Normal lower limb variants in children are a frequent cause of referral to orthopaedic specialists and often a cause of parental concern. Physiological variants of growth may improve or resolve spontaneously and thus, do not need any surgical intervention. A thorough history and examination, as well as an understanding of the natural progression of angular and rotational variants will assist general practitioners to reassure parents and to identify any pathological conditions which require specialist management.
Keywords: normal variants, development, lower limbs, children, musculoskeletal
Musculoskeletal symptoms in children are a common presentation in primary care.1, 2 Parents are often concerned about the appearance of their child’s legs or their gait and general practitioners might have some difficulty in reassuring them. A number of referrals to orthopaedic clinics can be classified as physiological variants of growth2 which do not need any operative intervention.3 The aim of this review is to aid clinicians in identifying these normal variants and any abnormal characteristics which are indicative of an underlying pathological condition.
- NORMAL PHYSIOLOGICAL VARIANTS
The most common variants of the lower limbs can be categorized into angular deformities, rotational deformities and flexible pes planovalgus.
- Angular Deformities
Genu varum (‘bow legs’) and genu valgum (‘knock knees’), the most frequently encountered angular deformities, refer to the tibiofemoral angle in the coronal plane, which can be evaluated by measuring the intercondylar and intermalleolar distances (Fig 1). Physiological variants tend to be symmetrical and painless. Normally, up to the age of 18 months and as the child begins to walk, genu varum (mean 15 degrees) can be noted. The normal tibial torsion frequently seen in this age group further exacerbates this manifestation and therefore, referral for genu varum is most common in the 10-14 month age group. As the child grows, the knees tend to go into a valgus position (mean 12 degrees) which, after 7 years of age, gradually corrects itself to the normal 7-8 degrees of valgus seen in adults.4 Consequently, referral for genu valgum generally occurs at 3-4 years of age. One must keep in mind that the normal physiological genu valgum may be exacerbated by flatfeet, ligamentous laxity and obesity.5 Alarm symptoms include pain, asymmetry, progression, unilaterality or association with other deformities e.g. short stature. Genu varum over the age of 2 years is a red flag and requires specialist referral to exclude an underlying pathological condition such as Rickets or Blount’s disease.
Presentations for painless genu varum also peak in adolescents participating in high impact sports such as football or rugby. The reason for this is suspected to be the result of high sporting demands on the developing skeleton.2 There is currently no concrete guidance which can be given to these individuals; however, if associated with pain, further investigations are necessary to exclude any co- existing pathology e.g. meniscal tears.