## 1 Introduction  
Osteoarthritis (OA) is mainly considered a disease of older people, as over one-third of the population over 65 years old present OA in at least one joint [1]. However, factors such as obesity, sports, genetic factors, work, previous injuries, or socioeconomic status can influence osteoarthritic changes in joints [2, 3] in younger populations. Knee osteoarthritis (KOA) was believed to be a mere cartilage degeneration disease caused by cartilage wear; however, it is now considered a complex articular metabolic disease associated with biomechanics, inflammation, and complex biological responses that affect the immune system (the cartilage, subchondoral bone, and synovial membrane) [4, 5]. In addition, during the process of inflammation in OA, inflammatory mediators stimulate chondrocytes to produce lysis enzymes, maintaining a vicious cycle consisting of inflammation, enzymes, chondolysis, and inflammation [6]. Hence, treatment for knee OA has aimed to improve the anatomical, metabolic, and physiological abnormalities that cause a vicious cycle. There are several potential treatments for this disease, including surgical administration, prescription drugs, physical activity, and traditional and new physical therapy methods [7]. Various treatment methods are currently being attempted. Orthologics, such as platelet-rich plasma (PRP) therapy, mesenchymal stem cell (MSC) therapy, and extracorporeal shock wave therapy (ESWT), are among these new treatments that are gradually gaining attention [8]. In particular, PRP injections have consistently outperformed HA injections in treating knee osteoarthritis, offering pain relief and improved function [9]. As a result, PRP is recommended for cases where HA has not been effective. According to a report by [PERSON] et al. [10], OA pain in the knee is dominated by pain from the subchondral bone and synovitis. The presence of a bone marrow lesion (BML), which is a lesion of the subchondral bone, is a risk factor for the structural progression of the disease; the presence of synovitis and joint effusion are also pathologies closely related to pain and disease progression. When considering the treatment of knee OA pain, it is important to understand the cause and pathology of pain and take an appropriate approach. In recent years, magnetic resonance imaging (MRI) has been used to diagnose knee joint pain, and it has become possible to observe BMLs in the subchondral bone or synovitis in detail. Therefore, the cause of knee OA pain can now be easily identified by MRI. APS, which is a condensed and processed form of PRP, has been developed for OA. In OA, the inflammatory cytokines interleukin (IL)-1\(\beta\) and tumor necrosis factor (TNF)-\(\alpha\) exacerbate cartilage destruction and OA progression. APS contains components that block the action of these inflammatory cytokines [11]. APS reportedly reduces knee OA pain and prevents OA progression [12]. It is effective in patients with synovitis-derived intra-articular hydrops and is recommended for patients with persistent intra-articular hydrops. On the other hand, ESWT has become a new conservative treatment for OA in recent years [8; 11; 13]. ESWT reduces pain and improves motor function. [PERSON] et al. [14] and [PERSON] et al. [15] reported ESWT as an effective and reliable non-invasive treatment that rapidly reduces BMLs on pain-related MRI and improves knee function. In 2018, [PERSON] et al. reported the first use of targeted ESWT for BMLs in knee OA [16]. This treatment method is based on the speculation that physical stimulation of bone marrow induced by ESWT may improve bone remodeling abnormalities and promote the healing of microfractures [16]. Bone and cartilage regeneration reduces inflammation, induces angiogenesis, stimulates stem cell activity, and improves tissue regeneration and healing [13]. In addition, ESWT promotes osteoblast growth, differentiation, and transforming growth factor (TGF)-81 expression.