The evolution of clinical gait analysis

Abstract

Kinematics is treated as a single topic in this manuscript and the emphasis is on early history, just as it was in Part I, Electromyography. Needless to say, neither kinematics nor electromyography, nor kinetics and energy (the latter to be included in Part III) are stand-alone components of clinical gait analysis. The only reason for this selective format is that it lessens my task to be able to write about one subject at a time. One of the consequences of this arbitrary separation is that some contributors, who have enriched more than one portion of clinical gait analysis, are highlighted only in the area in which they have contributed the most. I began with Kinesiological Electromyography in Part I because the earliest stirrings of the dream of clinical gait analysis were expressed in the development of KEMG (kinesiological electromyography). The early investigators realized that very little could be said about the dynamic action of muscles without KEMG. Next, in chronological order, came kinematics. I have been an active participant and eyewitness, and take full responsibility for attempting to write an early history at a time when most of the contributors are still alive. Ordinarily, history is written much later, in order to fully grasp the significance of individual contributions in the tapestry of the whole. As stated in Part I, Electromyography, the emphasis has been placed on the early history. The application of motion analysis to sports medicine, and sports medicine functional analysis, is covered only lightly here, and this should not be interpreted as minimizing its importance. The literature on this subject is now quite voluminous and it would not be possible to cover it adequately in this manuscript. Later historical writings may differ significantly and will hopefully give more recognition to pioneers in later generations: those physicians, engineers, physical therapists and kinesiologists who are lifting the level of clinical gait analysis and directing their energies in expanding clinical directions. It is hoped that this manuscript will prompt additional manuscripts, as well as letters to the editor of Gait and Posture on the content of this review paper.

Introduction

Accurate measurement of motion is central in any scientific method of gait analysis. Measurements of individual joint angular rotations, as well as translations of segments and of whole body mass, allow the comparisons with normal that are necessary to distinguish pathological from normal gait. Complex hardware and software are necessary to accomplish this task with accuracy and reliability. This component of clinical gait analysis has proven to be very challenging and the evolutionary process continues to this day.

The individual joint angles and the displacements of segments and of the whole body mass were recognized to be essential measurement requirements in the late 1800s by Braun and Fischer [1], [2], [3], [4], [5]. Their clever approach to kinematic analysis was to apply Geissler tubes to the limb segments, interrupt the illumination at regular intervals by a large tuning fork, and photograph the subject walking in total darkness with four cameras while the lenses were open. One camera was positioned in front of the subject, one behind, and one on each side, making their measurements tri-dimensional. The subjects were protected from electrical shock by wearing rubber suits resembling wet suits. The process of collecting data required 8 or 10 hours per subject and then it involved months of work to reduce the data and calculate kinematic measurements. This was a fantastic scientific achievement, however, because it was so time consuming, Braun and Fischer's method could only be applied in gait research.

One of the methods used by Eberhardt and Inman [6] in the 1940s also included the use of interrupted light. A photograph was obtained with the subject walking in front of the open lens of a camera while carrying small light bulbs located at the hip, knee, ankle and foot. A slotted disk was rotated in front of the camera, producing a series of white dots at equal time intervals. These dots could be laboriously connected to provide joint angles that could be manually measured. Again, this was a slow and labor-intensive process, not suitable for clinical application. In order to examine transverse plane rotations, Vern Inman, MD, PhD, drilled pins into the pelvis, femur, and tibia, and recorded pin rotation with the aid of a movie camera located above the subject [7]. One of his subjects, David Chadwick, MD, then a student at the University of California, Berkeley, later became the Medical Director of Children's Hospital of San Diego. He described his experience as ‘very painful’, something he would not have agreed to had he understood ‘what it would be like’. Needless to say, this technique gained very few followers, although there has been some recent use of pins inserted into bones in normal subjects for a different purpose, i.e. to determine the difference between movement of markers taped to the skin surface and those placed into the skeleton.