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Developmental dysplasia of the hip.

Introduction

Community practitioners have a unique role working with families and young children, and can prove vital in preventing problems associated with developmental hip dysplasia (DDH), which may affect a child for the rest of its life. This might be through preventing the condition by educating parents on safe swaddling, supporting a young mother struggling to adapt to her baby wearing a harness, or even by detecting a case that was not picked up through the current screening programme.

In this article, we hope to empower community practitioners by providing some facts and tips relevant to DDH so that they can provide support and education to parents going through a potentially difficult process.

DDH is a condition characterised by incomplete formation of the ball and socket of the hip joint during a child's growth, both before and after birth. DDH encompasses a range of pathologies, from a congruent hip joint with a shallow socket, through hip instability, to complete dislocation of one or both hips (Dezateux and Rosendahl, 2007).

In Caucasians, around one child in 1 000 is born with a dislocated hip, and one in 100 has a dysplastic hip at birth. It is believed to be caused by a combination of genetic factors and positional moulding in the womb. If undetected, it can cause chronic disability and necessitate hip replacement at a comparably young age. Thirty per cent of hip replacements performed under the age of 60 are thought to be due to DDH (Engesaeter et al, 2008).

If detected in the first few months of life conservative interventions can have good results, although some established dislocations still require surgical intervention (Suzuki, 1993). DDH was previously referred to as congenital hip dysplasia but this has been largely replaced in recognition of the facts that not all abnormalities are present at birth and that some dysplasia and instability normalises naturally during the first weeks of life (Kocher, 2000). Recognised risk factors include breech position, an affected first-degree relative, female sex, first born, multiple pregnancy, high birth weight and oligohydramnios. It is associated with congenital abnormalities such as metatarsus adductus (pigeon toe), torticollis (wry neck), infantile spina bifida and talipes equinovarus (club foot).

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Identifying DDH

The most reliable clinical signs in DDH are restricted abduction and leg length discrepancy. Asymmetry of the buttock and thigh creases is also suggestive of DDH but it must be remembered that this is only the case if it is associated with leg length discrepancy. In DDH, crease asymmetry occurs because of bunching of the soft tissues due to shortening of the leg caused by a dislocated hip. Crease asymmetry without leg length discrepancy is, therefore, unrelated to DDH.

Ortolani's and Barlow's test are also commonly used. Barlow's test (posterior pressure on a flexed and adducted hip) should detect an unstable or dislocatable hip (Figure 1), while Ortolani's test (flexion and abduction) should demonstrate the reduction of a dislocated hip (Figure 2). Unfortunately, Barlow's and Ortolani's tests have been shown to have low diagnostic accuracy (Dogruel et al, 2008). They are difficult to perform correctly and their value depends greatly on the experience of the examiner.

Screening

It has long been common practice for babies to undergo screening for DDH at birth and at six weeks with clinical examination; but due to the low diagnostic accuracy of physical examination, it is widely accepted that some form of radiological screening programme should be in place for the infant population (Morrissy and Cowie, 1987).

Ultrasound is a widely used and effective test for detecting DDH. It is a relatively cheap, safe, accessible and acceptable screening tool but requires a skilled practitioner to perform and interpret (Terjesen, 1996). X-ray is less reliable as the infant hip joint is largely made of cartilage so is not well demonstrated on plain radiographs and is unfavourable as it involves radiation exposure.

In a number of countries in Europe, universal screening programmes are in place where every newborn has an ultrasound scan. This is not the case in the UK, Scandinavia, or the USA, due primarily to a lack of clear financial benefits (Rosendahl et al, 1995; Clegg et al, 1999) and because some abnormalities picked up soon after birth resolve spontaneously with normal growth (Shipman et al, 2006).

Until recently, practice varied in the UK between primary care trusts. It has now been standardised and the NHS Newborn and Infant Physical Examination Programme (NIPE) recommends that babies with an abnormal physical examination at birth undergo ultrasound within two weeks and those with a significant risk factor (breech presentation or an affected first degree relative) are scanned within six weeks of birth (NHS Choices, 2012).

This targeted screening programme means that some cases may be missed, as over 60% of cases of DDH have no recognisable risk factor (Standing Medical Advisory Committee, 1986) and the sensitivity of clinical examination is low (Dogruel et al, 2008).

Fortunately, targeted screening has been able to reduce the rate of late presentations to 0.34 per 1 000 live births (Clarke et al, 2012). This does, however, mean that a large centre can still expect to see up to four children a year that present at a later stage, often requiring major surgery to correct a deformity that may have been amenable to non-operative treatment if detected earlier (Lotito et al, 2007).

