Congenital
disorders
These may be intrinsic malformations within a developing structure (e.g.
limb deficiency) (Fig. 27.2), or the result of extrinsic influences, for example
postural (Fig. 27.8), neuromuscular (Fig.
27.10) or a malformation elsewhere (Fig. 27.11). Regularly, however, we do not know why a congenital abnormality
(e.g. talipes equino varus) has occurred.
Nowadays,
diagnostic ultrasound can detect musculoskeletal abnormalities in utero. This
technology is creating both opportunities and difficulties in the management of
an unborn child. Whatever the cause, a significant abnormality diagnosed
prenatally or at birth can be devastating to a family. Support and advice from a
wide range of experts may be required.
Malformations
of the limbs and spine
Musculoskeletal structures develop alongside other body systems. By the
12th week of intrauterine life the spine and limbs are formed, the upper limbs
slightly ahead of the lower. Examples of how embryological structures can stray
from the path of normal development are shown in Table
27.4.
Because
the various organs are developing concurrently, the causes of malformation may
affect more than one system. Therefore, when presented with a limb anomaly one
should
consider associated abnormalities in, for example, the cardiovascular,
urogenital or nervous system.
However,
in most cases the children are usually otherwise normal and develop and function
well. They are regularly well motivated and do not admit to any disability in
spite of obvious physical abnormality. These aspects have to be understood when
considering treatment.
In the majority of cases there is no obvious cause, such as thalidomide. Occasionally a genetic (especially in skeletal dysplasia) or syndromic association [e.g. thrombocytopenia, absent radius (TAR syndrome)] is possible.
Congenital
malformations
Failure
of formation
These cases may present as multiple complex abnormalities (Fig.
27.12)
or fit recognisable patterns of deformity (Fig. 27.13). The defects may be
classified as transverse [e.g. con genital amputation through a limb) or
longitudinal (e.g. femoral deficiency (Fig. 27.13) or radial club hand
(Fig. 27.14)]. A longitudinal deficiency may be florid [e.g. tibial dysplasia
(Fig. 27.15)] or subtle [e.g. congenital pseudarthrosis of the tibia
(Fig. 27.16)].
The limb beyond the defect may be normal (Fig. 27.17) or abnormal
(Fig. 27.2).
Femoral
deficiency. This ranges in severity from a short femur to total absence.
Treatment varies accordingly.
A
short femur may be amenable to lengthening. The commonly associated coxa vara
may require correction beforehand by valgus osteotomy.
More
profound degrees are beyond the limits of surgical leg equalisation. However,
children usually function well in
Fibular
deficiency (Fig 27.2 and Fig
27.17). In this condition the tibia is short and bowed
anteriorly, often with an overlying skin dimple. The fibula is wholly or partly
absent. The foot is in equino valgus and commonly shows deficiency of the outer
rays. The condition also affects the whole limb. There is mild femoral
shortening and genu valgum and often the cruciate ligaments are absent.
Treatment
is dominated by the overall predicted shortening and the state of the foot. A
child with marked shortening and a deformed residual foot is best served by a
Syme’s amputation at about 1 year. If the foot is normal, it is reasonable
to consider correction of the equino valgus deformity and equalisation of leg
lengths. This may require a combination of lengthening of the affected tibia
and a shortening procedure, for example epiphysiodesis on the normal side.
Tibial deficiency (Fig. 27.15). The tibia is wholly or partially
absent. The foot is in equino varus and, in contrast to fibular deficiency, may
be augmented (e.g. polydactyly or diplopodia).
Reconstruction of the foot is usually unsuccessful except in mild cases.
If the tibia is absent a ‘through the knee’
amputation is indicated. If there is a tibial remnant a good option is
to fuse the fibula with this and fit the child with an extension prosthesis. It
is thereafter usually preferable to amputate the foot to allow better fitting of
the prosthesis.
