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 an extension prosthesis (Fig. 27.18). Indeed, there is a debate whether a child with a congenitally short limb is better served by complex leg equalisation surgery with its regular complications and joint stiffness or by early mobilisation in an extension prosthesis.

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 flat foot. There may be an associated ball and socket ankle joint. The calcaneonavicular bar can be demonstrated by plain radiographs, whereas computerised tomography (CT) best visualises the talocalcaneal bar. If conservative measures (e.g. analgesics, orthotics) fail, excision of the bar may be indicated. If degenerative changes ensue, arthrodesis may ultimately be required.

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, dysplastic nails, hair and teeth, polydactyly and congenital heart disease.

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 1(a) — the classic form; blue sclerae, autosomal dominant inheritance and the mildest clinically. Children and adults can be reasonably active with precautions. A neurological problem is premature deafness.

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.

  The diagnosis of 01 is usually possible from clinical data and radiographs. These can show classical appearances in the limbs, spine and skull (osteopenia, deformities, vertebral collapse and Wormian bones in the skull). However, there are borderline cases which pose great difficulties, especially if the differential diagnosis includes nonaccidental injury. There is yet no test which will unequivocally confirm the diagnosis of 01.

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.

  If fractures need fixation, special instruments are needed to overcome the hard bone.

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.