"Umbau Zones" are seen in all except -(AP 90)
High-Yield Explanation
Looser zones, also known as cortical infractions, Milkman's linesor (Looser-)Umbauzonen, are wide, transverse lucencies traversing part way through a bone, usually at right angles to the involved cortex and are associated most frequently with osteomalacia and rickets. They are pseudofractures and considered a type of insufficiency fracture. Typically, the fractures have sclerotic irregular margins and are often symmetrical. Aetiology osteomalacia renal osteodystrophy fibrous dysplasia hyperthyroidism Paget disease of bone X-linked hypophosphataemia osteogenesis imperfecta