Congenital
pseudoarthrosis of the tibia (Fig. 27.16). This is a subtle longitudinal defect
causing anterolateral bowing in the lower tibia. The condition may be associated
with neurofibromatosis or fibrous dysplasia. The deformity regularly progresses
to a beastly fracture for which treatment is difficult and prolonged. The whole
armamentarium of the fracture surgeon can be involved including intramedullary
fixation, traditional and advanced grafting techniques (e.g. vascularised
fibular graft and the Ilizarov method). Even then the pseudoarthrosis may not
heal and amputation becomes inevitable in a minority of cases. The
prepseudoarthrosis and the treated pseudoarthrosis should be braced until
skeletal maturity.
Congenital
pseudoarthrosis of the clavicle (Fig. 27.19). This defect of the midshaft of the
clavicle is probably related to the development of the subclavian artery as it
occurs on the right side unless there is dextrocardia.
The main problem is
cosmetic, although there may be discomfort. If treatment is undertaken the
options include excision of the defect with repair of its periosteal sleeve or
fixation and grafting.
Infantile
coxa vara. There is a defect of ossification in the femoral neck, leading to a
varus deformity usually requiring corrective osteotomy.
Failure
of separation
Syndactyly (fingers and toes) (Fig. 27.20). Three types are described,
simple (soft tissue only), complex (bones involved) and acrosyndactyly (digits
joined at their tips). Syndactyly as a regular component of syndromic conditions
(e.g. Apert’s syndrome, constriction ring). Where possible fingers should be
separated, although the techniques are demanding and involve flaps and skin
grafting. Separation of toes is rarely indicated.
Radioulnar
synostosis. The fused radius and ulna are shorter than their counterparts.
Abduction of the shoulder effectively mimics pronation. Therefore, a forearm
fixed in neutral rotation or slight supination can be compensated by the
shoulder and this allows virtually normal hand function. A forearm fixed in
pronation cannot be thus compensated and in such cases a rotation osteotomy to
bring the hand to the neutral or slightly supinated position may be indicated.
Tarsal
coalition. The usual patterns are calcaneonavicular (Fig.
27.21) or
talocalcaneal fusions by cartilaginous or bony bars. There may be pain as well
as stiffness, particularly in eversion, and the condition is also known as
peroneal spastic
Vertebral
and scapular anomalies. Vertebrae and ribs may be fused with resultant scoliosis
and/or chest wall deformity. Regularly, there are associated abnormalities
within the spinal column (e.g. diastomatomyelia) and elsewhere (e.g. urogenital
and cardiac systems).
Klippel—Feil
syndrome. This comprises multiple congenital abnormalities in the cervical spine
leading to a characteristic short, stiff neck and a low hairline. Torticollis,
facial asymmetry and webbing of the neck may be apparent.
Sprengel
shoulder. This is due to a failure of normal descent of the scapula which
remains high and small (Fig. 27.22). There may be a bony tether, the
omovertebral bar, between scapula and spine, which is also prone to anomalies.
Treatment
is largely for cosmetic reasons. Excision of the superomedial portion or
displacement osteotomy of the scapula is a better option than attempts to
reposition the whole bone.
Gigantism
A whole limb (Fig. 27.23) or part (Fig.
27.24) can be affected. The
condition may be idiopathic or associated with neurofibromatous or a vascular
malformation. The gigantic part is distressing
for the child and family. Procedures such as debulking and growth arrest are
usually unsuccessful. The best results are from amputation, where this is a
realistic option.
Polydactyly
Extra digits can be an isolated abnormality, part of a pattern of limb
malformation (e.g. tibial deficiency with diplopodia) or syndromic, as in
chondroectodermal dysplasia (Ellis—van Creveld syndrome) which consists of
short-limbed dwarfism,
Extra
digits usually requite removal. It is sometimes difficult to know which digit to
sacrifice (Fig. 27.25).
Skeletal
dysplasias
These generalised disorders of the skeleton are often genetically
determined. They may affect the whole or part of a bone. In some, for example
osteogenesis imperfecta, the condition is a generalised disorder affecting
connective tissue.
They
characteristically produce skeletal deformities and abnormal stature. Although
uncommon, they pose complicated problems in management. Their detailed
description is out with the scope of this book but it is possible to summarise
them along with suitable examples.
They
can be categorised into major groups shown in Table
27.5.
