Elsevier

Gait & Posture

Volume 26, Issue 4, October 2007, Pages 560-571
Gait & Posture

A new anatomically based protocol for gait analysis in children

https://doi.org/10.1016/j.gaitpost.2006.12.018Get rights and content

Abstract

Human movement analysis still suffers from the weakness of the currently used protocols for data collection and reduction. Reliable data comparisons and precise functional assessment require anatomically based definitions of the reference axes and frames, and therefore careful identification and tracking of the landmarks. When impaired children are analysed, the marker-set and other measurement procedures have to be minimised to reduce the time of the experiment and ensure patient collaboration. A new protocol is proposed for the analysis of pelvis and lower limb motion obtained as a compromise between these two requirements.

A marker-set is proposed which involves the attachment of 22 skin markers, the calibration by a pointer of 6 anatomical landmarks, and the identification of the hip joint centre by a prediction approach. Anatomical reference frames and joint rotations are defined according to current recommendations. The protocol was assessed by analysing a single child in several repetitions by different examiners, and a population of 10 healthy children, mean age 9.7-years-old. The entire analysis was repeated after subtraction of the offset by static posture angles. The minimum and maximum means of the standard deviations from five examiners of the same child were respectively 2.1° in pelvic obliquity and 6.8° in knee rotation. The minimum and maximum means of the standard deviations from the 10 healthy children were 2.1° in pelvic obliquity and 9.6° in knee internal–external rotation. The protocol is feasible and allows 3D anatomical-based measurements of segment and joint motion and data sharing according to current standards.

Introduction

Following the extraordinary progress that has been made since the developments introduced by the pioneers [1], gait analysis has become a fundamental examination in current clinical practice. The clinical usefulness of gait analysis has been established [2], [3], particularly in children with cerebral palsy [4], [5], [6], [7].

Reliable intra- and inter-subject comparison of gait patterns and the need to report kinematic variables in clinical terminology require anatomically based definitions of the reference axes and frames. Detailed functional assessment also requires precise identification of deformities of the musculoskeletal system (femur neck anteversion/antetorsion, tibial torsion, foot equinus, etc.). This knowledge is achieved only with a careful identification and tracking of anatomical landmarks, which requires prolonged data collection. The alternative would involve anatomical data based on magnetic resonance imaging of the specific subject [8]. These are rarely available.

On the other hand, procedural distress should be minimized. Children cannot always stand still for a long time, walk wearing a large number of markers, and perform additional motion trials. The marker-set and possible associated anatomical landmark calibration or anthropometric measurement procedures, therefore, must be minimised to contain the time taken for subject preparation and data collection. Finally, positioning the reflective markers should be limited to a few easily accessible locations, particularly in severe musculo-skeletal deformities.

Currently available protocols for motion data collection and reduction have been questioned for their inability to meet adequately these two contrasting requirements. The most commonly used protocol [9], [10], [11] involves the acquisition of a very small number of markers and no landmark calibration, but foot motion tracking is not fully 3D, and anatomical planes are defined visually by positioning marker-instrumented wands on the lateral aspect of the thighs and shanks. Wand alignment is also likely to enlarge skin motion artefact effects [12] and variability of the gait results [13]. Moreover, the reliability of some anthropometric measurements seems poor [14]. Another protocol [15] utilises fewer markers, but requires several anthropometric measurements and a special configuration for the cameras. In these two techniques, the complicated definitions render comparisons difficult. The ‘anatomical landmark calibration technique’ [16], [17], [18] enables accurate tracking of a large number of anatomical landmarks, but requires a time-consuming procedure for their identification, and three or more markers for each segment. It has been shown that landmark identification, marker placement, and data reduction affect considerably the calculation of kinematic and kinetic variables [13], [19], [20], [21], [22].

The purpose of the present work was to design and assess the viability of a novel protocol for the analysis of pelvis and lower limb kinematics able (a) to provide a complete description of 3D segment and joint motion on an anatomical basis, (b) to report these quantities in accordance with the recently proposed international recommendations, and (c) to limit the necessary procedures for data collection and reduction.

Section snippets

Definitions and analytical procedures

The following anatomical landmarks are tracked in space by applying a 10-mm-diameter spherical marker (see Fig. 1) to: the two most anterior and the two most posterior margins of the iliac spines (ASIS, PSIS), the most lateral prominence of the great trochanter (GT) and of the lateral epicondyle (LE), the proximal tip of the head of the fibula (HF), the most anterior border of the tibial tuberosity (TT), the lateral prominence of the lateral malleolus (LM), the aspect of the Achilles tendon

Results

  • (1)

    Intra-subject variability was very small. Time histories of the mean and standard deviation over the 10 trials of the joint rotations and moments are reported in Fig. 2, Fig. 3, respectively. Corresponding summarising values are reported in Table 2. In particular the average value of the standard deviation throughout the gait cycle (first column) represents variability for each single plot. The most repeatable rotation within the same child was knee Abd/Add (mean S.D. 1.5°) and the least was

Overview

Protocols for clinical gait analysis should pursue a thorough and reliable reconstruction of segment and joint kinematics based on subject-specific anatomical references on one hand, and rapid, simple, and practical procedures of data collection and reduction on the other hand, particularly when children are analysed. Anatomical reference frames should be defined using anatomical landmarks, and these should be chosen to be identified easily, preferably by external palpation, in a repeatable

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