Mueller–Weiss syndrome, also known as Mueller–Weiss disease, is a rare idiopathic degenerative disease of the adult navicular bone characterized by progressive collapse and fragmentation, leading to mid- and hindfoot pain and deformity. It is most commonly seen in females, ages 40–60. Characteristic imaging shows lateral navicular collapse. This disease had been historically considered to be a form of adult onset osteonecrosis, with blood flow cutoff to the navicular.