Observation
Observation is still the main treatment for the majority of small curves in
patients with juvenile idiopathic scoliosis, especially for curves that are
<20° to 25° at first recognition. Follow-up every four, six, nine,
or twelve months is indicated, based on the age of the patient, the magnitude
of the curve, and the characteristics of the clinical
deformity14,16.
For curves of 25° to 30° or higher, some treatment should be
considered because of the high probability of progression.
Orthotic Management
Curves between 25° and 50° and even up to 60° are initially
treated with an orthotic or bracing
program16,17.
Although an underarm thoracolumbosacral orthosis (TLSO) or a Boston-type brace
is usually effective for patients in this age range (depending on the location
of the apex of the major curve), traditionally the cervicothoracolumbosacral
orthosis (CTLSO) or Milwaukee brace has been preferred for these young
patients18. The
thoracolumbosacral brace should be used with caution because of the amount of
rib-cage compression that can be attained with this brace and because of the
length of time that is usually required for brace treatment. In contrast, the
Milwaukee brace provides correction more by way of axial lengthening than by
rib-cage compression. Thus, the Milwaukee brace is generally preferred if the
curve is fairly flexible. If the curve is rigid, then preliminary serial
casting via a Risser cast, similar to what is recommended for patients with
infantile idiopathic scoliosis, is commenced to obtain some correction prior
to fitting the child with a Milwaukee
brace16,17.
Bracing is performed on a part or full-time basis, depending on the size of
the curve and the age of the child. Reported success with bracing in the
management of juvenile idiopathic scoliosis has been variable. Kahanovitz et
al. reported an excellent prognosis with part-time bracing for curves
=35° and RVADs
=20°18.
However, patients with curves of =45° and RVADs of =20° had a
poor prognosis for successful brace treatment. If curves progress despite
brace treatment, the goals of treatment obviously change. Usually orthotic
treatment will have to be abandoned once the curve is 60°, depending on
curve flexibility and the size of the patient. Thus, surgical management may
need to be considered, especially with progression despite good compliance
with brace-wearing. Certainly, surgery should be avoided if at all possible in
very young juveniles (three to six years of age).
Surgical Management
Surgical treatment is not as clearly indicated for juvenile idiopathic
scoliosis as it is for adolescent idiopathic scoliosis. Because of the
differing characteristics of a patient who presents at three years of age as
compared with one who presents at nine years of age, the decision to proceed
with surgery can be extremely variable and difficult.
There are many important considerations in the surgical treatment of
patients who have juvenile idiopathic scoliosis. One of the foremost issues is
the expected loss of spinal height, and thus limited chest-wall growth and
lung growth, due to a spinal fusion procedure. Winter devised a formula for
determining the amount of potential shortening of the spinal column following
spinal fusion: 0.07 cm multiplied by the number of vertebral segments fused
and then multiplying the product by the number of years of remaining spinal
growth19. This
formula assumes complete cessation of longitudinal spinal growth after
posterior fusion and thus allows the surgeon to inform the family of the
estimated postoperative spinal shortening. However, the family must understand
that, without spinal fusion, more truncal height will be lost because of the
untreated progressive scoliotic deformity.
Another important consideration is the crankshaft phenomenon, which
describes continued anterior growth and spinal curvature with increased rib
prominence despite a solid posterior fusion in a skeletally immature
patient20. Most
patients with juvenile idiopathic scoliosis and open triradiate cartilages
will be at risk for the crankshaft phenomenon, as documented by Sanders et
al.21. To prevent
it, anterior release and fusion has been recommended in addition to a
posterior fusion (Figs. 2-A, 2-B, and
2-C). Another possible option is the use of segmental bilateral
pedicle screws to maintain a posterior-only fusion without an anterior fusion,
although this method has not yet been proven efficacious in the juvenile
idiopathic scoliosis patient population. Even patients with posterior
growing-rod instrumentation can be affected by the crankshaft phenomenon.
Growing-Rod Systems
Many standard and nonstandard surgical treatments may be applicable to
patients with progressive juvenile idiopathic scoliosis (Tables
I and
II). The most common
traditional treatment is a posterior instrumentation and fusion. Because of
concern about the crankshaft phenomenon, often a preliminary anterior release
and fusion is also
performed22.
Obviously, one of the main concerns with posterior instrumentation and fusion,
especially in the thoracic spine, is diminished chest-wall height and volume
and, thus, limited lung development and subsequent growth. For this reason, a
growing-type of posterior instrumentation has been in use for several decades
in an attempt to sequentially lengthen the spine and allow longitudinal growth
while still attempting to control progressive spinal
deformities23-25.
This approach, however, has been met with less-than-ideal results. The
standard growing-rod construct, consisting of a claw-hook proximal as well as
distal to the curve, with both hooks connected to a single rod, led to many
instrumentation failures, including implant pull-out and rod breakage,
requiring multiple revision
surgeries23-25.
In addition, unintended spontaneous spinal fusion or autofusion may occur over
the instrumented
levels26. In
addition to internal fixation, long-term brace-wear may also be
required27.
Recently, the use of dual rod implants, as is standard practice in
conventional posterior instrumentation and fusion, and the addition of pedicle
screws in the cephalad and/or caudad aspect of the implant construct, have
also become quite popular in an attempt to lessen the instrumentation problems
of the past28
(Figs. 3-A through 3-D). In
addition, the performance of an anterior and posterior growth arrest with
fusion has been found to provide suboptimal results compared with the use of
dual growing-rod constructs without apical
fusion28. Other
growing-rod construct options include the traditional Luque
trolley29, in which
sublaminar wires are utilized, and a new type of nonlocking pedicle screw
implant called the Shilla technique, which was recently devised by
McCarthy30. In this
system, the apex of the deformity is fixed and fused with pedicle screws,
while the ends of the construct are instrumented with screws that are not
locked to the rod. Thus, this technique theoretically allows for apical
control of the deformity and continued axial lengthening of the spine with
growth. This system can be considered a type of "pedicle
screw-trolley" procedure.
