Gout causes inflammation of joints primarily due to 

Gout is primarily caused by the accumulation of uric acid crystals in the joints. Uric acid is a metabolic waste product that can crystallise in the joints when present in high concentrations. These crystals trigger an immune response, leading to inflammation, pain, and swelling in the affected joint.

Gout is not primarily caused by cartilage degeneration/inflammation of the synovial membrane/excessive secretion of synovial fluid.