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The hip
Developmental dysplasia of the hip (DDH) ‫عادل الهنداوي‬0‫د‬
It was previously known as congenital dislocation of the hip (CDH), now it is
called DDH because it comprises a spectrum of disorders ranging from
acetabular dysplasia without dislocation to instability ( dislocation or
subluxation), the unstable hip could be reduced but it is dislocatable or it is
dislocated which is either reducible or irreducible.
The dislocation can result from shallow acetabulum (acetabular dysplasia)
or the dysplasia can result from the absence of the femoral head from the
acetabulum (dislocated femoral head).
Incidence; at birth the incidence is 10/1000 but after 3 wk it reduce to
1/1000 (most of them become stable), it affect female more than male
(7:1), the left hip more than right (3:1) & the condition is bilateral (1 in
every 5 cases).
Etiology;
1. Genetic factor: the DDH tend to run in families & in some population.
2. Hormonal factor: high level of maternal estrogen, progesterone & relaxin
in the last few weeks of pregnancy will cross the placenta & may
aggravate the ligammentous laxity in newborn infant, therefore the
condition is rare in premature who born before the hormone reach their
peak.
3. Intrauterine position: breach presentation increases the incidence.
4. Postnatal factor: the condition is more common is societies who swaddle
the babies with the legs together than in population who carry their
babies on the back with the legs widely abducted.
Pathology:
 At the birth: the capsule is stretched but no changes in the head & the
acetabulum.
 During the infancy: many of the changes will occur secondary to
abnormal position of the femoral head, these include (1) the femoral
head dislocated posterolateral to the acetabulum (2) the acetabulum is
shallow (3) the capsule is stretched (4) the ligamentum teres become
long & hypertrophied (5) the acetabular labrum turned inward & called
limbus .
 After weight bearing all the changes will increase & the femoral head will
press on the ilium above the acetabulum to form false socket & the
capsule will be squeezed between the iliopsoase & the acetabulum
taking the shape of hourglass, the surrounding muscle with time become
short.
Clinical features; (1) In neonatal period 2 tests are useful in the diagnosis of
DDH:
Ortolani’s test: normally when flexing both hips to 90 the hips can be
abducted to 90, if the hips are dislocated the abduction is limited, in
Ortolani’s test we try to reduce the dislocated hip by pressing on the
greater trochanter( with the hip flexed & abducted) if the hip reduced it is
reducible if not it is irreducible.
Barlow’s test: it is the reverse of Ortolani’s test, it is performed by flexing
the hip to 90 & adducting it then try to push the head out the acetabulum
by pressing with the thumb in the groin, if the head dislocated then it is
dislocatable.
(2) Late features: the mother may notice asymmetry in skin creases of the
proximal thigh (more prominent on the dislocated side), or there is
difficulty In applying napkin, on examination there is asymmetrical skin
crease, the leg is short & externally rotated, there may be wide perineal
gap (in case of bilateral dislocation), there is limited hip abduction & the
child walk with limp (unilateral DDH) or waddling gait (in bilateral DDH).
X-ray; during the first 6 months the femoral head & the acetabulum are
largely cartilaginous & the x-ray is not useful therefore the best way for the
diagnosis is the ultrasound.
After 6 months there are several radiological lines can be used (1)
Shenton’s line ; normally a line drown along the inferior border of the
femoral neck should be continuous with the line on the inferior border of
the superior pubic ramus, if it is broken then the hip is dislocated or
sublaxed, (2) Perkin’s line; it is a vertical line along the outer edge of the
acetabulum, the femoral head should be medial to this line,
(3)Hilgenreiner’s line; it is a horizontal line that pass through the center of
the triradiate cartilage, the femoral head should be below this line,(4) Von
Rosen’s line; with the hip abducted to 45 the femoral shaft should point to
the acetabulum.
.
Treatment; it depends on the age of the child; the aim is to obtain &
maintain concentric reduction of the femoral head within the acetabulum:
 From birth-6 months; in the first 3 weeks it need observation as 90% of
the DDH will become stable, at the age of 3 weeks; if the hip is stable then
no treatment is needed, if the hip is reduced but is dislocatable it need
abduction splint, if the hip is dislocated but it is reducible then reduction
& abduction splint. The abduction splint (Pavlik harness or Von Rosen)
should be continuing until the x-ray show good development of the
acetabulum.
 From the age of 6-18 months; the dislocation can be reduced by closed
reduction using skin traction on vertical frame (Gallow’s traction) with
gradually increasing abduction for 3weeks until reduction is achieved then
apply hip spica followed by splint. If closed reduction failed then open
reduction followed by hip spica then splint.
