Intended for healthcare professionals

Endgames Case Review

A limping child

BMJ 2016; 352 doi: https://doi.org/10.1136/bmj.i476 (Published 09 February 2016) Cite this as: BMJ 2016;352:i476
  1. David Lindsay, foundation year 2 doctor1,
  2. Sunil D’Souza, consultant trauma and orthopaedic surgeon1
  1. 1Department of Trauma and Orthopaedics, Royal Bolton Hospital, Bolton, UK
  1. Correspondence to: D Lindsay david.lindsay3{at}nhs.net

A 15 month old girl was referred to the orthopaedics department by her general practitioner with an abnormal gait and a tendency to fall over more than her peers. There was no history of trauma or family history of note, and she was otherwise well.

She was born by uncomplicated spontaneous vaginal delivery at term and began walking independently aged 13 months. The midwife had commented to the mother during neonatal examination that the left hip was “a bit clicky,” but this had not been investigated further.

On examination she walked, apparently pain free, with a left sided lurch. Her left leg was 2 cm shorter than her right leg. Hip instability tests were normal. The general range of motion in the left hip was good, but abduction was limited and the telescope test was positive. A plain radiograph of the pelvis was obtained (fig 1).

Questions

  • 1. What is the diagnosis?

  • 2. How can this condition be identified clinically?

  • 3. How can it be assessed radiologically?

  • 4. How is it usually managed?

  • 5. Why has the name of this condition changed?

Answers

1. What is the diagnosis?

Short answer

Left sided developmental dysplasia of the hip.

Discussion

Developmental dysplasia of the hip (DDH) covers a spectrum of disorders, from mild dysplasia of the acetabulum without displacement to subluxation, dislocation, and aplasia of the joint.1 2 3 4 The incidence of true DDH is probably 1.3-5 per 1000 live births, but it depends on the definition used and the population studied, although evidence suggests that neonatal hip instability is found in 34-55 per 1000 live births.5 6 7 The features of DDH develop during the antenatal period and the early years of life and have been associated with several factors. Rarely, “teratological” hip dysplasia and dislocation occur in utero, but most children have only subtle signs of abnormality, if any, at birth. DDH is thought to be related to abnormal fetal moulding on a background of genetic and other factors—intrauterine position (especially breech position), genetic predisposition, hormones (such as high levels of maternal oestrogen, progesterone, and relaxin in the third trimester), and post-natal factors (hip positioning) have all been implicated.8 9 10 11 12 13 The left hip is more commonly affected than the right and 20-35% of cases are bilateral.1 14 It is unclear whether primary acetabular or femoral dysplasia or femoral head-acetabular instability (or both) is the main cause. Most neonates who are identified as having a degree of hip instability at birth will go on to stabilise spontaneously and only a small fraction will develop dysplastic features. In his classic 1962 paper, Barlow found that one in 60 neonates had clinical evidence of instability but of these 60% stabilised in one week and 88% by eight weeks.15 Later studies also found that 90.4% of neonates with sonographic abnormalities suggestive of instability do not develop DDH.6

2. How can this condition be identified clinically?

Short answer

Limited hip abduction in flexion, leg length discrepancy (above knee), Barlow’s and Ortolani’s tests (normal in this case because the dislocated hip has become irreducible), asymmetrical skin creases, abnormal gait, and history.

Discussion

Risk factors in the history include family history of DDH, female sex, ethnicity, primiparity, oligohydramnios, breech delivery (especially frank breech), prematurity, plagiocephaly, congenital torticollis, infantile scoliosis, foot deformities (such as metatarsus adductus and talipes calcaneovalgus), high birth weight, and swaddling (hips continuously adducted and extended) as an infant.5 11 16 Of these, swaddling is the only easily modifiable risk factor and is prevalent in some populations. Risk may be minimised in these communities by promoting “hip safe” wrapping.

