Foot Function Is Well Preserved in Children and Adolescents with Juvenile Idiopathic Arthritis Who Are Optimally Managed

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Gait & Posture 38 (2013) 30–36

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Gait & Posture

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Foot function is well preserved in children and adolescents with juvenile

idiopathic arthritis who are optimally managed

a,c, a a b a

Gordon J. Hendry *, Danny Rafferty , Ruth Barn , Janet Gardner-Medwin , Debbie E. Turner , a

James Woodburn

Institute for Applied Health Research, Glasgow Caledonian University, Glasgow, UK

Department of Child Health, University of Glasgow, UK

School of Science and Health, University of Western Sydney, Sydney, NSW, Australia

A R T I C L E I N F O A B S T R A C T

Article history: Purpose: The objective of this study was to compare disease activity, impairments, disability, foot

Received 4 May 2012

function and gait characteristics between a well described cohort of juvenile idiopathic arthritis (JIA)

Received in revised form 7 October 2012

patients and normal healthy controls using a 7-segment foot model and three-dimensional gait analysis.

Accepted 11 October 2012

Methods: Fourteen patients with JIA (mean (standard deviation) age of 12.4 years (3.2)) and a history of

foot disease and 10 healthy children (mean (standard deviation) age of 12.5 years (3.4)) underwent

Keywords:

three-dimensional gait analysis and plantar pressure analysis to measure biomechanical foot function.

Juvenile idiopathic arthritis

Localised disease impact and foot-speciﬁc disease activity were determined using the juvenile arthritis

Multi-segment foot model

foot disability index, rear- and forefoot deformity scores, and clinical and musculoskeletal ultrasound

Kinematics

Kinetics examinations respectively. Mean differences between groups with associated 95% conﬁdence intervals

were calculated using the t distribution.

Plantar pressure distribution

Foot function Results: Mild-to-moderate foot impairments and disability but low levels of disease activity were

detected in the JIA group. In comparison with healthy subjects, minor trends towards increased midfoot

dorsiﬂexion and reduced lateral forefoot abduction within a 3–58 range were observed in patients with

JIA. The magnitude and timing of remaining kinematic, kinetic and plantar pressure distribution

variables during the stance phase were similar for both groups.

Conclusion: In children and adolescents with JIA, foot function as determined by a multi-segment foot

model did not differ from that of normal age- and gender-matched subjects despite moderate foot

impairments and disability scores. These ﬁndings may indicate that tight control of active foot disease

may prevent joint destruction and associated structural and functional impairments.

1. Introduction periarticular ankle region [6]. Unsurprisingly disruption to global

gait patterns has been frequently reported as an early and common

Juvenile idiopathic arthritis (JIA) is a chronic and progressive consequence of JIA [7,8].

inﬂammatory arthritis of childhood which often results in The impact of JIA on global function has been studied extensively

persistent and disabling foot impairments [1–3]. The primary with the use of patient reported outcome measures (PROMs) such as

disease process – synovitis, has a predilection for the lower limb the childhood health assessment questionnaire (CHAQ), a widely

joints and results in well-recognised clinical features including used 30 item measure of childhood disability [9,10]. Studies

joint pain, swelling, limited joint range-of-motion and develop- employing PROMs have demonstrated strong associations between

ment of deformity [3–5]. Inﬂammatory pathology is not limited to clinical symptoms such as pain or radiographically detected joint

joints and studies employing musculoskeletal ultrasonography destruction, with poor long-term functional outcomes [11]. At a local

have also detected tenosynovitis, enthesitis, and bursitis in the level, the impact of active disease and related impairments remain

unclear. The development of juvenile arthritis foot disability index

questionnaire (JAFI) [12], a 27 item measure organised by three

* Corresponding author at: School of Science and Health, University of Western dimensions related to impairment, activity limitation, and partici-

Sydney, Sydney, NSW, Australia. Tel.: +61 2 4620 3185; fax: +61 2 4620 3792.

pation restriction, has allowed researchers to quantify levels of

E-mail addresses: [email protected] (G.J. Hendry),

disease-related foot impairments and disability [1,2]. However

[email protected] (D. Rafferty), [email protected] (R. Barn),

questions remain regarding its sensitivity and speciﬁcity particularly

[email protected] (J. Gardner-Medwin),

[email protected] (D.E. Turner), [email protected] (J. Woodburn). during early stages of disease [2].

