatment is initiated in a timely manner, the leg curvature not only stops progressing during the child's growth, but actually diminishes or even disappears entirely.

If the child goes untreated, crura vara totalis progresses into crura vara inflexa due to the strong tension of the triceps surae muscle acting on the bone curvature arc. This type of deformity does not respond to conservative management and therefore requires surgical intervention.

Surgery is performed under general anesthesia with a tourniquet applied to the thigh. The Procedure consists of a corrective osteotomy of both leg bones at the apex of the deformity to restore the axis of the segment. In cases of severe angular deformity, a double osteotomy is sometimes necessary to restore the segment axis, ensure good bone end adaptation, and achieve fragment osteosynthesis. Postoperatively, a plaster cast is applied and removed after bone union has occurred. Occasionally, the surgery is concluded by applying an Ilizarov fixator, which allows for axis correction of the limb segment while preserving joint mobility.

Fig. 189. Post-rachitic varus deformity of the bones of the legs and thighs: a — clinical appearance, b — radiological view.

Crura vara anteflexa is typically a long-standing deformity that also cannot be treated conservatively. Furthermore, untreated children develop persistent leg curvatures with medial rotation, which likewise require surgical correction.

Surgeries are performed at the age of 3–4 years in the first two cases, and at 5–6 years in the others.

The surgery involves performing an osteotomy of the bones at the apex of the curvature, or sometimes a double osteotomy, to eliminate all Types of bone curvature and restore the foot to a normal position. If proper correction can be achieved in a single stage, the tibial fragments can be secured with internal hardware; otherwise, the deformity is corrected under anesthesia in a staged manner or using hardware Methods (Ilizarov fixator, pin-and-rod frame fixator, or corrective wires).

If bilateral leg surgery is necessary, the interval between operations should be at least 6 months.