Routine physical examination of the neonatal hip aims to identify clinical hip instability that may progress to DDH (except in rare cases of teratological hip). Examination of older children aims to identify evidence of established hip dysplasia or dislocation. Hip abduction can be limited, especially in flexion. Hip abduction of up to 90° is considered normal in an infant, and although an asymmetrical range of motion is a more worrying feature, DDH can be bilateral. Skin creases in the groin may be asymmetrical and there may be a leg length discrepancy, a positive Galeazzi test, or loss of external rotation. Hip instability tests include Ortolani’s and Barlow’s tests.4 17 18 Ortolani’s test aims to relocate a dislocated or subluxed hip by holding the patient’s thighs between thumb and forefinger (with the hips and knees flexed and the shins in the examiner’s palms) and applying pressure to the greater trochanter of the maximally abducted thighs. A palpable, low pitched clunk (as opposed to a normal higher pitched joint click) associated with detectable movement of the femoral head implies hip reduction with this manoeuvre. Barlow’s test is similar but aims to sublux an unstable (“dislocatable”) but in-joint hip. Pressure is applied to the patient’s groin with the thumb during abduction and adduction. A palpable, click-clunk suggests an unstable hip. These two tests for hip instability are most useful in infants aged 3 months or less and can appear normal if a dysplastic hip is dislocated and irreducible.

Gait abnormalities (such as limp or waddling gait), delayed walking, telescoping, hip pain and a limited range of motion at the hip may be detected in older children with DDH.19 The telescope test involves flexing the knee and hip of a supine patient to 90° and alternately applying axial compression and distraction in line with the femoral shaft while palpating for relative movement between the greater trochanter and pelvis with the free hand. The telescope test is not specific for DDH, and other pathology such as fractures can also produce a positive test result.

3. How can it be assessed radiologically?

Short answer

Ultrasound (age ≤6 months) or anteroposterior pelvic radiography (≥6 months).

Discussion

Ultrasound is commonly used in neonates and young infants (sensitivity 88.5%, 95% confidence interval 84.1% to 92.1%; specificity 96.7%, 96.4% to 97.4%; positive predictive value 61.6%; negative predictive value 99.4%).20 Sonographic features of neonatal hip instability are usually graded according to the Graf classification.21 22 This system is mainly based on assessment of the α angle (between the lateral vertical cortex of the ileum and the acetabular roof; >60° is considered normal), which assesses bony coverage of the femoral head, and the β angle (between the lateral vertical cortex of the ileum and the labral fibrocartilage; <55° is considered normal), which assesses labral coverage of the femoral head.

From around age 6 months, radiography of the hips may be used to aid evaluation (or from 3 months if ultrasound is not available).23 Potential features on plain radiographs include femoral head location, acetabular morphology, and femoral-acetabular alignment (fig 2). Although the size of the cartilaginous femoral head is often normal, ossification is usually delayed. The visualised or estimated location of the femoral head each side can be assessed relative to two geometrical features: Hilgenreiner’s line (fig 3; line H) and Perkin’s lines (fig 3; lines P1 and P2). Hilgenreiner’s line is drawn horizontally through the two tri-radiate cartilages that form the acetabular—the femoral heads should lie inferior to this point. Perkin’s line is drawn perpendicular to Hilgenreiner’s line (vertically) through the outer limit of each acetabulum—the femoral head should lie medial to this point. If the femoral heads have not yet ossified, the medial part of the femoral neck metaphysis should lie in the inferomedial quadrant of these lines.

Figure2

Fig 2 Anteroposterior radiograph of the pelvis with features of left sided developmental dysplasia of the hip: missing femoral head ossification nucleus and abnormal position of metaphysis (A), pseudoacetabulum (B), and shallow true acetabulum (C)

Figure3

Fig 3 Anteroposterior radiograph of the pelvis with Hilgenreiner’s line (line H) and Perkin’s lines (lines P1 and P2)

Acetabular morphology can be assessed with the acetabular roof angle (also known as the acetabular index; fig 4)—the angle between Hilgenreiner’s line and a line drawn through the centre of the tri-radiate cartilage and the most superolateral point of the acetabulum. This angle, which normally decreases with age, should generally not exceed 30°.24 An alternative anteroposterior pelvic view with the hips abducted to 45° can be used to assess Von Rosen’s lines. These lines, drawn through the centre of the femoral shafts, should intersect the ipsilateral acetabulum.25 Shenton’s line (a smooth arc from the inferior cortex of the femoral neck along to the superior edge of the obturator foramen; fig 4 line S) may also be disrupted. Other imaging modalities such as contrast arthrography, computed tomography, and magnetic resonance imaging may be used later during specialist treatment.