G.J. Hendry et al. / Gait & Posture 38 (2013) 30–36 31

Recent studies of foot function have improved our understand- trained paediatric musculoskeletal ultra-sonographer [DET] inde-

ing of foot impairments in adults with rheumatoid arthritis (RA) pendently assessed localised disease activity in the foot. Those

[13,14]. In particular, studies employing three-dimensional (3D) joints from the clinical examination were assessed for effusion,

multi-segmented foot models have demonstrated an ability to synovial hypertrophy (SH), and power Doppler signal (PDS).

quantify subtle but functionally important changes to foot Tendons were assessed for grey-scale features of ﬂuid within the

segment kinematics and kinetics at an early disease stage [15]. tendon sheath and PDS; the TA and PF for abnormal thickening, and

In contrast, little is known about the functional consequences of RCB for bursal effusion (bursitis). Standardised deﬁnitions for

active foot disease and/or residual impairments such as foot ultrasound (US) -derived pathology (deﬁned by the outcome

deformity in patients with JIA. measures in rheumatology 7 consensus statement) [22] were

Patients with JIA who have lower limb involvement tend to employed throughout. US imaging was conducted using an Esaote

walk slower, as a result of a reduced step length, reduced cadence Mylab 25 Gold (Genova, Italy) with LA435 (10–18 MHz) probe

and an increased period of double limb support [2,16]. Reduced (footprint size 40 mm Â 10 mm). US features were recorded as

peak pressures have been recorded in those with forefoot pain, present/absent.

metatarso-phalangeal (MTP) joint and lesser toe deformity [17].

While elevated focal pressures in the forefoot have previously been 2.3. Biomechanical foot function

associated with pes cavus foot types [8]. Abnormal ankle-joint-

complex motion has been described where the foot has been An 8 camera 120 Hz motion analysis system (Qualysis Oqus,

modelled as a single segment [7,16]. However this approach Gothenburg, Sweden) was used to track the motion of 25 surface-

provides limited information concerning other foot joint function mounted, spherical, and retro-reﬂective markers (5 mm and

compared to the multi-segment approach [18]. Accordingly, the 10 mm diameter) placed on the shank and foot which were

aim of this study was to compare disease activity, impairments, positioned in order to represent the underlying skeletal structure.

disability, foot function and gait characteristics between a well This model was adapted from the original model proposed by

described cohort of JIA patients and normal healthy controls using Hyslop et al. [23] previously to measure foot function in adults

a 7-segment foot model and 3D gait analysis. with psoriatic arthritis (See supplementary online material for full

model description), and was selected for use on the basis that JIA is

2. Methods an inﬂammatory arthropathy with similar disease features.

Visual3D software (C-motion, Inc., Rockville, MD, USA) was used

2.1. Patient selection to build segmented foot models which comprised the shank, a

single foot segment, rearfoot, midfoot, lateral forefoot, 1st

Fourteen patients with a deﬁnitive diagnosis of JIA, based on the metatarsal and hallux, based on the surface marker coordinates.

International League of Associations for Rheumatology (ILAR) Ground reaction forces (120 Hz) and plantar pressure distributions

criteria [19] were consecutively recruited from a phase II were measured separately using force (Kistler, Winterthur,

randomised controlled trial of a multi-disciplinary foot-care Switzerland) and pressure (Emed-X, Novel GmbH, Munich,

programme [20]. Participants had a documented history of active Germany) platforms. An instrumented walkway (GaitRite, CIR

inﬂammatory foot disease affecting the joints and/or soft tissues. systems, Clifton, NJ, USA) was used to measure spatial and

Ten community dwelling healthy children and adolescents temporal gait parameters.

matched as closely as possible by age and gender, with no history A pre-determined core set of foot biomechanical variables were

of trauma, neuromuscular or musculoskeletal diseases were selected a priori for analysis based on previous survey and gait

recruited for comparison. This study was approved by the Glasgow analysis data in RA, psoriatic arthritis and JIA [2,13–15,23]. These

West Local Research Ethics Committee on the 18th March 2008 included walking velocity, cadence, step length, double support

(reference number 08/S0709/36). All participants and parents/ time and cycle time as objective measures of global function.

