· any manifestation of hip instability
· neonatal instability
· established dislocation
· syn. developmental dysplasia of hip
· ability to dislocate or reduce femoral head into or out of acetabulum
· terms include
· dislocatable - fully dislocate
· subluxatable - movement felt but no dislocation
· dislocated - complete loss of contact
· irreducible - unable to be reduced
· subluxation - some contact
· abnormality of acetabulum
· acetabulum shallower than normal
· inclination of acetabulum more vertical than normal
· incidence
· of established CDH is 1 in 1000 live births
· of dislocable hips is 10 in 1000 live births
· of unstable hips is 15 in 1000 live births
· influenced by
· presence of screening programmes
· age of baby at examination
· experience of examiner
· more common in females
· F:M = 6:1 (5:1 - 8:1)
· more common in first-born
· left hip more often involved
· 2/3 of cases
· bilateral in 20%
· associated with
· congenital torticollis (20%)
· metatarsus adductus (2%)
· talipes calcaneovalgus (15%)
· nursery screening has
· decreased incidence of late dislocation
· increased incidence of early instability
· local study showed decrease of 85% in incidence of walking CDH
· different in sexes
Maternal hormones
· in females, baby has heightened response to maternal relaxin hormones
Familial hyperlaxity
· in males, usually familial hyperlaxity with collagen alteration
Intrauterine
· breech position is important risk factor
· 25% of patients with CDH born in breech position
· cf 2.5% in general community
· frank breech is highest risk (20%)
· in female breech
· 1 in 35 have dislocated hips
· 1 in 15 have unstable hips
· increased incidence with
· oligohydramnios
· twins
· increased incidence in firstborn may be explained by
· increased incidence of breech and oligohydramnios in firstborn
· in utero position may explain prevalence of left hip involvement
· usually vertex presentation (LOA)
· mother’s spine presses on baby’s left hip and adducts it
Postnatal
· decreased incidence where babies carried astride waist
· increased incidence where babies strapped to cradle board
· if child has CDH
· 5% of siblings affected
· 1% of brothers affected
· 10% of sisters affected
· nature of genetic predisposition unclear
· may be related to familial ligamentous laxity
· hip is spontaneously dislocating and reducing
· minimal anatomical changes
· findings
· laxity of hip joint capsule
· flattening of posterosuperior labrum
· ridge in acetabular cartilage just below labrum (neolimbus)
· no pathological changes
· hip capsule enlarges
· degree depends on how high up ilium femoral head lies
· capsule narrows at isthmus
· where iliopsoas crosses
· called zona orbicularis
· ligamentum teres becomes longer and thicker
· pulvinar hypertrophies
· is small amount of fibrofatty tissue normally in joint
· hip capsule may beccome adherent to
· articular cartilage of acetabulum
· outer surface of labrum and ilium
· labrum may invert
· femoral head dislocates upwards and backwards
· femoral head becomes more globular and less spherical
· femoral neck becomes more anteverted
· acetabulum becomes more anteverted
· false acetabulum develops in ilium
· indentation in wall of ilium that articulates with femoral head
· lined with fibrocartilage
· end result is formation of degenerative changes in femoral head
· space between femoral head and medial wall of acetabulum widens
· dysplasia of acetabulum develops
· increase in upward slope
· loss of depth
· increased anteversion
· posterosuperior labrum replaced by funnel-shaped areea
· end result is degenerative changes in acetabulum
· 50% of unstable hips resolve without treatment
· subluxation always leads to early degenerative disease
· dislocation causes less disability
· 60% have significant pain and disability
· 40% have no pain but abnormal gait and decreased agility
· increased incidence of pain with well-developed false acetabulum
Neonate
· suspected in
· female
· firstborn
· breech
· family history of CDH
· family history of ligamentous laxity
Infant
· difficulty with nappies due to limited abduction
· shortening of thigh
Child
· delay in walking or running
· limp
· increased lumbar lordosis
· toe walking
· intoeing
Neonate
· pelvis stabilised with one hand
· leg grasped with
· thumb on adductor tubercle
· ring finger on greater trochanter
· thigh abducted while lifting trochanter forward
· if hip dislocatable, dislocated in this position
· clunk of reduction felt in mid-abduction
· positive Ortolani’s test
· if hip dislocated and irreducible, reduced abduction
· thigh adducted while pushing medial thigh backward
· if hip reducible, reduced in this position
· clunk of dislocation felt in mid-abduction
· positive Barlow’s test
· may feel sliding of subluxable hip
· hip may be
· stable (O-B-)
· reduced but dislocatable (B+)
· reduced but subluxable (O-B-slide+)
· dislocated but reducible (O+)
· dislocated but irreducible (O-B-)
· innocent clicks from
· ligamentous teres
· iliopsoas bursa
· iliotibial tract
Infant
Unilateral
· limited abduction of hip
· < 60o suspicious and < 45o definite
· at age 1 mth, 30% with CDH may have preserved abduction
· at age 6 mths, only 10% with CDH have preserved abduction
· apparent shortening of femur
