Developmental dysplasia of the hip (DDH) (previously called congenital dislocation of the hip; CDH)

This is a spectrum of disorders ranging from dysplasia to subluxation through to frank dislocation of the hip. Early detection is important as it usually responds to conservative treatment; late diagnosis is usually associated with hip dysplasia which requires complex treatment often including surgery. Neonatal screening is performed as part of the routine examination of the newborn, checking if the hip can be dislocated posteriorly out of the acetabulum (Barlow's manoeuvre) or can be relocated back into the acetabulum on abduction (Ortolani's manoeuvre), as described on page 142. These tests are repeated at routine surveillance at 8 weeks of age. Thereafter, presentation of the condition may be with detection of asymmetry of skinfolds around the hip, limited abduction of the hip, shortening of the affected leg or a limp or abnormal gait.
In-toeing
Clinical features of in-toeing in children
Metatarsus varus
• Occurs in infants
• Passively correctable
• Heel is held in the normal position
• No treatment required unless it persists beyond 5 years of age and is symptomatic
Medial tibial torsion
• Occurs in toddlers
• May be associated with bowing of the tibiae
• Self-corrects within about 5 years
Persistent anteversion of the femoral neck
• Presents in childhood
• Usually self-corrects by 8 years of age
• May be associated with hypermobility of the joints
• Children sit between their feet with the hips fully internally rotated ('W' sitting)
• Most do not require treatment but femoral osteotomy may be required for persistent anteversion
Summary
Variations of musculoskeletal normality and differential diagnosis:

Perceived disorder Normal age range Differential diagnoses to consider

Bow legs 1-3 years Rickets, osteogenesis imperfecta, Blount's disease

Knock knees 2-7 years Juvenile idiopathic arthritis

Flat feet 1-2 years Hypermobility, congenital tarsal fusion

In-toeing 1-2 years Tibial torsion, femoral anteversion

Out-toeing 6-12 months Hypermobility, Ehlers-Danlos and Marfan's syndromes

Toe walking 1-3 years Spastic diplegia, muscular dystrophy

On neonatal screening, an abnormality of the hip is detected in about 6-10 per 1000 live births. Most will resolve spontaneously. The true birth prevalence of DDH is about 1.5 per 1000 live births. Clinical neonatal screening misses some cases. This may be because of inexperience of the examiner, but in some cases it is not possible to clinically detect dislocation at this stage, e.g. where there is only a mildly shallow acetabulum. To overcome these problems, some centres perform ultrasound screening on all newborn infants. It is highly specific in detecting DDH but is expensive and has a high rate of false positives, and is not recommended nationally. It is performed in some centres in infants at increased risk (family history, breech presentation).
If developmental dysplasia of the hip is suspected, a specialist orthopaedic opinion should be obtained. An ultrasound examination should be performed and allows detailed assessment of the hip, quantifying the degree of dysplasia and whether there is subluxation or dislocation. This information also helps in planning management and in avoiding unnecessary treatment. If the initial ultrasound is abnormal, the infant may be placed in a positioning device, which puts the hips in abduction (e.g. Craig splint), or in a restraining device (e.g. Pavlik harness for several months. Progress needs to be monitored by ultrasound or X-ray. The splinting must be done expertly, as necrosis of the femoral head is a potential complication
In most instances, a satisfactory response is obtained. If the hip has not stabilised or the condition is diagnosed late, hip abduction using traction and a further period of splinting (in a plaster hip spica) may be tried. If unsuccessful, an MRI or CT scan of the hip and/or an arthrogram will provide more detailed information of the joint. Weight-bearing on a dislocated hip should be avoided as it causes damage to the femoral head and acetabulum. Open reduction and derotation femoral osteotomy will be required if conservative measures fail

Table 26-2. Causes of limp

Age Painful limp Painless limp

1-3 years Septic arthritis/osteomyelitis Developmental dysplasia of the hip

Transient synovitis Neuromuscular, e.g. cerebral palsy

Trauma - accidental/non-accidental Unequal leg length

Juvenile idiopathic arthritis

3-10 years Transient synovitis Perthes disease (chronic)

Septic arthritis/osteomyelitis Developmental dysplasia of the hip

Trauma Neuromuscular disorders, e.g. Duchenne's

Juvenile idiopathic arthritis (JIA) muscular dystrophy

Perthes disease (acute) Juvenile idiopathic arthritis

Malignant disease, e.g. leukaemia

11-16 years Slipped upper femoral epiphysis (acute) Slipped upper femoral epiphysis (chronic)

Avascular necrosis of the femoral head Juvenile idiopathic arthritis

Juvenile idiopathic arthritis Dysplastic hip

Trauma

Septic arthritis/osteomyelitis

Bone tumours