Cartilage Surface Lubrication

Cartilage surface lubrication refers to the set of molecular and physical mechanisms that minimize friction and wear between opposing articular cartilage surfaces in synovial joints. This process is essential for smooth, pain-free joint movement and is critical for joint health, particularly under high mechanical loads. Key molecules involved are Hyaluronic Acid (HA), Lubricin (PRG4), and Phospholipids (PL), especially Phosphatidylcholine (PC). These molecules act synergistically to provide extremely low friction coefficients even under high physiological pressures. Efficient cartilage surface lubrication preserves joint function by minimizing mechanical wear, reducing energy loss during movement, and preventing chondrocyte damage. In osteoarthritis (OA) or injury, the concentration/molecular weight of HA decreases, and the structure/function of lubricin degrades, leading to higher friction coefficients, increased wear, inflammation, pain, and progressive joint degeneration.