This study is designed as a randomized, double-blind, placebo-controlled clinical trial with two parallel groups. All participants will receive a standardized physical therapy rehabilitation program. Participants will be randomly allocated into either a study group receiving metformin iontophoresis or a control group receiving placebo iontophoresis. Both participants and outcome assessors will be blinded to group allocation.

The study population will consist of postmenopausal women diagnosed with knee osteoarthritis. Postmenopause is defined as the absence of menstruation for at least 12 consecutive months. Participants will be randomly assigned to either the study or control group using a computer-generated randomization sequence. Allocation concealment will be ensured using sealed opaque envelopes. Both participants and outcome assessors will be blinded to the treatment allocation. The physical therapist applying iontophoresis will not be involved in outcome assessment.

Inclusion Criteria:

• • Postmenopausal women aged 50-70 years.

  • Clinical and radiographic diagnosis of knee osteoarthritis according to the American College of Rheumatology criteria.
  • Radiographic severity classified as Kellgren-Lawrence grade II or III.
  • Chronic knee pain for a duration of at least 3 months.
  • Pain intensity ≥4 on the Visual Analog Scale.
  • Ability to ambulate independently with or without assistive devices.
  • Ability to understand and follow instructions.
  • Willingness to participate and provide written informed consent.

Exclusion Criteria:

• • Severe knee osteoarthritis (Kellgren-Lawrence grade IV).

  • History of knee surgery or intra-articular injections within the previous 6 months.
  • Presence of inflammatory rheumatic diseases such as rheumatoid arthritis or gout.
  • Neurological disorders affecting lower limb function.
  • Uncontrolled metabolic, cardiovascular, or systemic diseases.
  • Current or recent use of metformin or other antidiabetic medications.
  • Skin lesions, infections, or hypersensitivity at the iontophoresis site.
  • Contraindications to electrotherapy such as pacemakers or implanted electronic devices.
  • Body mass index ≥35 kg/m².
  • Participation in another clinical trial within the last 3 months.

Postmenopausal Women