Congenital deformities

  Developmental dysplasia of the hip (DDH)

This term is more accurate than the older congenital dislocation of the hip (CDH) because it includes dislocation along with other less severe forms, all of which have in common a dysplasia or natural shallowness of the acetabulum. The femoral neck is usually anteverted.

There is a wide spectrum of presentation of DDH from birth to adult life. The condition can manifest as a neonate with clinical hip instability (Fig. 27.31), an infant with limited abduction (Fig. 27.32), a limping toddler (Fig. 27.33), a child or adolescent with dysplasia (Fig. 27.34), or an adult with established degenerative change (Fig. 27.35).

Incidence

This is highest in the neonate where environmental factors such as breech presentation, transient ligamentous laxity and the skills of examiners can influence the rate of detection of instability.

The incidence depends on the criteria by which the diagnosis is made. The rates of detection of neonatal instability in some series approach 20 per 1000 births, whereas the inci­dence of late presenting dislocations (after the age of 3 months) is generally in the order of 0.5—1 per 1000. The inference is that many cases will stabilise spontaneously and this creates a dilemma for the surgeon as to which cases should be treated

Aetiology

Many factors are related to DDH (Table 27.6). A family history of DDH increases the risk up to 30 times. The condition is five times more common in girls, possibly related to hormonal factors producing joint laxity. The left side is affected more commonly than the right.

Breech presentation, especially the extended position, first­born children and caesarean section are associated with increased neonatal instability, possibly through restricted foetal movement.

A foot deformity or torticollis should also alert the examiner to possible associated DDH. Finally, there may be hip dislocation or dysplasia in association with neuromuscular disease syndromic conditions and skeletal dysplasia.

Diagnosis

Neonate. The clinical examination is only part of the general examination. All newborn babies should be screened for hip instability by a skilled examiner using the Barlow and Ortolani tests (Fig. 27.31). The baby should be relaxed and the hips flexed to 90degreeIt is possible to reduce a dislocated hip by abduction and gentle forward pressure (Ortolani) or dislocate an unstable hip by adduction and gentle backward pressure (Barlow). In both cases a soft clunk is felt as the hip reduces or dislocates.

The specificity of clinical neonatal examination is 100 per cent (no false positives). However, its sensitivity is much lower; even skilled examiners are unable to eliminate late diagnosed cases.

Ultrasonography is a valuable test. It is more sensitive than clinical examination and can detect not only displacement of the femoral head but also varying degrees of dysplasia. Therein lies its weakness for it tends to over diagnose the condition and thus subject babies to unnecessary treatment. Also, it is very difficult to deliver universal ultrasound screening to communities where the population is mobile, the time in hospital is short, and obstetric and imaging services may be geographically separated.

Radiography can be helpful in the neonate provided care is taken in positioning the patient. However, X-rays are not generally reliable until approximately the age of 3 months (Fig. 27.36).

Infant. The hips should be examined as part of routine developmental checks, looking in particular for asymmetry, such as an extra thigh crease, shortening of a limb or limitation of abduction (Fig. 27.32).

Child. The child limps, the affected leg is externally rotated, there is an increased lumbar lordosis, and there is regularly an extra thigh crease and limited abduction. However, the signs may be subtle (Fig. 27.33) and easily misinterpreted as part of normal development in an unsteady toddler. A bilateral case is more difficult to diagnose because the gait is symmetrical. Indeed, the condition may be missed until late in childhood.

Adolescent. Pain is the usual feature and an X-ray will reveal dysplasia and possible subluxation.

Adult. Pain is again the usual complaint and X-rays may now show degenerative change as well as dysplasia (Fig. 27.35).

Treatment

Although the details of treatment vary at different ages the principles are the same (Table 27.7) and should all be considered before deciding which one is appropriate for an individual case. The objective is a stable congruous reduction through gentle methods so that the fragile growth plate is not damaged. Such an event (avascular necrosis) is a major complication and usually results in shortening, coxa vara and a greater trochant­er, which is high because its growth plate is not affected.

Infant. Traction and surgery are not indicated. The hips can usually be reduced (Ortolani) and should then be held in a harness or splint (Fig. 27.37) for about 8 weeks. A harness allows movement but requires more supervision, and out of expert hands carries a significant failure rate. A splint contains the hips better but thereby carries a risk of avascular necrosis.

A baby, for example, aged 6 months would usually require preliminary traction followed by closed reduction augmented by soft-tissue release (psoas and/or adductor).

An arthrogram is often helpful to define the abnormal soft tissues and confirm a satisfactory reduction.