Figure4

Fig 4 Anteroposterior radiograph of the pelvis with acetabular roof angles and Shenton’s line (line S) (disrupted on the left side)

4. How is it usually managed?

Short answer

Splinting for early presentations; late presentations may require surgery.

Discussion

Patients who present early (age <6 months with reducible hips) can usually be managed by abduction splinting using, for example, a Pavlik harness or Frejka pillow.26 27 The aim is to reduce any dislocation or subluxation and then maintain the femoral head within the acetabulum. This can be achieved by ensuring the legs fall passively into abduction when flexed. Depending on patient factors and the time and duration of treatment, splinting is up to 90% effective. Generally, the earlier treatment starts, the more likely it is that conservative measures will succeed. Therefore once identified, referral should not be delayed. Risks of splinting include osteonecrosis of the femoral head, transient femoral nerve palsy, inferior hip dislocation, knee injuries, and pressure sores.16 28 29

Children who present at age 6-18 months and those in whom abduction splinting is unsuccessful may require closed reduction followed by a period of spica casting. The hips of children who present late (over the age of 18 months) and those in whom conservative management is unsuccessful are usually irreducible and surgery is therefore required.30 Options include open reduction and spica casting, pelvic osteotomy, and femoral osteotomy (or a combination of the above). There are many potential surgical techniques for various situations. Salter rotational pelvic osteotomy is a common option used in younger children that increases anterolateral acetabular cover by a cut through the ilium and rotation through the pubic symphysis. Patients who are identified only as adults may require replacement with femoral and acetabular prostheses to enable reconstruction.

Outcomes after open reduction and innominate osteotomy in children are generally good in the short to medium term, allowing relatively normal hip function with associated decreases in morbidity. Many successfully treated hips will, however, eventually require joint replacement. Long term follow-up of a Canadian case series found that only 1% had received a total hip replacement 30 years after the procedure but that this figure rose to 46% at the 45 year mark.31 In the Norwegian National Joint Registry from 1987 to 1999, DDH-type disease was the main indication for 9% of all primary uncemented total hip replacements and 5% of primary cemented total hip replacements.32

5. Why has the name of this condition changed?

Short answer

It is no longer called congenital dislocation of the hip because some cases are now known to develop after a normal neonatal examination.

Discussion

“Congenital dislocation of the hip” has generally been replaced by “developmental dysplasia” because the second term better represents the spectrum of deformities and evolution of the deformity over time from birth.4 33 Not all cases of DDH can be identified by current clinical or radiological screening methods, and clinical and sonographic findings do not always correlate.6 Because as many as 15% of DDH cases are undetectable at birth,34 this disabling and treatable condition must be borne in mind when assessing children and even adults with abnormal gait or hip pain, even if they have previously had a normal examination (and perhaps ultrasound screen) at birth.35 The importance of early identification and management of suspected DDH is reflected in the current UK Newborn and Infant Physical Examination (NIPE) screening recommendations.36 37 38 These specify a detailed physical examination (including examination of the hips on a firm surface) within 72 hours of birth and a repeat examination at 6-8 weeks of age. Ultrasound examination within two weeks is recommended for any infant with positive features in the family history (defined by maternal response to direct questioning), history of breech presentation or delivery (including breech presentation at 36 weeks’ gestation, irrespective of eventual presentation or mode of delivery), or abnormal examination findings. Other worrying features are currently considered relative indications.

Patient outcome

The patient was referred to a paediatric hip subspecialist and is currently awaiting surgery.

Notes

Cite this as: BMJ 2016;352:i476

Footnotes

  • Competing interests: We have read and understood BMJ policy on declaration of interests and declare the following interests: none.

  • Provenance and peer review: Not commissioned; externally peer reviewed.

  • Parental consent obtained.

References

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