The
diagnosis is from clinical data, especially comparing the patient’s
measurements with standard growth charts, radiographs (typically a skeletal
survey) and further tests (e.g. biochemical). In some cases the diagnosis can be
made by ultrasound.
Osteogenesis
imperfecta (OI). This relatively common dysplasia (incidence 1:20 000 births)
is caused generally by an abnormality of collagen type I and thereby all
connective tissues are involved. The joints are loose, bones bend and break,
teeth can be abnormal (dentinogenesis imperfecta, DI) and there may be
neurological and gastrointestinal problems. The care of these children as with
many other dysplasias becomes multidisciplinary. In severe types the children
are unable to walk through weakness and deformity. Other methods of locomotion
must be used (e.g. bottom shuffling, crutches, wheelchairs).
Four
broad types of OI are described but it is not always possible to thus classify a
patient.
• Type II — lethal perinatal form.
• Type III (Fig. 27.26) — severe deforming type. Autosomal recessive.
Multiple fractures. The children rarely achieve walking. DI is common.
• Type IV — as for type I but the children are less active and the
sclerae are normal. DI is common.
Treatment
depends on the individual and the severity of the condition. Any advice must be
given within the context of what goals are achievable.
Much
can be done through occupational therapy, orthotics, seating and general
paediatric care.
The
orthopaedic surgeon can help with deformity correction and intramedullary
stabilisation of long bones using rods or wires. These can prevent recurrent
fractures and help those children who are strong enough to stand and walk.
The
value of treatments to increase bone strength (e.g. bisphosphonates) remains
unproven.
Osteopetrosis.
The bones are dense, hard and brittle. The milder tarda form is autosomal
dominant; the severe congenital type is recessive.
Death
may occur from lack of bone marrow. Distortion of the orbits may cause
blindness. Bone marrow transplantation can be successful.
Hereditary
multiple exostoses (diaphyseal aclasis) (Fig. 27.27). This is a relatively
common, autosomal dominant dysplasia. Cartilaginous-capped exostoses occur at
the metaphysis and the osteochondromas grow with the child and stop growing at
maturity. The lumps may cause mechanical or cosmetic problems which justify
their removal. There may be differential growth disturbances in the forearm or
leg leading to ankle, wrist and elbow deformities. Distortion of growth plates
may cause, for example, genum valgum. All of these deformities may require
surgical correction.
Malignant
change in an osteochondroma (chondrosarcoma) is possible, usually after
skeletal maturity. The combination of pain and/or enlargement is an indication
for further investigation.
Disorders
of the epiphyses. Multiple epiphyseal dysplasia can be autosomal dominant. It
causes irregular epiphyses which, in the hip can be confused with bilateral
Perthes’ disease. The hips and knees are prone to early degenerative change.
In
spondyloepiphyseal dysplasia the vertebrae are also affected and there may be
instability of the atlantoaxial joint.
Disorders
of the metaphyses. These result in short stature and deformities such as genum
varum which require correction (Fig. 27.28).
Achondroplasia.
This is the commonest cause of short-limbed dwarfism (Fig.
27.29). The
inheritance trait is autosomal dominant, although many cases arise as new
mutations.
The
limbs are short with wide metaphyses, there is lumbar lordosis, the forearm
bulges and the nasal bridge is low. Trunk height is maintained but spinal
stenosis is common.
Cleidocranial
dysostosis. This generalised dysplasia includes partial or complete absence of
clavicles, ossification defects in the skull, abnormal dentition and a wide
symphysis pubis. The absence of clavicles allows the shoulders to be brought
together in front of the chest (Fig. 27.30).
Storage
diseases. In the mucopolysaccharidoses, the intermediate metabolites of the
partial degradation of glycosaminoglycans are stored in various tissues
including bone marrow and connective tissues.
The
specific enzyme defects responsible for the various types of storage disease
(e.g. Hunter’s disease, Morquio’s disease) are becoming well known. Bone
marrow transplantation can be successful in certain types.
The
clinical manifestations include short stature, limb deformities, coarse
features, stiff joints, expanded bones, mental retardation and carpal tunnel
syndrome.