 From 18 month- 4 yrs; closed reduction is difficult at this age group
therefore the treatment of choice is open reduction with derotation
osteotomy of the femur & if the acetabulum is shallow then acetabular
osteotomy ( Salter’s osteotomy), then hip spica.
 Above the age of 4 yrs; if bilateral usually no treatment is needed because
failure of surgery on one side will convert it from symmetrical to
asymmetrical, if it is unilateral the do open reduction until the age of 8 yrs
 Adult; persistent dislocation in the adult will cause backache & difficulty in
the walking usually at the age of 30-40 yrs, if so it can be treated by total
hip arthroplasty.
Acquired dislocation of the hip
Dislocation occurring after the age of 1 is due to one of three causes;
1. Pyogenic arthritis: infection of the hip joint in infant may lead to
destruction of the femoral head which is largely cartilaginous with
distension of the joint with the pus with subsequent dislocation of the
joint.
2. Muscle imbalance: unbalanced paralysis in childhood usually after
cerebral palsy, myelomeningiocele, and poliomyelitis will cause weakness
of abductor muscles with subsequent dislocation of the hip.
3. Posttraumatic dislocation.
Femoral anteversion (In-toe gait)
It is a condition in which the child walk with toe directed inward & may trip
over his foot during running.
Causes; it depend on the age of the child:

Below the age of 3 yrs, it may results from forefoot adduction or tibial
torsion.

Above the age of 3 yrs, it result from excessive anteversion of femoral neck
causes the hip to be internally rotated.
Clinical features; the gait is clumsy, the child sit on the floor in television
position (W- position) & on standing the patellae are turned inwards
(squinting patellae).
CT scan; to measure the degree of anteversion by taking CT scan across the
hip & the knee then measuring the angle between the femoral neck & the
transverse axis across the femoral condyles.
Treatment; spontaneous correction is usual, if the condition persist after
the age of 8 yrs the surgical correction by femoral derotation osteotomy.
Coxa vara
Normally the neck-shaft angle at birth is 160 & in adult between 125-135, in
coxa vara the angle is less than 120. The disorder is either congenital or
acquired:
 Congenital coxa vara; it occur in infancy & early childhood & result from
a defect in endochondral ossification of the medial part of the femoral
neck, weight bearing the neck bent into varus.
Clinical features; it rarely cause hip pain, the leg is short, the thigh bowed & the
child walk with Trendelenburg gait because failure of abductor mechanism,
bilateral cases because they are symmetrical usually not seen until later when
they develop osteoarthritis of the hip.
X-ray; the Physeal line is vertical, the femoral neck is short, there may be a
small triangle fragment in the medial aspect of the femoral neck.
Treatment; this is by subtrochanteric valgus osteotomy, it is indicated if
deformity is unilateral, painful or progressive.
 Acquired coxa vara; this can occur at any age & it result from:
A. Bone softening disorders: like rickets, osteomalacia, osteoporosis, Paget’s
disease, infection, fibrous dysplasia…
B. Fractures like malunion of the subtrochanteric #, non union of femoral neck
# or slipped capital femoral epiphysis.
Treatment; by treating the underlying cause & correcting the deformity by
valgus subtrochanteric osteotomy.
Irritable hip
It is transient synovitis of the hip, characterized by transient hip pain &
restriction of movement in an otherwise healthy child,
Clinical features; it affect boys more than girls (2:1), the usual age is 6-12 yrs,
the patient presented with painful limp, examination reveals that hip
movements are restriction& painful. The condition last 1-2 weeks & resolve
spontaneously.
Investigations; blood investigations & x-ray are normal but U/S reveals mild
joint effusion.
Treatment; mild cases require restriction of activity, for severe cases bed
rest& skin traction, anti-inflammatory drugs like aspirin.
Perthes’ disease
It is a painful disorder of the child hood characterized by avascular necrosis of
the bony nucleus of the femoral head.
Pathogenesis; at the age of 4 months the femoral head receive its blood
supply from 3 sources (1) metaphyseal vessels which penetrate the growth
plate & supply the head (2) lateral epiphyseal vessels running in the retinacula
(3) small vessels in the ligamentum teres. The metaphyseal blood supply
decrease gradually until they disappear by the age of 4 yrs, the small blood
supply in the ligamentum teres increase by the age of 7 yrs, therefore
between 4 &7 yrs the blood supply to the head depend mainly on the lateral
epiphyseal vessels, any increase in the intracapsular pressure (from joint
effusion) will block these vessels leading to ischaemia.
