Other Neuromuscular Conditions and Spina Bifida

Ovid: Staying Out of Trouble in Pediatric Orthopaedics

Authors: Skaggs, David L.; Flynn, John M.
Title: Staying Out of Trouble in Pediatric Orthopaedics, 1st Edition
> Table of Contents > Section 3 – Special Maladies and Concerns > 15 – Other Neuromuscular Conditions and Spina Bifida

Other Neuromuscular Conditions and Spina Bifida
David L. Skaggs
John M. Flynn
John F. Sarwark



The array of diagnosable neuromuscular conditions
presenting in children is intimidating and interesting. Most of this
information is generally towards the periphery of most orthopaedic
surgeons’ knowledge. Stay out of trouble by knowing a few common
threads in these conditions that can help you identify a child with a
potential neuromuscular condition.
A common scenario occurs when parents bring a child to
an orthopaedic surgeon because the child walks funny, falls down, wants
to be carried when walking far, or some other seemingly innocuous
complaint. Ninety-nine percent of the time it is age appropriate, but
this chapter may help with the other 1%. Delay in diagnosis can have
serious implications, e.g., before Duchenne muscular dystrophy is
diagnosed, 20% of families already have conceived a second child. Do
not hesitate to examine the parents (subtle cavovarus feet,
café-au-lait spots, etc.) and ask for a family history. Many parents
have unrecognized subtle forms of the same disease of their child. This
aids in diagnosis of the child.
FIGURE 15-1 (A)
This child with a cavus foot has an underlying neuromuscular disorder.
In children with unilateral foot deformity, consider spinal pathology
as more likely; with bilateral foot deformity, consider underlying
neuromuscular disease as more common. (B) A child with bilateral cavo-varus feet with Charcot-Marie-Tooth. (C) Claw toes are also an indication of an underlying neuromuscular disease.
Do not become focused on one body part as many
neuromuscular conditions have multiple orthopaedic implications. For
example, a child with Charcot-Marie-Tooth (CMT) disease may present to
you with a foot deformity, but do not forget there is an increased risk
of scoliosis1 and hip dysplasia.2,3
This raises an important point even for pediatric orthopaedic surgeons
who feel comfortable seeing children with neuromuscular conditions.
Each condition has its own unique pitfalls, and it is probably
worthwhile to quickly review literature on a child’s condition prior to
instituting treatment. For example, children with various muscular
dystrophies have widely variable prognoses. Know the natural


and expected function of the condition prior to planning surgery as
many of these children may never be expected to walk, or even live very
long, which may influence whether surgery is indicated. If a muscle
biopsy is required, biopsy the weak muscle—i.e., the deltoid, for
shoulder girdle weakness.

Radiograph of a femur of a nonambulator with cerebral palsy who has
sustained multiple femur fractures. The clinical and radiographic
appearance of this fracture may be confused with infection.
Children with neuromuscular disease and decreased
ambulation are at an increased risk for osteopenic fractures. In an
insensate area, fractures are often not appreciated at the time of
injury, and present late as a swollen, red, and warm limb that is often
mistaken for infection by the inexperienced. To make things even more
confusing, the child may present with a fever and abnormal laboratory
studies. This scenario unfortunately occurs in children who have severe
communication challenges (Figs. 15-2, 15-3 and 15-4).
FIGURE 15-3 (A)
This boy with thoracic level spina bifida presented with a chief
complaint of (painless) leg swelling. The leg was warm to touch. (B) Radiographs demonstrate copious new bone formation. (C) To make matters even more confusing, when children with spina bifida fracture through the growth plate, there may be no
callus formation. Clinically, this young girl with thoracic level spina
bifida had motion through the Salter I fracture of the distal femur.
Nonambulators with osteopenia frequently have fractures of the distal
femoral metaphysis. Have a high index of suspicion when children who
were in a hip spica cast for hip surgery present with increasing pain
shortly after the spica cast was removed.
Fracture care in these children is quite different than
in otherwise normal, active children. First, mobilization should begin
as early as possible. If a child with progressive weakness and
increasing difficulty in walking (e.g., 11-year-old boy with Duchenne)
is in a long leg cast that prevents walking for 6 weeks, the child may
lose so much muscle strength that he never
walks independently again. You do not want to contribute to that.
Second, immobilize for as little a time period as possible.
Immobilization leads to localized osteopenia. These children already
have some degree of osteopenia to begin with; following immobilization,
fractures at other areas in the limb are quite possible. One of us
(DLS) assumed care of a spina bifida patient who spent 11 months in
lower extremity casts for


fractures at different locations. Third, these children often have
abnormal sensation; soft-tissue problems are more likely to occur, and
less likely to be recognized, than in the general population.