Toddler and young child. Although it is still possible to achieve reduction by closed methods it becomes more likely that, with age, open reduction along with femoral or innominate osteotomy will be required.

Open reduction. This is usually undertaken through the anterior approach. The iliac apophysis is split. The psoas is divided near its insertion. The capsule is opened and excess trimmed. The ligamentum teres and soft tissues in the acetabular floor are removed. The transverse ligament is divided. The inturned labrum (limbos) may also need to be cut in a radial fashion to allow entry of the femoral head. Reduction can then usually be achieved. However, in the majority of cases it is necessary to complement the reduction with a realignment femoral or innominate (Salter) osteotomy. If reduction is impossible because of a high dislocation, femoral shortening along with realignment is necessary. Postoperatively, the child is held in a cast for 6—8 weeks and then mobilised.

In later childhood, dislocations can still be treated by the combination of open reduction, femoral osteotomy and acetabuloplasty. However, the older the child the more difficult and unrewarding the surgery becomes, especially in bilateral cases.

Adolescent or young adult. Those presenting with a pain­ful dysplastic hip may require surgery. A realignment of the joint through pelvic or femoral osteotomy is only appro­priate if there is a congruous hip joint. Otherwise (i.e. sub­luxation) the acetabulum has to be augmented by other means, for example shelf arthroplasty.

Special cases. DDH associated with neuromuscular disease, syndromic disorders or skeletal dysplasia requires special thought. In such cases (e.g. arthrogryposis, spina bifida) sur­gery is likely to fail through redisplacement or stiffness. Therefore, it may well be in the child’s overall best interests to leave the hip joint alone and restrict one’s surgery by treating major limb malalignment by corrective osteotomy.

Coxa vara

This is a descriptive term that describes a decrease in the angle between the femoral neck and shaft. Many conditions can produce this deformity but three general categories are recognised.

Congenital — this is present at birth and results in shortening of the leg. It is often associated with femoral deficiency.

       Developmental (infantile) — coxa vara develops in early childhood and progresses with growth. The cause is likely to be related to defective enchondral ossification in the metaphysis. Corrective osteotomy may be required.

Acquired — this group includes cases where the deformity is due to a metabolic disorder (e.g. rickets), trauma (e.g. avascular necrosis in the treatment of DDH) and infection.

Congenital deformities of the feet

Congenital talipes equinus varus (club foot)

If ever there was a condition which exemplified ‘Beauty and the Beast’ this is it. The deformity can present over a wide spectrum of severity. At one end there are postural forms which respond easily to simple treatment; at the other there are severe fixed deformities which resist treatment and behave in a beastly fashion.

Incidence. This is generally quoted as one—two cases per 1000 babies.

Aetiology. Although the majority of cases is idiopathic, the condition can regularly be related to factors such as posture, heredity and associated conditions like neuromuscular disease (Table 27.8 and Fig. 27.38).

The risk of club foot is increased 20-fold if a first-degree relative has the condition, and there ate examples of racial prevalence, for example among Polynesians. The most difficult club feet tend to be in association with neuromus­cular, syndromic or dysplastic conditions.

Clinical features. The baby must be fully examined because of the links between foot deformity, hip disorder and other conditions. The diagnosis of club foot is usually obvious. The hindfoot and forefoot are in equinus and varus (Fig. 27.39). However, the stiffness varies from case to case and it is important to assess whether the deformity is likely to be postural or fixed (Fig. 27.40). Mild postural cases may be corrected above the plantigrade position, whereas a severe fixed deformity falls well short of this.

Pathological anatomy. In fixed deformity the navicular dislocates medially and downwards off the head of the talus, whose neck likewise becomes deformed in the same direction. The front of the os calcis goes medially under the talus, whereas the back of the os calcis is high and lateral, with tethers between it and the fibula. Several tendons are tight (tendo achilles, tibialis posterior, flexor hallucis longus, flexor digitorum longus) and there are contractures of joint capsules and ligaments. Debate continues as to which of the changes in club foot are primary and which are secondary.

Treatment. This depends on stiffness. Mild cases will respond to stretching, whereas fixed deformities will probably need surgery.

The parents must be given careful explanation of the condition. They should understand that club foot alone does not prevent a child walking, and even in the untreated case function can be good (Fig. 27.41). However, the foot cannot be made normal. It usually ends up smaller and stiffer and the calf is thinner. Finally, parents must realise that relapse can occur and, therefore, follow-up until maturity is necessary.

Most babies with significant congenital talipes equinus varus (CTEV) undergo stretching and strapping, usually supervised by a physiotherapist. Alternative methods include serial casts or splints.

