Why do patients with spastic hemiparesis circumduct their leg when walking?

• A. Weakness in hip flexors
• B. Loss of proprioception
• C. Increased tone of their lower limb makes it stiff
• D. Poor coordination

Answer: (C)

The main idea is that spastic hemiparesis produces increased muscle tone (spasticity) in the affected leg, making it stiff. That hypertonia makes shortening of the leg during the swing phase difficult, so the leg can’t flex and clear the ground in the usual way. To advance the limb and get the foot past the toes, the person moves the leg in an outward arc—the circumduction. This is a common compensatory pattern when the limb is stiff and the normal knee/ankle movements are limited by spasticity. Other ideas like isolated hip flexor weakness, loss of proprioception, or poor coordination don’t specifically explain the stiff, semicircular swing seen with spasticity, so the increased tone causing stiffness is the best explanation.