We have found less-rigid immobilization a useful
technique for fracture care in nonambulatory children with
neuromuscular conditions. This can be accomplished with semi-rigid
fiberglass and/or significant padding, such as polyurethane foam. This
decreases osteopenia secondary to immobilization, lessens the chance of
a secondary fracture at the edge of a rigid cast, and decreases skin
problems from poorly sensate soft tissues rubbing against the edge of a
hard cast.
The good news in this situation is that there is often
rapid and overwhelming callus formation, and the child’s demands
usually do not require anatomic reduction.
Duchenne is the most common of the muscular dystrophies,
and many other types of muscular dystrophy are less severe. The level
of creatine phosphokinase (CPK) may be 20-200X normal in children with
Duchenne, but can be elevated for patients with other forms of muscular
dystrophy as well as many other types of muscle disease. The CPK may be
elevated by birth in normal children, but should return to normal
quickly. Duchenne muscular dystrophies are not that rare, occurring in
1/3,500 births, so there is a good chance most orthopedic surgeons will
encounter a new patient at some point in their career. While Duchenne
is X-linked and thus occurs only in boys, beware that it can occur in a
child with Turner syndrome (XO), and other forms of muscular
dystrophies can occur in girls. Dr. Sarwark points out that Duchenne
can occur in girls in the setting of the Lyon Hypothesis, in which
there is inactivation of one of the two X chromosomes. Mental
retardation may be present—just because a boy has mental retardation
doesn’t mean he doesn’t have muscular dystrophy. Perhaps the greatest
way to stay out of trouble in Duchenne is to make it a practice to do
Gower’s test on all 3- to 6-year-old boys with gait abnormalities other
than torsion (see Fig. 2-1).

FIGURE 15-5 Pseudohypertrophy of the calf in the setting of weakness suggests Duchenne muscular dystrophy.
In contrast to the past, there is now something that can
be done for these children to prolong strength. While still early, it
appears that steroids significantly increase muscle strength,
performance, and pulmonary function, as well as slowing the progression
of weakness. Refer these children to a practitioner with experience in
this area. Minimize periods of immobility; once children are in a
wheelchair for 3 to 6 months, they are unlikely to ever walk again. In
general, minimize surgery. For most children, a percutaneous
tendoachilles lengthening (TAL), and possibly a posterior tibial tendon
release or transfer is all that is ever needed aside from possible
spine surgery. Do not be too aggressive in treating mild equinus in the
ambulatory child, as this may be protective against knee flexion
contractures. After a child is nonambulatory, foot surgery is unlikely
to improve quality of life and is performed only for comfort.
Scoliosis usually becomes progressive after cessation of walking. Use of steroids may delay development of scoliosis.7
As the disease progressively weakens the cardiac and pulmonary systems
with time, stay out of trouble by performing a spinal fusion early, at
20 to 30 degrees of scoliosis, before cardiopulmonary deterioration
becomes severe. There is an estimated 4% loss of forced vital capacity
(FVC) for every 10 degrees of spinal curvature.8
Some have suggested that a FVC of 35% is the minimum for safe spinal
fusion, though with approval and support from the pulmonologist,
cardiologist, and anesthesiologist, children with even worse pulmonary
function undergo surgery safely and successfully. Make certain the
family understands that although there is a realistic possibility of
death, especially in children with small FVCs, the more likely outcome
is the child needing a tracheotomy (which means a loss of verbal
communication), as well as the possible need for permanent mechanical
ventilation. It is also wise to discuss preoperatively with parents and
patient what to do if loss of spinal cord function occurs during the
surgery, such as leaving implants in place to maintain sitting balance.
The indications to fuse to the pelvis have been debated. In our
experience, and that of others, fuse to the pelvis during the primary
surgery.9 We believe the risk of
fusing to the pelvis during primary surgery is much less than extending
the fusion down to the pelvis years later following further
cardiopulmonary decline.
While children with arthrogryposis represent a myriad of
over 150 specific conditions, there are common clinical
characteristics. Children with the most common


amyoplasia, are generally of normal intelligence and the majority will
be able to ambulate. The joints (including bones, cartilage, muscle
units, ligaments, and skin) have never had the necessary movement in
utero for normal development, and will never have normal motion. This
is important for the surgeon and family to understand. Long-term
physical therapy is of little use, and may be psychologically
counterproductive when significant effort leads to little if any gains.
The goal of treatment is not
to create normal motion of joints, as this is a setup for failure. The
goal is to align the extremities and joints to maximize the ability to
stand, ambulate, and sit.

