CPT Anatomy, Biomechanics, & Gait Analysis 3 — Questions and Answers
Question 1: The sartorius muscle is unique because it crosses which two joints?
- Hip and ankle
- Knee and ankle
- Hip and knee (Correct answer)
- Sacroiliac and hip
Correct answer: Hip and knee
The sartorius is a biarticular muscle crossing both the hip and knee, functioning as a hip flexor/abductor and knee flexor.
Question 2: In gait analysis, 'cadence' is defined as:
- The distance covered in one complete gait cycle
- The number of steps taken per unit of time (Correct answer)
- The ratio of stance phase to swing phase
- The vertical displacement of the center of mass
Correct answer: The number of steps taken per unit of time
Cadence is the number of steps (or strides) per minute and is a key temporal parameter of gait.
Question 3: Which prosthetic foot feature is most beneficial for a transtibial amputee with a K3 activity level who frequently walks on uneven terrain?
- Single-axis foot with a rigid keel
- Solid ankle cushion heel (SACH) foot
- Multiaxial dynamic response foot (Correct answer)
- Carbon fiber energy-storing foot with rigid ankle
Correct answer: Multiaxial dynamic response foot
A multiaxial dynamic response foot allows motion in multiple planes, improving stability and adaptability on uneven surfaces for active users.
Question 4: The 'double support' phase of gait refers to the period when:
- Both lower extremities are in swing phase
- One foot is in contact with the ground
- Both feet are simultaneously in contact with the ground (Correct answer)
- The body's center of mass is at its highest point
Correct answer: Both feet are simultaneously in contact with the ground
Double support occurs twice per gait cycle (at initial contact and pre-swing) when both feet are simultaneously on the ground.
Question 5: Which bony landmark is most commonly used as the distal reference for measuring residual limb length in a transfemoral amputee?
- Medial femoral condyle (Correct answer)
- Greater trochanter
- Ischial tuberosity
- Lateral femoral epicondyle
Correct answer: Medial femoral condyle
The medial femoral condyle (or its equivalent in shorter residual limbs) serves as the standard distal reference point for transfemoral limb length measurement.
Question 6: During the swing phase of gait, the primary role of the hip flexors is to:
- Decelerate the limb before foot strike
- Advance the limb forward through hip flexion (Correct answer)
- Stabilize the pelvis against gravity
- Control knee extension at terminal swing
Correct answer: Advance the limb forward through hip flexion
Hip flexors (primarily iliopsoas) contract concentrically during initial swing to accelerate and advance the limb forward.
Question 7: Kyphosis of the thoracic spine can alter prosthetic gait by primarily causing:
- Increased lordosis and anterior pelvic tilt
- Forward shift of the center of mass, requiring compensatory anterior socket tilt (Correct answer)
- Lateral pelvic drop during stance
- Increased cadence and shortened stride length
Correct answer: Forward shift of the center of mass, requiring compensatory anterior socket tilt
Thoracic kyphosis shifts the center of mass anteriorly, which must be accommodated by prosthetic alignment and socket positioning.
CPT Anatomy, Biomechanics, & Gait Analysis 3
The sartorius muscle is unique because it crosses which two joints?