Slipped upper femoral epiphysis
This
is a shear failure through the hypertrophic tone of the upper femoral growth
plate (physis). The capital epiphysis slips backwards and downwards. SUFF is
uncommon. For example, a family doctor in Britain is likely to see only one case
in a working lifetime (Table 28.2). Although the condition is classically
described in a very overweight (Pickwickian) child, it can occur in a tall or
muscular child. Conversely the physis can be weakened by injury or disease, e.g.
renal failure, radiotherapy, hyperthyroidism. Thus no type of body build can be
considered safe from SUFF (Fig. 28.7).
Classification
The condition can be
graded according to the degree of slippage as measured in the lateral X-ray.
However, such classifications are prone to inconsistencies in
measurement owing to differences in. positioning and interobservor error.
Moreover, they do not relate easily to treatment. There are better
classifications, e.g. those of Dunn or Loder (Table
Clinical features
Boys
and girls are more or less equally affected hut girls tend to get the condition
earlier, e.g. ages 9—14 as opposed to 11—16. A girl who has reached menarche is virtually immune. Although the classically overweight picture is
commonly seen, no body habitus is exempt.
As
the severity and speed of slippage varies, so does the classical presentation.
An early chronic (stable) slip may be the cause of mild intermittent pain which
is ignored or missed, whereas an unstable acute on chronic or late chronic slip
may result in catastrophic loss of function in the limb.
The
diagnosis of early slips is usually delayed because this relatively rare
condition is not suspected or the symptoms are
minor.
Pain is classically felt in the groin and thigh but may he referred to the knee.
Any child with knee pain should have the hips examined and if necessary X-rayed.
The
backward and downward displacement of the epiphysis causes the lower limb to
adduct, externally rotate and extend. The hip thereby shows apparent shortening
with loss of abduction, internal rotation and flexion.
Investigations
The
diagnosis is confirmed on the lateral radiograph hut the features are regularly
seen on the anterior—posterior view. A computerised tomography (CT) scan can
help in defining whether the growth plate is open (Fig. 28.11). Blood tests are
usually un helpful un less there is a suggestion of metabolic or endocrine
disorder, e.g. renal failure or hyperthyroidism.
Treatment
The
child should be placed on protected weight bearing or even bed rest and traction
prior to surgery.
The
choices for treatment are fixation in situ
or realignment, either by reduction of the slip or osteotomy (Table
28.4).
When
the growth plate is open one should fix in
situ if at all possible (Fig. 28.12) because realignment through the growth
plate carries a significant risk of AVN. The treatment of unstable slips is
thereby controversial. However, an extreme
Postoperatively
the child should he on protected weight hearing for 6 weeks and followed up
until both growth plates are fused. The family should be warned of the risk of
slippage on the contralateral side (20 per cent). Any evidence of this through
symptoms or X-rays demands fixation of that side as well. Routine prophylactic
pinning of the opposite side is normally reserved for those children at special
risk, e.g. renal failure, hypothyroidism.
Complications
Avascular
necrosis
This
is serious and disabling. It may occur as the result of an acute on chronic
slip or may he caused in the course of treating an unstable slip (Fig.
28.14).
Part
or all of the head may be involved and the condition does not usually manifest
itself radiologically until several months after treatment.
This
is a poorly understood condition possibly related to autoimmune causes,
whereby the hip joint stiffens and narrows. Chondrolysis is not related to the
severity of slippage and indeed can occur after prophylactic pinning of the
contralateral. hip.
Treatment
is to prevent contracture and keep the hip mobile while healing occurs.
Osteoarthritis
Although
osteoarthritis is a common effect of SUFE, it is generally a forgiving
complication. Hips generally function