Spontaneous osteonecrosis of the lateral navicular is also known as Mueller Weiss syndrome. The typical appearance is a collapse of the lateral aspect of the navicular, resulting in a comma-shaped deformity. The development of early osteoarthritis is common.

Although the precise etiology remains subject of debate, the combination of relatively poor blood supply of the navicular and localized mechanical strain are contributing factors for the development of osteonecrosis. 

Women are more affected than men with a mean age of 47 years.