This study aims to compare the effectiveness and safety of High-Intensity Laser Therapy (HILT) with conventional physical therapy treatments in patients with knee osteoarthritis. Knee osteoarthritis is a common condition, especially in older adults, causing pain, stiffness, reduced movement, and difficulty performing daily activities. Current treatments focus on reducing pain and improving joint function.

In this study, 100 patients with knee osteoarthritis will be divided into two groups. One group will receive HILT combined with therapeutic exercises, while the other group will receive conventional physical therapy modalities along with the same exercises. The treatment outcomes will be evaluated over time.

The main outcomes include pain reduction (measured by pain scales such as WOMAC and VAS), improvement in joint function, and structural changes in the knee assessed by MRI. In addition, laboratory tests will be used to measure inflammation, cartilage health markers, and oxidative stress before and after treatment.

The goal is to determine whether HILT provides better pain relief, improves joint function, and is safe compared to standard therapy. The results may help improve rehabilitation strategies for patients with knee osteoarthritis.

Knee Osteoarthritis is a chronic degenerative joint disorder characterized by progressive cartilage loss, pain, stiffness, and functional limitation. It is a leading cause of disability, particularly among older adults, and its prevalence is increasing with population aging.

Non-surgical management is the first-line approach and includes exercise therapy and physical modalities aimed at reducing pain and improving joint function. High-Intensity Laser Therapy is a non-invasive modality that delivers high-energy light to tissues, promoting cellular activity, increasing adenosine triphosphate (ATP) production, enhancing microcirculation, and reducing inflammation and edema. In contrast, Low-Level Laser Therapy has been more extensively studied, while evidence regarding HILT remains limited.

This study is a randomized comparative trial designed to evaluate the efficacy and safety of HILT compared with conventional physical therapy modalities in patients with knee osteoarthritis. A total of 100 participants meeting the American College of Rheumatology criteria will be recruited from rheumatology and rehabilitation centers in Erbil, Iraq. Participants will be randomly assigned to one of two groups: (1) HILT combined with therapeutic exercise, or (2) conventional physical therapy modalities combined with therapeutic exercise.

The primary outcome is pain intensity at 4 weeks, assessed using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain subscale or Visual Analogue Scale (VAS). Secondary outcomes include pain at 8 weeks and functional status. Structural joint changes will be evaluated using magnetic resonance imaging (MRI), including assessment of cartilage thickness, joint irregularity, effusion, and osteophyte formation.

Laboratory assessments will be conducted before and after intervention to evaluate biological effects. These include inflammatory markers (C-reactive protein), gene expression markers related to cartilage metabolism (TGFB1, FOXO1, COMP, and MMP3) measured by RT-PCR, and oxidative stress markers (malondialdehyde [MDA] and superoxide dismutase [SOD]) measured using ELISA.

Eligible participants are adults aged 40-75 years with clinically and radiographically confirmed knee osteoarthritis who are able to provide informed consent and comply with study procedures. Exclusion criteria include contraindications to laser therapy (e.g., malignancy, epilepsy, photosensitivity, or local infection), recent knee surgery, advanced osteoarthritis requiring surgical intervention, pregnancy or lactation, and severe comorbid conditions that may affect participation or outcomes.

Data will be analyzed using Statistical Package for the Social Sciences (SPSS, version 21). Ethical approval will be obtained from the relevant institutional review bodies, and written informed consent will be obtained from all participants. Confidentiality will be maintained throughout the study.

This study aims to determine whether HILT provides superior clinical and biological outcomes compared with conventional physical therapy modalities in the management of knee osteoarthritis.

Inclusion Criteria:

• Diagnosis of Knee Osteoarthritis: Patients must have a clinical and radiographic diagnosis of knee OA according to the American College of Rheumatology (ACR) criteria, including evidence of joint space narrowing, osteophyte formation, and other degenerative changes observed on X-rays or MRI.

Age: Adults aged between 40 and 75 years. Willingness to Participate: Participants must provide informed consent and be willing to adhere to the study protocol, including attending all treatment sessions and follow-up assessments.

Kellgren-Lawrence Grade: Patients with knee OA grades 1-3 (mild to moderate OA).

Exclusion Criteria:

• Contraindications to Laser Therapy:

Active malignancy History of epilepsy Photosensitivity disorders Active infection in the treatment area

Surgical History:

Patients who have undergone knee surgery within the past 6 months Scheduled surgery during the study period

Advanced Disease:

Kellgren-Lawrence Grade 4 (severe OA) where surgical intervention is indicated

Pregnancy or Lactation:

Pregnant or lactating women

Severe Comorbidities:

Uncontrolled diabetes Severe cardiovascular disease Neurological disorders that might interfere with participation or affect treatment outcomes

Individual participant data (IPD) will not be shared publicly. This decision is based on: (1) protection of participant privacy and confidentiality in accordance with Iraqi health research regulations and institutional ethical guidelines; (2) the need to protect data integrity for ongoing PhD thesis completion and future publications; (3) local institutional policies regarding data sharing. De-identified summary data may be available from the principal investigator upon reasonable request and with appropriate data use agreements after completion of the PhD program and primary publications.

N/A - This is an open-label study with no masking.