First off, do not be confused by terminology. Spina
bifida occulta, a lack of complete formation of the posterior arch
(usually of L5 and present in about 10% of the population) is not spina bifida (Fig. 15-6). By definition it is a normal variant and there are no sequelae, other than parental distress.
In true spina bifida (or myelomeningocele) it is
important to remember that the abnormality is not just at the end of
the spine—it’s the whole central nervous system. Problems such as
hydrocephalus, Chiari malformations, and others are an expected part of
spina bifida.
FIGURE 15-6 Spina bifida occulta. Spinous processes of L3 and L4 are visible (black arrows). An absent spinous process at L5 (white arrow) is consistent with spina bifida occulta in an otherwise normal child.
Level of Involvement
The child’s function, and to some extent orthopaedic
problems, are largely determined by the level of motor involvement,
defined as the lowest level with 4/5 strength or better. The Can-Can
dance can help one determine levels (Fig. 15-7).
Document the level of involvement on a regular basis to help recognize
deterioration of function and, if needed, begin a search for the
underlying cause.
It has been taught that if the quadriceps are grade 4/5
or better, the child will be a walker, if there is no significant
cognitive pathology. This is just not true in most cases. Walkers are
most often L4 (grade 4/5 hamstring) or better, though even many
children with low-lumbar and sacral lesions will not be long-term
walkers. In one study looking at patients between 10 and 30 years of
age, half of those with sacral lesions are not community ambulators.10
Another misconception is that the disease is static.
While the congenital lesion may not change, deterioration in ambulation
can be expected for a variety of factors, including CNS problems
(shunting and tethering) and increased mass outstripping poor muscle
strength. While outcome varies by center and population, Rancho Los
Amigos Medical Center reviewed 35 patients with sacral level lesions


were initially community ambulators. At an average age of 29 years they
found a decline in the ability to walk in 11 of 35 patients, and over
half had ostomyelitis.11
Keep out of trouble by sharing with families early on that
deterioration in ambulation is an expected part of the disease and not
necessarily anyone’s fault.

Can-Can Dance: Spina Bifida Levels for Everyone. Need 4/5 strength to
make the level. These may not be exact, but they are easy to remember,
easy to do, and makes it easy to notice when something is changing. L1, hip flexion (iliacus, psoas, sartorius); L2, hip adduction (hip adductors); L3, knee extension (quadriceps); L4, knee flexion (medial hamstrings); L5, hip abduction (tensor fascia lata, gluteus medius, gluteus minimus); S1, hip extension and ankle plantar flexion (gluteus maximus, gastrocnemius, soleus).
Hip and knee contractures are common and best prevented
by positioning and range of motion exercises. For overall mobility the
importance of weight control cannot be overstressed to parents—before
it becomes a problem. Up to one third of children with spina bifida are
latex sensitive, thus treat all children with this condition as if they
are latex sensitive. There are no definitive tests to prove they are
not, and the stakes of anaphylaxis are too high to risk when prevention
is so simple.4

If a spinal deformity is progressing rapidly, it may be
secondary to underlying or changing CNS pathology (syrinx,
Arnold-Chiari type II, tethered cord, shunt malfunction). Investigate
with an MRI of the entire spine and neurosurgical assessment of shunt
function. Scoliosis >45 degrees is very uncommon in L5 and sacral
level patients, and if present is usually due to underlying CNS
pathology. Beware that congenital scoliosis is also frequently present;
go with traditional treatment such as early fusion of a unilateral bar
opposite a hemivertebrae, as applicable.
When a severe lumbar kyphosis, or gibbus is present, the
aorta and vena cava are too short to allow full correction of the
deformity, thus vertebral bodies are removed to shorten the spine.
There are anecdotes of acute vascular insufficiency leading to loss of
legs following an overly aggressive correction. Consider an arterial
line with blood pressure monitoring in the lower extremities or pulse
oximetry when planning significant corrections of a sharp kyphosis.
Dislocated hips do not influence walking ability.
Surgical treatment of dislocated hips in ambulatory children has been
advocated. A comprehensive study of ambulatory children with L3 and L4
level spina bifida who underwent surgical hip reduction found that
benefits were marginal at best, and patients with failed operations had
worse function than those who were not operated on.13
A frequent and unfortunate outcome of attempts to reduce a dislocated
hip in spina bifida is a stiff hip, which may interfere with
positioning and transfers. In our experience we have never seen a child
whose hip we wished we’d reduced, but have seen many attempts at hip
reduction we wished hadn’t been done. Dr. Sarwark says the principle is symmetry and mobility free of contractures.

