Participants With Knee Osteoarthrosis

The PG and JG were injected with autologous PRP at baseline. The injection was performed by the same clinician with 10 years of experience in knee joint injections. Participants were seated with their knees extended, and the needle was inserted through the joint space into the intra-articular cavity of the knee, administering approximately 2.5 mL of PRP into each knee joint. Thirty millilitres of venous blood were drawn from the participant's elbow vein, and approximately 5 mL of PRP was obtained for bilateral knee joint injection by using a TD5A tabletop low-speed centrifuge manufactured in China. The first centrifugation was performed at 2500 revolutions per minute (rpm) for 3 minutes, followed by a second centrifugation at 2300 rpm for 6 minutes.

The IG and JG exercises followed the methods of our previous research, with participants undergoing an 16-week ICQ intervention five times per week. Each session consisted of isometric contractions and relaxations of the quadriceps muscle for 5 seconds each, in sets of 30 repetitions, for a total of 10 sets, with a 30-second rest between sets. During this period, researchers conducted weekly follow-up calls or face-to-face interviews with participants to understand their living conditions, ensuring that they did not change their original lifestyle habits and did not engage in any other form of regular fitness activities. Participants who did not comply were not included in the final data analysis.

Platelet-Rich Plasma Combined with Isometric Contractions of Quadriceps

Initially, all participants received identical health education in the form of thematic lectures once per week for 40 minutes each. The content included the following aspects: emphasising the importance of close cooperation with physicians as key to maintaining health; the process of the occurrence and development of KOA, along with its treatment methods; the role of family and social support in improving the condition; establishing a reasonable daily activity routine, such as protecting the affected knee joint, avoiding long-distance fatigue, mountain climbing, ascending and descending high-rise stairs and various adverse body postures (prolonged standing, kneeling and squatting); and advising those who are overweight to reduce their body weight. On this foundation, the four groups of participants underwent the following interventions.