Liposomal composite gel for knee osteoarthritis: mechanical and physicochemical properties assessment and clinical outcomes of a single-arm prospective study

Introduction Knee osteoarthritis (OA) impairs joint lubrication and biomechanics, causing pain and functional decline. Hybrid hyaluronic acid-phospholipid systems have shown enhanced boundary lubrication and favorable viscoelastic properties in experimental models, supporting clinical relevance. Objectives To evaluate the rheological and tribological properties, safety, and clinical outcomes of a liposomal composite gel in knee OA with a minimum 6-month follow-up. Methods This study was conducted in two stages. The first involved the rheological and tribological assessment of the liposomal composite gel using amplitude sweep testing and ball-on-cartilage tribometry. The second was a prospective study of 50 symptomatic patients who received three intra-articular knee injections. Pain and function were assessed using the Visual Analog Scale and the Western Ontario and McMaster Universities OA Index at baseline and at 2, 6, 14, and 28 weeks, with follow-up at 2 years. Objective assessments included Timed Up and Go, Five Times Sit-to-Stand, 10-Meter Walk Test, and Maximal Voluntary Isometric Contraction, which were evaluated up to 28 weeks. Results Rheological analysis demonstrated a broad linear viscoelastic region, while tribological testing showed a 13–14% reduction in friction coefficient compared with controls. Pain and stiffness decreased significantly within two weeks (p ≤ 0.01) and remained improved through 28 weeks and at 2 years (p ≤ 0.0001). Functional performance and extensor muscle strength improved significantly (p = 0.008). Conclusions The liposomal composite gel exhibited favorable rheological and tribological properties and resulted in rapid and durable improvements in pain and in knee OA with a favorable safety profile. Level of evidence IV.