Developmental Dysplasia of Hip

Dr. Utsav Agrawal

It is a spectrum of intra-capsular displacement of femoral head from its normal relationship with acetabulum before, during or just after birth.

Presents in different form in different agesThe syndrome in newborn consists of instability of

hip such that femoral head can be partially or fully be displaced from the acetabulum and be reducible on examination.

The term DDH encompasses syndrome ranging from dysplasia and subluxation to frank dislocation.

Dysplasia – Deficient development of acetabulum. Obliquity and loss of concavity of acetabulum

with intact shenton’s line.Subluxation – Displacement with some contact

remaining between articular surfaces. Has widened tear-drop- head distance, centre edge angle <20, break in shenton’s line.

Dislocation – Complete displacement of joint with no contact between original articular surfaces.

Teratologic Dislocation – occurs with other disorders like myelodysplasia, arthrogryposis, etc.are dislocated at birth,have limited range of motion,not reducible

Risk FactorsFemale : Male – 6:1First bornFamily history (6% one affected child, 12% one affected parent, 36%

one child + one parent)OligohydramniosBreech delivery –in 1in 35 breech deliveries, increased in frank breechNative Americans - swaddling cultures

Incidence 1.4/1,000 in newborns(40% after 1st week, 10% after 1 month) 10/10,000 born with subluxation or dysplasia 2.3 /100 have clinical finding 8/100 have ultrasound abnormality

Associated Conditions Torticollis – 15-20% Metatarsus adductus – 1.5 – 10% Oligohydramnios

Etiology

1. Congenital 2. Teratologic Eg. Asso with AMC3. Syndromic – with larson, Freeman-sheldon

syndrome, diastrophic dysplasia4. Neuromuscular – asso with spasticity, polio,

meningomyelocele

Etiology is multifactorial and influenced by genetic, hormonal and ecological influences.

Inheritence – Autosomal Dominant trait with incomplete penetrance

Predisposing factorsLigamentous laxity – d/t newborn’s response to maternal

relaxin hormone.- Increased ratio of collagen III to collagen I.

Prenatal positioning/mechanical forces - in breech delivery (more in frank breech-risk20%). As left sacro-anterior position is more common than right, left hip is at higher risk for dislocation.- more in first born- more in oligohydramnios

Post-natal positioning – WaddlingRacial predilection - in blacks and Asians.

in whites and Native Americans

DevelopmentBoth femoral head and acetabulum develop from the

same piece of mesenchyme of primitive limb bud. A cleft appears to separate them at 7-8 wks. Hip joint is developed at 11 th wk.

At birth, acetabulum is composed of cartilage with a thim rim of fibro-cartilage around it(Labrum)

The structure of the acetabulum is determined by the femoral head which is placed inside it.

Centre for ossification of femoral head appears between 4th and 7th months of post-natal life and grows until physeal closure.

Acetabulum fuses at around 18yrs.Any deviation from normal embryogenesis leads to

malformations. E.g. PFFD

Development in DDHAt birth, the affected hip spontaneously slide in and out

of the acetabulum. Postero-superior wall of acetabulum looses it sharp contour and neolimbus is formed.

This sliding in-and-out produces a ‘clunk’Some hips spontaneously reduce and undergo normal

development, while others develop secondary changes.Secondary barriers to reduction develop –

Thickened limbus which then hypertrophies and inverts presenting as a diaphragm between femoral head and acetabulum

Pulvinar – pad of fatty tissue in depths of acetabulumLigamentum teres elongates and thickensTransverse acetabular ligament hypertrophyHour-glass constriction of hip capsulecontracted ilio-psoas cause further capsule narrowing

If stable reduction is achieved at early stages (till about 8 yrs), the structures remodel and normal development ensues.

Changes in hip that remain dislocated – acetabular roof gradually becomes more oblique, cavity flattens, medial wall thickens

In adults, presents as high riding dislocation and cases with fully dislocated hip may remain free from degenerative changes.

In adults with untreated subluxated hips, instability persists and degenerative changes appear including subchondral sclerosis, cyst, osreophyte formation, loss of articular cartilage.

Clinical FeaturesGait abnormality - Adductor lurch/ waddling

gaitLimb length inequalityGalleazi’s signAsymmetric gluteal foldsIncreased lumbar lordosisScoliosisLimited AbductionTelescopy of hipHigh placed G.T.Ortolani’s signBarlow’s signKlisic’s sign

Klisic’s Sign

InvestigationsX-raysUltrasoundCTMRIArthrography – Gold

standardOn Xrays- Hilgenreiners line

- Perkins line- Shenton’s line- Acetabular Index- Centre-edge angle of wilberg- Acetabular depth to width – normally >38%- Widened acetabular tear-drop

Von-Rosen’s view – with hip abducted internally rotated, and extended

In normal hips, medial beak of the femoral metaphysis lies in lower inner quadrant

27 in newborn, 20 around 2 yrs. Maximum – 30

Centre edge angle of Wilberg

19 or more in 6-13 yrs25 or more in above 14 yrs

Ultrasonography1. Static non-stress technique – Graf2. Dynamic stress technique – Harcke 3. Dynamic standard minimum examination (DSME)Graf Technique – Morphologic assessment, relies on

anatomic landmarks3 lines-

Baseline- line of ilium as it intersects bony and cartilaginous portions of acetabulumInclination line – Line along the margin of cartilaginous acetabulumAcetabular roofline – Along the bony roof

Angle between roof and base line – Alpha - >60 ,evaluates bony acetabulum

Angle between inclination and base line- Beta - <55 , evaluates cartilaginous acetabulum

Graf ClassificationClass Alpha

angleBeta angle Description treatment

I >60 <55 Normal -

II 43-60 55-77 Delayed ossification

Observe/harness

III <43 >77 Lateralisation

Pawlik harness

IV unmeasurable

- Dislocated Pawlik harness/ closed vs open reduction

ArthrographyGOLD STANDARDUsing Sodium-diatriazoate 76% in 1:1 dilution through median sub-adductor approach

Findings- Blunting of rose thorn sign outlining the limbusHour-glass constriction of capsuleMedial pooling of dye >7mmFilling defect in acetabular floor d/t pulvinarFilling defect in acetabulum d/t hypertrophied ligamentum teres

Management0-6 months – First watch, if ortolani +ve Pawlik harness in 100-

110` flexion till 6 to 8 wks before weaning is started

Follow-up weekly using USGSuccess- 70-90%6 – 18 months – closed reduction and immobilization in hip spica.

May require adductor tenotomy before reduction.Position – Flexion > 90`, abduction 30-40` (within safe zone of

Ramsey) internal rotation – 10-15`Hyperflexion may cause femoral nerve palsy and inferior

dislocation.Excessive abduction/internal rotation may cause AVN.Duration – 6 weeks- 6 monthsCheck after every 6 wks and re-apply cast in case of instability.Reduction considered stable if abduction can be done till 20`

from max. abduction and extension beyond 90` without redislocation

Indication for open reduction – Failed closed reductionPersistent subluxationsoft tissue interpositionunstable reduction

18 months – 3 yrs – open reduction, may require osteotomy

Beyond 3 yrs – Open reduction + osteotomy + acetabular reconstruction