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What should we think about or look at, in case of patella dislocation in children?
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Congenitaland
habitual dislocation
of the patella
Congenital (or persistent lateral) dislocation of
the patella is the most severe form of the
pathology spectrum. It is presents in early
infancy and could result in early malrotation
and shortened extensor mechanism. This entity
must be differentiated from habitual (or
obligatory) dislocation of the patella which
often presents later in childhood and find
spontaneous reduction of the patella with
flexion and extension of the knee.
More common associated syndromes are:
1) Down syndrome
is one of the most common
chromosomal abnormalities in human,
occurring in 1 in 700-1000 live births. Avariety
of orthopedic manifestations can occur in
relation to ligamentous laxity, muscular
hypotonia, and joint hypermobility: cervical
spine instability, scoliosis, foot disorder (pes
planus, metatarsus), hip disorder, and genu
valgum and patella dislocation (10 to 20% of
patients) [1]. Life expectancy has improved
mainly for advances in the management of
cardiac anomalies, infections, and leukemia.
Surgical intervention in children with Down
syndrome has a high risk of complications,
particularly infection and wound healing
problems. Careful anesthetic airway manage
ment is needed because of the associated risk
of cervical instability.
2) Larsen’s syndrome
is a disease of
generalized defect in collagen. This rare and
severe syndrome is characterized by flat,
hyperteloric facies, multiple dislocations of the
joints, club foot deformity, and long cylindrical
fingers. Many of these patients died of early
complications secondary to dislocation of the
cervical spine, tracheomalacias, heart disease,
and severe respiratory infection. These children
pose a problem of planning early treatment
.
Clubfeet must be treated conservatively early,
and operation should be postponed until after
knee deformities (dislocated knee or patella)
are corrected by plaster cast and/or early
operation. Unilateral hip dislocations should be
treated surgically in the second year of life.
Treatment of bilateral hip dislocations is best
neglected. Finally, the spinal status of these
children must be monitored throughout their
life [6]. Differential diagnosis is tricho
rhinophalangeal syndrome (associated with
laxity of the skin and joints) which can be
mistaken for the Larsen syndrome.
3) Diastrophic dysplasia
and recessivemultiple
epiphyseal dysplasia (rMED) are non-lethal
conditions of a family of the more common
generalized skeletal dysplasia.
Double-layered
patella (DLP) or “multilayered” patella
, a
form of partite patella consisting of anterior and
posterior components, is hardly suggestive for
this diagnosis. When symptomatic, surgical
fusion of the patellar fragments in DLP using
threaded screw has been suggested [7].
4) Rubinstein-Taybi syndrome
(RTS) is a well-
defined complex of congenital malformations
characterized by mental and growth retardation,
broad thumbs, broad big toes, and typical face.
Associated patellar instability demands early
recognition and treatment to prevent potentially
catastrophic gait disturbances [8].
5) Beals-Hecht syndrome
(BHS) also known
as congenital contractural arachnodactyly, is
caused by a defect in fibrillin as in Marfan
syndrome. This syndrome is characterized by a
multitude of clinical findings including
arachnodactyly, narrow body habitus
,
scoliosis, congenital contractures, and external
ear deformities. Restrictive lung disease may
be associated with the severe scoliosis and
thoracic cage abnormalities in this syndrome.
6) Ellis van Creveld syndrome
(EVCS) is a
rare chondroectodermal dysplasia, genetically
transmitted with a recessive autosomal pattern,
which involves the skeletal system (valgus
deformity with lateral dislocation of the patella,
polydactyly), nails and teeth [11]. In about 50
to 60 percent of cases, the affected individuals
show
cardiac abnormalities
. Aortic atresia,
hypoplasia of the ascending aorta or of the left
ventricle is also reported. About half of the
patients die in the childhood due to cardio
respiratory complications.