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Reactive Oxygen And Nitrogen Species Induce Protein And Dna Modifications Driving Arthrofibrosis Following Total Knee Arthroplasty., Theresa A Freeman, Javad Parvizi, Craig J Della Valle, Marla J Steinbeck

Theresa A Freeman

BACKGROUND: Arthrofibrosis, occurring in 3%-4% of patients following total knee arthroplasty (TKA), is a challenging condition for which there is no defined cause. The hypothesis for this study was that disregulated production of reactive oxygen species (ROS) and nitrogen species (RNS) mediates matrix protein and DNA modifications, which result in excessive fibroblastic proliferation.

RESULTS: We found increased numbers of macrophages and lymphocytes, along with elevated amounts of myeloperoxidase (MPO) in arthrofibrotic tissues when compared to control tissues. MPO expression, an enzyme that generates ROS/RNS, is usually limited to neutrophils and some macrophages, but was found by immunohistochemistry to be expressed …

Mast Cells And Hypoxia Drive Tissue Metaplasia And Heterotopic Ossification In Idiopathic Arthrofibrosis After Total Knee Arthroplasty., Theresa A Freeman, Javad Parvizi, Craig J Dela Valle, Marla J Steinbeck

Theresa A Freeman

ABSTRACT: BACKGROUND: Idiopathic arthrofibrosis occurs in 3-4% of patients who undergo total knee arthroplasty (TKA). However, little is known about the cellular or molecular changes involved in the onset or progression of this condition. To classify the histomorphologic changes and evaluate potential contributing factors, periarticular tissues from the knees of patients with arthrofibrosis were analyzed for fibroblast and mast cell proliferation, heterotopic ossification, cellular apoptosis, hypoxia and oxidative stress. RESULTS: The arthrofibrotic tissue was composed of dense fibroblastic regions, with limited vascularity along the outer edges. Within the fibrotic regions, elevated numbers of chymase/fibroblast growth factor (FGF)-expressing mast cells were …