DPM Orthotic Device Prescription 2 — Questions and Answers
Question 1: Which posting technique in a root neutral cast orthosis corrects for a forefoot varus deformity?
- Rearfoot varus post
- Forefoot valgus post
- Forefoot varus intrinsic post (Correct answer)
- Lateral heel skive
Correct answer: Forefoot varus intrinsic post
A forefoot varus intrinsic post is used to accommodate or correct a forefoot varus deformity by raising the medial forefoot.
Question 2: A patient presents with a cavus foot and lateral ankle instability. Which orthotic modification best addresses both issues?
- Medial heel skive with valgus forefoot post
- Lateral heel skive with lateral flange (Correct answer)
- Varus rearfoot post with metatarsal pad
- Deep heel cup with medial flange
Correct answer: Lateral heel skive with lateral flange
A lateral heel skive shifts the subtalar joint axis medially, reducing supination, while a lateral flange provides lateral ankle support.
Question 3: What is the primary purpose of a metatarsal bar placed proximal to the metatarsal heads on an orthotic device?
- Increase ground reaction force at the MTP joints
- Offload pressure from the metatarsal heads (Correct answer)
- Correct hallux abducto valgus deformity
- Stabilize the midtarsal joint
Correct answer: Offload pressure from the metatarsal heads
A metatarsal bar redistributes plantar pressure proximally, relieving pressure at the metatarsal heads.
Question 4: In Root biomechanical theory, which condition is described as the subtalar joint being inverted from its neutral position when the forefoot is perpendicular to the bisection of the calcaneus?
- Forefoot valgus
- Rearfoot varus
- Forefoot varus (Correct answer)
- Tibial varum
Correct answer: Forefoot varus
Forefoot varus is defined as an inverted forefoot relative to the rearfoot when the subtalar joint is in neutral position.
Question 5: A dancer with a flexible flatfoot needs an orthosis that allows toe-off freedom. Which shell material is most appropriate?
- 3mm Polypropylene
- Rohadur acrylic
- 3mm Subortholen (Correct answer)
- Carbon fiber
Correct answer: 3mm Subortholen
Subortholen (polypropylene variant) in thinner gauges provides adequate control while remaining flexible enough for dynamic dance movements.
Question 6: Which clinical finding most strongly indicates the need for a first ray cutout modification on a functional foot orthosis?
- Hallux limitus with a plantarflexed first ray (Correct answer)
- Tibialis anterior tendinopathy
- Tailor's bunion deformity
- Peroneal muscle weakness
Correct answer: Hallux limitus with a plantarflexed first ray
A plantarflexed first ray with hallux limitus requires a first ray cutout to allow the first ray to plantarflex and improve hallux dorsiflexion during propulsion.
Question 7: When fabricating an orthosis for a diabetic patient with loss of protective sensation, which top cover material is preferred?
- Leather
- Korex foam
- Plastazote (polyethylene foam) (Correct answer)
- Vinyl
Correct answer: Plastazote (polyethylene foam)
Plastazote is a closed-cell polyethylene foam that heat-molds to foot contours, provides excellent cushioning, and minimizes shear stress for insensate feet.
DPM Orthotic Device Prescription 2
Which posting technique in a root neutral cast orthosis corrects for a forefoot varus deformity?