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 external fixators offer the opportunity of restoring the patient to normal height, but take time and have severe complications.

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.