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In general, the earlier DDH is detected, the easier it is to treat. Health visitors and community nurses may be the first health professionals to be alerted to a missed case of DDH. Through a high index of suspicion and appropriate referral, a community practitioner can save a child from a lifetime of hip problems, potentially involving numerous major surgeries. DDH should be suspected in the presence of any of the physical findings previously mentioned, or in a child with an uneven gait or a painless limp. If there is any clinical suspicion, expedient referral for ultrasound (or X-ray if older than six months) can quickly confirm or rule out the diagnosis.

However, it should be remembered that universal ultrasound screening is not the perfect solution as it can lead to over-treatment of hips that would normalise naturally as the child grows (Rosendahl et al, 1994) and doubts exist as to its cost-effectiveness (Rosendahl et al, 1995). Recent systematic reviews have been unable to recommend universal screening (Woolacott et al, 2005; Shorter et al, 2011).

Guidance for parents on swaddling

The practice of swaddling babies has been growing in popularity recently as it is thought to improve sleep and reduce crying (Meyer and Erler, 2011). There is a high incidence of DDH in cultures in which babies are swaddled with the hips extended and legs together (Kutlu et al, 1992). This type of swaddling during infancy has been shown to be the most significant risk factor for hip dysplasia in such cultures (Dogruel et al, 2008). Keeping the legs in this position holds the ball in an unnatural position within the socket, preventing normal maturation of the joint (Figure 3). In contrast, cultures that carry their children in the straddle or 'jockey' position have very low rates of DDH (Figure 4) (Salter, 1968).

If swaddling is to be performed, the arms may be tightly wrapped but the legs should have room to move freely, with the hips able to bend up and out. The International Hip Dysplasia Institute has released guidance on 'hip-healthy swaddling' (see: http:// hipdysplasia.org).

Conservative management

If diagnosed before six months of age, the first line of treatment for most children will be an orthosis. The most commonly used in the UK is the Pavlik harness. This is a flexion-abduction orthosis, consisting of an anterior flexion strap and a posterior abduction strap for each leg, a chest strap, and two shoulder straps. If employed before six months, it is successful in over 90% of cases (Grill et al, 1988). It is the authors' practice to review the child weekly while wearing the harness, with an ultrasound scan to ensure the hip is in joint and developing well. These review clinics can be very busy, so parents may find they have unanswered questions or concerns that can be addressed later in the community.

Treatment is usually continued until three consecutive ultrasound scans are normal. The harness is then weaned over a four week period. However, treatment protocols do vary between centres, particularly regarding to the weaning process, with some surgeons electing not to wean at all.

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There is currently no evidence or guidance as to which method works better. Skin problems in the groin crease may occur and can be treated with hydrocolloid dressings. The harness can, rarely, put pressure on the brachial plexus at the shoulder or the femoral nerve in the groin (Mooney and Kasser, 1994; Murnaghan et al, 2011). Any child that stops moving an arm or leg while in the harness should therefore be urgently reviewed by the treating orthopaedic surgeon.

If conservative treatment is successful, the child will normally be followed up closely with periodic ultrasound scans until six months of age and X-rays beyond that, to ensure the hips continue to grow and mature normally.

Surgical treatment

If conservative treatment fails to relocate the hip, or the child presents at an older age, surgery may be necessary. In the first instance, this involves a closed reduction under general anaesthetic. The hip is manipulated back into joint and held with an orthosis or a hip spica plaster cast. This may be combined with a small surgical procedure to release a tight tendon, particularly on the inside of the hip (an adductor tenotomy).

If closed reduction is unsuccessful, an open reduction is performed, which involves more extensive surgery. This is often combined with procedures in which the bones are cut to realign the femur and the pelvis in order to keep the hip in joint.

Summary

Although a rigorous screening programme exists throughout the UK, community health professionals should remain vigilant for missed cases of DDH, as the earlier treatment is initiated, the simpler and less invasive it is likely to be. Any doubt regarding an infant's hips can be easily and safely allayed with ultrasound scanning.

Evidence does not exist to support ultrasound screening of all infants. Tight swaddling with the legs together increases the risk of DDH and should be avoided. The Pavlik harness is a commonly used treatment which may be encountered in the community. Although complications are rare, some may require urgent review by the treating surgeon.

Key points

* Only children with a significant risk factor now receive routine ultrasound screening in the UK, meaning some cases can be missed

1 The later the diagnosis is made, the harder the condition is to treat

* Community practitioners can play a key role in the diagnosis of the condition and in supporting and educating parents

* Swaddling must be performed safely in order for the hips to develop normally

No potential competing interests declared

References

Clarke NM, Reading IC, Corbin C, Taylor CC, Bochmann T. (2012) Twenty years experience of selective secondary ultrasound screening for congenital dislocation of the hip. Arch Dis Child 97(5): 423-9.

