Polio
and other flaccid paralysis
After the initial acute phase of polio, there should be a rapid
improvement in motor function to a steady state. During this time it is
important that joints are kept mobile and morale is kept up. In children,
compensatory development of other unaffected muscles may allow the child to lead
an almost normal life despite quite marked paralysis of some muscle groups.
However, tendon transfers can prove very useful in any form of flaccid
paralysis, especially if the following rules are adhered to.
• Muscles should only be transferred which are of normal power.
• It must be expected that muscles will drop at least one grade
of power when transferred.
• Where possible, muscles should be transferred which operate in
the same way or in the same phase of normal movement as the muscle that they are
supposed to replace.
• Tendon transfers should not go round sharp corners where they
will lose their efficiency.
In
children it is important to try and balance muscle power around joints so that
deformity does not arise.
Specific
tendon transfers
Long thoracic nerve, weakness of thoratis anterior and winging of the
scapula can be treated by transferring the pectoralis minor into the
inferiomedial aspect of the scapula musculocutaneous nerve. The
brachioradialis is spared in an injury to the musculocutaneous nerve and remains
as the only weak flexor of the elbow joint. If its insertion is advanced
proximally up the humerus to obtain better leverage its power increases.
Radial
nerve palsy
This is a common injury after a fracture of the humerus and if there is
no prospect of return of function, then transfers of flexor tendons to the
extensor side will stabilise the wrist and allow extension of the fingers. The
classic transfer is the Robert Jones. Pronator teres is inserted into extensor
radialis longus to restore wrist extension. Flexor carpi ulnar is inserted
into extensor digitorum to restore finger extension. Pal-mans longus when
present is inserted into extensor polices longus to restore thumb extension.
Median
nerve
There is a number of tendon transfers to improve function of the thumb
depending on the level of the median nerve palsy. In distal median nerve palsy,
flexor digitorum superfascialis of the ring finger can be passed across to the
thumb to help with opposition.
Lateral
popliteal nerve
This leads to a foot drop which can be treated by transfer of the
tibialis posterior tendon to take the place of tibialis anterior by routing
through the interosseous membrane.
Bone
operations for flaccid weakness
Arthrodesis is especially useful where flaccid weakness is proximal with
a normally functioning distal limb. Fusion at the wrist dramatically improves
the function of the hand while fusion of the shoulder can make a flail limb
functional again. The arthrodesis may also release active muscles for use
elsewhere in tendon transfers. Arthrodesis does not work well in cerebral palsy
where the spasticity tends to deform the arthrodesis. However, if spastic
tendons have been released and there is a persistent fixed flexion deformity, an
osteotomy may be simpler than a radical release of capsule. This is particularly
true around the knee.
Splintage
Modern splints can be very lightweight and cosmetically not prominent.
Splints can be built with springs and locks to improve function. Great care must
be taken if there is any sensory loss in the limb to make certain that the
splints fit well. Splintage may need to be combined with tendon release and with
osteotomy, especially in the severe cavus foot of the child with cerebral palsy,
where both a soft-tissue release and bony fusion will be needed to prevent
recurrence of the deformity.
Leg
length discrepancy
This can be corrected with a shoe raise and in some cases with stapling
of epiphyses on the opposite side to reduce growth. Modern techniques of leg
lengthening using
Limbs
with both sensory and motor loss
A flail limb without sensation may be more of a hazard than a help to
the patient and may be better amputated. This is particularly true if the limb
is scarred and deformed.