guardians provided their informed consent to participate in this Intersegment kinematics, kinetics and plantar pressure distribu-

study. tion parameters were selected to best capture the functional

changes associated with joint and soft-tissue damage in JIA. Initial

2.2. Demographic, disease and clinical examination foot contact angle, rearfoot terminal stance range-of-motion in the

sagittal plane, peak vertical ground reaction forces, ankle joint

Age, gender, body mass index, disease subtype, disease moment and ankle joint power were selected to describe the three

duration, and current pharmacological therapy were recorded rocker functions of the foot [13,24]. Peak rearfoot eversion, peak

for each patient. Functional health status was recorded using the lateral forefoot abduction, peak 1st metatarsal dorsiﬂexion, peak

CHAQ [10]. Local disease impact was measured using the JAFI [12]. hallux dorsiﬂexion, minimum navicular height, midfoot and lesser

Localised disease activity was estimated by a podiatrist [GH] who toe contact areas, and peak pressures in the rear- and forefoot were

recorded tender and swollen joint scores in the foot for the ankle, selected to describe localised functional impairments, compensa-

subtalar, calcaneocuboid, talonavicular, MTP, interphalangeal joint tions and deformities [13,14]. The average velocity and duration of

of the hallux and proximal interphalangeal joints of the lesser toes the centre-of-pressure (CoP) throughout the foot, heel, midfoot,

(range 0–14). Tender and swollen soft tissue sites in the foot were forefoot and toe regions was recorded to quantify compensatory

also recorded for the tibialis posterior, ﬂexor digitorum longus, foot-loading strategies associated with degraded and adapted

ﬂexor hallucis longus, peroneus longus and peroneus brevis (antalgic) gait [25]. Peak midfoot dorsiﬂexion was selected for

tendons, the retro-calcaneal bursa (RCB), and the calcaneal exploratory analysis as both high- and low-arched midfoot posture

tendo-achilles (TA) and calcaneal plantar fascia entheses (PF) is a frequent clinical ﬁnding in JIA.

(range 0–8). Fore- and rearfoot deformities were measured using A relaxed standing (static) trial was collected for the foot from

the structural index (SI) [21]. The SI summates hallux valgus, 5th each participant in order to deﬁne 08 (neutral) for the kinematic

MTP exostosis, lesser toe deformities and MTP subluxation for the data [26]. Kinematic and kinetic and parameters were collected

forefoot (range 0–12) and calcaneal valgus/varus, ankle range of from 5 barefoot walking trials in each patient. Spatial and temporal

motion and pes planus/cavus deformities of the rearfoot (range 0– parameters were recorded from 5 barefoot self-selected walking

7). The weight-bearing varus/valgus alignment of the heel was speed trials over the walkway. Plantar pressure distribution

measured using a standard hand-held goniometer [15]. A fully parameters were collected separately from 5 barefoot trials using

32 G.J. Hendry et al. / Gait & Posture 38 (2013) 30–36

a two-step protocol [27]. Kinematic, kinetic and plantar pressure where appropriate to dimensionless quantities using the formulae

measurements were estimated from 5 trials of the right limb for all described by Hof [28].

participants. Automated software routines (Novel GmbH, Munich,

Germany) were used to deﬁne the rearfoot, midfoot, forefoot, 3. Results

lesser toe and hallux regions of the foot for plantar pressure

distribution. 3.1. Demographic and clinical characteristics

2.4. Statistical analysis Demographic, disease and clinical characteristics are sum-

marised in Tables 1 and 2. Fourteen JIA patients (10 female, 4

Statistical analyses were performed using SPSS 18.0 (SPSS Inc. male) with a mean age of 12.4 years (SD 3.2) were studied. This

Chicago, IL, USA). Clinical and biomechanical variables were was a heterogeneous sample including patients with variable JIA

summarised as mean and standard deviation (SD) or median disease subtype, disease duration and medication. All patients

(range). The small sample size did not permit formal inferential were in receipt of disease-modifying anti-rheumatic drugs

hypothesis testing, therefore mean differences between groups (DMARDs) and/or biologic therapies. Ten control subjects (6

and associated 95% conﬁdence intervals (CI) were calculated using female, 4 male) with a mean age of 12.5 years (SD 3.4) were

the t distribution [15]. Mean motion patterns of intersegment studied for comparison. Control subjects were closely matched to

kinematics were normalised to 101 time points (0–100% stance) JIA case subjects by age and BMI, but had a greater proportion of

and both groups’ ensemble averages (Æ1SD) were superimposed M:F than the JIA subjects. Functional impairment scores (CHAQ)

and displayed graphically. Discrete gait variables were normalised were typically in the mild-to-moderate category (>0.13 to <0.63)

Table 1

Demographic and disease characteristics.

