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DDH: causes and examination: embryology, risk factors and identification of developmental dysplasia of the hip (DDH).

Developmental dysplasia of the hip (DDH) is the most common congenital musculoskeletal disorder of childhood. (1) It includes hips that are unstable, subluxated, dislocated and/or have malformed acetabulae. (2) In 1989, Klisic introduced the term to replace congenital dislocation of the hips, (3) which suggested dislocation at birth and did not include developing dislocation or acetabular dysplasia over time. (4)

An incidence of 1.5 to 20 cases per 1000 births in developed countries is widely quoted, (5) with variation due to differences in screening method, timing of diagnosis, (6) and definitions. No systematic review provides good evidence that screening is beneficial, but failure to recognise DDH in the newborn or in early infancy can lead to late diagnosis and treatment, with possible long-term disability. (7)

Development of DDH

It is important to understand hip joint development in order to appreciate the abnormalities that occur and lead to hip dysplasia. (8) Hip formation begins at around seven weeks' gestation. The femoral head and acetabulum are formed by separation of foetal tissue by a cleft. When positioned properly, the femoral head will help shape the cavity that becomes the acetabulum. (9) If the femoral head's position is incorrect or its movement is restricted during the pregnancy, a shallow socket may result. By 11 weeks, the hip joint complex is formed. (10) Both components are largely cartilaginous and remain vulnerable in utero to external forces (such as in oligohydramnios) or internal forces such as those influenced by developing musculature or lack of foetal movement (as in spina bifida or arthrogryposis).

During embryological development of the hip joint, the four significant periods to consider are the 12th week, the18th week, 36 to 40 weeks, and the immediate postnatal period. (11)

At around 12 weeks' gestation, the limbs rotate outward 90[degrees] so that the knees are pointing forward. The hips adopt the position that they will maintain for the continuation of the pregnancy. If a dislocation occurs at this stage, it is termed 'teratologic' because the rest of the hip development will now be affected. Neuromuscular conditions such as myotonic dystrophy often lead to teratologic dislocations at this stage.

At around 18 weeks, muscles and ligaments start to develop around the hip. If the foetus can move around normally in the uterus, this will ensure development of the soft tissues and allow continued enlocation of the femoral head within the developing acetabulum.

The last four weeks of the pregnancy are critical in the development of DDH. Important factors are breech presentation and reduced amniotic fluid reducing the foetus' movements, especially in a large baby. The onset of labour is associated with a surge in maternal hormones that influence joint laxity. During delivery, the hips can be affected by a frank breech, or a hypotonic baby with lax hip joints.

After birth, the infant's lower limbs move from flexion-abduction to more extension-adduction, putting the hips at further risk. Swaddling, side-lying or asymmetry of lying posture (as in 'moulded' babies) can influence hip development. At birth, the femoral head is at its most shallow, (9) and with an 'abnormal' hip posture and general joint laxity this can result in subluxation or complete dislocation. In the weeks following birth, growth of the acetabulum increases significantly, but depends on an enlocated, stable femoral head. Normally at birth, there is a tight fit between the femoral head and acetabulum. (11) Surface tension from synovial fluid helps maintain enlocation of the femoral head, and this tight fit is reduced or lost in DDH.

If the hip is dislocated at birth, a combination of a shallow acetabulum, tightness of the joint capsule and shortening of the surrounding soft tissues will make relocation of the joint more difficult over time. Early detection of DDH is therefore essential for best treatment outcome. It is imperative that examination of the newborn is carried out by a properly trained clinician, as an unstable hip may be overstretched by an over zealous examination, and an inexperienced examiner may miss a subtle instability. (12) Clinical examination of a newborn baby can appear normal but later at ultrasound scan a dislocation is detected.

Clinical examination

For best results, clinical examination of a neonate's hips should be carried out when the infant is calm and relaxed. The hips are flexed to 90[degrees] and the examiner's thumbs are placed on the medial thigh, with the middle (or ring) finger placed over the greater trochanter. The Ortolani and Barlow manoeuvres (see Box 1) are used to identify dislocation and instabilility.

The Ortolani test may be negative but the Barlow positive, indicating the hip is enlocated but unstable. In a newborn, immediate treatment may not be necessary in an enlocated but unstable hip, since it may correct spontaneously. In this case, advice on maintaining hip abduction, prevention of further stress to the joint by not lifting by the feet to change nappies, and an early ultrasound scan is indicated. Barlow's test by inexperienced clinicians who are not gentle may actually lead to an increased risk of instability. (12)

Teratologic dislocations, irreducible at birth, occur early in foetal development. Physical signs are the unilateral limitation of abduction, a shortened femur and asymmetry of thigh, groin or buttock creases. If both hips have irreducible dislocations, the only clue may be poor abduction bilaterally.

