Knee osteoarthritis (KOA) is a chronic, progressive degenerative joint disease characterized by cartilage and bone degeneration, synovial inflammation, and structural changes. Clinically, it presents with pain, morning stiffness, swelling, crepitus, and limited range of motion, leading to functional impairment, gait abnormalities, and reduced quality of life. Globally, KOA affects ~302 million people. In Saudi Arabia, prevalence rises from 30.8% (ages 46-55) to >60% (ages 66-75), with higher rates in older, female, and obese individuals. Key risk factors include aging, female sex, obesity, prior knee injury, and genetics. The condition imposes significant health burdens and socioeconomic costs.

The International Classification of Functioning, Disability, and Health (ICF) identifies KOA as a major cause of physical disability. Pain, restricted motion, and muscle weakness drive quality-of-life decline. While pharmacological treatments exist, physical therapy interventions (education, exercise, weight loss) are crucial, though their success depends on patient behavioral change.

Traditional biomedical education inadequately addresses chronic pain. Pain neuroscience education (PNE) teaches the biology and physiology of pain, supported by a biopsychosocial assessment. PNE is increasingly used by physiotherapists for chronic pain management.

Quadriceps weakness contributes to functional decline in KOA. Conventional high-load resistance training may exacerbate joint pain; thus, low- to moderate-intensity training is recommended. Blood flow restriction training (BFRT) partially restricts arterial inflow and occludes venous outflow during low-load exercise, originally developed as "kaatsu training" in Japan. BFRT is used in rehabilitation and performance training across healthy individuals, athletes, older adults, and hypertensive patients. Factors affecting adaptations include occlusion pressure, type (continuous/intermittent), exercise intensity, and volume. Low-load resistance with BFRT reduces joint pain and increases muscle strength and mass in older adults, including those with KOA risk factors.

A systematic review of six RCTs on BFRT in KOA patients showed significant pain improvement in four studies, but meta-analysis did not confirm a significant difference. Combining exercise therapy and education is recommended for musculoskeletal pain reduction; pain education alone reduced healthcare spending by 45% over three years. However, physical therapists underutilize pain management approaches, and knowledge gaps remain barriers.

Controlled clinical studies on BFRT in KOA are lacking. This randomized trial aims to evaluate whether BFRT, PNE, and standard treatment improve pain, function, muscle thickness, and patient satisfaction in KOA patients.

KOA is a chronic, progressive, and severe degenerative joint disease marked by the slow degeneration of articular cartilage and subchondral bone, synovial inflammation, and structural changes in the meniscus and ligaments. Clinically, it is characterized by chronic knee pain, morning stiffness, swelling, crepitus, and a restricted range of motion (ROM). These signs and symptoms frequently result in functional impairment, gait abnormalities, and a significant decline in quality of life.

KOA is a common degenerative disease characterized by joint swelling, discomfort, stiffness, functional impairments, severe muscle atrophy, and even incapacity. According to statistics, KOA affects an estimated 302 million people worldwide. In Saudi Arabia, the prevalence of knee osteoarthritis (KOA) rises from 30.8% in those aged 46-55 to over 60% in those aged 66-75. KOA is particularly common in older, female, and obese people. The condition is strongly correlated with high BMI, inactivity, and aging. It frequently results in severe discomfort and restricted movement.

This syndrome is becoming more prevalent as the population ages and physical fitness declines; it imposes a greater health burden on individuals and has a substantial impact on the healthcare system and socioeconomic expenditures.

According to the International Classification of Functioning, Disability, and Health (ICF), KOA leads to activity limitations and participation restrictions as well as impairment. It is one of the leading causes of physical disability among the general population. In addition to causing considerable impairment, this condition results in a notable decrease in quality of life due to pain, limited range of motion, and loss of muscle strength.The Key risk factors of KOA include aging, gender differences (women more than men), obesity, previous knee injuries, and genetic factors.

Besides pharmacological treatments, physical therapy intervention such as (education, exercise, and weight loss) are crucial for managing KOA subjects, The effectiveness of such treatments depends on the patient's willingness to change their behavior, which can be difficult to achieve.

Due to scientific advances in pain treatment and rising rates of chronic pain prevalence, the traditional biomedical educational model was unable to adequately address pain. In pain science education, the process of teaching the underlying biology and physiology of pain is known as pain neuroscience education (PNE).Physiotherapists increasingly use PNE in the treatment of chronic pain patients. PNE should be preceded by a comprehensive biopsychosocial assessment in order to evaluate pain neurophysiology and biopsychosocial interactions and give the patient a voice in this process.

Functional decline in KOA patients is associated with quadriceps weakness. In conventional interventions to strengthen muscles, high-load or high-intensity resistance training is commonly used. Adults with KOA are recommended to perform low- to moderate-intensity resistance training to improve muscle strength and limit joint pain.

Blood flow restriction training (BFRT) involves partially restricting arterial blood flow into muscles as well as occluding the venous outflow during exercise. It was first introduced into the literature by Japanese doctor called Yoshiaki Sato in Japan in 1987 who used tourniquet ischemia to induce muscle fatigue. This technique was originally called "kaatsu training," meaning "training with added pressure." Kaatsu training is now performed all over the world and is more commonly referred to as "BFRT" and achieved using a pneumatic tourniquet system.

In addition to physical rehabilitation, BFRT is used for physical training and performance in healthy individuals. There has been extensive research into its value as a training tool, including elite- and amateur-level athletes, untrained young and older adults, and hypertensive individuals.

There were different Factors affecting exercise adaptations with BFR including pressure of occlusion (partial or complete), type of occlusion (continuous or intermittent), intensity of exercise, and volume of exercise with BFR.

The combination of low-load resistance training with BFRT may help to reduce training related joint pain. In BFRT training, the exercising limb is compressed externally and blood flow is mildly restricted to the activated skeletal muscle. It has been independently validated that BFRT resistance training can increase skeletal muscle strength and mass in older adults, especially those with risk factors for knee osteoarthritis.

The results of Gama Linhares and colleague's systematic review, which was done on six RCTs included in this meta-analysis, four studies showed a significant improvement in pain with the use of the BFRT in KOA patients (p < 0.05). However, the results of the meta-analysis did not confirm this significant difference.

A combination of exercise therapy and education was recommended as the most effective intervention for reducing musculoskeletal pain. In addition, using pain education alone reduced health care spending by 45% over three years. Pain management approaches don't seem to be widely used by physical therapists in clinical settings. Moreover, pain management prescriptions are lacking in knowledge, making pain a bigger barrier in areas where knowledge is lacking. It is therefore important to emphasize the importance of education and effective therapeutic exercise(s).

To our knowledge, controlled clinical studies investigating the effect of BFRT in KOA subjects are currently lacking. Therefore, the current randomized trial aims to examine whether interventions of BFRT, PNE, with standard treatment can serve as an effective method for improving pain, function, muscle thickness, and patient satisfaction in patients with KOA.

Inclusion Criteria:

• Male and female Age ≥ 40years.
• Clinical and radiographic diagnosis of unilateral knee osteoarthritis KOA (Kellgren-Lawrence grade 2, or 3).
• Willing to attend 3 supervised sessions/week for 8 weeks.
• Able to provide informed consent.

Exclusion Criteria:

• Peripheral vascular disease, active cancer, lower limb infection, open wound
• history of intra-articular injections within the last 3 months
• medical condition that may affect their ability to perform exercise (uncontrolled cardiovascular, or neurological disorders)
• cognitive and psychiatric disorders

will be used for other future research projects