Normal variants and self-limiting conditions

The range of normality in the development of the musculoskeletal system is wide (Table 27.2). At all ages the appear­ance of a child’s limbs or spine includes the components of rotation, angulation and joint laxity. When these are added to the natural clumsiness of a developing youngster it is not surprising that parents may be concerned whether their off­spring is normal. Therefore, all consultations must be thorough and sympathetic.

Common reasons for referral are intoeing, bow legs (Fig. 27.4), knock-knees and flat feet (Fig. 27.5). None can be judged in isolation. For example, intoeing (foot progression angle) is the result of the various torsional and angulation components within the femur, tibia and foot.

For example, the child in Fig. 27.6 is normal. The condition is symmetrical and symptomless, the joints are supple and there is no evidence of skeletal dysplasia or systemic disease such as neurological or metabolic condition.

Conversely, the child in Fig. 27.7 is abnormal. There is asymmetry and evidence of a systemic disorder (rickets).

Self-limiting conditions (Table 27.3) are outside the definition of normal variance because they do not fulfil the ‘five Ss’ rule. They include postural deformities such as calcaneo valgus (Fig. 27.8), moulded baby syndrome (plagiocephaly, infantile scoliosis, tight hip adductors), metatarsus varus (Fig. 27.9) and ‘growing pains’. Asymmetry, stiffness and symptoms may be present. The conditions usually correct spontaneously or with minimal treatment such as stretching exercises.