Clegg J, Bache CE, Raut VV. (1999) Financial justification for routine ultrasound screening of the neonatal hip. J Bone Joint Surg Br 81(5): 852-7.

Dezateux C, Rosendahl K. (2007) Developmental dysplasia of the hip. Lancet 369(9572): 1541-52.

Dogruel H, Atalar H, Yavuz OY, Sayli U. (2008) Clinical examination versus ultrasonography in detecting developmental dysplasia of the hip. Int Orthop 32(3): 415-19.

Grill F, Bensahel H, Canadell J, Dungl P, Matasovic T, Vizkelety T. (1988) The Pavlik harness in the treatment of congenital dislocating hip: report on a multicenter study of the European Paediatric Orthopaedic Society. J Pediatr Orthop 8(1): 1-8.

Kocher MS. (2000). Ultrasonographic screening for developmental dysplasia of the hip: an epidemiologic analysis (Part I). Am J Orthop (Belle Mead NJ) 29(12): 929-33.

Kutlu A, Memik R, Mutlu M, Kutlu R, Arslan A. (1992) Congenital dislocation of the hip and its relation to swaddling used in Turkey. J Pediatr Orthop 12(5): 598-602.

Lotito FM, Sadile F, Cigala F. (2007) Surgical treatment of hip dislocation in early inf ancy. Hip Int 17(Suppl 5): S35-43.

Meyer LE, Erler T. (2011) Swaddling: a traditional care method rediscovered. World J Pediatr 7(2): 155-60.

Mooney JF 3rd, Kasser JR. (1994) Brachial plexus palsy as a complication of Pavlik harness use. J Pediatr Orthop 14(5): 677-9.

Morrissy RT, Cowie GH. (1987) Congenital dislocation of the hip. Early detection and prevention of late complications. Clin Orthop Relat Res (222): 79-84.

Murnaghan ML, Browne RH, Sucato DJ, Birch J. (2011) Femoral nerve palsy in Pavlik harness treatment for developmental dysplasia of the hip. J Bone Joint Surg Am 93(5): 493-9.

NHS Choices. Change to guidance on ultrasound examination of the hips in screening for developmental dysplasia of the hips (DDH). Available from: http:// newbornphysical.screening.nhs.uk/standards [Accessed October 2012].

Rosendahl K, Markestad T, Lie RT. (1994) Ultrasound screening for developmental dysplasia of the hip in the neonate: the effect on treatment rate and prevalence of late cases. Pediatrics 94(1): 47-52.

Rosendahl K, Markestad T, Lie RT, Sudmann E, Geitung JT. (1995) Cost-effectiveness of alternative screening strategies for developmental dysplasia of the hip. Arch Pediatr Adolesc Med 149(6): 643-8.

Salter RB. (1968) Etiology, pathogenesis and possible prevention of congenital dislocation of the hip. Can Med Assoc J 98(20): 933-45.

Shipman SA, Helfand M, Moyer VA, Yawn BP. (2006) Screening for developmental dysplasia of the hip: a systematic literature review for the US Preventive Services Task Force. Pediatrics 117(3): 557-76.

Shorter D, Hong T, Osborn DA. (2011) Screening programmes for developmental dysplasia of the hip in newborn infants. Cochrane Database Syst Rev 7(9): CD004595.

Standing Medical Advisory Committee (1986) Screening for the detection of congenital dislocation of the hip. Arch Dis Child61(9): 921-6.

Suzuki S. (1993) Ultrasound and the Pavlik harness in CDH. J Bone Joint Surg Br 75(3): 483-7.

Terjesen T. (1996) Ultrasound as the primary imaging method in the diagnosis of hip dysplasia in children aged <2 years. J Pediatr Orthop B 5(2): 123-8.

Woolacott NF, Puhan MA, Steurer J, Kleijnen J. (2005) Ultrasonography in screening for developmental dysplasia of the hip in newborns: systematic review. BMJ 330(7505): 1413.

Daniel Westacott MBBS MRCS

Specialist Registrar in Trauma and Orthopaedic Surgery

Giles Pattison MBBS MSc(Med Ed) FRCSEd

FRCSEd(Tr&Orth) FHEA

Consultant Paediatric Orthopaedic Surgeon

Stephen Cooke MBChB FRCS(Tr & Orth)

Consultant Paediatric Orthopaedic Surgeon

Warwick Orthopaedics, University Hospital of Coventry and Warwickshire

Correspondence: dan_westacott@hotmail.com
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Title Annotation:PRACTICE: PEER REVIEWED
Author:Westacott, Daniel; Pattison, Giles; Cooke, Stephen
Publication:Community Practitioner
Date:Nov 1, 2012
Words:2450
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