Patient Age (years) Gender BMI JIA Disease DMARD CHAQ (0–3) JAFIIMP (0–4) JAFIAL (0–4) JAFIPR (0–4) (kg/m2) subtype duration

(years)

1 13 F 20.4 Other 3 MTX, TNFa 1.75 2 3 1

2 7 F 15.9 Ext oligo 6 MTX, TNFa 0.125 0 1 0

3 18 M 19.7 Poly+ 5 Abatacept 1.125 3 2 3

4 11 F 15.0 Poly+ 2 MTX, TNFa 0.25 1 0 0

5 13 M 22.2 jPsA 2 MTX, ICI 0 1 0.5 1.5

6 11 F 18.9 PolyÀ 6 MTX, TNFa 1 1 2 2.5

7 14 M 28.4 ERA 5 TNFa 0.625 2 2 2

8 9 F 23.5 Oligo 8 Adalimumab 0.625 1 1 1.5

9 16 F 22.2 PolyÀ 3 MTX, TNFa 0.25 1 1 1.5

10 10 F 14.5 jPsA 5 Adalimumab 0.5 2 2 2.5

11 17 F 20.0 PolyÀ 13 Adalimumab 0 1 1 1

12 9 F 15.0 Oligo 7 MTX, ICI 0.125 2 1 1.5

13 14 F 24.9 jPsA 7 MTX 0.375 0 0 0

14 12 M 16.5 PolyÀ 2 MTX, TNFa 1.25 2 1 2

Summary values 12.4 (3.2) 10:4 19.8 (4.0) – 5.3 (3.0) – 0.4375 (0–1.75) 1 (0–3) 1 (0–3) 1.5 (0–3)

Reference values 12.5 (3.4) 6:4 19.8 (3.6) – – – 0 (0) 0 (0–1) 0 0

BMI: body mass index; DMARD: disease modifying anti-rheumatic drug; CHAQ: childhood health assessment questionnaire; JAFI: juvenile arthritis foot disability index; imp:

impairment; al: activity limitation; pr: participation restriction; Ext oligo: extended oligoarthritis; Poly+: rheumatoid factor positive polyarthritis; PolyÀ: rheumatoid factor

negative polyarthritis; jPsA: juvenile psoriatic arthritis; ERA: juvenile enthesitis related arthritis; Oligo: oligoarthritis, MTX: methotrexate; TNAa: anti-tumour necrosis

factor alpha; ICI: intra-articular corticosteroid injection.

Table 2

Disease and clinical characteristics.

Patient TJC (0–14) SJC (0–14) TSTC (0–8) SSTC (0–8) USEFF (0–14) USSYN (0–14) SI FF (0–12) SI RF (0–7) RSFP (8)

1 1 3 0 1 5 0 0 4 À10

2 0 0 0 0 0 0 0 2 À2

3 4 0 0 0 7 0 5 5 À25

4 0 0 0 0 3 0 3 4 À10

5 0 0 5 5 0 0 0 5 À8

6 0 0 0 0 2 2 2 2 À10

7 1 1 3 2 2 0 0 3 À3

8 0 0 1 3 0 0 1 3 À5

9 0 0 0 0 0 0 2 2 À3

10 0 0 0 0 0 0 0 4 À15

11 0 2 0 7 6 2 2 2 À5

12 3 3 3 3 3 2 0 5 À11

13 5 2 2 0 4 2 2 2 À4

14 2 2 0 0 0 1 0 4 À7

Summary values 0 (0–5) 0 (0–3) 0 (0–5) 0 (0–7) 3 (0–7) 0 (0–2) 0.5 (0–5) 3.5 (2–5) À7.0 (7.8)

Reference values 0 0 0 0 0 0 0 0.5 À3.2 (3.2)

TJC: tender joint counts; SJC: swollen joint counts; TSTC: tender soft tissue counts; SSTC: swollen soft tissue counts; USEFF: ultrasound effusion; USSYN: ultrasound synovitis; SI

FF: forefoot structural inxex; SI RF: rearfoot structural index; RSFP: relaxed standing foot posture (negative value: valgus, positive value: varus).

Mean (standard deviation), all other summary and reference values = median (range).

