Hip disorders are common in chil-dren with cerebral palsy and cover a wide spectrum—from the hip at risk to subluxation, dislocation, and dislocation with severe degenera-tion and pain..
Trang 1Hip disorders are common in
chil-dren with cerebral palsy and cover a
wide spectrum—from the hip at
risk to subluxation, dislocation, and
dislocation with severe
degenera-tion and pain Three principles
guide the management of these
dis-orders First, the pathophysiology
of spastic hip dysplasia differs from
that of developmental dysplasia of
the hip (Table 1) In children with
cerebral palsy, the hips are usually
normal at birth; with growth,
how-ever, a combination of muscle
im-balance and bony deformity leads to
progressive dysplasia Second, the
natural history of hip dysplasia is
marked by increasing dysfunction
With progression of hip subluxation
or dislocation, there is an
increas-ingly adverse effect on hygiene,
sit-ting, and gait, as well as pain by
early adulthood for many of those affected.1,2 Third, salvage options for the skeletally mature patient with a neglected hip are limited
The care of hip disorders in patients with cerebral palsy has incorporated early detection and comprehensive treatment This has resulted in greatly improved outcomes, al-though certain aspects of the patho-physiology and management remain controversial
Epidemiology and Natural History
The reported incidence of hip dys-plasia in patients with cerebral palsy varies widely, ranging from 2% to 75%.3 The children with the most severe neurologic involvement tend
to have the worst hips,4and patients who never achieve the ability to sit independently have the highest risk.5 Lonstein and Beck6 found hip subluxation or dislocation in 7% of independent ambulators but
in 60% of dependent sitters Chil-dren who can pull themselves to a standing position by age 3 years have a better prognosis, with a lower incidence of hip problems.5 The natural history of spastic hip dysplasia varies, but many of the children who progress to disloca-tion develop a chronically painful hip by early adulthood.1-3 This pro-gression of dysplasia is gradual, generally occurring over a period of several years Once a hip begins to subluxate, it rarely improves with-out treatment Exceptions include a hip that becomes the abducted side
in a windblown deformity or a hip
on the low side of the pelvic obliquity caused by scoliosis Hips with a
Dr Flynn is Assistant Professor of Ortho-paedics, Division of Orthopaedic Surgery, The Children’s Hospital of Philadelphia, Phila-delphia, PA Dr Miller is Associate Professor
of Orthopaedics, Department of Orthopaedic Surgery, Alfred I duPont Institute, Wilmington, DE.
Reprint requests: Dr Flynn, The Children’s Hospital of Philadelphia, 34th and Civic Center Boulevard, Philadelphia, PA 19104-4399 Copyright 2002 by the American Academy of Orthopaedic Surgeons.
Abstract
Hip disorders are common in patients with cerebral palsy and cover a wide
clin-ical spectrum, from the hip at risk to subluxation, dislocation, and dislocation
with degeneration and pain Although the hip is normal at birth, a combination
of muscle imbalance and bony deformity leads to progressive dysplasia The
spasticity or contracture usually involves the adductor and iliopsoas muscles;
thus, the majority of hips subluxate in a posterosuperior direction Many
patients with untreated dislocations develop pain by early adulthood Because
physical examination alone is unreliable, an anteroposterior radiograph of the
pelvis is required for diagnosis Soft-tissue lengthening is recommended for
children as soon as discernable hip subluxation (hip abduction <30°, migration
index >25%) is recognized One-stage comprehensive hip reconstruction is
effective treatment for children 4 years of age or older who have a migration
index >60% but who have not yet developed advanced degenerative changes of
the femoral head Salvage options for the skeletally mature patient with a
neglected hip are limited.