Surgeons generally advise nonoperative treatment for 3 months when it is likely to be clear whether soft-tissue surgery is needed. If so, persisting with stretching and splintage is unlikely to remain effective. Indeed, persistent or over-vigo­rous stretching may cause a breach in the midfoot to produce a rocker bottom deformity which is very difficult to treat.

Primary surgery. This can be undertaken at 3 months, but most surgeons prefer to wait until after 6 months of age. In infants who are handicapped in other ways, and whose prognosis for walking is unclear, it is wiser to wait even longer.

The operation depends on the severity of the condition. The structures to be considered for division or lengthening are tendons (achilles, tibialis posterior, flexor hallucis longus, flexor digitorium longus), joint capsules (ankle, subtalar, calcaneocuboid, talonavicular, naviculocuneiform) and ligaments (talofibular, calcaneofibular, talotibial, peroneal sheath, plantar fascia).

The surgical approach depends on what are to be divided. The posterior route alone will suffice for most cases, whereas a pantalar release will require a more extensive approach (e.g. Cincinnati). Temporary wires may be used to fix reduced joints, especially the talonavicular. In very severe cases (e.g. arthrogryposis, sacral agenesis) soft-tissue surgery alone will not correct the deformity. In this event, talectomy may be indicated.

Postoperatively, an above-knee cast is applied with the knee at a right angle and the foot as dorsiflexed as the wound and the circulation will allow. The cast is changed at 2—3 weeks when further correction is gained. Difficult cases may need more than one change. Plasters are retained for 8 weeks or so. Thereafter, continuing splintage and supportive footwear may be needed according to severity.

Secondary surgery. Recurrence of deformity (relapse) is, unfortunately, common in severe cases and bony surgery is ultimately necessary.

However, most surgeons try to avoid such surgery in patients under the age of 5 years. Meanwhile, repeat soft-tissue release and/or transfer of the tibialis anterior tendon may hold the foot, at least temporarily.

Later on, collateral release (division of medial structures combined with calcaneocuboid fusion), wedge tarsectomy, triple arthrodesis, supramalleolar osteotomy and the Ilizarov technique are possible salvage operations.

  Congenital vertical talus

This is a rare condition, 100 times less common than club foot (Fig. 27.42). The hindfoot is in equinus with the talus vertical.

The navicular is dislocated on to the neck of the talus and the combination gives the appearance of a rocker bottom foot. However, unlike the deformity caused by over-correction of club foot, the talus and os calcis retain a normal relationship.

The condition is regularly associated with neurological disorder. Surgical correction is usually required and involves complex reconstruction of the foot.

  Congenital elevation of the fifth toe

  The little toe is hypoplastic and sits upon its neighbour. Surgical correction is usually undertaken for cosmetic and/or shoe-fitting problems.

Curly toes

The third and fourth toes are usually affected and flexed at their distal interphalangeal joints. The condition may correct spontaneously and surgery (normally flexor tenotomy) should be delayed until after the age of 3 years, as for symptomatic toes.

Congenital abnormalities of the knee

Patella

There is a number of congenital conditions involving the patella, which may be absent or hypoplastic in association with the nail—patella syndrome. Other features of the syndrome include hypoplasia and splitting of the nails, elbow abnormalities and bony spurs on the ilium. The patella may be bipartite and confused with a fracture; the separate ossicle is usually superolateral. There may be congenital dislocation of the patella, which is small and fixed to the lateral femoral condyle; a fixed flexion deformity of the knee and genu valgum will be noted.

Discoid meniscus

The lateral meniscus is almost always involved, and there is either a complete discoid meniscus of normal mobility or the anterior and lateral attachment is deficient resulting in hypermotility. The latter type causes problems of locking and pain. Surgery is often required but where possible meniscal pre­serving techniques should be used because total meniscectomy invariably leads to degenerative change.

Congenital dislocation of the knee

The joint is hypo extended with the tibia displaced forwards on the femur. Mild cases are postural and related to malpresentation (e.g. extended breech). They can be treated by simple splintage or exercises. More severe ones involve quadriceps contractures, which require surgical release (quadricep plasty).

Congenital deformities of the fingers

Camptodactyly

This is a nontraumatic flexion deformity of the little finger at the proximal interphalangeal joint. Most cases are better left alone as function is usually normal.

Clinodactyly

This is a curvature of a digit in the radioulnar direction. It may be associated with other syndromes.

Kirner’s deformity

This affects the little finger in which there is radial and palmar curving of the distal phalanx.