G.J. Hendry et al. / Gait & Posture 38 (2013) 30–36 33 AB C 20 15 120

5 10 80

-5 0 40 RF Df (+)/Pf(-)° RF inv(+)/eve(-)°

-15 -10 Nav Height (mm) 0

0255075100 0255075 100 0255075100 D EF

15 15 0 5 5 -10

-5 -5 -20

-15 1st Met Df (+) / Pf (-)° -30 -15

Midfoot Df (+)/Pf (-)°

0255075 100 0255075100 Lat FF Add(+) / Abd(-)° 0255075100 G H I

80 3.5 0.2 2.5 60 -0.2 1.5 40 -0.6 0.5 -1.0 20 -0.5 -1.4

Hall Df (+) / Pf (-)° 0 -1.5 -1.8

Ankle Moment (Nm/Kg) 0255075100 Ankle Joint Power (W/Kg) 0255075100 0255075100

% of stance phase

Fig. 1. Selected kinematic- and kinetic-time curves over 100% of the stance phase of gait (x-axis) for patients with JIA (black line with error bars represents mean Æ 1 standard

deviation) versus controls (grey shaded area represents mean Æ 1 standard deviation). (A) Rearfoot frontal plane motion; (B) rearfoot sagittal plane motion; (C) navicular height; (D)

midfoot sagittal plane motion; (E) 1st metatarsal sagittal plane motion; (F) lateral forefoot transverse plane motion; (G) hallux sagittal plane motion; (H) ankle joint power and (I)

ankle joint moment.

for JIA patients, although these ranged from no impairment to were the same in both groups. The JIA group showed trends

moderate impairment. towards slight increases in midfoot dorsiﬂexion (95% CI of mean

JAFI scores for localised foot impairments and disability were in differences did not cross zero), reductions in lateral forefoot

the mild-to moderate category (1 to 2) but were variable abduction and decreases in peak hallux dorsiﬂexion (95% CIs of

between JIA subjects. Median (range) scores for each domain were mean differences crossed zero). However these differences on

1 (0–3) (impairment and activity limitation) and 1.5 (0–3) average were small and in the 3–58 range.

(participation restriction). There were low levels of clinically The distribution of plantar pressure was not different between

detected disease activity in the joints and soft tissues as indicated the two groups in terms of midfoot and lesser toe contact areas

by tender and swollen joint and soft tissue counts. Foot joint (Table 3). Pressure in the rearfoot, 1st metatarsal and lateral

effusions detected using US were a typical ﬁnding in patients with forefoot regions were on average 35 kPa and 43 kPa lower

JIA, suggesting that subclinical disease was present in several respectively, and 1 kPa respectively higher in the children with

patients. Mild forefoot and moderate rearfoot deformities were JIA. However 95% CIs of mean differences included zero suggesting

recorded in patients with JIA, who typically exhibited a marginally a minor trend only. The JIA children walked with a reduced step

more valgus foot posture than controls. length, reduced walking velocity, and increased cadence, in

comparison with control subjects although double-support time

3.2. Gait analysis was unaffected (Table 3). The average velocity of the COP through

the foot regions was similar for both groups (Table 4). The duration

Ensemble average kinematic-time and kinetic-time variables of the COP was slightly increased in the midfoot and slightly

are summarised in Fig. 1 and core biomechanical variables in Table decreased in the forefoot regions in the JIA patients in comparison

3. The magnitude and timing of the kinematic and kinetic variables with control subjects.

during the stance phase of gait were similar for both groups. The

average patterns for the JIA patients did not deviate outside normal 4. Discussion

limits (Fig. 1). Trends were observed for reduced peak ankle joint

plantarﬂexor moment, joint power, and the peak vertical ground This is the ﬁrst study to report selected 3D kinematics and

reaction force at initial contact and terminal stance in the children kinetics, spatio-temporal parameters, and plantar pressure distri-

with JIA, however 95% CIs of the mean differences for each variable bution in a group of JIA children and adolescents in receipt of

crossed zero (Table 3). No difference could be detected for in the optimised medical management. Results indicate only small

initial and terminal stance contact angles for the foot relative to changes in foot function consistent with degraded and adapted

the ground. Medial longitudinal arch posture, as indicated by the gait. These ﬁndings are in contrast to past studies which have

navicular height, was not different between the two groups. The shown marked changes in foot function [3,4,7,8,16]. In an era of

rearfoot ROM and peak eversion and 1st metatarsal dorsiﬂexion optimal medical management exploiting DMARD and biological

34 G.J. Hendry et al. / Gait & Posture 38 (2013) 30–36

Table 3

Gait analysis variables with group mean differences and associated 95% conﬁdence intervals.