J Am Acad Orthop Surg 2002;10:198-209 Patients With Cerebral Palsy
John M Flynn, MD, and Freeman Miller, MD
Trang 2migration index (MI) >50% do not
reduce spontaneously;
approxi-mately one third will progress to
dislocation.3 The greatest risk of
dislocation occurs during middle
childhood ages (4 to 12 years) Later
dislocation may be due to
unrecog-nized hydrocephalus or shunt
dys-function.7 As the hip progresses
from subluxation to dislocation, the
articular cartilage of the femoral
head is subjected to enormous
pres-sure from the surrounding soft
tis-sues and rapidly degenerates
Dislocated hips are more painful
than hips that remain subluxated or
reduced; subluxated hips are only
slightly more painful than reduced
hips.3
Anatomy and Pathophysiology
In children with spastic hip dyspla-sia, the hip joint is normal at birth.8 With growth, excessive muscle tone exerts a constant force on the devel-oping hip, leading to deformation of both the proximal femur and acetab-ulum Because the spasticity or con-tracture usually involves the adduc-tor and iliopsoas muscles, most hips subluxate in a posterosuperior direc-tion The hip’s center of rotation gradually shifts from the center of the femoral head to the lesser trochanter
Femur
The abnormalities of the
proxi-mal femur, including dysplastic and degenerative changes, persistence of fetal anteversion, and coxa valga, have been characterized both radio-graphically and pathologically The spastic hip adductors and flexors drive the femoral head into the pos-terolateral acetabular labrum The capsule and superior rim of the ace-tabulum cause focal deformation of the femoral head This indentation locks the femoral head at the lateral acetabular margin, leading to pain from cartilage erosion (Fig 1) The epiphysis becomes wedge-shaped and displaces superolaterally In one study of three-dimensional computed tomography (CT) scans, all nonambulatory patients had deformities of the femoral head that ranged from mild medial flattening
to wedge-shaped defects.9 In most hips, the lesser trochanter is en-larged while the greater trochanter maintains its normal proportions Most evidence suggests that in spastic hip dysplasia, femoral ante-version is increased The neck-shaft angle also may be somewhat higher
in certain children, although most of the coxa valga seen on radiographs
is caused by the anteversion Chil-dren with spastic hip dysplasia have normal anteversion at birth, but the normal decrease in antever-sion does not occur during early childhood
Acetabulum
Great progress has been made in understanding the acetabular ab-normalities in spastic hip dysplasia Computerized mathematical mod-els demonstrate that a child with spastic hip disease has a sixfold increase in hip-force magnitude.10 This constant abnormal force causes changes quite early The acetabular index (AI) in affected children is normal until 30 months of age, then becomes notably higher.11 Studying arthrograms, Heinrich et al12found that the bony maturation of the acetabulum is retarded by
deforma-Table 1
Comparison of Spastic Hip Dysplasia and Developmental
Dysplasia of the Hip
Developmental Dysplasia
Findings at birth Hip usually normal Hip usually abnormal
Age at risk Usually normal in the first Most often recognized in
year of life; recognized the first year of life after age 2 yr
Detection Radiographs needed in Physical examination in
Etiology Spastic muscles drive femoral Mechanical factors
head out of an otherwise (eg, breech), ligamen-normal acetabulum, pelvic tous laxity, abnormal
Childhood Progressive subluxation Progressive subluxation
Natural history Pain in many subluxated or Pain in many subluxated
dislocated hips by second hips by fourth or
Acetabular Usually posterosuperior Usually anterior
deficiency
Early measures Muscle lengthening Pavlik harness or closed
reduction Missed or failed Hip osteotomies, often Closed or open reduction,
early measures without open reduction often without
osteoto-mies (before age 18 mo) Salvage Castle procedure osteotomy, Usually total hip
interposition arthroplasty replacement
Trang 3tion of the lateral pelvic
cartilagi-nous anlage that occurs before or
during the subluxation The
great-est increase in the deformation of
the acetabulum occurred in hips
with an MI of 52% to 68%
In most cases, the acetabular
defi-ciency is posterosuperior.13
Insta-bility is usually unidirectional,
fol-lowing a trough created by pressure
of the femoral head (Fig 2) In the
rare cases of extension posturing,
the dislocation and associated
ace-tabular deficiency is anterior After
analyzing three-dimensional CT
scans, Kim and Wenger14confirmed
that the major acetabular deficiency
normally coincided with the
direc-tion of the subluxadirec-tion or
disloca-tion but stressed that excepdisloca-tions
occur There is no agreement as to
whether the acetabulum is actually
shallow9or normal in depth.13
Special Cases
Windblown Hip
Windblown hip describes an
adduction deformity of one hip and
an abduction deformity of the other,
resulting in pelvic obliquity and
pelvic rotation Windblown hips
are caused by asymmetric activity
of the adductors, abductors, and internal and external rotator mus-cles, usually affecting totally in-volved nonambulatory children with severe spasticity Electromyo-graphic studies have shown that the adductors are overactive on both sides, while the abductor is overac-tive only on the abducted side.15 The relationship of scoliosis to wind-blown hips remains controversial
Black and Griffin16studied 80 pa-tients and concluded that in-frapelvic obliquity (caused by the asymmetric muscle forces around the hip) is more important than suprapelvic obliquity caused by sco-liosis Infrapelvic obliquity occurs first, and the hip on the infrapelvic high side is almost always the one that dislocates
Anterior Dislocation
Subluxation or dislocation occurs anteriorly in only 1.5% of cases
Most of these occur in severe quad-riplegia with extension posturing or hypotonia Three clinical scenarios have been identified: (1) patients with hip extension, external rota-tion, and adduction with knee
