This randomized, controlled clinical trial will evaluate the safety and effectiveness of autologous adipose-derived stromal vascular fraction (SVF) therapy in patients with knee osteoarthritis (OA) grades II-IV, compared with standard chondroprotective (CP) treatment. The study will enroll male and female patients and follow them for 12 months, assessing pain (VAS), function (WOMAC, KOOS, SF-36), radiologic progression, and safety (adverse events). The trial aims to determine whether SVF therapy provides superior clinical outcomes and to inform evidence-based recommendations for OA management in the Serbian population.

Knee osteoarthritis (OA) is a progressive degenerative joint disorder characterized by cartilage loss, subchondral bone remodeling, synovial inflammation, and joint pain. It is a leading cause of disability worldwide, particularly affecting weight-bearing joints such as the knee. The pathological process involves a combination of mechanical stress, inflammatory cytokine activity, and abnormal tissue remodeling, leading to progressive cartilage degradation and functional impairment. OA is increasingly recognized as a biologically active disease rather than a simple "wear-and-tear" condition, with complex interactions among chondrocytes, synoviocytes, immune cells, and extracellular matrix components.

Current non-surgical therapies, including analgesics, physiotherapy, and chondroprotective agents, primarily address symptom control and functional preservation, without altering the underlying degenerative process. Surgical interventions, such as osteotomy or total knee arthroplasty, are reserved for advanced disease but are associated with risks and limited applicability in younger or active patients. These limitations have prompted the exploration of regenerative medicine approaches that aim to restore joint homeostasis and promote cartilage repair.

Autologous adipose-derived stromal vascular fraction (SVF) has emerged as a promising regenerative therapy for knee OA. SVF is a heterogeneous cell population derived from adipose tissue, comprising mesenchymal stem cells (MSCs), pericytes, endothelial progenitors, and other stromal cells. These cells possess anti-inflammatory, immunomodulatory, and trophic properties that can support tissue repair both directly and indirectly. SVF may contribute to cartilage regeneration through differentiation of MSCs into chondrocytes, secretion of growth factors and cytokines that stimulate resident chondrocytes, modulation of synovial inflammation, and promotion of angiogenesis in the subchondral bone. Compared to bone marrow-derived MSCs, adipose tissue provides a more abundant and easily accessible source of regenerative cells with minimal donor site morbidity.

Preclinical studies and early clinical trials have demonstrated that intra-articular injection of adipose-derived SVF is feasible, safe, and associated with improvements in pain, function, and cartilage quality. However, there is a paucity of controlled clinical data directly comparing SVF therapy with standard chondroprotective interventions, particularly in the Serbian population. The present study is designed to address this gap by systematically evaluating the clinical efficacy, safety, and regenerative potential of SVF in patients with moderate to severe knee OA.

This trial will employ rigorous, standardized methodologies for SVF isolation and administration, using a closed mechanical system to obtain a highly viable and potent cell population. By combining clinical assessments with imaging-based evaluation of cartilage repair, this study aims to generate comprehensive data on both symptomatic and structural outcomes. The results are expected to provide critical evidence to support the integration of SVF therapy into standard orthopedic practice, potentially offering a regenerative alternative for patients with degenerative knee disease.

Inclusion Criteria:

• Adults (≥18 years).
• Radiologically confirmed knee OA (grades II-IV, Kellgren-Lawrence scale).
• KOOS pain score ≤ 60 points.
• Symptomatic degenerative knee disease with at least 6 months of persistent pain.
• No history of major knee trauma or prolonged immobilization (>10 days)

Exclusion Criteria:

• Minors (<18 years).
• Asymptomatic OA (KL grade 0-I).
• Severe axial deformity (varus >10°, valgus >10°).
• Current anticoagulant or antiplatelet therapy.
• Intra-articular corticosteroid injection within the past 6 months.
• History of major knee trauma or surgery.