lipoatrophia semicircularis lipoatrophia semicircularis lipoatrophia semicircularis is a medical condition in humans, commonly known as ribbed thighs.lipoatrophia semicircularisother namessemicircular lipoatrophy)specialtydermatology it consists of a semicircular zone of atrophy of the subcutaneous fatty tissue located mostly on the front of the thighs. skin and underlying muscles remains intact. lipoathrofia semicircularis caused by armrest edge 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. cause it is not yet clear what exactly causes semicircular lipoatrophy. some hypotheses are that it is caused by localized pressure or by electromagnetic fields. diagnosis