ex-tension contractures; (2) patients with hip extension, external rota-tion, and abduction with knee flex-ion contractures; and (3) patients with severe hypotonia with no con-tractures.17 Seating children with anterior dislocations and contrac-tures is very difficult Because of an associated thoracolumbar kyphosis,
a semirecumbent position is re-quired About 50% of children with anterior dislocations have pain.17
Physical Examination
During the physical examination of the hips, abduction should be tested with the hip and knee extended The child with a windblown hip may have a “pseudo-Galeazzi” sign due to the one-sided adduction con-tracture that creates the appearance
of a leg-length discrepancy.15 Knees and ankles also should be tested for range of motion, and the spine examined for evidence of scoliosis
If the child is nonambulatory, the spine and pelvis should be evalu-ated in the sitting position to assess pelvic obliquity and its effect on seating Physical examination alone
is unreliable to diagnose most pos-terosuperior spastic hip subluxa-tions or dislocasubluxa-tions In patients with anterior dislocations, the
Figure 1 A, Anteroposterior pelvic radiograph of a 17-year-old boy with quadriplegic
cerebral palsy Constant severe pain in the left, adducted hip worsened after his pelvic
obliquity was corrected with spinal fusion A Castle femoral resection was done to allow
him to sit comfortably B, The resected femoral head has a triangular shape and evidence
of advanced degenerative changes, including complete loss of articular cartilage on the
medial, lateral, and superior surfaces.
Figure 2 A three-dimensional
reconstruc-tion of a preoperative CT scan showing typical posterosuperior dislocation The acetabulum is severely dysplastic in the area of dislocation but normal anteriorly.
Trang 4oral head may be palpable as a
prom-inent, hard mass in the groin
Radiologic Evaluation
The supine anteroposterior
radio-graph of the pelvis is used to screen
and follow children at risk for spastic
hip dysplasia Both the MI and AI
should be measured (Fig 3)
Be-cause the MI depends on the
posi-tion of the legs, imaging should be
done in neutral adduction/abduction
The upper limit of normal for the MI
is 25% at age 4 years;18however, the
measurement error of the MI is
±10% Rotation of the pelvis will
decrease the AI on the lower side.11
Forward pelvic tilt (eg, with a fixed
flexion deformity of the hip) will
de-crease the AI and can make the
femoral/acetabular relationship
dif-ficult to interpret (Fig 4) To get an
accurate assessment of the
acetabu-lum, the technician should
maximal-ly flex the contralateral hip and knee
to eliminate the lumbar lordosis
A direct relationship exists be-tween the MI and AI The AI stead-ily increases as the MI increases, measuring about 40° when the MI is 50%.8 The shape of the sourcil has been classified as of two types.19 In type 1, the lateral corner is sharp and below the weight-bearing dome
of the acetabulum (Fig 3) In type 2, the lateral corner is blunted, turned upward, and above the weight-bearing dome
In some cases, additional preop-erative imaging studies may add valuable information CT with three-dimensional reconstruction allows the surgeon to assess defor-mities of the femoral head and the location of the area of greatest acetabular deficiency (posterosupe-rior in most, but not all, patients)
Adding a cut through the distal femur allows calculation of femoral anteversion CT with three-dimen-sional reconstruction is also useful for accurate analysis of anterior hip dislocation; the MI may be normal because these hips do not dislocate laterally.17 Real-time ultrasound is
a quick, accurate, and less expen-sive alternative to measure femoral anteversion without radiation
Ultrasound is particularly good in cases of coxa valga, where CT may
be inaccurate
Preoperative arthrography does not help with decision-making in spastic hip dysplasia In the child with spastic hip disease, the hip is typically normal for the first few years and the femoral head at the time of surgery is much more ossi-fied than it is in a child with devel-opmental dysplasia Adequacy of reduction is easily evaluated without
an arthrogram By comparison, the child with developmental dysplasia
of the hip is usually less than 2 years old with a minimally ossified femoral head that has been abnormal since in-fancy Arthrography in developmen-tal dysplasia of the hip will outline the cartilage and show interposed tis-sue that is blocking reduction
Nonsurgical Management
Several nonsurgical measures have been used to prevent or slow the progression of spastic hip dysplasia Physical therapy has traditionally been used to help preschool-age children with cerebral palsy reach their maximum potential A therapy program should include activities designed to maintain hip motion and promote weight bearing How-ever, there is no convincing evi-dence that therapy alone prevents hip subluxation Abduction bracing does not prevent hip dislocation20 and, if used aggressively, actually may cause windblown hips or hyperabduction deformity.21 Botu-linum toxin A can be injected into the adductors to temporarily de-crease tone for 4 to 6 months, but no long-term studies have compared its efficacy to that of no treatment or therapy alone The iliopsoas, a major factor in spastic hip disease, is difficult to inject reliably
The most important facet of non-surgical management is careful monitoring During the preschool years, hip abduction, with the hips and knees extended, should be
test-ed and recordtest-ed The MI and AI
Figure 3 Subluxated hip (right side of
illustration) The migration index (MI) is
calculated by dividing the width of the
uncovered femoral head (A) by the total
width of the femoral head (B) The
acetab-ulum is dysplastic (type 2 sourcil), with the
lateral corner of the acetabulum above the
weight-bearing dome Normal hip (left
side of illustration) with the acetabular
index (AI) indicated There is a normal
(type 1) sourcil; the lateral corner is sharp
and below the weight-bearing dome H =
horizontal axis.