Placing iodineimpregnated surgical drape and skin adherent between the
perineum and wound helps keep the wound from becoming soiled. Children
with spina bifida have a much higher incidence of gram-negative and
mixed floral infections, possibly due to wound contamination from
FIGURE 15-9 (A)
Child with thoracic level spina bifida with skin graft directly
adherent to bone over the progressive kyphotic gibbus with frequent
ulceration. Plastic surgical consultation concluded that there was no
means of providing soft-tissue coverage for traditional posterior
spinal instrumentation. (B) Preoperative lateral supine radiograph demonstrates rigid nature of kyphosis. (C) Surgery was performed with no incision distal to L3, by placing the rods directly into the vertebral bodies of L-4-S1. (D) Intraoperative imaging with preliminary K-wires assists in correct placement of rods.

Stay out of trouble by telling the parents to expect
knee (and hip) contractures to develop over time. Physical therapy and
sleeping in knee immobilizers may help. As many children with spina
bifida have weak quadriceps to begin with, the addition of knee flexion
contractures makes walking even more difficult. The use of ground
reaction ankle-foot orthoses (AFOs) help prevent knee flexion
contractures, as well as accommodate for quadriceps weakness. Children
with absent or very weak quadriceps strength may benefit from
knee-ankle-foot orthoses (KAFOs) to assist in standing, transfers, and
ambulation. This is one of the few remaining indications for bracing
above the knee in contemporary pediatric orthopaedics.
Stay out of trouble by remembering that the goal of
orthopaedic care in spina bifida feet is a braceable, supple,
plantigrade foot. Fusions are generally contraindicated, as a stiff,
insensate foot is a setup for ulcers.
When performing clubfoot surgery, resect 1 to 2 cm of
all tendons to help minimize recurrence and minimize future surgeries.
Although this sounds extreme, a flexible, braceable foot is far
superior to a rigid deformed foot prone to ulcers. Even in children
with thoracic level involvement, in which the muscles to the foot are
not normally innervated, the muscle tendon units can act as deforming
1. Walker JL, Nelson KR, Stevens DB, et al. Spinal deformity in Charcot-Marie-Tooth disease. Spine. 1994;19(9):1044-1047.
2. Kumar
SJ, Marks HG, Bowen JR, et al. Hip dysplasia associated with
Charcot-Marie-Tooth disease in the older child and adolescent. J Pediatr Orthop. 1985;5(5):511-514.
3. Pailthorpe CA, Benson MK. Hip dysplasia in hereditary motor and sensory neuropathies. J Bone Joint Surg Br. 1992;74(4):538-540.

4. Dormans JP, Templeton JJ, Edmonds C, et al. Intraoperative anaphylaxis due to exposure to latex (natural rubber) in children. J Bone Joint Surg Am. 1994;76(11):1688-1691.
5. Read L, Galasko CS. Delay in diagnosing Duchenne muscular dystrophy in orthopaedic clinics. J Bone Joint Surg Br. 1986;68(3):481-482.
6. Marshall PD, Galasko CS. No improvement in delay in diagnosis of Duchenne muscular dystrophy. Lancet 1995;345(8949):590-591.
7. Alman BA, Raza SN, Biggar WD. Steroid treatment and the development of scoliosis in males with duchenne muscular dystrophy. J Bone Joint Surg Am. 2004;86(3):519-524.
8. Kurz LT, Mubarak SJ, Schultz P, et al. Correlation of scoliosis and pulmonary function in Duchenne muscular dystrophy. J Pediatr Orthop. 1983;3(3):347-353.
9. Alman BA, Kim HK. Pelvic obliquity after fusion of the spine in Duchenne muscular dystrophy. J Bone Joint Surg Br. 1999;81(5):821-824.
10. De Souza LJ, Carroll N. Ambulation of the braced myelomeningocele patient. J Bone Joint Surg Am. 1976;58(8):1112-1118.
11. Brinker MR, Rosenfeld SR, Feiwell E, et al. Myelomeningocele at the sacral level. Long-term outcomes in adults. J Bone Joint Surg Am. 1994;76(9):1293-1300.
12. Cochrane DD, Rassekh SR, Thiessen PN. Functional deterioration following placode untethering in myelomeningocele. Pediatr Neurosurg. 1998;28(2):57-62.
13. Alman BA, Bhandari M, Wright JG. Function of dislocated hips in children with lower level spina bifida. J Bone Joint Surg Br. 1996;78(2):294-298.
Sarwak JF, Lubicky JP, eds. Caring for the Child with Spina Bifida. American Academy of Orthopaedic Surgeons; 2004.

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