Pathology; the condition take 2-4 yrs to complete passing through 3 stages:
1. Ischemic stage, the femoral head ossific nucleus dead but the overlying
cartilage continues to grow so the x-ray shows increase joint space.
2. Revascularization stage, new bone will be formed over the dead bone so
the x-ray will show increase bone density, some of the dead bone will be
resorbed & replaced by fibrous tissue revealed by decrease density on x-
ray, the combined picture of increase & decrease density of the epiphysis
will give the x-ray appearance of fragmentation, the metaphysis become
wider & porotic
3. Remodeling stage, if the repair process is rapid the femoral head will
restore its normal shape, but if the repair process is slow the head will
collapse & the growth will distorted, the femoral head will become
mushroom or oval shape & become elongated & displaced laterally from
the acetabulum.
Clinical features; the boys are affected more than girls(4:1), the age of
presentation 4-8 yrs, the patient complain from painful limping for weeks
which may recur intermittently.
On examination the child look well, there may be muscle wasting, the hip is
irritable & all movements are painful & restricted especially abduction.
X-ray; (1) early stage there is widening of the joint space & asymmetry of
bony nucleus ,(2) later on there is increase of bone density &
fragmentation,(3) still later there is flattening of the femoral head, lateral
displacement of the head, the metaphysis become wide & rarefied. (4)
Sagging rope sign, it is a sclerotic line curving across the femoral neck (Sshape line) represent the distal margin of metaphyseal resorption.
Prognosis; it depends on several factors:
1. Age, if the child is < 6 yrs the prognosis is good, the older the child the
worse the prognosis.
2. Sex, it is more common in male if the female affected the prognosis is
worse.
3. Degree of head involvement, the greater the amount the worse the
prognosis.
Head at risk; these are radiological signs which predict to worse outcome,
these signs when present indicate that the head is no longer concentric with
the acetabulum & its normal development will be affected, these signs are:
 Progressive uncovering of the epiphysis.
 Calcification in the cartilage lateral to the ossific nucleus.
 Radiolucent area in the lateral part of the bony epiphysis (Gage’s sign).
 Severe metaphyseal resorption & distortion.
Treatment; there are 2 modalities of treatment:
A. Symptomatic treatment; by bed rest with skin traction until the pain
subside usually within 3 weeks, then resume normal activities but avoid
sport with checking x-ray every month.
B. Containment treatment; it means keeping the femoral head contained
within the acetabulum during healing to restore its normal shape, the
containment can be achieved by one of two methods:
 Keeping the hip widely abducted by plaster splint or removable brace
for at least 1 yr.
 Surgery, by either subtrochanteric varus osteotomy or innominate
osteotomy of the pelvis.
If the hip is irritable the initial treatment is symptomatic, the definitive
treatment will depend on the age of the child & the severity of the disease:
1. Children <6 yrs the treatment is symptomatic.
2. Children 6-8 yrs, if head involvement is mild then symptomatic
treatment, if it is severe then containment.
3. Children >9 yrs, require containment treatment by operation.
Slipped capital femoral epiphysis (epiphysiolysis)
It is displacement of the proximal femoral epiphysis (head) through the
hypertrophic zone of the growth plate it occur during the puberty (14-16 yrs),
affect boys > girls (3:1), the left hip affected more than right & the condition
is bilateral in 20% of the cases.
Etiology;
1. Hormonal disturbances: like hypothyroidism or hypogonadism as the
condition occur more in sexually immature, fatty adolescent (due to
deficiency of sex hormones which are necessary for fusion of growth
plate) or occur in tall adolescent (due to excessive secretion of growth
hormone which lead to increase in the length of the patient), in both
conditions there is increase weight of the patient causing excessive stress
across the growth plate.
2. Trauma: which can be major trauma leading to acute slipping (30% of the
cases), or repeated mild trauma lead to slow progressive slipping (70% of
the cases).
Pathology;
The slipping occur through the hypertrophic zone of the epiphysis, the
femoral head remain in the acetabulum, the femur roll into external rotation
& the femoral neck displaced anteriorly threatening the anterior retinacular
vessels of the femoral head which to avascular necrosis of the femoral head.
The slipping may lead to premature fusion of between the epiphysis & the
metaphysis.
Clinical features;
In 30% the condition occur as acute slip & in 70% it is chronic progressive slip,
sometime it is acute on chronic, the patient is a child around puberty & either
fatty sexually immature or thin tall.
The patient complains from groin pain which may radiate to the knee with
limping (these symptoms may recur with exercise).
On examination the limb is short & externally rotated with limitation of
movement.
