Which ankle-foot orthosis modification is used to address dorsiflexion and knee instability in the early to mid-stance phase?

• A. AFO + DF stop
• B. Arizona AFO
• C. SMO
• D. UCBL

Answer: (A)

The key idea is controlling how the tibia moves over the foot during early stance to keep the knee stable. An ankle-foot orthosis that includes a dorsiflexion stop provides a defined limit to how far the ankle can dorsiflex in that portion of gait. By restricting dorsiflexion, the tibia doesn’t translate forward excessively over the foot, which helps maintain a more stable knee moment and reduces knee instability as weight-bearing begins. This setup also preserves a functional heel rocker and allows some plantarflexion, but prevents the tibia from moving into excessive dorsiflexion that could lead to knee collapse or instability in the early to mid-stance phase.

Other devices offer broad ankle stabilization or foot alignment without specifically limiting dorsiflexion to the same degree, so they don’t target the precise control of tibial progression and knee stability in that gait window.