Which AFO is used to prevent knee buckling or excessive knee flexion?

• A. AFO: Dorsiflexion spring assist (Klenzak Joint)
• B. AFO: Posterior leaf spring
• C. Molded AFOs
• D. AFO: metal anterior stop

Answer: (D)

Knee buckling during stance is often caused by forward tibial progression as the body weight loads the leg. The design that addresses this directly uses an anterior stop on the AFO to limit how far the tibia can translate forward by restricting ankle dorsiflexion. With that forward motion kept in check, the knee is maintained in a more extended position and the tendency to buckle is reduced.

Dorsiflexion spring assist focuses on pulling the foot into dorsiflexion for toe clearance and doesn’t stop tibial forward movement during stance. A posterior leaf spring mainly assists with foot clearance and energy return, not knee stability. Molded AFOs are customizable shapes but may not include a mechanism to prevent knee buckling. The metal anterior stop specifically provides the forward-limiting feature needed to prevent excessive knee flexion.