A quantitative description of self-selected walking in adults with Achondroplasia using the gait profile score

Abstract

Background: Achondroplasia is characterised by a shorter appendicular limb-to-torso ratio, compared to age matched individuals of average stature (controls). Previous work shows gait kinematics of individuals with Achondroplasia differing to controls, but no global quantification of gait has been made in adults with Achondroplasia. Aim: The aim of this study was to quantify gait differences between a group of adult males with Achondroplasia and controls during self-selected walking (SSW) using the Gait Profile Score (GPS). Design: Whole body motion analysis of 10 adults with Achondroplasia (22 ± 3 yrs) who had not undergone leg lengthening and 17 adult controls (22 ± 2 yrs) was undertaken using a 14 camera VICON system (100 Hz). For each group, fifteen root mean squared Gait Variable Scores (GVS, units°) were computed from lower limb kinematic data and then summed to calculate GPS (°). Results: The group with Achondroplasia had higher GVSs than controls in 10 of the 15 measures (P < 0.05) with the largest differences found in ankle plantar/dorsiflexion (P < 0.001), knee flexion/extension (P < 0.001), and hip internal/external rotation (P < 0.001). The GPS value of the group with Achondroplasia was 64% higher than controls (11.4°(2.0) v 4.1°(1.8), P < 0.001). Conclusion: Gait is quantitatively different in adults with Achondroplasia compared to controls. The differences in GPS between groups are due to differences in joint kinematics, which are possibly manifested by maintaining toe-clearance during swing. Gait models derived from the anatomy of individuals with Achondroplasia may improve these data.

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

“…1 and 2). These data not only confirm the previous sagittal descriptions of groups with Achondroplasia [4,[11][12][13], but also helps explain the larger GPS reported in this population [4]. It has previously been suggested that the gait of individuals with Achondroplasia is more flexed to accommodate toeclearance during swing phase [11].…”

“…The slower SSW of the Achondroplasic group compared to controls was unsurprising given gait speed is determined by stride length, which is in turn determined somewhat by leg length which is short in the Achondroplasic group [4,16]. Despite the difference in SSW speed between groups, no time normalised temporal differences existed, which is consistent with other spatio-temporal observations of gait in shorter versus taller comparisons [18].…”

“…Whilst there are subtle differences in sagittal kinematic patterns between the presented and other cohorts with Achondroplasia [4,[11][12][13], there are more substantial differences in the frontal plane kinematics of the knee between the available data sets. In the present study, the Achondroplasic group's knee is in a neutral position during stance phase (Fig.…”

“…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.…”