Excellent balance skills despite active and inactive juvenile idiopathic arthritis - unexpected results of a cross-sectional study.

OBJECTIVES: Postural control (PC) is fundamental for human movements. Different factors, such as injuries or diseases, can adversely affect PC. The purpose of this study was to evaluate PC in juvenile idiopathic arthritis (JIA) patients with different disease activity levels in comparison to healthy peers. METHODS: JIA patients with active and inactive lower limb joints (n=36 each group) were examined. Both groups have been on medication and have had physiotherapy for at least 5 years. For comparison, an age- and gender-matched healthy control group (CG; n=36) participated. PC was measured bipedal on a balance-board (S3-Check, TST, Großhoeflein), with an instable tilting between left and right. The parameters of interest were the best results of Stability Index (STI), Sensorimotor Index (SMI) and Symmetry Index (SYI) out of 4 test trials as well as JIA disease-related variables. Data were analysed with descriptive statistics, comparison of averages, linear regression and correlations (p<0.05). RESULTS: The three groups showed no differences in anthropometric characteristics and SYI (p>0.05). In both JIA groups, STI and SMI were lower than indices of CG (p<0.05), indicating better stability and motor control. Balance indices did not differ between active and inactive JIA patients (p>0.05). CONCLUSIONS: JIA patients showed better PC than CG. Possible explanations are an increased body-awareness due to long-term physiotherapy and daily coordination training due to compensatory movements. The positive results highlight the success of individual, interdisciplinary treatment in JIA and can be used to promote recommendations for safe sport participation.

Combined three-dimensional gait and plantar pressure analyses detecting significant functional deficits in children with juvenile idiopathic arthritis.

BACKGROUND: Children suffering from juvenile idiopathic arthritis (JIA), a heterogeneous group of chronic inflammatory joint diseases, adapt to individual gait patterns to avoid loading of inflamed, swollen and painful joints. As the interpretability of previous studies is limited, this study aims to assess the functional capacity, loads and plantar pressure distribution in the gait of a homogeneous JIA group. RESEARCH QUESTION: Does a symmetrical lower limb joint involvement influence the gait dynamics in JIA patients, and how are the results of three-dimensional gait analysis (3DGA) and pedobarography related? METHODS: Fifty JIA patients with symmetrical hip, knee and ankle joint arthritis and 27 healthy controls performed 3DGA and pedobarography at self-selected walking speeds. Kinematics and kinetics of lower limb joints were retrospectively compared in range of motion and in time-normalized waveforms. Plantar load was evaluated by measuring peak pressure, pressure-time integral and maximum force of the whole foot and ten selected foot regions. 1D-SPM analysis, parametric and non-parametric statistical significance tests and correlation coefficients were used for statistical analysis. RESULTS: JIA patients had a significantly slower walking speed with an anteriorly tilted pelvis and a reduced extension motion of all joints of the lower limb. The horizontal ground reaction forces and generated hip and ankle power during propulsion phase were small. Patients experienced reduced loading at toe regions, which correlated with limited ankle plantarflexion motion in the push-off phase. The total peak pressure was significantly increased and loads at lateral midfoot and metatarsal regions were higher in patients. SIGNIFICANCE: Symmetrical lower limb arthritis is linked to crouch-like gait and restricted gait dynamics with increased total peak pressure. The results confirm earlier results of 3DGA and provide new insights regarding waveform analysis and plantar loading in JIA patients. The used methods help to design individualized functional treatment of JIA patients.

Accuracy and precision of loadsol® insole force-sensors for the quantification of ground reaction force-based biomechanical running parameters.

Force plates represent the "gold standard" in measuring running kinetics to predict performance or to identify the sources of running-related injuries. As these measurements are generally limited to laboratory analyses, wireless high-quality sensors for measuring in the field are needed. This work analysed the accuracy and precision of a new wireless insole forcesensor for quantifying running-related kinetic parameters. Vertical ground reaction force (GRF) was simultaneously measured with pit-mounted force plates (1 kHz) and loadsol® sensors (100 Hz) under unshod forefoot and rearfoot running-step conditions. GRF data collections were repeated four times, each separated by 30 min treadmill running, to test influence of extended use. A repeated-measures ANOVA was used to identify differences between measurement devices. Additionally, mean bias and Bland-Altman limits of agreement (LoA) were calculated. We found a significant difference (p < .05) in ground contact time, peak force, and force rate, while there was no difference in parameters impulse, time to peak, and negative force rate. There was no influence of time point of measurement. The mean bias of ground contact time, impulse, peak force, and time to peak ranged between 0.6% and 3.4%, demonstrating high accuracy of loadsol® devices for these parameters. For these same parameters, the LoA analysis showed that 95% of all measurement differences between insole and force plate measurements were less than 12%, demonstrating high precision of the sensors. However, highly dynamic behaviour of GRF, such as force rate, is not yet sufficiently resolved by the insole devices, which is likely explained by the low sampling rate.

