The method for the surgical treatment of the severe forms of the Erlacher-Blount disease in the children includes determining tibiofemoral angle for osteotomy of the tibia at a specified level, correcting these bones towards the side opposite to their deformation at an angle sufficient to normalize the arrangement of the mechanical axis of the lower extremity relative to the center of the knee joint and the following fixation of the shin bone fragments with external fixation device for a period of consolidation of the respective bone fragments. Additionally, the lateral angle of the slope of distal articular surface of the femur and the medial angle of the slope of the proximal articular surface of the tibia are defined. The lateral part of the proximal growth area of tibia is blocked simultaneously. The medial part of the distal growth area of femur is blocked in the case of valgus deformity of the distal epimetaphysis or the lateral part of the distal growth area of femur is blocked in the case of varus deformity of the distal epimetaphysis. In the case of valgus deformity of the distal epimetaphysis, the shin bones are corrected by the angle equaling the sum of tibiofemotal angle and deformity angle of epimetaphysis of femur.In the case of varus deformity of the distal epimetaphysis, the shin bones are corrected by the angle equaling the difference between tibiofemotal angle and deformity angle of epimetaphysis of femur. At the level of osteotomy, the shin bones are elongated with the aid of the external fixation apparatus at a daily rate of 1 mm starting on the Day 7 postoperatively. The length of elongation is defined as L = 0,7 (17- n), wherein L is the required length of elongation, cm； n – age of the children (years). When the required length is attained, the external fixation device is demounted. Postoperatively, the patient is followed up once in three months for assessing the rate of correction of the deformity of the distal epimetaphysis of femur. Then t
