Biomechanics and Foot Kinesiology

Comprehensive vocabulary flashcards covering basic biomechanical laws, gait cycle mechanics, joint anatomy, and clinical foot assessment measures.

Kinesiology

The study of human movement, encompassing anatomical and mechanical components.

Mechanics

The study of motion and the effect of forces on an object.

Law of inertia

Newton’s 1st law stating that an object will remain at rest or in a constant motion unless compelled to change state by an external force.

Newton's Second Law

$$F = m \times a$$

Biomechanics

The study of biological systems by the application of the laws of physics.

Static

The system that is not moving or moving at a constant velocity with no acceleration.

Equilibrium

A state where forces are cancelling each other out.

Dynamic

Evaluation of movement when there is a change in velocity, involving an increase or decrease of acceleration.

Kinematics

The study of the characteristics of motion, including ROM, spatial, and temporal/time factors, without reference to forces.

Kinetics

The study of forces acting on a system that define the force(s) causing movement at a joint or lower leg segment.

Sagittal plane

An imaginary 2D surface where movement occurs about a medial and lateral axis.

Frontal/Coronal plane

An imaginary 2D surface where movement occurs about an anterior posterior axis.

Transverse plane

An imaginary 2D surface where movement occurs about a vertical axis.

Talocrural joint

The ankle joint featuring articulation between the talus, tibia, and fibula.

Mortise joint

A term for the distal tibia and fibula structure vital for joint stability.

Heel rocker

Gait phase beginning at heel strike where dorsiflexors contract eccentrically to lower the foot.

Ankle rocker

Gait phase beginning when the foot is flat on the ground as the tibia and fibula rotate over the foot.

Forefoot rocker

Gait phase beginning at heel lift where plantarflexion occurs ($14^{\circ}$) and power is generated for swing phase.

Subtalar Joint (STJ)

The joint formed by the talus and calcaneus bones.

Windlass mechanism

A mechanism where tension on the plantar fascia raises the MLA by approximately $6\,mm$ between midstance and latestance.

Osseous Locking mechanism

The process to fully pronate the MTJ where external rotation of the leg and STJ supination causes the cuboid’s superior border to lock with the calcaneus.

1ST MTPJ

Articulations between the head of the 1st metatarsal and 1st proximal phalanx requiring $> 65^{\circ}$ of active dorsiflexion.

Functional hallux limitus

A condition where the 1st ray has limited plantarflexion, which in turn limits hallux dorsiflexion.

Stress

Normalised force or pressure applied to a tissue.

Strain

Normalised deformation, expressed as a percentage change from original tissue dimensions.

Compressive stress

A stress applied perpendicular to the tissue surface.

Shear stress

A stress applied parallel to the tissue surface.

Foot Posture Index (FPI)

A 6-item checklist used to determine if a standing foot is pronated, supinated, or neutral, with scores ranging from $-12$ to $+12$.

Navicular height

The distance between the navicular tuberosity and the ground measured in a relaxed resting calcaneal position.

Navicular drop

A measure of foot pronation determined by the difference in navicular height between STJ neutral and a relaxed position.

Navicular drift

The displacement of the navicular bone within the transverse plane.

Supination resistance

A manual test used to determine the amount of force required to re-supinate the sub-talar joint in a weight-bearing foot.

Tailor’s Bunion

Also known as a Bunionette, it is the enlargement of the lateral aspect of the 5th metatarsal head.