Neuromuscular
orthopaedics
In neuromuscular conditions such as polio, spina bifida, cerebral palsy
and the muscular dystrophies, imbalance of muscles and the effects of gravity
can result in deformity. Orthopaedic surgery has a valuable role in properly
selected patients. However, it is important to remember that surgery is only an
incident in the continuing care of these patients. The support of parents, other
medical specialists, therapists, orthotists and teachers is essential for good
results. The care of these children should be delivered in a co-ordinated way,
usually through a paediatrician or general practitioner.
This is usually due to infection by one of three types of poliomyelitis
virus, although other members of the enterovirus group can cause clinically and
pathologically indistinguishable disease. Effective vaccination has been
present for almost 40 years but the disease has not been eliminated from certain
parts of the world. The virus enters the oropharyngeal route, passing via the
alimentary lymph nodes to enter the circulation with an incubation period of
6—20 days. One or 2 per cent of patients develop neurological disease as the
virus affects the anterior horn cells, particularly in the cervical and lumbar
enlargements (as well as parts of the brain including the medulla). Weakness in
a muscle is in proportion to the number of motor units destroyed. Up to 60 per
cent of units have to be damaged before weakness is clinically detectable.
Muscles innervated by the cervical and lumbar enlargements are most commonly
affected and
In
the chronic stage which can be as much as 2 years after onset of the disease,
orthopaedic surgery may be indicated. Joint deformities will largely be dictated
by the muscle groups affected, although certain patterns of deformity, such as
flexion contracture of the knee and hip and calcaneus of the hindfoot, are
common. Patients with a weak quadriceps and a flexion contracture may develop
‘knee—hand gait’ in which the hand supports the knee which cannot be
locked into extension. In severe cases patients have to crawl and the pattern
adopted is a guide to the muscle groups affected. When all muscles acting on a
joint are paralysed it will become flail and unstable. It is surprising that
such joints rarely show degenerative changes. When the paraspinal muscles are
affected a scoliosis may develop. A disused lower limb grows shorter than normal
and leg-length discrepancy is common.
If surgery is to be undertaken in poliomyelitis, it should be preceded by a full assessment, including muscle charting. If orthoses are being considered, it is important to be certain these will be appropriate in the patient’s home environment.
The
surgical options in polio include:
• tendon transfer to augment or replace weak muscles;
• release of contractures by soft-tissue release and/or corrective
osteotomy. The knee—hand gait can often be abolished by extension osteotomy of
the distal femur which allows the knee to lock in extension. However, in some
cases a contracture may help the patient and the surgeon must be circumspect
about releasing it (Fig.
• stabilisation of flail joints by arthrodesis;
• spinal fusion and instrumentation for scoliosis;
• leg equalisation surgery.
Cerebral
palsy
This is classically a nonprogressive injury to the developing brain that
usually occurs in the neonatal period. There are several potential causes such
as anoxia, intracerebral haemorrhage and infection. There is a strong
association with prematurity. In such cases it is debatable whether the
neurological damage is due to a naturally impaired brain or caused during
delivery. Severe neurological impairment may also be part of syndromic or
genetic conditions. Finally there may not be any obvious cause for a child’s
neurological condition. On rare occasions such a child presenting as ‘cerebral
palsy’ may respond to dopamine treatment.
Cerebral
palsy is often not apparent at birth and may only be suspected as an infant
fails to reach milestones or shows
In
cerebral palsy there are various patterns of disability depending on the type
and distribution of the motor disturbance (Table 28.5).
It is also
helpful to grade the condition according to function which should include
intellectual ability and whether there is epilepsy (Table
28.6).
The
commonest type of disturbance is spasticity which tends to affect flexors rather
than extensors. Orthopaedic surgery can only have limited goals in cerebral
palsy as it deals with peripheral effects rather than the central problem.
Moreover, the orthopaedic surgeon is usually part of a large team involved in
the care of the child.
The
aim of surgery should be to improve function and facilitate the care of these
patients by correcting or preventing deformity. Regular physiotherapy to
stretch contractures (Fig. 28.25a and b) and supervise the use of orthoses is
essential (Fig. 28.26). Realistic goals must be set. It has to be explained that
results can be unpredictable and disappointing especially in dystonic cases. The
immediate postoperative care may be hampered by difficulties with nursing and
skin problems due to pressure from casts. Rehabilitation is usually prolonged.
The
goals and scope of treatment are usually determined by the anatomical
distribution and functional ability as follows.
Hemiplegia
The children walk independently and the hip is not at risk. The common
problems in the lower limb are equinus or
The
upper limb in hemiplegia is often badly affected. Surgical options to improve
function significantly are sadly few but some help can also be given to improve
the cosmetic appearance of the hand.
The
common deformities are equino valgus, knee flexion and adduction, internal
rotation and flexion at the hip. There
Total
body involvement
The children are usually very impaired mentally as well as physically.