Core biomechanical variables JIA Controls Mean difference (95% CI)

Kinematic/kinetic variables

Peak ankle joint moment (Nm/kg) À1.37 (0.15) À1.45 (0.22) À0.09 (À0.24, 0.07)

Norm peak ankle joint moment À0.005 (0.002) À0.006 (0.002) 0.0004 (À0.001, 0.002)

Peak ankle joint power (W/kg) 1.89 (0.83) 2.17 (0.89) 0.28 (À0.45, 1.01)

Norm ankle joint power 0.005 (0.003) 0.004 (0.002) À0.0003 (À0.003, 0.002)

Peak force initial contact (BW) 1.06 (0.07) 1.08 (0.13) 0.02 (À0.64, 0.10)

Norm force initial contact 0.003 (0.001) 0.003 (0.001) 0.0004 (À0.001, 0.001)

Peak force terminal stance (BW) 1.08 (0.07) 1.11 (0.09) 0.04 (À0.03, 0.10)

Norm force terminal stance 0.003 (0.001) 0.003 (0.001) À0.0002 (À0.001, 0.001)

Initial contact angle (8) 16.9 (3.4) 17.4 (3.0) 0.5 (À2.3, 3.3)

Terminal stance angle (8) À51.5 (7.4) À52.4 (10.6) À0.8 (À8.4, 6.8)

Minimum navicular height (mm) 34 (11) 35 (8) 2 (À7, 10)

Peak rearfoot eversion (8) À8.0 (5.7) À7.0 (5.6) 1.0 (À3.9, 5.9)

Rearfoot terminal stance ROM (8) 12.1 (4.4) 12.7 (6.2) 0.6 (À3.9, 5.0)

Peak midfoot dorsiﬂexion (8) 7.3 (3.5) 4.3 (2.7) À3.0 (À5.8, À0.3)

Peak 1st met dorsiﬂexion (8) À12.6 (7.8) À11.7 (4.2) 0.9 (À4.7, 6.6)

Peak lateral forefoot abduction (8) À5.5 (5.2) À9.1 (4.1) À3.6 (À7.7, 0.5)

Peak hallux dorsiﬂexion (8) 58.0 (13.7) 62.3 (12.2) 4.3 (À6.9, 15.6)

Pressure variables

Midfoot contact area (cm ) 19.0 (12.3) 19.0 (4.5) À0.0 (À8.5, 8.4)

Lesser toes contact area (cm ) 7.6 (2.3) 7.5 (3.3) À0.2 (À2.5, 2.2)

Rearfoot peak pressure (kPa) 320 (90) 355 (113) 35 (À51, 121)

1st metatarsal peak pressure (kPa) 281 (103) 325 (179) 43.3 (À76, 163)

Lateral forefoot peak pressure (kPa) 248 (180) 247 (62) À1.1 (À125, 122)

Spatiotemporal parameters

Step length (cm) 59.9 (6.5) 63.4 (9.9) 3.5 (À3.5, 10.4)

Norm step length (cm) 0.7 (0.1) 0.8 (0.1) 0.0 (À0.1, 0.1)

Double support time (%GC) 19.8 (4.3) 19.0 (3.3) À0.7 (À4.1, 2.6)

Cycle time (s) 1.1 (0.2) 1.1 (0.1) À0.0 (À0.1, 0.1)

Walking velocity (cm/s) 108.0 (17.2) 115.8 (20.7) 7.8 (À8.3, 23.9)

Norm walking velocity 38.5 (7.3) 40.6 (6.3) 2.1 (À3.8, 8.0)

Cadence (steps/min) 128.2 (45.8) 118.6 (11.1) À9.7 (À40.5, 21.2)

Norm cadence 36.6 (11.8) 34.3 (3.4) 3.9 (À10.2, 5.8)

CI: conﬁdence interval; BW: body weight; ROM: range of motion; GC: gait cycle; Norm: dimensionless normalisation [28].

therapies [29], the ﬁndings may indicate that suppression and tight Despite this detailed analysis of foot function revealed only

control of active foot disease prevents or reduces the frequency and subtle changes some indicative of degraded and some of adapted

severity of joint destruction and the associated structural and gait. By contrast, studies reported in the pre-biological and tight

functional impairments. control era, often where disease factors and treatment regimes

