Lipoatrophia semicircularis, also known as semicircular lipoatrophy,[1] is a medical condition in humans, commonly known as ribbed thighs.

It consists of a semicircular zone of atrophy of the subcutaneous fatty tissue located mostly on the front of the thighs.

Semicircular lipoatrophy mainly affects office workers.

The ribs in the thighs are typically between 2 and 4 cm high and are typically located at about 72 cm above the ground, which is the standard height of office furniture.

Some hypotheses are that it is caused by localized pressure[2][3], by blood circulation problems[4], or by electromagnetic fields.