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
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’