Risk factors

Certain risk factors can predispose hip dysplasia in some infants. The following must be referred for an ultrasound scan and orthopaedic examination:

* Infants with abnormal hip examination such as a 'clunk' on Ortolani's manoeuvre, positive Barlow's manoeuvre, limitation of abduction, apparent shortening of femur and asymmetry of hip, thigh and buttock creases (DDH has been known as 'clicky hips', so many babies with a click on examination are referred--most are benign 'soft tissue' clicks, but inexperienced clinicians may have difficulty in discriminating this)

* Breech lie (especially 'frank breech' with extended and adducted legs) in utero during the third trimester (11,16,17)

* Family history of treated hip dysplasia (11,18,19)

A number of factors are not recommended for further assessment by the National Screening Committee, but should still be considered because higher incidences of DDH have been reported:

* Postural deformity of the feet, suggesting a lack of space for normal movements within the uterus toward the end of the pregnancy. (11,15-17,20,21)

* Congenital knee dislocation, in which hip dislocations occur in almost half (22)

* Infants who present with congenital muscular torticollis (16,17,25)

* Oligohydramnios (15,20,21,23)

* Syndromic babies. (11)

Other important factors include female gender, (15,20,21,23) first-born infants (due to an unstretched uterus and tighter abdominal muscles), (11,15,21,23) ethnicity, (8,11) and swaddling or use of cradle boards. (23,24)

Surveillance and referral

Clinical surveillance starts with the newborn and infant physical examination immediately after birth, then within 72 hours and at six to eight weeks. Babies with a clinical abnormality and positive Barlow or Ortolani tests are referred immediately for further assessment--usually an orthopaedic examination and ultrasound scan within a week or two. Most babies are referred from maternity units by paediatricians or nurse practitioners. Referrals for babies with stable hips but DDH risk factors would be seen at around four to six weeks of age. Those discharged early may have their initial paediatric check by the GP. Babies with risk factors that are missed at birth are often picked up by the health visitor or GP at their six- to eight-week check. At this stage, asymmetry of lying posture and thigh or hip creases, as well as conditions such as congenital muscular torticollis, become more evident. Despite efforts to introduce a national programme, hip screening in the UK depends on local protocols. Those who screen and refer need the appropriate expertise, confidence and understanding of risk factors to minimise late presentation of DDH.
Box 1: Ortolani and Barlow manoeuvres

In the Ortolani manoeuvre, one hand
is placed on the femur and the other
is used to stabilise the pelvis. The
hip is then gently abducted and
pressure applied to the upper femur
by the middle finger. A positive
Ortolani sign is described as the
palpable and sometimes audible
'clunk' as the dislocated femoral
head moves over the posterior rim of
the acetabulum and relocates. The
more shallow or poorly formed the
acetabulum, the easier it is to miss the sign and the hip may simply
feel 'lax'. Resistance may be felt at around 60[degrees], and gentle
traction of the femur with continued abduction may be required to
relocate the femoral head--if resistance continues, the hip may be
irreducibly dislocated. If an unstable hip is missed at the newborn
stage, it becomes more difficult to detect a positive Ortolani
test. (4) For 70 years, this manoeuvre has followed Marino Ortolani's
original description. (13)


The Barlow manoeuvre is a provocative test of hip instability
(subluxation or dislocation), performed by gently adducting the
hip while pushing the femur posteriorly. (1,4,15) Again, the pelvis
should be stabilised. With the thumb on the inner side of the thigh,
backward pressure is applied to the head of the femur. A positive
sign is described if the femoral head is felt to move backward over
the labrum (the fibro-cartilaginous rim of the acetabulum) onto the
posterior aspect of the joint capsule (a movement of not more than
0.5cm and often accompanied by a 'clunk'), then the hip is said to
be subluxatable. If the hip moves completely out of the acetabulum
it is said to be dislocatable.


(1) Herring JA. Developmental dysplasia of the hip. In: Herring JA (Ed.). Tachdjian's Pediatric Orthopaedics. Philadelphia: Saunders, 2002.

(2) American Academy of Paediatrics. Clinical practice guideline: early detection of developmental dysplasia of the hip. Pediatrics, 2000; 105(4): 896-905.

(3) Klisic P. Congenital dislocation of the hip: a misleading term. J Bone & Joint Surgery, 1989; 71-B: 136.

