COF Lower Extremity Orthotics 3 — Questions and Answers
Question 1: A patient with Charcot-Marie-Tooth disease who walks with a cavus foot deformity and drop foot would be BEST served by:
- A rigid rocker-bottom shoe modification only
- A custom AFO with rigid ankle and lateral heel wedge
- A prefabricated dorsiflexion-assist AFO with lateral forefoot post (Correct answer)
- A standard UCB foot orthosis
Correct answer: A prefabricated dorsiflexion-assist AFO with lateral forefoot post
A dorsiflexion-assist AFO addresses drop foot while a lateral forefoot post accommodates the cavus and supination tendency common in CMT.
Question 2: During gait analysis, a patient wearing a solid AFO demonstrates excessive knee flexion at loading response. The MOST likely cause is:
- AFO set in too much plantar flexion
- AFO set in too much dorsiflexion (Correct answer)
- Insufficient medial-lateral heel posting
- Shoe heel that is too high
Correct answer: AFO set in too much dorsiflexion
Excessive AFO dorsiflexion creates a plantarflexion-inhibited rollover, generating a flexion moment at the knee during loading response.
Question 3: A fitter is evaluating a KAFO for a patient with post-polio syndrome. The patient has weak quadriceps (2/5) but intact hip extensors. The MOST appropriate knee joint is:
- Free knee joint
- Drop-lock (ring lock) knee joint
- Polycentric knee joint
- Bail lock knee joint (Correct answer)
Correct answer: Bail lock knee joint
A bail lock allows the patient to release the lock by pressing the bail against a chair, enabling easy sitting while providing stance-phase stability.
Question 4: In orthotic management of tibialis posterior tendon dysfunction (TPTD) Stage II, the goal of the orthosis is to:
- Rigidly prevent all subtalar motion
- Support the medial longitudinal arch and limit subtalar eversion while allowing some motion (Correct answer)
- Offload the forefoot only
- Provide a fixed equinus position
Correct answer: Support the medial longitudinal arch and limit subtalar eversion while allowing some motion
Stage II TPTD (flexible deformity) is managed with semi-rigid orthoses that support the arch and reduce subtalar eversion without eliminating all motion.
Question 5: A child with cerebral palsy (spastic diplegia) requires an AFO that blocks plantarflexion but allows free dorsiflexion. This design is called a(n):
- Posterior stop AFO (Correct answer)
- Anterior stop AFO
- Floor reaction AFO
- Dynamic ankle AFO
Correct answer: Posterior stop AFO
A posterior stop AFO uses a posterior trimline or mechanical stop that limits plantarflexion while permitting dorsiflexion, reducing toe walking.
Question 6: Which measurement is CRITICAL when fitting a patellar tendon-bearing (PTB) KAFO to ensure proper load transfer away from a painful tibial fracture?
- Thigh circumference at mid-femur
- Distance from medial tibial plateau to floor and exact PTB shelf height (Correct answer)
- Shoe size and heel height
- Ankle circumference at the malleoli
Correct answer: Distance from medial tibial plateau to floor and exact PTB shelf height
Precise measurement of the tibial plateau height ensures the PTB shelf bears load at the patellar tendon rather than over the fracture site.
Question 7: A rigid carbon fiber AFO that is too short in the footplate (ending at the metatarsal heads) will MOST likely cause which gait problem?
- Increased medial-lateral instability
- Excessive heel rise at terminal stance
- Inadequate toe rocker with early forefoot rollover (Correct answer)
- Plantar fascia irritation only
Correct answer: Inadequate toe rocker with early forefoot rollover
A footplate that ends before the toes prevents normal toe rocker mechanics, causing abrupt, unstable forefoot rollover at terminal stance.
COF Lower Extremity Orthotics 3
A patient with Charcot-Marie-Tooth disease who walks with a cavus foot deformity and drop foot would be BEST served by: