PC PC Biomechanics & Orthotics 1 — Questions and Answers
Question 1: During normal gait, which phase involves the foot being flat on the ground with the body's center of mass directly over the foot?
- Midstance (Correct answer)
- Loading response
- Terminal swing
- Pre-swing
Correct answer: Midstance
Midstance is the phase of the gait cycle when the entire foot is in contact with the ground and the body's center of mass passes over the supporting limb.
Question 2: What is the primary function of a custom foot orthosis prescribed for overpronation?
- Control excessive subtalar joint eversion and medial arch collapse (Correct answer)
- Increase ankle dorsiflexion range of motion
- Reduce forefoot pressure by redistributing it to the heel
- Correct digital deformities such as hammertoe
Correct answer: Control excessive subtalar joint eversion and medial arch collapse
Custom orthotics for overpronation are designed to limit excessive eversion of the subtalar joint and support the medial longitudinal arch, improving lower extremity alignment.
Question 3: The subtalar joint (STJ) neutral position is used as a reference point in orthotic casting. What does STJ neutral mean?
- The position where the STJ is neither pronated nor supinated, with the calcaneus aligned under the leg (Correct answer)
- The position of maximum dorsiflexion of the ankle
- The angle of the forefoot relative to the rearfoot at rest
- The position of the metatarsals when weight-bearing
Correct answer: The position where the STJ is neither pronated nor supinated, with the calcaneus aligned under the leg
STJ neutral is the theoretical position where the subtalar joint is in neither pronation nor supination, used as the reference for neutral casting of functional foot orthotics.
Question 4: Which type of orthotic material is most appropriate for a patient with diabetic neuropathy requiring pressure reduction?
- Accommodative orthotic with soft, cushioning materials (e.g., PPT, Plastazote) (Correct answer)
- Rigid polypropylene functional orthotic
- Semi-rigid carbon fiber plate
- Hard acrylic shell orthotic
Correct answer: Accommodative orthotic with soft, cushioning materials (e.g., PPT, Plastazote)
Accommodative orthotics made from soft materials redistribute plantar pressure and reduce shear forces, critical for preventing ulceration in patients with diabetic neuropathy.
Question 5: What is the term for the abnormal inward rolling of the foot during the stance phase of gait?
- Overpronation (Correct answer)
- Oversupination
- Equinus
- Adduction
Correct answer: Overpronation
Overpronation refers to excessive inward rolling (eversion) of the foot during stance, often associated with medial arch collapse and various lower extremity overuse injuries.
Question 6: A patient presents with metatarsalgia (pain under the ball of the foot). Which orthotic modification best offloads the affected metatarsal heads?
- Metatarsal pad placed proximal to the metatarsal heads (Correct answer)
- Heel cup elevation
- Morton's extension plate
- Toe crest support
Correct answer: Metatarsal pad placed proximal to the metatarsal heads
A metatarsal pad positioned just proximal to the metatarsal heads redistributes pressure away from the painful metatarsal heads, providing symptomatic relief.
PC PC Biomechanics & Orthotics 1
During normal gait, which phase involves the foot being flat on the ground with the body's center of mass directly over the foot?