Type 1
A B Type 2
Figure 4 Anteroposterior pelvic radio-graph of a child with bilateral spastic hip dislocation shows the difficulty of measur-ing the AI and MI, or interpretmeasur-ing the rela-tionship between the femur and the acetab-ulum, with a severe hip flexion contracture that tilts the pelvis.
Trang 5should be measured on the
antero-posterior pelvic radiograph
Cere-bral palsy patients aged 2 through
8 years should have an orthopaedic
examination twice a year If
abduc-tion of either hip drops below 45°
or the MI is >25%, the hips are at
risk and an anteroposterior pelvic
radiograph should be obtained at
each examination The physician
should not be lulled into a false
sense of security by a normal
radio-graph of an infant; this may
repre-sent a hypotonic phase before the
pathologic forces have begun to do
their damage.5 Hip subluxation
typically begins between the ages
of 2 and 6 years
Caretakers of infants or toddlers
with cerebral palsy often press the
orthopaedic surgeon to estimate the
probability that surgical treatment
of the hips will be needed Because
so many factors contribute to the
risk of spastic hip dysplasia, there is
sparse evidence to support precise
predictions Cooke et al22
retrospec-tively measured the radiographs of
462 patients with cerebral palsy,
studying the predictive effects of the
AI, MI, and neck-shaft angle They
found that a high AI was the most
powerful predictor of hip
disloca-tion All patients with dislocation
had an AI >30° at age 4 years; the
AI was <30° in all patients without
dislocation However, these data should be interpreted with caution
Acetabular dysplasia and pelvic tilt and rotation complicate the accurate measurement of AI Prospective studies are needed to establish reli-able guidelines
Surgical Management Indications for Surgery
Spastic muscles should be length-ened early to prevent the devel-opment of deformity Early com-prehensive reconstruction may be considered if the hip cannot be man-aged with muscle lengthening The natural history of spastic hips sug-gests that untreated dislocations may become painful Reconstruc-tion or salvage opReconstruc-tions for a painful degenerated hip are limited and generally disappointing
Soft-Tissue Lengthening
Soft-tissue lengthening should be done as soon as progressive hip subluxation is recognized Damage
to the acetabulum by the pathologic forces through the femoral head may be greatest before age 4 years.5 Soft-tissue lengthening is indicated
in a child less than 8 years of age who is found to have hip abduction
of <30° and an MI of 25% to 60%
(Fig 5) Lengthening is contraindi-cated in a child with no contractures
or spasticity or in a child 4 years of age or older with subluxation so advanced that bony reconstruction is indicated (MI >60% to 100%) How-ever, lengthening may be appropri-ate in some cases of severe subluxa-tion if the child is very young (<4 years of age) or has multiple medical problems Although one study showed that the failure rate in this age group was 44%, more than half were successfully treated; in the remainder, major bony surgery could be postponed until the bone stock was more substantial and the risk of recurrence lower.23
Soft-tissue lengthening around the hip is done through a transverse skin incision made 1 to 3 cm distal
to the inguinal crease The fascia over the adductor longus tendon is opened longitudinally and the ten-don is transected, taking care to avoid injury to the anterior branch
of the obturator nerve below A myotomy of the gracilis is done next If hip abduction has not improved to 45°, the anterior branch
of the obturator nerve is retracted and the adductor brevis muscle is lengthened until 45° of abduction is obtained Using the interval be-tween the adductor brevis and the pectineus, the iliopsoas tendon is
Figure 5 A, Anteroposterior pelvic radiograph of a 2+6 year-old child with spastic quadriplegia who presented with advanced
subluxa-tion bilaterally Too young for reconstrucsubluxa-tion, the child underwent bilateral soft-tissue lengthening B, Six years after surgery, the hips
are located and the child needed no further hip surgery.