Another recent growing-rod system, developed by Campbell et al., utilizes
implants that extend from rib-to-rib or ribs-to-spine in an attempt to control
progressive juvenile spinal deformity and expand the
chest31. In these
techniques, claw-hooks on bilateral ribs are applied laterally, with caudal
implants resting on ribs that are more distal or more often on the upper to
midlumbar spine than the ribs chosen for use with hook or pedicle screw
implants. These types of hybrid rib-spine constructs are as yet unproven for
the treatment of juvenile idiopathic scoliosis; however, they represent
another option in order to avoid exposure and instrumentation of proximal
thoracic vertebrae, which are often quite small and provide a more tenuous
fixation in very young patients.
Halo-Gravity Traction
One common technique often utilized, especially in juvenile patients with
severe scoliotic deformities (>80°, with or without a severe thoracic
or thoracolumbar kyphosis >70°), is the use of halo-gravity
traction32. In this
technique, with the patient under general anesthesia, a six up to eight-pin
halo is placed; then, the patient is placed in upright halo-gravity traction
for two to six weeks or longer. Daily, the patient sits, stands, and walks
while undergoing axial traction applied to the spine through the halo.
Progressive weight is added until 32% to 50% of body weight is applied, which
usually allows the entire trunk to be suspended in the sitting position by the
traction weight through the skull. We have found this technique to be very
useful for slow correction of severe deformities, especially in young patients
and in those with fairly severe preoperative pulmonary compromise, as it
provides a safer environment for definitive anterior and/or posterior
procedures. In addition, the axial traction performed while the patients are
awake, in our experience, has decreased the risk of the development of
neurologic deficits during the traction and subsequent surgical
correction32. As
there is a risk of pin-site problems and cranial nerve palsy from the
traction, the patients must be monitored carefully. Acute cranial nerve
palsies usually respond to a lessening of traction weight. Traction can be
applied preoperatively or perioperatively following anterior release in very
serious cases.
Anterior and Posterior Spinal Fusion
Definitive procedures for older juvenile patients (eight to ten years of
age) usually consist of an anterior and posterior spinal fusion. This is
usually performed on the same day with an open or endoscopic anterior release
followed by a definitive posterior spinal fusion and segmental spinal
instrumentation with use of an appropriate-size instrumentation system for
these often small-size
patients33-37.
It is very important not to attempt to cheat proximal or distal levels as
continued growth will often lead to an "adding-on phenomenon" with
deformity progression cephalad to and/or caudad to the spinal instrumentation
and fusion levels. Standard segmental spinal instrumentation techniques are
performed with hooks, wires, and/or pedicle screws, depending on the
preference of the surgeon. In these young patients it is important to achieve
a solid posterior fusion mass, which can be accomplished with autograft bone
supplemented with allograft bone as required.
Occasionally, if the patient is large enough, isolated anterior
instrumentation and fusion may be applied in an attempt to correct a single
major curve. However, one must always be aware that continued spinal growth
may cause other minor curves to progress even if those curves initially seem
innocuous. Anterior instrumentation and fusion often can be done in the
thoracolumbar and/or lumbar region, but the limiting factors are often the
size of the vertebral bodies to be instrumented and the bone, which is often
quite soft. Single-screw, single-rod constructs may be applied along with
anterior structural devices, such as structural allograft bone or titanium
cages in the thoracolumbar/lumbar spine, if required, to maintain optimal
sagittal
alignment38,39.
Growth Modulation Techniques
Alternative devices that modulate spinal growth are becoming available,
including intervertebral stapling to produce a tethering effect. Convex disc
stapling represents an attempt to apply principles similar to those used in
physeal stapling in the lower extremities for correction of angular
malalignment. Thus with convex stapling, continued concave growth will
hopefully maintain or even correct scoliosis deformities over
time40. Indications
for the use of this technique in patients with juvenile idiopathic scoliosis
are not precisely known at this time. Posterior growing-rod instrumentation
and definitive spinal fusion may be performed at any time in patients with
juvenile idiopathic scoliosis who have previously undergone stapling
anteriorly.
Another treatment option that may be available in the future for
progressive juvenile idiopathic scoliosis is anterior tethering. In this
technique, single screws are placed in the vertebral bodies anteriorly, and
then a polypropylene tether is placed between the screw heads, which may be
shortened and compressed to correct the deformity during this surgical
procedure. In this technique, the discs are left unaffected, and motion of the
spine, although not normal, theoretically allows 5° of freedom, with a
loss of motion only when bending away from the tether (to the left for a
right-sided scoliosis tethering). Stapling and/or tethering procedures are
growth-modulation procedures, which ultimately may be utilized for smaller
deformities in an attempt to avoid secondary manifestations of scoliosis that
are much more difficult to correct with definitive spinal instrumentation and
fusions.
All surgical procedures to correct scoliosis involve a struggle to control
spinal deformity in a growing spine while guarding against the complete
immobilization of the vertebrae. It is hoped that the next decade will usher
in major advances in the treatment of juvenile idiopathic scoliosis, as these
deformities are among the more challenging of progressive spinal deformities.
There will come a day when progressive scoliosis will be treated with
correction of the deformity, either internally or externally, without a spinal
fusion. Until then, we should analyze each deformity on an individual basis,
keeping in mind that the optimal treatment for the control or correction of
deformity will be the one that entails the least amount of short and long-term
morbidity. ?