(4) Catterall A. What is congenital dislocation of the hip? J Bone & Joint Surgery (Br), 1984; 66-B: 469-70.

(5) Patel H; Canadian Task Force on Preventative Health Care. Preventive health care, 2001 update: screening and management of developmental dysplasia of the hip in newborns. Canadian Medical Association Journal, 2001; 164(12): 1669-77.

(6) Bialik V, Bialik GM, Blazer S, Sujov P, Wiener F, Berant M. Developmental dysplasia of the hip: a new approach to incidence. Pediatrics, 1999; 103(1): 93-9.

(7) Shipman SA, Helfand M, Moyer VA, Yawn BP. Screening for developmental dysplasia of the hip: a systematic literature review for the US Preventative Services Task Force. Pediatrics, 2006; 117(3): e557-76.

(8) Aronsson DD, Goldberg MJ, Kling TF, Roy DR. Developmental dysplasia of the hip. Pediatrics, 1994; 94(2 Pt1): 201-8.

(9) Ponseti IV. Growth and development of the acetabulum in the normal child: anatomical, histological and roentgenographic studies. J Bone & Joint Surgery, 1978; 60A: 575-85.

(10) Weinstein SL, Mubarek SJ, Wenger DR. Developmental hip dysplasia and dislocation: part I. J Bone & Joint Surgery, 2003; 85-A(9): 1824-32.

(11) Witt C. Detecting developmental dysplasia of the hip. Advanced Neonatal Care, 2003; 3(2): 65-75.

(12) Moore FH. Examining infants' hips: can it do harm? J Bone & Joint Surgery, 1989; 71-B: 4-5.

(13) Ortolani M. Un segno poco noto e sua importanza per la diagnosi precoce di prelussazione congenita dell'anca. Pediatria; 1937; 45: 129-36.

(14) Barlow TG. Early diagnosis and treatment of congenital dislocation of the hip. J Bone & Joint Surgery (Br), 1962; 44-B: 292-301.

(15) Holen KJ, Terjesen T, Tegnander A, Bredland T, Saether OD, Eik-Nes S. Ultrasound screening for hip dysplasia in newborns. J Pediatric Orthopedics, 1994; 14: 667-73.

(16) Cunningham KT, Moulton A, Benningfield SA, Maddock CR. A clicking hip in a newborn baby should never be ignored. The Lancet, 1984; 1(8378): 668-70.

(17) Jones DA, Powell N. Ultrasound and neonatal hip screening: a prospective study of 'high risk' babies. J Bone & Joint Surgery, 1990; 72-B: 457-9.

(18) Wynne-Davies R. Acetabular and familial joint laxity: two aetiological factors in congenital dislocation of the hip: a review of 589 patients and their families. J Bone & Joint Surgery, 1970; 52-B: 704-12.

(19) Marks DS, Clegg J, al-Chalabi AN. Routine ultrasound screening for neonatal hip instability: can it abolish late-presenting congenital dislocation of the hip? J Bone & Joint Surgery (Br), 1994; 76: 534-8.

(20) Clarke NM. Role of ultrasound in congenital hip dysplasia. Archives of Disease in Childhood, 1994; 70: 362-3.

(21) Chan A, McCaul KA, Cundy PJ, Haan EA, Byron-Scott R. Perinatal risk factors for developmental dysplasia of the hip. Archives of Disease in Childhood, 1997; 76: F94-100.

(22) Nogi J, MacEwan GD. Congenital dislocation of the knee. J Pediatric Orthopedics, 1982; 2(5): 509-13.

(23) Akman A, Korkmaz A, Aksoy MC, Yazici M, Yurdakok M, Tekinalp G. Evaluation of risk factors in developmental dysplasia of the hip: results of infantile hip ultrasonography. Turkish Journal of Pediatrics, 2007; 49(3): 290-4.

(24) Van Sleuwen BE, Engelberts AC, Boere-Boonekamp NM, Kuis W, Schulpen TW, L'Hoir MP. Swaddling: a systematic review. Pediatrics, 2007; 120(4): e1097-106.

(25) Tien Y-C, Su J-Y, Lin G-T, Lin S-Y. Ultrasonographic study of the coexistence of muscular torticollis and dysplasia of the hip. J Pediatric Orthopedics, 2001; 21: 343-7.

Annie Hurley Paediatric orthopaedic physiotherapy practitioner, Nuffield Orthopaedic Centre, Oxford
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Title Annotation:CLINICAL UPDATE
Author:Hurley, Annie
Publication:Community Practitioner
Article Type:Report
Geographic Code:4EUUK
Date:Sep 1, 2009
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