Choosing advanced injection options for knee osteoarthritisArthrosamid, a 2.5% polyacrylamide hydrogel given as a single 6 mL knee injection, is designed to stay in the joint and has extension data showing WOMAC pain improvements maintained to five years. MFAT, PRP and BMAC offer biologic alternatives, but their evidence is smaller and less consistent.Arthrosamid, a 2.5% polyacrylamide hydrogel given as a single 6 mL knee injection, is designed to stay in the joint and has extension data showing WOMAC pain improvements maintained to five years. MFAT, PRP and BMAC offer biologic alternatives, but their evidence is smaller and less consistent.