Biomechanical Analysis and Gait Mechanics

Biomechanical analysis studies the forces and motions of the body during posture and movement, and gait mechanics applies this to walking. In prosthetics and orthotics it provides the framework for understanding how a device alters joint motion, muscle demand and the forces passing through the limb across the gait cycle, and it supplies the measurement tools, such as motion capture and force plates, used to evaluate device performance.

Definition

Biomechanical analysis and gait mechanics is the study of the kinematics (motion) and kinetics (forces) of human movement, especially walking, including the phases of the gait cycle and the methods used to measure them, applied to understanding how prosthetic and orthotic devices interact with the body.

Scope

This topic introduces the gait cycle, the kinematic and kinetic quantities used to describe it, and the instrumentation of gait and biomechanical analysis as they relate to prosthetic and orthotic devices. It is a reference treatment of concepts and methods, not a clinical protocol for assessing or treating an individual.

Core questions

• What are the phases of the gait cycle and the events that define them?
• What kinematic and kinetic quantities describe walking?
• How do prosthetic and orthotic devices alter gait mechanics?
• What instruments are used to measure gait and biomechanical variables?

Key concepts

• Gait cycle (stance and swing phases)
• Kinematics (joint angles, motion)
• Kinetics (joint moments, ground reaction force)
• Spatiotemporal parameters (cadence, step length, speed)
• Energy storage and return
• Motion capture and force plates
• Energy cost of walking

Mechanisms

Walking is described as a repeating gait cycle divided into stance and swing phases, with events such as initial contact and toe-off marking transitions. Kinematics records how joints move; kinetics records the forces and moments behind that motion, including the ground reaction force measured by force plates. Instrumented motion capture, force plates and sometimes electromyography together quantify these variables. When a limb segment or joint is replaced or supported by a device, the mechanics change: the device sets how load is transmitted and how energy is absorbed or returned, so analysis compares device-influenced gait against normal patterns to characterize performance and compensations.

Clinical relevance

Biomechanical and gait analysis underpins how prosthetic and orthotic devices are evaluated and compared in research and practice, and it provides the vocabulary for describing how a device affects walking. The entry is descriptive reference material about concepts and measurement methods; it does not constitute a diagnostic or treatment procedure for an individual.

Evidence & guidelines

Evidence combines biomechanical primary studies of kinematics, kinetics and interface loading with systematic reviews that attempt to relate device features to function. A systematic review by van der Linde and colleagues (2004) found that heterogeneity in study methods makes firm component-level conclusions difficult, underscoring the importance of standardized gait-analysis methods.

History

Quantitative study of human locomotion grew from nineteenth-century chronophotography and early force measurement into instrumented gait laboratories. Jacquelin Perry's work synthesized clinical gait analysis into a widely used framework, and the spread of optical motion capture, force plates and computational modelling from the late twentieth century onward made detailed biomechanical evaluation of prosthetic and orthotic gait routine in research settings.

Seminal works

• perry-1992
• van-der-linde-2004

Frequently asked questions

What is the gait cycle?

The gait cycle is one full sequence of walking events for a single limb, conventionally divided into a stance phase (when the foot is on the ground) and a swing phase (when it is not), bounded by events such as initial contact and toe-off.

How is gait measured in the laboratory?

Gait is commonly measured with optical motion-capture cameras that track markers to record kinematics, force plates that record the ground reaction force for kinetics, and sometimes electromyography to record muscle activity.