Angular deformities of lower limb in children: Correction for whom, when and how?

Abstract

Angular deformities are common presentations in childhood and adolescent age group. It is important to differentiate a true deformity from a physiological deformity, this requires measurement of the intercondylar and intermalleolar distance. Once a true deformity is diagnosed, the apex of the deformity requires to be established. Lower limb frontal plane deformities are evaluated with a true AP standing radiographs of the entire lower limb from hip to ankle. Mechanical or anatomical axis calculation gives the apex (CORA) as well as the magnitude of deformity. Frontal plane deformities require surgical intervention. In younger children, growth modulation surgery allows correction of the deformity with minimal morbidity and without the need for osteotomy. Older children, adolescents and adults require corrective osteotomy. The corrective osteotomy can be closed wedge, open wedge, or a dome osteotomy. The osteotomy may be stabilized with internal fixation with plate and screws or an intramedullary implant as is dictated by the level of osteotomy and the local bony anatomy. External fixators allow gradual and precise correction of the deformity.

Keywords: Angular deformities; Children; Deformity correction.

Fig. 1

Outline of full length x ray of lower limb in a patient of genu valgum. The mechanical axis of the limb is calculated by a line drawn from center of hip to center of ankle. In this patient the line is passing lateral to the center of knee indicating a medial mechanical axis deviation of the lower limb (Dashed line). Also note that the valgus in the femur with abnormal mechanical lateral distal femoral angle.

Fig. 2

a. Outline of full length x ray of lower limb in a patient of genu varum. After drawing the normal mechanical axis of hip and knee, the magnitude of deformity is 55° in diaphyseal region of femur. b. Outline of full length x ray of lower limb in a patient of genu varum. After drawing the normal mechanical axis of knee and ankle, the magnitude of deformity is 49° in diaphyseal region of tibia.

Fig. 3

a. CT scan showing physeal bar in the region of distal femur physis. (Arrow). b. MRI images of the same patient showing physeal bar in the region of distal femur physis. (Arrow).

Fig. 4

Follow up case of Figure of 8 plate for genu valgum. Note the divergence of screws indicating that guided growth has happened.

Fig. 5

a. Radiographs of a 14 years old girl with bilateral genu valgum and CORA in distal femur. b. Radiographs of the same child after bilateral corrective osteotomy.

Fig. 6

a. Radiographs of a 12 years old girl with left sided genu varum following malunited fracture of proximal tibia and CORA in proximal tibia. b. Radiographs of same patient with Ilizarov and SUV 6 axis correction system in place. c. Radiographs of same patient after correction of the deformity.