· Galeazzi’s sign
· extra thigh folds
Bilateral
· more difficult
· symmetrical limitation of abduction
· Klisic’s line
· line from ASIS to greater trochanter
· should point to umbilicus
· points horizontally in CDH
· Nelaton’s line
· line from ischial tuberosity to ASIS with thigh adducted and flexed
· greater trochanter should lie caudad to it
· greater trochanter lies cephalad it in CDH
Child
Unilateral
· limp
· abductor lurch
· Trendelenburg gait
· short-leg component
· may toe-walk
· positive Trendelenburg sign
· decreased ROM
· mild flexion contracture
· limitation of abduction
· no limitation of rotation
Bilateral
· increased lumbar lordosis
· waddling gait
· bilateral positive Trendelenburg sign
· bilateral decreased ROM
Position
· AP pelvis
· hips adducted to neutral
· hips flexed 20-30o
Symmetry
· obturator foramina should be symmetrical
Lines
Hilgenreiner’s line
· horizontal line
· joining triradiate cartilages
Perkin’s line
· vertical line
· through lateral edge of acetabulum
Acetabular line
· oblique line
· from Hilgenreiner’s line to lateral edge of acetabulum
Centre-edge line
· line from centre of ossific nucleus to lateral edge of acetabulum
Shenton’s line
· curved line
· along inferior neck of femur and superior margin of obturator foramen
Measurements
Quadrants
· 4 quadrants
· formed by intersection of Hilgenreiner’s and Perkin’s lines
· ossific nucleus (or metaphyseal beak) usually lies in inferior medial quadrant
Acetabular index
· angle between Hilgenreiner’s line and acetabular line
· normally is 25-30o
Centre-edge angle
· angle between Perkin’s line and centre-edge line
· normally is > 25o
Shenton’s line
· usually uninterrupted arc
von Rosen’s view
· AP pelvis with legs abducted 45o
· lines along femoral shafts should
· pass through acetabulum
· intersect at sacrum
Findings
· widened medial joint space
· increased distance between ossific nucleus or metaphyseal beak and acetabular teardrop
· delayed development of ossific nucleus
· appears later
· is smaller
· dysplasia of acetabulum
· irregular lateral margin
· acetabular index > 35o
· superior and lateral migration of proximal femur
· ossific nucleus or metaphyseal beak does not lie in inferior medial quadrant
· centre-edge angle < 20o
· Shenton’s line broken
· von Rosen’s view
· line does not pass through acetabulum
· lines intersect to side of sacrum
· more sensitive diagnostic tool than
· clinical examination
· plain radiographs
· best done after 4 wks
· limited use after 6 mths
· may be performed in supine or lateral position
· views include
· coronal neutral
· coronal flexed
· transverse
· dynamic stress
· most important view is coronal neutral
· features are
· should be in midacetabular plane (head round)
· ilium should be straight vertical line
· identify
· ilium
· labrum
· pubis
· triradiate cartilage
· ischium
· ossific nucleus
· metaphysis
· look for
· acetabular development
· femoral-acetabular relationship
· interpretation
· head 60% in acetabulum - normal
· head < 50% in acetabulum - subluxed or dislocated
· diagnoses
· normal
· subluxed
· dislocated
· acetabular dysplasia
· normal hip shows
· projection of labrum
· abnormal hip shows
· widened medial joint space
· blunting of labrum superiorly
· enlargement of ligamentum teres
· bulge in acetabular cartilage of neolimbus
· hourglass constriction of capsule
· infolding of labrum
· may be useful in evaluating reduction
· useful
· while child in POP
· after 6 mths when ultrasound not used
· Dunn
· normal
· subluxed
· dislocated
· false acetabulum
· septic dislocation
· destructive changes
· proximal femoral epiphseal separation
· normal acetabulum
· best time for treatment is in newborn period
· goal is to
· flex and abduct hips
· thus reduce femoral head and maintain it in reduced position
· achieved by
· Pavlik harness
· von Rosen splint
Algorithm
Nursery screening
· child examined soon after birth by Paediatric team
· abnormalities reported to Orthopaedic team
· child reassessed by Orthopaedic team as soon as able
1. hips found to be subluxable or dislocatable
· place child in splint with hips reduced
· use von Rosen splint
· assess splint fit every 3 weeks
· remove splint at 12 weeks
· assess and x-ray hips at age 6 mths
· assess and x-ray hips at 18 mths
· assess and x-ray hips until definitely normal
· final assessment at age 5
2. hips found to be normal or equivocal
· obtain ultrasound
· if abnormal, proceed as above
· if normal, assess and x-ray hips at 6 mths
3. hips found to be dislocated and irreducible
· leave until age 18 mths
· then open reduction and femoral osteotomy
Late referral
1. hips found to be subluxable or dislocatable
· as above
· use Pavlik harness
2. hips found to be dislocated and irreducible
· leave until age 18 mths
· then open reduction and femoral osteotomy
Von Rosen splint
· best suited to newborn
· consists of
· padded malleable aluminium splint
· two uprights for shoulders
· two legs for thighs
· two wings for torso
· applied with
· uprights not impinging on neck or ears
· legs holding hips in 60-90o flexion and midabduction
· worn for 8-12 weeks
· not removed by parents
· results
· normal hip in 99%
· complications
· skin irritation
Pavlik harness
· most commonly used splint
· most suitable for older child
