DPM Biomechanics & Gait Analysis 2 — Questions and Answers
Question 1: During the loading response phase of gait, which muscle group acts eccentrically to control the rate of foot plantarflexion?
- Gastrocnemius-soleus complex
- Tibialis anterior (Correct answer)
- Peroneus longus
- Extensor digitorum longus
Correct answer: Tibialis anterior
The tibialis anterior contracts eccentrically during loading response to lower the foot to the ground in a controlled manner.
Question 2: The 'double support' phase of the gait cycle refers to:
- Both feet simultaneously in swing phase
- Both feet simultaneously in contact with the ground (Correct answer)
- Single-limb stance at maximal loading
- The period of terminal swing
Correct answer: Both feet simultaneously in contact with the ground
Double support occurs twice per gait cycle when both feet are simultaneously on the ground, comprising approximately 20% of the cycle in normal walking.
Question 3: Which kinematic variable most reliably differentiates normal walking from antalgic gait?
- Increased cadence on the affected side
- Shortened stance phase on the painful limb (Correct answer)
- Increased swing phase on the uninvolved limb
- Decreased step width bilaterally
Correct answer: Shortened stance phase on the painful limb
In antalgic gait, the stance phase on the painful limb is shortened as the patient unloads it quickly to minimize pain.
Question 4: Root's criteria for a 'normal' subtalar joint neutral position includes the forefoot being:
- Inverted 5° relative to the rearfoot
- Perpendicular to the bisection of the posterior calcaneus (Correct answer)
- Everted 2° relative to the rearfoot
- Plantarflexed relative to the rearfoot
Correct answer: Perpendicular to the bisection of the posterior calcaneus
Root defined the ideal forefoot position as perpendicular (90°) to the bisection of the posterior calcaneus when the subtalar joint is in neutral.
Question 5: Which segment of the foot is considered the primary shock absorber during initial contact?
- First metatarsal head
- Calcaneal fat pad (Correct answer)
- Midtarsal joint
- Navicular tuberosity
Correct answer: Calcaneal fat pad
The calcaneal fat pad is highly specialized adipose tissue that absorbs and dissipates impact forces at initial contact.
Question 6: In a patient with a rigid forefoot valgus deformity, which compensatory motion is most commonly observed at the subtalar joint?
- Excessive supination
- Excessive pronation (Correct answer)
- No compensatory motion
- Adduction of the forefoot
Correct answer: Excessive pronation
A rigid forefoot valgus forces the subtalar joint into compensatory pronation to allow the medial forefoot to contact the ground.
Question 7: The 'windlass mechanism' is most effectively engaged when:
- The ankle is maximally dorsiflexed with toes plantarflexed
- The toes are dorsiflexed during propulsion (Correct answer)
- The subtalar joint is maximally pronated
- The midtarsal joint is fully mobile
Correct answer: The toes are dorsiflexed during propulsion
Dorsiflexion of the toes during propulsion winds the plantar fascia around the metatarsal heads, raising the medial arch and supinating the foot.
DPM Biomechanics & Gait Analysis 2
During the loading response phase of gait, which muscle group acts eccentrically to control the rate of foot plantarflexion?