X-ray;
 On AP view: a line drawn along the upper border of femoral neck should
pass through the femoral head; if not this mean that the head is
slipped.(Trethowan’s sign)
 On lateral view: the angle between the growth plate line & the line that
pass through the centre of the femoral neck should be 90, if it is less than
90 this means that the head is slipped.
Complications;
1. Avascular necrosis of the femoral head from forceful manipulation or
damage to the retinacular vessels during surgery.
2. Chondrolysis of the articular cartilage
3. Deformities like coxa vara (neck-shaft angle less than 20) result from
premature fusion of the growth plate.
4. Slipping at other side.
5. Secondary osteoarthritis of the hip.
Treatment; is by surgical stabilization of the slip, depending on the degree of
the slip:
 Minor slip; when the slip less than 1/3 of the width of the femoral head,
this require fixation in situ (without reduction) by 2-3 screws that pass
through the femoral neck into the epiphysis.
 Moderate slip; when the slip between 1/3-2/3 of the width of the femoral
head, in this we accept the deformity & do fixation in situ, then after 2 yrs
if the deformity is severe we do corrective osteotomy below the neck.
 Severe slip; when the slip is more than 2/3 of the width of the femoral
head, this can be treated by open reduction & internal fixation or by
fixation in situ followed by corrective osteotomy.
Pyogenic arthritis of the hip
It is usually seen in children less than 2 yrs, the causative microorganism is
staphylococcus.
The infection starts either as an arthritis or as an osteomyelitis of the proximal
femur with secondary arthritis.
Clinical features; the child look ill & in pain, the limb is held still, on
examination the point of tenderness is over the hip & all movements are
restricted.
Investigations;
 X-ray: early on it show soft tissue swelling with displacement of femoral
head.
 U/S: shows joint effusion.
 Aspiration: reveals pus.
Complications; if the infection not treated early, the femoral head & neck will
destroy with development of pathological dislocation of the hip.
Treatment; drainage the hip by arthrotomy, antibiotics & resting the hip by
traction or abduction splint.
Osteonecrosis (avascular necrosis of the femoral head)
Femoral head is the commonest site of osteonecrosis because its peculiar
blood making it vulnerable to ischaemia from arterial cut-off, venous stasis,
intravenous stasis, intraosseous sinusoidal compression or combination of
these factors.
Causes; it is either (1) posttraumatic following # of the femoral neck or hip
dislocation the main cause here interruption of arterial blood supply, or
(2) non-traumatic Osteonecrosis this is either idiopathic or it is secondary to
some other conditions like steroids, alcohol intake, infiltrative
disorders(Gaucher’s disease), sickle cell disease, caisson disease, SLE.
Pathology (staging) the condition is divided into 4 stages:
Stage I; there is little or no pain, the x-ray look normal but the MRI will show
the changes. The definitive diagnosis is by bone biopsy.
Stage II; the patient complain from hip pain & limitation of movement, the xray will show increase sclerosis within the femoral head (sign of repair
process) the femoral head contour is preserved (no collapse of the head)
Stage III; there is more advanced stage in which there is structural destruction
of the femoral head with loss of the normal contour of the head.
Stage IV; there is collapse of the articular surfaces with secondary
osteoarthritis.
Clinical features; usually the patient is about 20-40 yrs, present with pain,
limping &, the condition is bilateral in 50% of the cases.
On examination there is limping, +ve Trendelenburg sign, the thigh muscles
are wasted, the limb is short because of the collapse of the femoral head,
restriction of all hip movements especially abduction & external rotation.
There is tendency of the hip to roll into external rotation during passive
flexion because the tries to get the damaged part away from stress.
X-ray; during the early stages it is normal, the first signs appear only 6-9
months after the occurrence of bone death. First there is increased density of
the femoral head (sclerosis) resulting from reactive new bone formation from
the surrounding live bone, then destructive changes appears in the necrotic
segment as a thin subchondral fracture line called (crescent sign), then there
is flattening & collapsed of the femoral head & finally osteoarthritis of the
femoral head.
MRI; the MRI will shows the changes in the bone marrow long before the xray, there is a band of altered signal intensity running through the femoral
head.
Treatment; it depends on the stage of the disease; the underlying causative
factors should be treated if possible:
Stage I & II: analgesia, avoid weight bearing on the affected side by using
crutches & by osseous decompression to relief venous stasis & intraosseous
hypertension which will relieve the pain & improve blood supply to the
femoral head.
Stage III: this can be treated by realignment osteotomy to bring the affected
area of the head away from point of maximum stress.
Stage IV: this can be treated by arthrodesis or arthroplasty (partial or total)