Biomechanics of walking in adolescents with progressive pseudorheumatoid arthropathy of childhood leads to physical activity recommendations as therapeutic focus.

BACKGROUND: Progressive pseudorheumatoid arthropathy of childhood is a rare disease with an estimated prevalence of approximately 1/1,000,000. The disease manifests around the age of three to eight years and progresses with symptoms of early fatigue, muscle weakness, joint swelling and stiffness. The resulting functional limitations are often described as having a waddling gait. Walking is difficult and can be managed with multilevel compensation movements only. Aims of this study were to determine typical malpositions that arise during walking and to identify preventive strategies to reduce excessive joint damage. METHODS: This study presents data of three-dimensional gait analysis of nine patients with progressive pseudorheumatoid arthropathy of childhood (♀=2; ♂=7; 13.3y; 47.0kg; 1.39m; BMI: 24.2kg/m(2)) performed with eight infrared cameras and the Plug-in-Gait Model. For comparison of spatiotemporal and kinematic parameters with age-matched healthy controls (♀=6; ♂=3; 13.4y; 49.0kg; 1.61m; BMI: 18.9kg/m(2)), the Mann-Whitney U-test was applied with a significance level of P<0.05. FINDINGS: The patients had a significantly lower height, but higher BMI. Walking speed was reduced with wide, but short steps and significant motion anomalies in the pelvis, hips, knees and ankles. Small ranges of motion in propulsion-supporting movements were typical, especially in the sagittal plane. The gait analysis revealed dominant compensatory movements in pelvic obliquity and rotation. INTERPRETATION: The deficits can be attributed to pronounced muscle weakness plus functional joint impairment and pain. Therapeutic preventive strategies therefore should consider continuous muscle power exercises, stretching programmes and restrictive weight control.

Pathophysiology of juvenile idiopathic arthritis induced pes planovalgus in static and walking condition: a functional view using 3D gait analysis.

BACKGROUND: Patients suffering from juvenile idiopathic arthritis (JIA) frequently have affected ankle joints, which can lead to foot deformities such as pes planovalgus (JIA-PPV). Usually, JIA-PPV is diagnosed by examining the foot in non-weightbearing or in weightbearing, static condition. However, functional limitations typically appear during dynamic use in daily activities such as walking. The aim of this study was to quantify the pathophysiology of JIA-PPV in both static and dynamic condition, i.e. in upright standing and during the stance phase of walking using three-dimensional (3d) gait analysis. METHODS: Eleven JIA patients (age = 12y) with at least one affected ankle joint and fixed pes planovalgus (≥5°) were compared to healthy controls (CG) (n = 14, age = 11y). Kinematic and kinetic data were obtained in barefoot standing and walking condition (1.1-1.3 m/s) with an 8-camera 3d motion analysis system including two force-plates and one pressure distribution plate. All participants were prepared using reflecting markers according to the Oxford Foot and Plug-in-Gait Model. Results were compared using the Mann-Whitney-U-test and Wilcoxon signed-rank test (p < 0.05). RESULTS: In comparison to CG, JIA-PPV had an excessive hindfoot/tibia eversion (p < 0.001) and a forefoot/hindfoot supination (p < 0.001) in both static and walking condition. JIA-PPV showed a greater hindfoot/tibia eversion during walking (midstance) compared to standing (p = 0.021) in contrast to CG. The arch index, measured by plantar pressure distribution, indicates a reduced arch height in JIA-PPV (p = 0.007). Patients had a lower maximum dorsiflexion of hindfoot/tibia (p = 0.001) and a lower plantarflexion of forefoot/hindfoot (p = 0.028), both when standing and walking. The kinetic results showed lower maximum ankle dorsiflexion moments (p < 0.037) as well as generated ankle power (p = 0.086) in JIA-PPV. CONCLUSIONS: The pathophysiology of JIA-PPV during walking indicated that excessive hindfoot eversion produces accessory symptoms such as a reduced arch height, increased forefoot supination and reduced propulsion effect of the ankle. Muscular and coordinative insufficiency caused by arthritis can lead to the observed increased hindfoot eversion from static to dynamic condition. Conventional static or passive foot examination techniques probably underestimate deformity in JIA pes planovalgus. 3d gait analysis might be helpful in early diagnosis of this condition, especially in JIA patients with affected ankle joints.