Osteoarthritis (OA) is the most common progressive condition affecting joints. It mainly affects the knees and hips as predominant weight-bearing joints. Knee osteoarthritis (KOA) accounts for a large proportion of osteoarthritis and presents numerous symptoms that impair quality of life, such as stiffness, pain, dysfunction, and even deformity. For more than two decades, intra-articular (IA) treatment options for managing knee osteoarthritis have included analgesics, hyaluronic acid (HA), corticosteroids, and some unproven alternative therapies. Before effective disease-modifying treatments for knee osteoarthritis, treatments are primarily symptomatic, mainly including intra-articular corticosteroids and hyaluronic acid, so these agents represent the most frequently used class of drugs for managing knee osteoarthritis. But research suggests other factors, such as the placebo effect, have an essential role in the effectiveness of these drugs. Several novel intra-articular therapies are currently in the clinical trial processes, such as biological therapies, gene and cell therapies. Besides, it has been shown that the development of novel drug nanocarriers and delivery systems could improve the effectiveness of therapeutic agents in osteoarthritis. This review discusses the various treatment methods and delivery systems for knee osteoarthritis and the new agents that have been introduced or are in development.

The high costs and extensive time needed for the treatment of critical-sized bone defects are still major clinical concerns in orthopedic surgery; therefore, researchers continue to look for more cost and time-effective methods. This study aims to investigate the effects of a decellularized omentum scaffold with a combination of platelet-rich plasma (PRP) and mesenchymal stem cells on the healing of critical-sized bone defects. Wistar albino rats (n = 30) were investigated in five groups. Critical-sized bone defects were formed on bilateral radius shafts. No scaffold, decellularized omentum, omentum with PRP and omentum + mesenchymal stem cells was used in group 1 (control group), 2, 3 and 4, respectively. In addition, omentum with a combination of mesenchymal stem cells +PRP was used in group 5. After 6 weeks, both radiological and histological healing were evaluated comparatively among the groups. After the use of a decellularized omentum scaffold, vitality of new cells was maintained, and new bone formation occurred. When compared to the control group, radiological healing was significantly better (p = 0.047) in the omentum and omentum + PRP-treated groups. Furthermore, histological healing was better in the omentum and omentum + PRP-treated groups than the control group (p = 0.001). The use of a decellularized omentum scaffold is suitable in the healing of critical bone defects.