Describe Poliomyelitis — Orthopaedic Aspects in detail.

Definition

Poliomyelitis is a viral infection (poliovirus, an enterovirus) that attacks the anterior horn cells of the spinal cord, producing a pure lower-motor-neuron, flaccid paralysis — without sensory loss. Though now rare where vaccination is widespread, its late orthopaedic sequelae remain important, especially in regions where the disease was endemic. The disease has an acute stage, a stage of recovery, and a residual (chronic) stage of paralysis and deformity, which is the orthopaedic concern.

Pathology & Features

Destruction of anterior horn cells causes asymmetrical flaccid paralysis with wasting; because only the motor cells are affected, sensation is preserved. Muscle imbalance across joints (some muscles paralysed, their antagonists acting unopposed), together with growth, leads to fixed deformities (e.g. Equinus, flail joints, scoliosis), joint instability, shortening of the limb (growth retardation), and trophic/vasomotor changes.

Principles of Management

Management differs by stage. In the acute stage, care is supportive (rest, respiratory support, positioning to prevent deformity). In the convalescent stage, physiotherapy maintains range and strengthens recovering muscles, with splints to prevent deformity. The residual stage is where reconstructive orthopaedic surgery is used to improve function.

Reconstructive Surgery in the Residual Stage

The aims are to correct deformity, stabilise flail joints, balance muscle power and equalise limb length. Procedures include soft-tissue release of contractures, tendon transfers (to rebalance a joint by re-routing a working muscle), arthrodesis (to stabilise a flail or unstable joint, e.g. The foot or shoulder), osteotomy to correct bony deformity, and leg-length equalisation. Calipers/orthoses support flail limbs for walking. Treatment is individualised and planned around the pattern of working and paralysed muscles.

Assessing the Patient for Surgery

Planning reconstruction in the residual stage depends on a meticulous muscle chart that grades the power of every muscle across each affected joint, because the whole strategy is to use the working muscles to compensate for the paralysed ones. The surgeon assesses which deformities are flexible or fixed, whether joints are stable or flail, and the degree of limb-length discrepancy, then sequences procedures logically — first correcting fixed deformity and stabilising the skeleton, then rebalancing muscle power by transfer, and finally equalising length.

Post-polio Syndrome

Decades after the original illness, some survivors develop post-polio syndrome — new weakness, fatigue and pain in previously affected (and sometimes apparently unaffected) muscles, thought to result from the gradual failure of the enlarged motor units that had compensated for the original cell loss. It is managed supportively with energy conservation, appropriate orthoses and graded activity, and it is important to recognise so that new weakness in a polio survivor is not mistakenly attributed to a fresh neurological disease.

Sensation is preserved — unlike most other causes of paralysis.

• Poliovirus destroys anterior horn cells → pure LMN flaccid, asymmetrical paralysis, sensation intact.
• Residual stage: fixed deformities, flail/unstable joints, limb shortening.
• Acute → supportive; convalescent → physiotherapy/splints to prevent deformity.
• Residual reconstructive surgery: soft-tissue release, tendon transfer, arthrodesis, osteotomy, limb equalisation.
• Only transfer muscles with adequate power, across a corrected, stable joint; orthoses support flail limbs.