Synovial Histopathology Across a Spectrum of Hip Disorders: From Pre-Arthritic Femoroacetabular Impingement to Advanced Osteoarthritis
Abstract
Objective: The objective of this thesis was to provide insight into early changes in osteoarthritis pathogenesis. Histopathology of synovium was investigated in femoroacetabular impingement (FAI), FAI with early hip osteoarthritis, and advanced hip osteoarthritis.
Methods: Synovium biopsies were collected from ten FAI, fourteen FAI with early osteoarthritis, and twelve advanced osteoarthritis patients. Histopathological grading allowed assessment of osteoarthritis-associated features. Microvessel density and maturity were determined through immunofluorescent labelling of CD31 and a-smooth muscle actin. Immunohistochemical staining was applied to calculate CD105+ microvessel density.
Results: In all groups, vascularization was prominent, with a mean [95% confidence interval] of 1.66 [1.41, 1.91]. Mature density was greater than immature (83.84 [64.14, 103.55] versus 13.12 [9.46, 16.78] microvessels/mm2). Low CD105+ density (3.06 [0.78, 5.34] microvessels/mm2) suggests microvessel inactivity.
Conclusion: Mature, inactive microvasculature was prominent across this spectrum of hip osteoarthritis. These findings support the theory of differences between hip and knee osteoarthritis pathophysiology.