Paeds- limb develop + variations Flashcards
Disorders of knee alignment
Children at birth normally have varus knees (bow legs) which become neutrally aligned at around 14 months, progressing to 10 to 15° valgus (knock knees) at age 3 and then gradually regress to the physiologic valgus of 6° by around the age of 7‐9.
Parents may often be concerned at the appearance however the vast majority develop normal alignment and most cases need reassurance only. Some people develop minor degrees of varus or valgus alignment which often can be familial.
Different types of deformity
Pathological varus or valgus is where alignment is considered outside the normal range (+/‐ 6° from mean value for age).
Measurements can be taken on xrays and charted against normal reference ranges.
Valgus deformity
A valgus deformity at the knee will result in a more of a knock knee appearance with a larger gap than normal between the feet/ankles.
Varus deformity
A varus deformity will result in a larger gap between the knees.
Deformity causes & treatment
majority of cases of bow legs or knock knees will resolve by the age of 10 but genu varum or excessive genu valgum after the age of 10 may require surgery.
Many are idiopathic, whilst some are familial. Some cases may be due to an underlying skeletal disorder (skeletal dysplasia, Blount’s disease), physeal injury with growth arrest (usually unilateral) or biochemical disorder (rickets).
Bow legs
genu varum may be due to a growth disorder of the medial proximal tibial physis know as Blount disease resulting in marked and persisting (beyond 4‐5 years) varus deformity.
may require surgical correction by osteotomy.
condition can also occur in adolescence where growth plate restriction on the medial side with a small plate and screws may be required.
rarer causes of pathologic genu varum include rickets, tumour (osteochondroma), traumatic physeal injury and skeletal dysplasia.
Persistent bow legs are at risk of early onset medial compartment osteoarthritis.
Knock knees
genu valgum include rickets, tumours (enchondromatosis), trauma and neurofibromatosis whilst some cases are idiopathic.
Again excessive deformities can be corrected by osteotomy or growth plate manipulation surgery.
In‐toeing
refers to a child who, when walking and standing will have feet that point toward the midline.
The abnormality is often exaggerated when running and children are felt by their parents to be clumsy and wear through shoes at an alarming rate.
There are a number of causes of in‐toeing.
Femoral neck anteversion
as part of normal anatomy the femoral neck is slightly anteverted (pointing forwards).
Excess femoral neck anteversion can give the appearance of in‐toeing (as well as knock knees).
However the degree of apparent in‐toeing is not of a magnitude which would warrant surgical intervention.
Flat feet
part of normal variation and usually do not reflect underlying pathology.
At birth all feet are flat, as we begin to walk and the muscles develop the arch will also develop. Some children continue to have flat feet which persist into adulthood without any functional problem.
Flat feet investigation & treatment
The key is to determine if the flat feet are mobile or fixed. Mobile/flexible flat feet are those where the flattened medial arch forms with dorsiflexion of the great toe (Jack test).
Flexible flat footedness may be related to ligamentous laxity, may be familial or may be idiopathic.
The flat footedness may only be dynamic (present on weight bearing only).
Flexible flat‐footedness in children is a normal variant.
Medial arch support orthoses are not required. (In adults mobile flat foot may be related to tibialis posterior tendon dysfunction – see later).
In the rigid type of flat footedness the arch remains flat regardless of load or great toe dorsiflexion. This implies there is an underlying bony abnormality (tarsal coalition where the bones of the hindfoot have an abnormal bony or cartilaginous connection) which may require surgery. It also may represent an underlying inflammatory disorder or a neurological disorder.
Curly toes
Minor overlapping of the toes and curling of toes is common with the fifth toe is most frequently affected.
Again most will correct without intervention but they can occasionally cause discomfort in shoes and persistent cases in adolescence may require surgical correction.
