COF Orthotic Fitting Principles 2 — Questions and Answers
Question 1: When evaluating a patient for a custom foot orthosis, which measurement is most critical for determining the correct shell length?
- Arch height at full weight-bearing
- Heel-to-toe length and metatarsal head position (Correct answer)
- Ankle circumference at the malleoli
- Navicular drop measurement in sitting
Correct answer: Heel-to-toe length and metatarsal head position
Shell length is determined by heel-to-toe length and the position of the metatarsal heads to ensure the orthosis provides support without causing forefoot pressure.
Question 2: A patient with pes planus presents with medial knee pain. Which orthotic intervention addresses the kinetic chain relationship?
- Lateral wedge with rearfoot post
- Medial wedge with rearfoot post (Correct answer)
- Metatarsal pad without posting
- Heel cup without intrinsic correction
Correct answer: Medial wedge with rearfoot post
A medial wedge with rearfoot post corrects excessive pronation that causes internal tibial rotation, which contributes to medial knee stress.
Question 3: Which casting position is recommended when fabricating a custom foot orthosis intended to capture subtalar neutral?
- Full weight-bearing on a foam impression box
- Non-weight-bearing with subtalar joint in neutral and midtarsal joint locked (Correct answer)
- Semi-weight-bearing on a pressure mat
- Weight-bearing on a plaster slab
Correct answer: Non-weight-bearing with subtalar joint in neutral and midtarsal joint locked
Non-weight-bearing casting with the subtalar joint in neutral and midtarsal joint pronated captures the true neutral alignment without soft tissue distortion.
Question 4: An orthosis prescribed as 'UCBL' (University of California Biomechanics Lab) is specifically designed to control which condition?
- Plantar fasciitis with heel pain
- Severe pes planus with hindfoot valgus (Correct answer)
- Metatarsalgia with forefoot pain
- Morton's neuroma with interdigital pain
Correct answer: Severe pes planus with hindfoot valgus
The UCBL orthosis features deep heel cups and medial/lateral flanges to aggressively control severe hindfoot valgus and flexible flatfoot.
Question 5: When fitting a prefabricated wrist-hand orthosis, which wrist position is considered the 'functional position' for most resting splints?
- Full wrist extension at 45 degrees
- Neutral at 0 degrees
- Wrist extended 20-30 degrees with fingers in slight flexion (Correct answer)
- Wrist flexed 10 degrees with fingers extended
Correct answer: Wrist extended 20-30 degrees with fingers in slight flexion
The functional position of 20-30 degrees wrist extension with slight finger flexion maintains optimal tendon length and allows for basic prehension.
Question 6: During follow-up, a patient reports that their AFO causes a red mark over the fibular head. What is the most likely cause?
- The trim line is too far anterior
- Excessive proximal brim height compressing the peroneal nerve region (Correct answer)
- The footplate is too long
- The ankle joint is set in too much plantarflexion
Correct answer: Excessive proximal brim height compressing the peroneal nerve region
Pressure over the fibular head indicates the proximal brim or the lateral wall of the AFO is impinging on the peroneal nerve, requiring relief grinding or adjustment.
Question 7: Which posting method adds material beneath the orthotic shell to tilt the entire foot in the frontal plane?
- Intrinsic posting
- Extrinsic posting (Correct answer)
- Topcover modification
- Metatarsal bar addition
Correct answer: Extrinsic posting
Extrinsic posting adds wedge material under the shell's rearfoot or forefoot to tilt the foot without changing the shell shape itself.
COF Orthotic Fitting Principles 2
When evaluating a patient for a custom foot orthosis, which measurement is most critical for determining the correct shell length?