Trang 6isolated In nonambulatory patients,
the tendon is divided near the lesser
trochanter In ambulatory patients,
the iliopsoas tendon is retracted as
far proximally as possible and only
the psoas tendon is divided, leaving
the iliacus fibers intact A proximal
hamstring lengthening can be
added in nonambulatory patients if
the knee cannot be extended
beyond 45° (popliteal angle >45°)
Neurectomy of the anterior
branch of the obturator nerve
should not be done in ambulatory
patients The risk of obturator
neu-rectomy is an abduction
contrac-ture—a marked disability for both
walkers and sitters However, it is
unclear whether the abduction
con-tractures noted in the past were due
to the neurectomy or to the spica
casting and abduction bracing
com-monly used after muscle
lengthen-ing Obturator neurectomy may be
appropriate in severely involved,
nonambulatory children, but
guide-lines are not yet well established
Patients are maintained on
diaz-epam (0.1 to 0.2 mg/kg per dose)
every 6 hours to treat the substantial
muscle spasms of the early
postop-erative period Morphine or
co-deine can be given for pain control
Although many surgeons still use
spica or abduction casting after
muscle lengthening, our
postopera-tive protocol is designed to allow
immediate therapy Knee
immobi-lizers and an abduction pillow can
be used for 1 month On the second
day after surgery, therapy for hip
and knee range of motion is begun
Prone lying is encouraged to
pro-mote hip extension Radiographs
are obtained every 6 months
Be-cause most of the improvement
after soft-tissue lengthening occurs
within 6 months, the radiograph
taken 6 months after surgery is an
excellent indication of eventual
suc-cess or failure.23
The success of soft-tissue
length-ening is closely related to the degree
of subluxation at the time of the
surgery Cornell et al24found that if the MI was <40%, soft-tissue length-ening had an 83% success rate
With an MI ≥ 40%, soft-tissue sur-gery alone was successful in only 23% of children All of the hips with
an MI >60% failed An AI >27° was also highly predictive of failure
Age at the time of surgery did not have a significant predictive effect
In a study of 147 hips treated with a protocol of soft-tissue lengthening and immediate mobilization with
no abduction bracing, Miller et al23 found that 88% had a good or fair result (MI <40%) at final follow-up
Hip Reconstruction
Indications and Planning
Patient age and severity of sub-luxation are the two most important factors to consider in hip recon-struction Ideally, hip reconstruc-tion should be done in patients 4 years of age or older but before per-manent, advanced degenerative changes occur Analyzing the 11- to 18-year follow-up of their hip recon-structions, Brunner and Baumann25 found that children less than 4 years
of age had a 96% loss of correction
of the neck-shaft angle They rec-ommended that surgery be post-poned until the child is 8 to 10 years old, if possible Furthermore, from
a practical standpoint, older chil-dren have better bone stock for plate fixation The upper age limit depends on the degree of degenera-tive changes that develop Once the femoral head begins to flatten medi-ally and latermedi-ally, loss of articular cartilage is probable and pain relief after reconstruction is unlikely
Another factor to consider is severity of subluxation The capital femoral epiphysis begins to lose the support of the bony pelvis at an MI
of approximately 50%.12 There is a low probability that soft-tissue lengthening alone can successfully reverse the severely compromised anatomy and mechanics of a hip
with such advanced subluxation Thus, hip reconstruction is indicated for children 4 years of age or older who have severe subluxation (MI
>60%) or dislocation but who have not yet developed advanced degener-ative changes of the femoral head that are unlikely to remodel Hip recon-struction is recommended for chil-dren less than 8 years old who have failed soft-tissue lengthening (MI
>40% 1 year postoperative) and for children more than 8 years old with
an MI >40% but no signs of advanced degenerative change on radiographs Evidence is increasing that the most effective treatment for the severely subluxated or dislocated hip is a one-stage comprehensive approach that includes soft-tissue lengthening; a shortening varus derotation osteotomy of the femur (VDRO); a capsulotomy when nec-essary; and a peri-ilial acetabu-loplasty.1,19,25,26 The soft-tissue lengthening is done initially to achieve at least 45° of hip abduction; otherwise, the varus osteotomy would result in adduction Shorten-ing may be the most important com-ponent of the VDRO Computer-ized mathematical models show that to normalize the mechanical forces of the spastic hip, one must lengthen the psoas, iliacus, gracilis, and adductor longus and brevis muscles, which can reduce the force
