Mature and inactive microvessels are prominent in areolar synovium of femoroacetabular impingement and hip osteoarthritis patients

Objective: To provide insight into the earliest changes in hip osteoarthritis (OA) pathogenesis. Histopathology of synovium was investigated in patients with femoroacetabular impingement (FAI), FAI with early hip osteoarthritis, and advanced hip osteoarthritis. Methods: Synovium biopsies were collec...

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Main Authors: Ronan J. Anderson, Brent A. Lanting, C. Thomas Appleton, Ryan M. Degen
Format: Article
Language:English
Published: Elsevier 2025-09-01
Series:Osteoarthritis and Cartilage Open
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Online Access:http://www.sciencedirect.com/science/article/pii/S2665913125000615
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author Ronan J. Anderson
Brent A. Lanting
C. Thomas Appleton
Ryan M. Degen
author_facet Ronan J. Anderson
Brent A. Lanting
C. Thomas Appleton
Ryan M. Degen
author_sort Ronan J. Anderson
collection DOAJ
description Objective: To provide insight into the earliest changes in hip osteoarthritis (OA) pathogenesis. Histopathology of synovium was investigated in patients with 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 α-smooth muscle actin. Immunohistochemical staining was applied to calculate CD105+ microvessel density, providing insight into microvessel activity. Results: In all groups, vascularization was prominent, with a mean [95 ​% confidence interval] of 1.64 [1.40, 1.89]. In all three groups, mature microvessel density was greater than immature microvessel density (82.32 [62.92, 101.71] versus 14.84 [9.86, 19.83] microvessels/mm2). Low CD105+ microvessel density across all groups (3.14 [0.92, 5.37] microvessels/mm2) suggests microvessel inactivity. Inflammatory composite scores were significantly greater in the advanced OA (1.08 [0.84, 1.32]) versus the FAI group (0.47 [0.26, 0.68]), and in the advanced OA versus the FAI with early OA group (0.69 [0.49, 0.89]) (p ​< ​0.017). Conclusion: Synovium from patients with FAI (with and without hip osteoarthritis) demonstrated synovitis and other OA-associated changes. Mature, inactive microvasculature was prominent in all three groups investigated. Histopathological similarities between FAI and hip OA synovium indicate that disordered synovium appears in FAI patients. These findings highlight a potential role of synovial changes in the progression from FAI to hip OA, underscoring the need for early intervention and further investigation into early disease mechanisms.
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spelling doaj-art-8162c85bc0e74ffb98dd70fee3b2b6bc2025-08-20T02:32:54ZengElsevierOsteoarthritis and Cartilage Open2665-91312025-09-017310062510.1016/j.ocarto.2025.100625Mature and inactive microvessels are prominent in areolar synovium of femoroacetabular impingement and hip osteoarthritis patientsRonan J. Anderson0Brent A. Lanting1C. Thomas Appleton2Ryan M. Degen3Schulich School of Medicine &amp; Dentistry, University of Western Ontario, London, ON, N6A 5C1, Canada; Corresponding author.Bone and Joint Institute, University of Western Ontario, London Health Sciences Centre-University Hospital, London, ON, N6A 5B5, Canada; Department of Surgery, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, N6A 5C1, CanadaBone and Joint Institute, University of Western Ontario, London Health Sciences Centre-University Hospital, London, ON, N6A 5B5, Canada; Department of Medicine, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, N6A 5C1, CanadaBone and Joint Institute, University of Western Ontario, London Health Sciences Centre-University Hospital, London, ON, N6A 5B5, Canada; Department of Surgery, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, N6A 5C1, CanadaObjective: To provide insight into the earliest changes in hip osteoarthritis (OA) pathogenesis. Histopathology of synovium was investigated in patients with 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 α-smooth muscle actin. Immunohistochemical staining was applied to calculate CD105+ microvessel density, providing insight into microvessel activity. Results: In all groups, vascularization was prominent, with a mean [95 ​% confidence interval] of 1.64 [1.40, 1.89]. In all three groups, mature microvessel density was greater than immature microvessel density (82.32 [62.92, 101.71] versus 14.84 [9.86, 19.83] microvessels/mm2). Low CD105+ microvessel density across all groups (3.14 [0.92, 5.37] microvessels/mm2) suggests microvessel inactivity. Inflammatory composite scores were significantly greater in the advanced OA (1.08 [0.84, 1.32]) versus the FAI group (0.47 [0.26, 0.68]), and in the advanced OA versus the FAI with early OA group (0.69 [0.49, 0.89]) (p ​< ​0.017). Conclusion: Synovium from patients with FAI (with and without hip osteoarthritis) demonstrated synovitis and other OA-associated changes. Mature, inactive microvasculature was prominent in all three groups investigated. Histopathological similarities between FAI and hip OA synovium indicate that disordered synovium appears in FAI patients. These findings highlight a potential role of synovial changes in the progression from FAI to hip OA, underscoring the need for early intervention and further investigation into early disease mechanisms.http://www.sciencedirect.com/science/article/pii/S2665913125000615Femoroacetabular impingementOsteoarthritisSynoviumSynovitisMicrovascular dysfunction
spellingShingle Ronan J. Anderson
Brent A. Lanting
C. Thomas Appleton
Ryan M. Degen
Mature and inactive microvessels are prominent in areolar synovium of femoroacetabular impingement and hip osteoarthritis patients
Osteoarthritis and Cartilage Open
Femoroacetabular impingement
Osteoarthritis
Synovium
Synovitis
Microvascular dysfunction
title Mature and inactive microvessels are prominent in areolar synovium of femoroacetabular impingement and hip osteoarthritis patients
title_full Mature and inactive microvessels are prominent in areolar synovium of femoroacetabular impingement and hip osteoarthritis patients
title_fullStr Mature and inactive microvessels are prominent in areolar synovium of femoroacetabular impingement and hip osteoarthritis patients
title_full_unstemmed Mature and inactive microvessels are prominent in areolar synovium of femoroacetabular impingement and hip osteoarthritis patients
title_short Mature and inactive microvessels are prominent in areolar synovium of femoroacetabular impingement and hip osteoarthritis patients
title_sort mature and inactive microvessels are prominent in areolar synovium of femoroacetabular impingement and hip osteoarthritis patients
topic Femoroacetabular impingement
Osteoarthritis
Synovium
Synovitis
Microvascular dysfunction
url http://www.sciencedirect.com/science/article/pii/S2665913125000615
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