Which condition is a contraindication for the use of an SMO?

The choice indicating significant equinovarus as a contraindication for the use of a supramalleolar orthosis (SMO) is appropriate due to the specific biomechanical requirements that the SMO cannot accommodate effectively. An SMO is primarily designed to provide support around the ankle and foot, allowing for some movement at the level of the foot while assisting with alignment and stability.

In cases of significant equinovarus, where there is a severe plantarflexed (downward) and inverted (toward the body's midline) position of the foot, the SMO may not provide adequate correction or control. The rigid structures needed to manage the severe deformity could exceed what the SMO offers, leading to further instability or improper fit, which may hinder function rather than assist it.

Conditions like dorsiflexion weakness, mild spastic diplegia, or hypotonic cerebral palsy may benefit from the use of an SMO, as these conditions generally require support to facilitate better foot alignment and function without the complexities introduced by significant equinovarus deformity.