on the joint to near normal The benefit of VDRO comes not from the redirection of force but from the bone shortening that acts like a muscle release or lengthening De-creasing femoral anteversion, neck-shaft angle, or both have little effect
on the forces.10 The indications for a capsulotomy are not well estab-lished McNerney et al26 recom-mended an open reduction and cap-sulorrhaphy on every hip with an
MI >70%; they found that only 3%
of such hips resubluxated after open reduction and capsulorrhaphy, while 60% resubluxated when the procedure was not done Miller et
Trang 7al19recommended medial
capsulot-omy when abduction is <20° and
the whole femoral head does not
reduce under the acetabulum after
the pelvic osteotomy
The acetabulum has a very limited
ability to remodel once advanced
dysplasia has developed.11
Al-though the surgeon can choose from
several different pelvic osteotomies
to address such dysplasia,
varia-tions of the Dega acetabuloplasty
have proved to be best.1,19,26 The
acetabuloplasty should be done in
all dislocated hips In subluxated
hips, the surgeon should consider
both the AI and the shape of the
sourcil When the AI is ≥ 25°26or
when there is a type 2 sourcil,19an
acetabuloplasty should be done
(Fig 6) Acetabuloplasty is relatively
contraindicated if the triradiate
car-tilage is closed or if advanced
de-generative changes have developed
in the femoral head
Technique
When hip abduction is <45°, a
soft-tissue lengthening is done first
The femoral osteotomy is designed
to achieve a neck-shaft angle of
approximately 100° in
nonambulato-ry and 120° in ambulatononambulato-ry patients.19
Because the protocol includes
imme-diate mobilization and therapy, the
femur must be rigidly fixed (eg, a 90°
blade plate) In nonambulators or
household ambulators, the level of
the osteotomy is planned so that the
entire lesser trochanter is removed,
effecting a release of the iliopsoas In
community ambulators, the lesser
trochanter is kept with the proximal
fragment and the iliopsoas is
pre-served by a more proximal
lengthen-ing With the chisel for the blade
plate in place, the proximal femur is
abducted If the femoral head does
not reduce into the acetabulum, a
medial and anterior capsulotomy is
done and any other blocks to
reduc-tion are addressed
The acetabular osteotomy is done
through an anterior approach in the
interval between the sartorius and tensor fascia lata The edge of the hip capsule is cleared, beginning anteriorly near the anteroinferior iliac spine and working all the way posterior to the triradiate cartilage, taking care to avoid exposing or entering the sciatic notch Under fluoroscopic guidance, a straight osteotome is used to create a peri-capsular cut in the ilium 5 mm above the joint This osteotomy extends from the anterior-inferior iliac spine to the triradiate cartilage but does not extend into the sciatic notch The osteotome, placed as posteriorly as possible in the oste-otomy, is used to lever open the os-teotomy (Fig 7, A) In most cases, the maximum acetabular deficiency
is posterosuperior, so the triangular piece of iliac crest allograft is tapped into the osteotomy as posteriorly as possible, thus making the maximum coverage in the area of greatest dys-plasia (Fig 7, B)
With the acetabular osteotomy complete, the femur can be fixed To judge the amount of femoral short-ening needed, the popliteal angle is
a good gauge With the hip flexed 90° and the knee fully extended
(popliteal angle = 0°), the amount of femoral overlap is marked Usually between 1 and 3 cm is removed, and the femoral shaft is fixed to the blade plate The shortening decreases the remaining force on the joint caused
by contracted muscles, including the hamstrings In ambulatory patients,
a distal hamstring lengthening can
be done prior to the femoral
osteoto-my to reduce the amount of femoral shortening needed If both hips are being reconstructed, leg lengths can
be equalized when the second side is shortened Anteversion should be corrected to between 0° and 15° Overzealous derotation will leave the hip retroverted, increasing the risk of posterior dislocation
The postoperative regimen in-cludes the use of diazepam and narcotics, similar to the muscle-lengthening procedure With stable fixation, no cast or orthotic is needed When a cast is used (eg, if fixation seems inadequate or regular post-operative therapy is not available), the surgeon should be vigilant for skin problems, pulmonary compli-cations (eg, pneumonia), and insuf-ficiency fractures after cast removal Sitting and therapy for range of
Figure 6 A, Anteroposterior pelvic radiograph of advanced hip subluxation (65%) in a
7-year-old child The acetabulum is dysplastic with a type 2 sourcil B, The same patient
after one-stage reconstruction with adductor lengthening, a shortening VDRO with blade plate fixation, and acetabuloplasty.
