PC PC Biomechanics & Orthotics 2 — Questions and Answers
Question 1: Which condition is characterized by limited ankle dorsiflexion and is a major biomechanical contributor to plantar fasciitis and forefoot overload?
- Equinus deformity (Correct answer)
- Hallux rigidus
- Tibialis posterior dysfunction
- Pes cavus
Correct answer: Equinus deformity
Equinus deformity (limited ankle dorsiflexion <10°) forces the foot to compensate through excessive pronation or early heel rise, overloading the plantar fascia and forefoot.
Question 2: In gait analysis, what does the term 'toe-out angle' (foot progression angle) describe?
- The angle between the long axis of the foot and the direction of travel (Correct answer)
- The degree of hallux valgus deformity
- The angle of calcaneal eversion during stance
- The degree of forefoot supination relative to the rearfoot
Correct answer: The angle between the long axis of the foot and the direction of travel
The foot progression angle (toe-out angle) measures how much the foot is rotated outward relative to the line of walking, which reflects rotational alignment of the entire lower limb.
Question 3: What is the role of the windlass mechanism in foot biomechanics?
- Dorsiflexion of the hallux tightens the plantar fascia, raising the medial arch and supinating the foot for propulsion (Correct answer)
- Plantarflexion of the hallux increases medial arch height at heel strike
- The peroneal tendons wind around the fibula to stabilize the ankle
- Contraction of the intrinsic foot muscles elevates the lateral arch during midstance
Correct answer: Dorsiflexion of the hallux tightens the plantar fascia, raising the medial arch and supinating the foot for propulsion
The windlass mechanism occurs when hallux dorsiflexion during propulsion tightens the plantar fascia around the metatarsal head, raising the arch and supinating the subtalar joint for a rigid lever.
Question 4: A patient is diagnosed with tibialis posterior tendon dysfunction (PTTD). Which deformity pattern is most associated with this condition?
- Flatfoot (pes planovalgus) with heel valgus and forefoot abduction (Correct answer)
- Cavus foot with heel varus and clawing of toes
- Equinus with metatarsus adductus
- Hallux valgus with sesamoid displacement
Correct answer: Flatfoot (pes planovalgus) with heel valgus and forefoot abduction
Progressive PTTD leads to loss of medial arch support, causing a flexible flatfoot with heel valgus and forefoot abduction (the 'too many toes' sign).
Question 5: Which orthotic posting is used to correct a forefoot varus deformity?
- Medial forefoot post (raises the medial side of the forefoot) (Correct answer)
- Lateral forefoot post (raises the lateral side of the forefoot)
- Rearfoot lateral wedge
- Heel elevation
Correct answer: Medial forefoot post (raises the medial side of the forefoot)
Forefoot varus (medial forefoot inverted relative to rearfoot in STJ neutral) is corrected with a medial forefoot post that fills the gap under the medial column.
Question 6: What gait abnormality is commonly observed in a patient with a drop foot due to peroneal nerve palsy?
- Steppage gait (exaggerated hip flexion to clear the foot during swing) (Correct answer)
- Trendelenburg gait (pelvic drop on the stance side)
- Antalgic gait (shortened stance phase on the affected side)
- Scissor gait (knees crossing midline)
Correct answer: Steppage gait (exaggerated hip flexion to clear the foot during swing)
Drop foot results in inability to dorsiflex the ankle, requiring exaggerated hip and knee flexion (steppage gait) during swing phase to prevent the toes from dragging on the ground.
PC PC Biomechanics & Orthotics 2
Which condition is characterized by limited ankle dorsiflexion and is a major biomechanical contributor to plantar fasciitis and forefoot overload?