Which KAFO joint arrangement allows knee flexion in swing while maintaining extension in stance?

Which KAFO joint arrangement allows knee flexion in swing while maintaining extension in stance?

• A. Free motion joint
• B. Free motion joint with drop lock
• C. Offset joints with drop lock
• D. Adjustable motion with drop lock

Answer: (C)

The important idea is how a KAFO can control the knee differently in stance and swing using both joint geometry and a locking mechanism. An offset knee joint positions the hinge axis not exactly where the knee’s natural axis is, which helps keep the knee more stable in stance by using the alignment with body weight and ground reaction to favor extension. When a drop lock is engaged, the knee is held in full extension for stance, providing a solid, supported position. Then, for swing, the user unlocks that drop mechanism to allow the knee to flex for foot clearance. This combination—offset joints to promote stance stability and a drop lock to enable swing flexion—delivers knee flexion in swing while maintaining extension in stance. Other options either lack the locking mechanism needed to reliably hold extension during stance or rely on a design that doesn’t optimize stability in stance or clearance in swing, making them less effective for this specific gait requirement.

The important idea is how a KAFO can control the knee differently in stance and swing using both joint geometry and a locking mechanism. An offset knee joint positions the hinge axis not exactly where the knee’s natural axis is, which helps keep the knee more stable in stance by using the alignment with body weight and ground reaction to favor extension. When a drop lock is engaged, the knee is held in full extension for stance, providing a solid, supported position. Then, for swing, the user unlocks that drop mechanism to allow the knee to flex for foot clearance. This combination—offset joints to promote stance stability and a drop lock to enable swing flexion—delivers knee flexion in swing while maintaining extension in stance.

Other options either lack the locking mechanism needed to reliably hold extension during stance or rely on a design that doesn’t optimize stability in stance or clearance in swing, making them less effective for this specific gait requirement.