Trang 8motion can begin on the second
postoperative day, and standing can
begin as early as 1 week as comfort
permits Several months of therapy
for range of motion and gait training
is recommended Symptomatic plates
can be removed once the osteotomy
heals
The one-stage comprehensive
approach (Fig 8) has yielded
excel-lent results Using the
comprehen-sive technique, 95% of hips were
stable more than 2 years after
sur-gery, 82% were pain free, 14% had
partial relief, and 4% had persistent
pain.19 Others1,26,27have reported
similar excellent results Persistent
pain is more likely when
preopera-tive radiographs show lateral
fem-oral head flattening.19
Special Cases
Windblown Hip
The windblown hip remains a
difficult clinical problem Unilateral
adductor lengthening is
recom-mended for windblown hips to
avoid unilateral abduction and a
pelvis that is impossible to
con-trol;5,15however, the failure rate is high Abel et al28reported failure in one third of patients, noting that hyperabduction may occur after an ipsilateral adductor release unmasks the abduction tone Bilateral recon-struction with varus shortening osteotomies (VDRO) gives symme-try of appearance and motion Al-though recurrence can be seen with growth, bilateral reconstruction is much more likely to give lasting improvement than soft-tissue proce-dures.28
Anterior Dislocation
For an anterior hip dislocation, the indications for reconstruction are pain and difficulty with sitting
The knee flexion or extension con-tractures should be addressed with muscle lengthening The hip recon-struction includes a varus shorten-ing femoral osteotomy (VDRO) and
a Pemberton-type osteotomy to cre-ate good anterior coverage.17 Selva
et al17reported a good outcome in
11 of 13 patients The authors felt that results in posterior dislocations were better because anterior
dislo-cations are so rare and the affected children have severe neurologic in-volvement
Hip Subluxation After Selective Dorsal Rhizotomy
Children may develop progres-sive hip subluxation after selective dorsal rhizotomy Generally, there
is no adduction contracture Non-ambulatory children with preexist-ing dysplasia are most at risk and should be followed after rhizotomy with a radiograph of the hip each year for several years When pro-gressive subluxation is noted, a hip reconstruction should be done; however, lengthening of the adduc-tors usually is not needed
Salvage Procedures
If muscle lengthening does not succeed in treating subluxation, one-stage comprehensive hip recon-struction has achieved a reported success rate >90% Thus, with an-nual monitoring and appropriately timed surgery, few hips should need a salvage procedure How-ever, many adolescents with cere-bral palsy still present with a pain-ful dislocated hip and advanced degenerative changes They are often unable to sit comfortably and may have skin breakdown and poor perineal hygiene The basic types of femoral salvage options are re-section, redirection, interposition-replacement, and arthrodesis Some surgeons have successfully used a Chiari osteotomy or shelf arthro-plasty for late treatment of hips not amenable to a peri-ileal osteotomy Among the various types of fem-oral resection, the Castle procedure has produced the best results for a painful spastic hip dislocation with degenerative changes in the femoral head.29 Using an extraperiosteal dissection, the femoral head is re-sected distal to the lesser trochanter The rectus and vastus lateralis mus-cles are sewn over the remaining femoral shaft, and the gluteal
mus-Sciatic
notch
Anterior-inferior iliac spine
Ischium
Pubis
Bone grafts
Figure 7 Acetabuloplasty technique A, The osteotome is used to open the osteotomy at
the site of maximum deformity (usually posterosuperior), and the largest piece of graft is
placed in this position B, Completed acetabuloplasty, with the graft in place.
Trang 9cles are interposed between the
fe-mur and the acetabulum Although
the original recommendations
in-cluded 6 weeks of postoperative
skeletal traction, no evidence
sup-ports the necessity of 6 weeks A
few days in traction, with or
with-out a few weeks of abduction
cast-ing or braccast-ing, may be as successful
and more practical Postoperative
pain often persists for 9 to 12 months
before resolving Some surgeons
recommend measures to prevent
heterotopic ossification (HO) In a
series reported by McCarthy et al,4
12 of 56 hips had HO, but all
pa-tients were able to sit The Castle
procedure is contraindicated in
patients who have not reached
skeletal maturity; younger patients
can have excessive proximal
migra-tion of the femoral shaft and
persis-tent pain.4
Another salvage option for
non-ambulatory patients is a
redirection-al osteotomy In a child with severe
adduction but no pain, a valgus
osteotomy (at least 60°) can put the
legs in a more abducted position, allowing for improved perineal care
McHale et al30described a procedure
in which the femoral head is
resect-ed and a subtrochanteric valgus osteotomy is used to direct the lesser trochanter into the acetabulum and the remaining femoral shaft away from the pelvis There was good pain relief in six hips
Other salvage options include arthrodesis and arthroplasty In patients who might be candidates for a Castle procedure but who are skeletally immature, a total shoul-der prosthesis has been used as an interposition arthroplasty31(Fig 9)
In one series of eight arthrodeses, six were considered successful, yet seven patients had complications, including pseudarthrosis in two.32 Root et al32had 13 successful total hip replacements in a series of 15 but noted problems with recurrent dislocations, loosening, bending of the prosthesis, and proximal migra-tion of the greater trochanter More recently, Buly et al33 reported
long-term pain relief and an 86% 10-year survival rate of total hip replace-ments in 18 patients ranging from
16 to 52 years old They used selec-tive tendon releases and spica casts
to reduce the risk of dislocation
HO occurred in 58% of patients but did not seem to have a major clini-cal impact Total hip replacement should be reserved for skeletally mature, highly functional ambula-tors whose hips have advanced degenerative changes precluding reconstruction
Complications
While hip reconstruction or sal-vage carry the attendant risks of any major surgery, additional complica-tions are associated with the
severe-ly involved child Stasikelis et al34 found complications in 68% of pa-tients with gastrostomy or trache-ostomy tubes but in only 12% of those without; complications oc-curred in 29% of nonambulators but
in only 8% of ambulators Compli-cations after hip osteotomy
oc-A
C
B
Figure 8 A, Preoperative anteroposterior radiograph of a
9-year-old patient who had a complete left hip dislocation and pain B,
Both hips were reconstructed (left—comprehensive reconstruc-tion, right—VDRO to balance rotareconstruc-tion, adducreconstruc-tion, and leg
lengths) C, Ten years postoperatively, both hips remained well
reduced and the patient was pain free.
