KAFO indications include weakness of the quadriceps. Which grade of quadriceps weakness is cited as an indication?

• A. Grade 5
• B. Grade 4 or less
• C. Grade 3
• D. Grade 2

Answer: (B)

KAFOs are used when knee stability is needed because the quadriceps cannot reliably keep the knee extended during stance. In muscle testing, the quadriceps strength ranges from normal (able to resist full resistance) to zero. When the quadriceps are grade 4 or less, they can move the knee against gravity with some weakness but cannot maintain a steady knee extension under body weight. That insufficient control makes knee buckling a real risk during standing and walking, so an external knee–ankle–foot orthosis that stabilizes the knee is indicated. A grade 5 would usually not require a KAFO, while grade 3 or lower reflects more severe weakness that may need different devices or interventions, but the standard indication cited is grade 4 or less.