COF Fitting & Adjustment Techniques 2 — Questions and Answers
Question 1: When fitting a prefabricated AFO, which measurement is most critical to ensure proper fit at the ankle?
- Calf circumference at the widest point
- Malleolar width and ankle circumference (Correct answer)
- Foot length from heel to longest toe
- Knee circumference at mid-patella
Correct answer: Malleolar width and ankle circumference
Malleolar width and ankle circumference determine whether the AFO will accommodate bony prominences and prevent pressure sores.
Question 2: A patient with a custom KAFO reports lateral knee pain after one week of use. The most likely cause is:
- Insufficient knee flexion stop
- Medial upright set too far from the limb
- Lateral knee joint aligned too distal (Correct answer)
- Thigh band positioned too proximal
Correct answer: Lateral knee joint aligned too distal
A lateral knee joint positioned too distal creates a valgus moment arm that concentrates pressure on the lateral condyle.
Question 3: The 'three-point pressure system' in orthotic fitting primarily serves to:
- Distribute weight evenly across the entire limb
- Correct or accommodate deformity through opposing forces (Correct answer)
- Reduce friction between the orthosis and skin
- Increase proprioceptive feedback to the patient
Correct answer: Correct or accommodate deformity through opposing forces
A three-point pressure system applies a primary corrective force and two counter-forces to achieve controlled alignment.
Question 4: When adjusting a thermoplastic AFO for a patient with increased spasticity, the fitter should:
- Heat and reform the ankle section to increase dorsiflexion assistance (Correct answer)
- Add a toe extension spring to reduce toe drag
- Check that the trim lines are posterior to the malleoli to allow dorsiflexion
- Ensure the foot plate extends to the metatarsal heads only
Correct answer: Heat and reform the ankle section to increase dorsiflexion assistance
Reforming the thermoplastic at the ankle can adjust the angle of set to better manage plantar flexion tone in a spastic limb.
Question 5: A patient using a wrist-hand orthosis (WHO) complains of numbness in digits 4 and 5. The fitter should first check:
- Tightness of the proximal forearm strap
- Pressure over the hypothenar eminence and ulnar styloid (Correct answer)
- Alignment of the metacarpophalangeal joints
- Length of the finger trough component
Correct answer: Pressure over the hypothenar eminence and ulnar styloid
Ulnar nerve compression at the hypothenar eminence or ulnar styloid commonly produces numbness in the ring and little fingers.
Question 6: During dynamic AFO fitting, the fitter notices the patient's knee hyperextends at midstance. The appropriate adjustment is to:
- Set the AFO in slight plantar flexion
- Increase the stiffness of the posterior leaf spring
- Set the AFO in slight dorsiflexion (Correct answer)
- Extend the trim lines anteriorly
Correct answer: Set the AFO in slight dorsiflexion
Setting the AFO in slight dorsiflexion creates a knee flexion moment at midstance, counteracting genu recurvatum.
Question 7: Which padding material is most appropriate for relieving pressure over a bony prominence in a rigid orthosis?
- Closed-cell polyethylene foam
- Open-cell polyurethane foam
- Silicone gel pad (Correct answer)
- Wool felt
Correct answer: Silicone gel pad
Silicone gel pads distribute pressure evenly over bony prominences and resist bottoming out better than foam materials.
COF Fitting & Adjustment Techniques 2
When fitting a prefabricated AFO, which measurement is most critical to ensure proper fit at the ankle?