· consists of
· chest strap supported by shoulder straps
· boots attached to chest strap with anterior (flexion) and posterior (abduction) straps
· applied with
· chest strap at nipple line
· anterior straps tightened to achieve 100o flexion
· posterior straps lightly tightened to allow adduction to within 7 cm of knees touching
· worn for 6-12 weeks
· not removed by parents if hips unstable
· weekly review for checking and adjusting
· x-ray when splint applied
· x-ray at end of treatment
· results
· normal hip if dysplastic in 95%
· normal hip if dislocated in 80%
· complications
· improper adjustment or refitting by parent
· failure to achieve reduction
· avascular necrosis (0-15%)
· hyperflexion with femoral nerve palsy and inferior dislocation
· also applies to failures of splint in those < age 6 mths
· usually have irreducible hip
Traction
· admission to hospital
· coronal skin traction applied
· abduction increased 10o every day to 70o
· traction continued for 1 week
Closed reduction
· child taken to theatre for EUA
· percutaneous adductor tenotomy performed if significant adductor tightness
· assessment made of
· stability
· reducibility
· position of reduction and dislocation
· safe zone cone (range between redislocation and maximum abduction)
· hip reduced
· arthrogram may be performed to evaluate reduction
· arthrogram interpretation
· good outcome associated with medial joint space < 5 mm
· poor outcome associated with medial joint space > 7 mm
· hip spica applied
· hip flexed 90o
· abduction in safe zone
· position confirmed with x-ray
· cast changed at 8 weeks
· cast changed again at 8 weeks
· if hip stable, splinted in less flexion and abduction
· if unstable or irreducible, open reduction at 18 mths
Open reduction
Indications
· unstable hip
· irreducible hip
· uacceptable widening of medial joint space on arthrogram
Timing
· at age 18 mths
· advantages
· anatomy more easily recognisable
· higher successful reduction rate
· disadvantages
· may delay walking age
· theoretical decreased time for acetabular remodelling
Technique
· Smith-Peterson approach
· capsule opened
· head identified
· ligamentum teres detached from head
· followed down to acetabular floor
· ligament and pulvinar removed
· limbus removed
· transverse acetabular ligament sectioned
· head reduced
· tight capsulorrhaphy performed esp. superiorly
· femoral osteotomy performed if excessive traction at time of reduction
· spica cast applied
Complications
· usually due to inexperienced surgeon
· most common are
· failure of reduction
· damage to articular cartilage
· neurovascular injury
· failure of reduction may necessitate repeat operation
· may lead to avascular necrosis
· more difficult
· soft tissue contractures
· hour glass capsular constriction
· cartilagenous remodelling
Open reduction and femoral osteotomy
Technique
· open reduction as above
· osteotomy of proximal femur
· just distal to lesser trochanter
· amount resected depends on overlap with head reduced
· usually about 2 cm
· derotation performed
· to correct significant anteversion
· varus seldom created
· only if true valgus exists (cf. anteversion)
· osteotomy fixed with Coventry or small Richards plate
· if significant uncovering, acetabular procedure indicated
Redislocation
· may occur after closed or open reduction
· noted on x-ray or CT in spica or at spica change
· following closed reduction
· treated with open reduction
· following open reduction
· treated with repeat open reduction
Acetabular dysplasia
· treated with acetabular procedure
Avascular necrosis
Aetiology
· result of treatment
· does not occur in untreated hip
· due to
· immobilisation in excessive abduction
· forceful closed reduction
· vascular damage at open reduction
· reduced by
· prereduction traction
· adductor tenotomy
X-ray
· four types
1. ossific nucleus
· temporary irregular ossification
· femoral head will subsequently be normal
2. lateral physis
· femoral head will tilt into valgus
· lateral portion of femoral neck will be short
3. central pysis
· femoral neck will be short
4. whole physis and ossific nucleus
· femoral neck will be short and in valgus
· will be trochanteric overgrowth
Outcome
· coxa breva and coxa magna
· Trendelenburg gait or lurch
Treatment
1. trochanteric arrest
· arrest of trochanteric physis
· to reduce overgrowth
2. trochanteric transfer
· if trochanter has reached level of femoral head
· transferred distally and laterally
· directed at acetabular dysplasia
· acetabulum can remodel to
· age 18 mths (Salter)
· age 5 yrs (Lindstrom)
· dysplasia improves
· only with concentric reduction
· most rapidly in first 6 mths
Salter innominate osteotomy
Indications
· younger child (< age 5 yrs)
· mild to moderate dysplasia
· concentric reduction
Technique
· osteotomy of pelvis
· acetabulum rotated anteriorly and laterally over femoral head
· triangular graft placed between 2 fragments
· rotation occurs through symphysis pubis
· x-ray shows narrowing of obturator foramen
Shelf arthroplasty
Indications
· older child (> age 8 yrs)
· congruous reduction impossible
Technique
· extra-articular bony buttress over uncovered anterolateral portion of femoral head
· iliac wing graft placed over hip capsule
· resorption common