CTO Device Fitting & Adjustment 4 — Questions and Answers
Question 1: A patient returns with a custom foot orthosis (CFO) complaining that it slides forward in the shoe. The MOST effective solution is:
- Add a top cover layer to the orthosis
- Check shoe fit and recommend a shoe with a firm heel counter (Correct answer)
- Reduce the length of the orthosis
- Prescribe a softer durometer EVA base
Correct answer: Check shoe fit and recommend a shoe with a firm heel counter
A firm heel counter in the shoe holds the heel in place, preventing the orthosis and foot from sliding forward during gait.
Question 2: When adjusting plantarflexion resistance in a posterior leaf spring (PLS) AFO, trimming the lateral borders of the plastic will:
- Increase plantarflexion resistance
- Decrease plantarflexion resistance (increase flexibility) (Correct answer)
- Have no effect on resistance
- Only affect mediolateral stability
Correct answer: Decrease plantarflexion resistance (increase flexibility)
Trimming the lateral borders of a PLS AFO narrows the cross-section of plastic, reducing stiffness and decreasing plantarflexion resistance.
Question 3: Which measurement is essential before selecting an off-the-shelf lumbosacral orthosis (LSO) to ensure proper fit?
- Iliac crest height
- Waist circumference at the umbilicus (Correct answer)
- Thigh circumference
- Thoracic kyphosis angle
Correct answer: Waist circumference at the umbilicus
Waist circumference at the umbilicus is the primary sizing measurement for most off-the-shelf LSOs as it determines the panel and strap length needed.
Question 4: A patient with a tibial fracture brace (PTB orthosis) reports pain at the patellar tendon bar after one week of use. The technician should first:
- Remove the patellar tendon bar entirely
- Assess the bar position and lower it if it is too proximal (Correct answer)
- Replace the entire orthosis
- Add extra padding to the bar
Correct answer: Assess the bar position and lower it if it is too proximal
Pain at the patellar tendon bar often results from the bar being positioned too proximally, compressing the patella rather than the tendon; lowering it corrects this.
Question 5: For a diabetic patient requiring an AFO, which liner material provides the BEST combination of pressure relief and moisture management?
- Neoprene
- Silicone rubber
- Plastazote (polyethylene foam) (Correct answer)
- Leather
Correct answer: Plastazote (polyethylene foam)
Plastazote is heat-moldable, pressure-distributing, and lightweight, making it the preferred liner for insensate diabetic feet at risk for skin breakdown.
Question 6: When checking the rotational alignment of a KAFO, the technician should ensure the knee joint axis is:
- Parallel to the long axis of the tibia
- Aligned with the anatomical knee flexion axis in the frontal plane (Correct answer)
- Set at 5 degrees of external rotation
- Perpendicular to the coronal plane of the thigh
Correct answer: Aligned with the anatomical knee flexion axis in the frontal plane
The mechanical knee joint axis of the KAFO must align with the anatomical knee flexion axis to allow smooth, pain-free motion without tissue stress.
Question 7: A patient fitted with a cock-up splint for radial nerve palsy finds that the fingers tend to curl into flexion. The most appropriate modification is to:
- Add a dorsal finger extension assist attachment (Correct answer)
- Increase wrist extension angle to 45 degrees
- Reduce the forearm trough length
- Switch to a volar wrist orthosis
Correct answer: Add a dorsal finger extension assist attachment
A dorsal finger extension assist attachment (dynamic outrigger) supports the fingers in extension, addressing the metacarpophalangeal drop caused by radial nerve palsy.
CTO Device Fitting & Adjustment 4
A patient returns with a custom foot orthosis (CFO) complaining that it slides forward in the shoe.
The MOST effective solution is: