Biomechanics & Gait Analysis Flashcards

When prescribing a KAFO for a patient with quadriceps weakness, the primary biomechanical goal is to:

Answer: Maintain knee extension moment throughout stance phase

A KAFO for quadriceps weakness aims to provide a knee extension moment during stance, preventing the knee from buckling under body weight.

The 'rocker bottom' sole modification on a shoe or AFO primarily functions to:

Answer: Facilitate forward progression of the center of mass without requiring ankle motion

A rocker bottom allows the center of mass to advance forward during terminal stance by substituting for ankle plantarflexion/push-off when ankle motion is limited.

During observational gait analysis, a patient demonstrates a lateral trunk lean toward the stance limb. This is most commonly associated with:

Answer: Ipsilateral hip abductor weakness

Lateral trunk lean (Trendelenburg gait) occurs ipsilaterally to compensate for weakness of the hip abductors on the same side as the stance limb.

The 'ankle rockers' (heel rocker, ankle rocker, forefoot rocker) described by Perry describe energy-efficient mechanisms during which phase of gait?

Answer: Stance phase only

Perry's three ankle rockers (heel, ankle, and forefoot) all occur during the stance phase of gait to facilitate smooth forward progression of the body's center of mass.

A patient with a complete L3 spinal cord injury would most likely require which type of orthosis for community ambulation?

Answer: Knee-ankle-foot orthosis (KAFO)

An L3 complete injury preserves hip flexion and some knee extension but results in absent ankle control and absent knee stability, necessitating KAFO support for functional ambulation.

In biomechanical analysis, 'kinetics' refers to the study of:

Answer: Forces and moments that cause or result from movement

Kinetics is the branch of biomechanics concerned with the forces, moments, and powers that cause or result from movement, as distinguished from kinematics which describes motion.

Which gait deviation is most commonly associated with a rigid plantarflexion contracture (equinus deformity) during the loading response?

Answer: Absence of heel contact (forefoot or toe strike pattern)

A rigid equinus contracture prevents heel rocker function, causing the patient to contact the ground with the forefoot or toes instead of the heel at initial contact.