Elsevier

Gait & Posture

Volume 80, July 2020, Pages 391-396
Gait & Posture

A spatio-temporal and kinematic description of self-selected walking in adults with Achondroplasia

https://doi.org/10.1016/j.gaitpost.2020.06.030Get rights and content

Highlights

  • Gait is more flexed in adults with Achondroplasia than controls.

  • Time normalised spatial-temporal events are the same between groups.

  • Toe clearance occurs in Achondroplasia because of greater flexed position.

  • Vertical oscillations of the body’s mass centre are smaller in Achondroplasia.

Abstract

Background

Achondroplasia is characterised by a shorter appendicular limb to torso ratio, compared to age matched individuals of average stature (controls). Despite the well documented shorter leg length of individuals with compared to controls, there are few complete descriptions of gait kinematics reported for the population.

Aim

The aim of this study was to report the spatio-temporal and kinematic characteristics of self-selected walking (SSW) in a group with Achondroplasia (N = 10) and age matched group without Achondroplasia (controls, N = 17).

Method

Whole body 3D analysis of both groups was conducted using a 14 camera VICON system. Spatio-temporal and kinematic variables were determined through a Plug-in-Gait model. SSW was obtained from an average of three trials equating to a total of ∼120 m walking.

Results

The group with Achondroplasia were 23 % slower (P < 0.001), had a 29 % shorter stride length (P < 0.001) and a 13 % higher stride frequency (P < 0.001) compared to controls. There were no differences in time normalised temporal measures of left toe off (P = 0.365), right heel contact (P = 0.442) or the duration of double support (P = 0.588) between groups. A number of discrete joint kinematic differences existed between groups, resulting in the group with Achondroplasia having more ‘flexed’ lower limbs than controls throughout the gait cycle.

Conclusion

Differences in absolute spatio-temporal variables between groups is likely due to the shorter leg length of the group with Achondroplasia, while their more flexed position of the lower limbs may facilitate toe-clearance during the swing phase.

Introduction

Achondroplasia is the most prevalent type of skeletal dysplasia and is defined by shorter stature due to disproportionately smaller limb to torso length, compared to age matched able-bodied individuals, hereafter referred to as ‘controls’ [[1], [2], [3]]. Despite these well documented differences, few investigations have commented on how the shorter lower limb lengths of individuals with Achondroplasia may alter their functional tasks, such as walking. It has recently been shown that the Gait Profile Score (GPS) of adults with Achondroplasia is higher than controls [4]. However, while GPS is useful in describing a global difference in gait between populations, it does not pertain to mechanisms that describe the overall difference in gait. While individuals with Achondroplasia appear to be unaffected by gait limiting pathologies, such as those that are explained by neurological impairment, muscle weakness, amputation or skeletal deformity [[5], [6], [7], [8], [9], [10]], their shorter legs and relatively longer foot (foot-to-leg length ratio) appear to lead to greater knee flexion and ankle dorsiflexion angles during the entire stride compared to controls [4,11]. To date there appear to be four data sets that describe gait and lower limb joint kinematics during self-selected walking (SSW) in groups with Achondroplasia, all of which show subtle differences in kinematic patterns compared to controls [4,[11], [12], [13]], with some suggesting these differences are required to avoid toe contact with the floor during swing [4,11]. None of these studies however, provide a full spatio-temporal or kinematic analysis of gait in any population with Achondroplasia, who have not undergone leg lengthening surgery, to help further explain the differences in kinematics compared to controls. The aim of this study was to therefore describe time normalised kinematic gait patterns of SSW in adults with Achondroplasia who had not undergone leg lengthening surgery and compare these measures to controls. It was hypothesised that there would be kinematic differences between groups for all lower limb joints, but due to the lack of data describing Achondroplasic gait, these hypotheses are two-tailed.

Section snippets

Participants

After written consent, 10 males with Achondroplasia (Achondroplasic group) and 17 able-bodied males (controls) volunteered to participate in the study (Table 1). All participants reported they were free from lower limb injury and the Achondroplasia group have not undergone leg lengthening surgery. Ethical approval was obtained from the local committee and each participant attended one testing session at a gait laboratory where anthropometric and kinematic assessments at SSW were conducted.

Kinematic measures

Anthropometric measures

There was no difference in age between groups (P = 0.487), but the Achondroplasic group were 23 % shorter in stature (P < 0.001), were 19 % lighter (P < 0.001) and had a 41 % shorter leg than controls (P < 0.001, Table 1).

Spatio-Temporal

The Achondroplasic group were 23 % slower (P < 0.001), had a 29 % shorter stride length (P < 0.001) and a 13 % higher stride frequency than controls (P < 0.001, Table 2). When presented as dimensionless values, the group with Achondroplasia had a longer stride than controls

Discussion

This study aimed to describe spatio-temporal and kinematic parameters of the lower limbs during SSW gait in a group of adults with Achondroplasia who had not undergone limb lengthening surgery. The main findings were that adults with Achondroplasia walk slower and have a greater stride frequency than controls and the same group are more ‘flexed’ at the pelvis, hip, knee and ankle throughout the stride cycle than controls.

The slower SSW of the Achondroplasic group compared to controls was

Conclusion

The current study aimed to present a comprehensive analysis of time normalised lower limb gait kinematics in a homogenous adult population with Achondroplasia who had not undergone limb lengthening surgery. We have demonstrated that this group walk slower and have a higher stride frequency and shorter stride length than controls. Numerous differences in discrete kinematics of the lower limbs exist between the groups, which combine to present a more flexed gait in the Achondroplasic group. The

Declaration of Competing Interest

The authors have no conflict of interest.

Acknowledgements

The authors would like to thank the Dwarf Sports Association (Dronfield, UK. Registered Charity number: 1041961) for their assistance in recruitment and Dream it Believe it Achieve it (Northwich, UK. Registered Charity Number: 1153116) for which D. Sims received initial postgraduate funding.

Cited by (3)

  • Lower limb biomechanics during gait in children with Achondroplasia

    2021, Journal of Biomechanics
    Citation Excerpt :

    In two recent studies on physically active and otherwise healthy adult male subjects with Achondroplasia, subjects were reported to have greater overall global involvement compared to controls and a more flexed position throughout gait for the lower limbs (Sims et al., 2019, Sims et al., 2020). Shorter legs and a longer relative foot length (foot-to-leg length ratio) were suggested as possible contributors to this flexed position (Sims et al., 2020). Based on the current literature it is difficult to understand fully how gait in children with Achondroplasia is altered compared to their typically developed (TD) peers.

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