However, in some, whereas the physical disability may be severe the child can be
intellectually bright. There are usually difficulties with incontinence,
feeding, nutrition and epilepsy.
The
orthopaedic goals in such cases can be summarised as follows.
• Hips. These are at risk of dislocation because of
adductor and psoas spasm. The joints should be monitored clinically and
radiologically. Preventive measures include exercises, abduction splints and
seating adaptation. If the hip is displacing early surgical options include
adductor release of femoral osteotomy (Fig 28.28 and
Fig 28.29). In late
dislocations which are painful and pose severe nursing or seating problems, the
combination of open reduction, femoral osteotomy and acetabular augmentation may
be necessary.
• Seating. Proper seating is important and is a major factor in
maintaining posture and minimising deformity (Fig. 28.30). If hips, knees or
ankles pose problems in achieving good seating and transfers usually because of
flexion deformities, then soft tissue releases will have to be considered.
• Communication skills. The child should be in the
school best suited to his or her particular needs and potential. Computers and
electronics can help parents and teachers in this regard.
Unfortunately, most children with spina bifida have profound lower limb
weakness and sensory loss (Fig. 28.31). They regularly need multidisciplinary
help from paediatricians, orthopaedic surgeons, neurosurgeons, therapists and
orthotists.
However,
not all spina bifida produces severe disability (Fig.
28.32). Occult forms may
cause subtle changes in neurology as a child grows. If a lower limb deformity,
weakness or urinary symptoms develop it is advisable to seek neurosurgical help
as, with growth, there may be tethering of nerve roots or other pathology such
as a syrinx which can be amenable to surgery.
The
lack of protective sensation means that minor cuts and abrasions may pass
unnoticed and lead to infection. Once this involves bone it is extremely
difficult to eradicate. Patients and carets must therefore adopt a daily routine
of foot inspection and must always try to protect skin. Surgery to the foot in
spina bifida is largely to achieve a plantigrade foot which can be fitted with
an orthosis and moulded footwear to avoid areas of pressure.
Hip
dislocation is common in spina bifida. Most surgeons do not operate for
dislocation because of the relatively poor results and prefer to advise it to be
left mobile and painless.
Flexion
contractures at hip or knee can be treated by soft-tissue release and/or
osteotomy. External rotation of the tibia may cause the medial side of the foot
to drag along the ground. This can be helped by internal rotation osteotomy of
the tibia. Spina deformity is common in higher level lesions and usually takes
the form of a kyphosis. This can be controlled with a brace but spinal fusion
and instrumentation may be necessary (see Chapter 20).
Muscular
dystrophy
The details of the many types of muscular dystrophy which vary in
severity and age at presentation are beyond the scope of this book. However, a
short discussion of a severe and classical type, namely Duchenne dystrophy,
exemplifies the diagnostic and therapeutic approaches, which may be applicable
throughout the spectrum of the muscle dystrophies.
Duchenne
dystrophy is inherited as a sex-linked condition and only boys are affected.
They are not usually diagnosed until after walking, which is delayed. They may
present as toe walkers or show difficulties with mobility. For example, when
getting up from the floor they use their hands on their thighs to push
themselves up into the erect position. They often have thick calves (pseudohypertrophy)
and the Achilles tendons are tight. The clinical features plus a raised creatine
phosphokinase (CPK) confirm the diagnosis.
The
condition is sadly progressive. The children usually come off their feet in late
childhood or early teens and die in late adolescence or early adult life. At
present there is no cure but gene therapy holds some hope for the future.
Treatment
is multidisciplinary and aims to keep the children as mobile as possible and
prevent deformity. Immobilisation after any surgery must be for as short a
time as possible. Walking can be prolonged by percutaneous lengthening of the
Achilles tendons and orthoses.
The
spine is particularly liable to deformity. This may be lessened by bracing and
seating. However, it regularly progresses beyond these measures whereupon
surgical stabilisanon is worthwhile, otherwise the deformity may become very severe and
the management difficult and unpleasant for the child during his or her final
years. The timing of spinal surgery is important. It should be done before the
vital capacity has deteriorated to a dangerous level.
Torticollis
(wryneck)
This is frequently related to neurological or muscular conditions. The
causes of the abnormal neck posture can be summarised as:
• cervical — congenital and acquired conditions of the cervical
spine, painful or otherwise;
• pharyngeal — usually infection, e.g. tonsillitis;
• ocular — squints or visual field defects;
• intracranial — posterior fossa tumours;
• muscular — contracture of the sternomastoid;
• habitual — no obvious organic cause.
The
classical type is due to contracture of either or both anatomical heads of the
sternomastoid muscle (Fig. 28.33). The cause of contracture is usually unknown.
It can follow a
Treatment
is usually by surgical release of the contracture followed by physiotherapy and
exercises to re-educate the child back to normal posture and movement.