Innate immunity, bone and cartilage metabolism in children with developmental dislocation of the hip - pilot study

Objective Search for the relationship between innate immunity and bone and cartilage metabolism in patients with developmental dislocation of the hip (DDH). Material and methods The study included 27 patients with DDH who underwent reduction of the hip at pediatric orthopaedic department of the Federal State Budgetary Educational Institution of Higher Education «Privolzhsky Research Medical University» of the Ministry of Health of the Russian Federation. The patients aged 15.0 ± 1.7 months. The study enrolled the babies diagnosed with grades III, IV, V unilateral or bilateral DDH as classified by M.V. Volkov, 1978. Patients with hip dysplasia (grade I DDH) or congenital hip subluxation (grade II DDH) were excluded from the study. The control group consisted of 15 patients without musculoskeletal pathology. The mean patients' age was 24.0 ± 1.8 months. Peripheral blood monocytes, toll-like receptor (TLR2, TLR4, TLR5) expression, serum concentrations of fibroblast growth factors (FGF), vascular endothelial growth factor (VEGF), serum magnesium, type I, II collagen and aggrecan were measured in patients of major and control groups. Results DDH patients showed statistically significant differences in all the parameters measured except for the type 2 collagen with decrease in peripheral blood monocyte and increase in TLR2 and TLR5 expression, slight increase in the serum magnesium with decreased concentration of aggrecan and increased FGF level. There was a two-fold decrease in VEGF level and a two-fold increase in type I collagen concentration. There were moderate significant correlations for monocyte matches TLR2 and TLR2 - TLR5 in major group. Three main factors detected with factor analysis included (1) monocytes, TLR2 and TLR5 as most meaningful, (2) FGF and type 2 collagen and (3) aggrecan. Conclusion The findings suggested that specific factors of innate immunity can be involved in the pathogenesis of DDH. Toll receptors regulate many metabolic pathways and connective tissue metabolism, More studies are needed to further explore this topic.