Using a well‐established mouse model of degenerative joint disease with global deficiency in proteoglycan 4 (Prg4‐/‐),[32, 33] we revealed hallmark TMJ structure degeneration from a 3D perspective that was coupled with a drastically vascularized and innervated lateral capsule and synovial tissues and altered condyle vasculature networks not previously reported. Here, PRG4 is linked to osteoarthritis.