Cartilage Biomarker Response to Acute Mechanical Loading in Women With Knee Osteoarthritis: Comparison by Antiresorptive Treatment Status

This study evaluates how acute mechanical loading affects cartilage degradation biomarkers in postmenopausal women with mild-to-moderate knee osteoarthritis. Participants will be grouped according to their existing antiresorptive treatment status: denosumab users, bisphosphonate users, and a control group. All participants will undergo a 30-minute treadmill walking session at a comfortable and tolerated speed. Blood samples will be collected immediately before and within 0-2 minutes after walking to measure changes in cartilage degradation biomarkers, including cartilage oligomeric matrix protein (COMP) and matrix metalloproteinase-3 (MMP-3). The study aims to determine whether the biomarker response to acute mechanical loading differs according to antiresorptive treatment status.

Inclusion Criteria: * Postmenopausal women aged 60-80 years. * DEXA-confirmed diagnosis of osteoporosis or osteopenia. * Clinically and radiographically confirmed knee osteoarthritis, with Kellgren-Lawrence grade 2 or 3 in at least one knee. * Knee MRI performed within the previous 3 months. * Bilateral hand radiographs performed within the previous 6 months. * Pain intensity of at least 20 mm on the Visual Analog Scale (VAS) during activity. * Ability to tolerate the standardized acute mechanical loading protocol consisting of 30 minutes of treadmill walking. * Non-sarcopenic status according to the STAR protocol. * Ability to provide written informed consent. Exclusion Criteria: * Inflammatory arthritis, including rheumatoid arthritis, psoriatic arthritis, or ankylosing spondylitis. * Active gout or calcium pyrophosphate deposition (CPPD) attack. * History of total knee arthroplasty or major knee surgery. * Intra-articular knee injection within the previous 12 months. * Change in antiresorptive therapy within the previous 6 months. * Previous osteoanabolic therapy. * Systemic corticosteroid use for ≥3 months at a dose equivalent to ≥5 mg/day of prednisone. * Glomerular filtration rate (eGFR) \