Levels of substance P in both serum and synovium from patients among different groups. (A) Contents of SP in serum by an ELISA assay. Serum samples were obtained from patients with DDH (n = 40), DDH&OA (n = 40) and normal people (n = 31) recruited in this research. (B) Concentration of SP levels in synovial of fossa acetabuli from patients in separate groups. 1 extraction stands for SP secreted from free nerve endings in synovial tissue, whereas 2 extraction means SP generated from non-neuronal cells (*P < 0.05). (C)-(D) Gender differences of serum SP levels was investigated in each group (*P < 0.05).