A gel injection for the knee helps improve joint lubrication when natural synovial fluid becomes thinner or less effective, which often happens with arthritis., This gel acts as a cushion and Natural Lube: Products and DIYs to Try, Ingredients to Avoid, More Knee Viscosupplementation Complete Orthopedics & Podiatry 13 Types of Gel Injections for Knees Compared Joint Relief Institute DIY Personal Lubricant Going Zero Waste Gel injections (also called viscosupplementation) are used to treat joint pain from arthritis, especially in the knee. The gel acts as a lubricant and shock absorber inside the joint, helping reduce friction,