CPO CPO Biomechanics & Gait Analysis 1 — Questions and Answers
Question 1: During normal walking gait, which phase accounts for approximately 60% of the gait cycle?
- Swing phase
- Stance phase (Correct answer)
- Terminal swing
- Loading response
Correct answer: Stance phase
Stance phase comprises roughly 60% of the gait cycle while swing phase accounts for the remaining 40%.
Question 2: Which gait deviation is most commonly observed in a patient with a transtibial prosthesis that has excessive socket flexion?
- Lateral trunk bending
- Vaulting
- Knee instability at midstance (Correct answer)
- Early heel rise
Correct answer: Knee instability at midstance
Excessive socket flexion in a transtibial prosthesis shifts the ground reaction force posterior to the knee, causing instability at midstance.
Question 3: What is the term for the forward progression of the body over a stationary foot during midstance?
- Push-off
- Tibial advancement (Correct answer)
- Controlled plantarflexion
- First rocker
Correct answer: Tibial advancement
Tibial advancement describes the forward progression of the tibia over the stationary foot during the stance phase of gait.
Question 4: In amputee gait analysis, 'vaulting' on the sound limb is most often a compensatory mechanism for which prosthetic issue?
- Insufficient prosthetic foot dorsiflexion
- Excessive prosthetic foot dorsiflexion
- Prosthetic limb being too long (Correct answer)
- Weak hip abductors on residual limb side
Correct answer: Prosthetic limb being too long
Vaulting (rising on the toe of the sound limb) is a compensatory strategy when the prosthetic limb is functionally too long, allowing foot clearance during swing.
Question 5: The center of pressure (COP) path during stance phase normally progresses in which direction?
- Lateral to medial, then distal
- Posterior heel to metatarsal heads, medially to hallux (Correct answer)
- Evenly distributed across entire plantar surface
- Anterior to posterior
Correct answer: Posterior heel to metatarsal heads, medially to hallux
Normal COP progression moves from the posterior lateral heel forward along the lateral border to the metatarsal heads and then medially to the hallux.
Question 6: Which biomechanical principle explains why a longer prosthetic keel results in a smoother rollover during late stance?
- Increased inertia reduces angular acceleration
- Larger moment arm increases plantarflexion torque
- Extended lever arm smooths the transition through second and third rockers (Correct answer)
- Longer keel lowers the center of mass
Correct answer: Extended lever arm smooths the transition through second and third rockers
A longer forefoot lever arm extends the effective rocker radius, smoothing the rollover transition from the second to third rocker during late stance.
CPO CPO Biomechanics & Gait Analysis 1
During normal walking gait, which phase accounts for approximately 60% of the gait cycle?