Angular Variations: Genu Varum (Bowleg) and Genu Valgum (Knock-Knee)


Angular Variations: Genu Varum (Bowleg) and Genu Valgum (Knock-Knee)


Physiologic angulation

Angular variations at the knee (bowleg [varus] or knock-knee [valgus]) that fall within 2 standard deviations of the mean

Angular orientation of the lower limbs follows a predictable pattern of normal development during childhood.

Before 2 years of age, most children demonstrate up to 15 degrees of physiologic genu varum (bowleg).

By 2 years of age, spontaneous improvement occurs and neutral alignment is the norm.

Children then proceed to develop exaggerated valgus, which peaks by about 3 to 5 years of age and then corrects toward the normal adult value of 5 to 7 degrees of valgus by age 8 years.

Physiologic genu varum and valgum are typically symmetrical.

Idiopathic angulation

Angular variations at the knee (bowleg or knock-knee) that fall outside 2 standard deviations of the mean (Figure 26-1).

This variation may be familial.

Idiopathic genu valgum (knock-knee) is commonly seen in girls with obesity.

In the supine position with the knees fully extended, the distance between the medial malleoli is greater than 8 cm.

Pathologic angulation

Rickets may cause genu varum or valgum (see Chapter 68, Skeletal Dysplasias).

Pathologic angulation is usually associated with short stature.

Radiographs show characteristic widening of the physes and help to establish the diagnosis along with serum laboratory values (ie, calcium, phosphorous, alkaline phosphatase, vitamin D, parathyroid hormone).

Blount disease is a pathologic cause of varus deformity at the knee in juveniles.

Focal growth disturbance of the medial proximal tibial epiphysis produces tibia vara.


Figure 26-1. Normal values for the knee angle are shown in degrees and intercondylar in intermalleolar distance. Abbreviation: SD, standard deviation.

Reproduced from Heath CH, Staheli LT. Normal limits of knee angle in white children—genu varum and genu valgum. J Pediatr Orthop 1993;13:259–262 (, with permission from Wolters Kluwer Health and the Pediatric Orthopaedic Society of North America.

This occurs commonly in children with overweight who walk at an early age and are of African descent.

It is often associated with significant internal tibial torsion.

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Mar 12, 2022 | Posted by in ORTHOPEDIC | Comments Off on Angular Variations: Genu Varum (Bowleg) and Genu Valgum (Knock-Knee)

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