IHC staining and gray value analysis of substance P and NK-1R in human synovial of fossa acetabuli. (A-B: IHC of SP), (D-E: IHC of NK-1R). Representative images are from patients with DDH (A and D); DDH&OA (B and E). (C and F) stands for gray value analysis of the IHC staining (*P < 0.05). Scale bars: (A-B) 400 times magnified; (D-E): 100 times magnified. Thin arrows in (A-B) represent positive staining of nerve fibers-like SP. Thick arrows in (B) indicate nerve bundles-like SP. Thin arrows in (D-E) display fibers-like staining of NK-1R. Thick arrows in (D) show perivascular located staining of NK-1R.