Inflammation, angiogenesis and sensory nerve sprouting in the synovium of bony ankylosed and not bony ankylosed knees with end‐stage haemophilic arthropathy

Introduction Clinical practice showed that patients with haemophilia (PwH) with bony ankylosed end‐stage haemophilic arthropathy knees reported milder pain than those with not bony ankylosed knees. Aim To compare the differences in pain sensation and the histopathological differences in synovial samples of affected knee joints between PwH with bony ankylosed end‐stage haemophilic arthropathy knees and those with not bony ankylosed knees. Methods From January 2011 to December 2019, the synovial samples of knee joints were collected during total knee arthroplasty (TKA) surgery for end‐stage haemophilic arthropathy. The visual analogue scale (VAS, 0–10) pain score was reviewed from the chart data of the patients. The thickness of the inner layer of the synovium in haematoxylin and eosin (H&E) staining sections was measured. The expression levels of Ki67, IL‐1β, TNF‐α, CD31, VEGF, NGF and PGP9.5 in the synovium were detected by immunohistochemistry (IHC) method. Results Fifty‐two end‐stage haemophilic arthropathy knee synovial samples from 36 male PwH (34 type A and 2 type B) were collected. Fifteen knees had bony ankylosed (BA‐group), and 37 were not bony ankylosed (Not‐BA‐group). The mean age of patients at TKA surgery of BA‐group and Not‐BA‐group was 32 years (15) and 32 years (10), respectively (p = 0.824). Before TKA surgery, the mean VAS pain scores of patients in the Not‐BA‐group were significantly higher than those in the BA‐group (p