The patients with JIA described in this study were heteroge- are not reported, demonstrate marked degenerative and adapted

neous for age, disease subtype and disease duration. With gait disturbances [7,8,16,17,30]. These include changes to overall

established disease the majority were treated with a biological gait pattern characterised by reduced walking velocity and

agent and/or methotrexate. This optimised medical approach shortened step and stride length [16] altered load and pressure

appears to have lessened the overall foot disease burden as distribution characteristic of both high-arch and ﬂat-foot posture

indicated by low levels of self/parent-reported pain, functional [8]; disturbance of the normal sagittal rocker function [17,30];

loss and disability. Ultrasound examination indicated on-going and muscle imbalance and reduced muscle strength [7,30]. In

active disease in approximately one-third of children. However, terms of joint kinematics, reduced ankle plantarﬂexion in

it is acknowledged that signiﬁcant discrepancies still exist terminal stance has been demonstrated where the foot was

between clinical and US examinations of foot disease in JIA [6]. modelled as a single segment [16]. In many of these studies there

is little or no information provided on disease subtype, disease

activity, active joint disease, morbid foot state, or medical and

Table 4

non-pharmacological interventions making direct comparisons

Regionalised centre-of-pressure analysis with group mean differences and

difﬁcult. However, Dekker et al. [1] demonstrated strong

associated 95% conﬁdence intervals.

relationships between disease activity and foot-related impair-

Variable Region JIA Controls Mean difference

ments and disability using the JAFI questionnaire. The JAFI

(n = 14) (n = 10) (95% CI)

scoring system may be vulnerable to a moderate ﬂoor effect,

VCoP (m/s) Foot 0.28 (0.03) 0.31 (0.05) 0.03 ( 0.01, 0.06)

ave À resulting in insensitivity for detecting impairments [2]. Never-

Heel 0.26 (0.08) 0.30 (0.09) 0.04 (À0.04, 0.11)

theless in the present study active disease was low and this was

Midfoot 0.42 (0.13) 0.48 (0.08) 0.06 (À0.03, 0.15)

associated with low levels of self-reported foot impairment and

Forefoot 0.22 (0.04) 0.22 (0.05) 0.00 (À0.04, 0.04)

Toes 0.67 (0.25) 0.69 (0.24) 0.02 (À0.19, 0.23) functional disability measured using the JAFI. This study adds

additional evidence suggesting the articular function in the foot

DCoP Heel 24.9 (6.1) 24.8 (6.2) À0.2 (À5.5, 5.1)

can be well preserved when disease activity is suppressed using

(% stance) Midfoot 21.5 (6.9) 19.2 (4.1) À2.3 (À7.4, 2.7)

Forefoot 46.2 (9.3) 48.5 (5.3) 2.4 (À4.4, 9.2) optimised medical care.

Toes 7.3 (3.2) 7.5 (2.3) 0.12 (À2.3, 2.7) In other inﬂammatory joint diseases, in particular rheumatoid

arthritis, marked changes in foot function has been demonstrated

VCoPave (m/s): average velocity of the centre of pressure; DCoP (% stance): duration

of the centre of pressure; CI: conﬁdence interval. in a number of studies in both early and established disease

G.J. Hendry et al. / Gait & Posture 38 (2013) 30–36 35

[13–15]. The failure to detect important functional changes in the Acknowledgements

JIA group in comparison can be explained by the cumulative

effects of destructive joint disease in the RA patients who, in most We would like to thank all the patients, who participated in this

studies, have longer disease duration and sub-optimal drug study. Special thanks are also extended to Dr Ben Stansﬁeld for

management. However, even in JIA patients the lag time in which providing valuable advice on normalisation procedures.

to gain optimised case with disease remission or low disease state

can take time and in that time joint and soft-tissue damage can Appendix A. Supplementary data

occur. Subtle changes were observed in the present study

including reduced walking speed and some changes to mid-foot Supplementary data associated with this article can be found,

arch posture. At the individual patient level some children did in the online version, at http://dx.doi.org/10.1016/j.gaitpost.

have marked impairments and this would indicate that on-going 2012.10.009.

studies, in particular inception cohort designs from onset of

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Support

Protocol for the foot in juvenile idiopathic arthritis trial (FiJIA): a randomised

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