Trang 10curred in 25% of the 79 patients
studied, with postoperative death in
3 patients Most of these
complica-tions were fractures or decubitus
ulcers, which may be attributable to
postoperative casting In our
expe-rience with more than 400 hip
reconstructions without
postopera-tive casting, there have been no
deaths, and fractures and skin
breakdown are rare even in the
most seriously involved children
Complications after hip surgery
in cerebral palsy can result from the
procedure or the aftercare Matsuo
et al35studied the effect of obturator
neurectomy and found
hyperabduc-tion in the group that had
under-gone neurectomy They and other
investigators stress the importance
of preserving the adductor brevis
muscle and its nerve supply,
espe-cially in ambulatory patients
The reported incidence of
osteo-necrosis of the femoral head in
chil-dren after hip reconstruction ranges
from 0% to 11%.1,19,26 The blood
supply might be compromised either by the femoral osteotomy, as
a result of increased pressure on the femoral head, or during psoas tenot-omy.1 An adequate femoral short-ening may play a key role in pre-vention,1 just as in reconstruction for developmental dysplasia of the hip in older children Fortunately, osteonecrosis rarely has a notably adverse effect on results; in most cases, the hips are still mobile and pain free
HO is commonly seen in radio-graphs within a few months of hip surgery In a review of 192 patients with cerebral palsy, Krum and Miller36noted that HO was particu-larly severe in the few patients who had both hip and spine surgery within a short period of time In the group who had hip adductor length-ening, mild to moderate HO was noted in 21 of 61 patients; however,
2 of 5 patients who had both a spine fusion and hip soft-tissue lengthen-ing had severe, painful HO that
required surgical treatment Unex-plained irritability or motion loss several weeks after surgery may be the first indication of its occurrence Many protocols have been suggested
to prevent HO Anti-inflammatory medications, such as aspirin and in-domethacin, have not been reliable
in preventing HO in patients with cerebral palsy Radiation therapy to the area at risk on the second or third postoperative day (either a sin-gle dose or a divided dose on se-quential days) has been more suc-cessful Occasionally, it can be so debilitating that surgical interven-tion is necessary
Many children with cerebral palsy, particularly nonambulators, have decreased bone density They are at a particularly high risk for insufficiency fractures if their post-operative regimen includes spica casting In the few weeks after cast removal, fractures may occur with transfers or in physical therapy The most common fracture site is the dis-tal femur To decrease the risk of postimmobilization fractures and to minimize stiffness and prolonged loss of function, many centers have abandoned the use of postoperative spica casting altogether Miller et al used immediate mobilization after hip reconstruction and had a 4% fracture rate, much lower than the 10% to 29% noted in patients treated with spica casts.19 Improved nutri-tion, careful therapy, and limited immobilization will help minimize fracture risk in this vulnerable popu-lation
Summary
Managing spastic hip dysplasia is
an important part of caring for chil-dren with cerebral palsy Because the natural history of dislocations is often pain by young adulthood, and because the salvage options at that stage are limited, the goal is careful screening and early treatment Hip
Figure 9 A, Anteroposterior radiograph of a 19-year-old man who had severe pain after
an unsuccessful Girdlestone femoral resection Note the extent of the proximal migration
of the femur B, The same patient 3 years after a total shoulder prosthesis was used as an
interposition arthroplasty The patient remained pain free.