## 4 Discussion  
In the current study, DPT, OT, and home-based exercise therapy were applied to three groups of adult patients with symptomatic primary KOA, and the efficacy of the treatments was compared. DPT and OT were performed using both intraarticular and periarticular methods. The efficacy of treatments at week 6 and week 12 was compared with the baseline values. As a result of the study, all three treatment modalities showed positive effects on many outcome parameters. When the three methods were compared with each other, it was observed that in the 6 th week, OT was more effective than DPT in two parameters (VAS-rest, VAS-movement) and more effective than the home-based exercise program in five parameters (VAS-rest, VAS-movement, WOMAC-stiffness, WOMAC-function, and WOMAC-total). In the 12 th week, OT was more effective than DPT in three parameters (VAS-rest, VAS-movement, and WOMAC-stiffness) and more effective than the home-based exercise program in five parameters (VAS-rest, VAS-movement, WOMAC-stiffness, WOMAC-total, and ROM-active). It is stated that home exercise programs in KOA patients are safe and effective, especially in terms of pain reduction and strength development. According to a systematic review evaluating the effectiveness of exercise programs in the treatment of KOA, exercise program implementation showed positive physical and functional results on at least one outcome variable [30]. In this study, it was observed that the home exercise program applied by the patients had positive effects on many parameters except ROM-passive at the 6 th and 12 th weeks in the treatment of KOA. Many studies are investigating the use of DPT in the treatment of KOA and comparing the effectiveness of DPT with other treatment methods. The intraarticular dextrose concentration used in various studies ranges from 10% to 25%. The injection regime (number of injections, break durations, follow-up times) presents wide variations [17]. DPT has more beneficial effects than saline and home-based exercise therapies [27] and similar effects with PRP in reducing pain severity [26]. DPT can provide safe, significant, and sustained improvements in knee pain, function, and stiffness scores in adults with moderate-to-severe KOA [17]. In long term follow-up studies of DPT, the improvements in WOMAC scores were continued in week 52 [27] and year 2.5 [31]. The method of application is also an important determinant of the effectiveness of DPT. While no significant improvement was observed in WOMAC scores in a study in which DPT was applied via intraarticular and periarticular methods [26], significant improvements were observed in other studies [27; 28]. A long-term follow-up study revealed that the positive effects of intraarticular and periarticular administration of DPT on WOMAC and pain scores continued at the 52-week control [31]. In addition, periarticular use of DPT alone is also effective in relieving KOA symptoms [32]. In this study, intraarticular and periarticular administration of DPT improved WOMAC scores. Our study supports the findings in the literature that intraarticular and periarticular use of DPT is effective in relieving KOA symptoms. The current study showed significant improvements in DPT, ozone, and exercise groups in WOMAC scores of stiffness, physical function, and total, both at 6 weeks and 12 weeks, compared to baseline. Considering WOMAC total scores 47.8% of patients of the OT group, 47.9% of patients of the DPT group and 25.1% of patients of the HEP group showed significant improvements from baseline at week 12. The OT and DPT groups were more effective than the HEP group, but they were not superior to each other. The use of OT in treatment of has become widespread in recent years [33; 34]. OT application in KOA contributes to a decrease in pain intensity, disappearance of edema and increase in mobility. Although the mechanism of action is not fully known, OT has favorable effects on pain relief by decreasing oxidative stress, improving anti-inflammatory pathways and blood circulation [35].