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
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 abnormalityRisk Factors Female : Male – 6:1 First born Family history (6% one affected child, 12% one affected parent, 36% one child + one parent) Oligohydramnios Breech delivery –in 1in 35 breech deliveries, increased in frank breech Native Americans - swaddling culturesAssociated Conditions Torticollis – 15-20% Metatarsus adductus – 1.5 – 10% Oligohydramnios
EtiologyEtiology is multifactorial and influenced bygenetic, hormonal and ecological influences.1. Congenital2. Teratologic Eg. Asso with AMC3. Syndromic – with larson, Freeman-sheldon syndrome, diastrophic dysplasia4. Neuromuscular – asso with spasticity, polio, meningomyelocele 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 oligohydramniosPost-natal positioning – WaddlingRacial predilection - in blacks and Asians. in whites and Native Americans
Development Both 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 DDH At 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 acetabulum Ligamentum teres elongates and thickens Transverse acetabular ligament hypertrophy Hour-glass constriction of hip capsule contracted 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 Features Gait abnormality - Adductor lurch/ waddling gait Limb length inequality Galleazi’s sign Asymmetric gluteal folds Increased lumbar lordosis Scoliosis Limited Abduction Telescopy of hip High placed G.T. Ortolani’s sign Barlow’s sign Klisic’s sign
Centre edge angle of Wilberg 19 or more in 6-13 yrs 25 or more in above 14 yrs
Ultrasonography1. Static non-stress technique – Graf2. Dynamic stress technique – Harcke3. 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 acetabulum Inclination line – Line along the margin of cartilaginous acetabulum Acetabular roofline – Along the bony roofAngle between roof and base line – Alpha - >60 , evaluates bony acetabulumAngle between inclination and base line- Beta - <55 , evaluates cartilaginous acetabulum
Arthrography GOLD STANDARD Using Sodium-diatriazoate 76% in 1:1 dilution through median sub-adductor approach Findings- Blunting of rose thorn sign outlining the limbus Hour-glass constriction of capsule Medial pooling of dye >7mm Filling defect in acetabular floor d/t pulvinar Filling 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 reduction Persistent subluxation soft tissue interposition unstable reduction18 months – 3 yrs – open reduction, may require osteotomyBeyond 3 yrs – Open reduction + osteotomy + acetabular reconstruction