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.