A pseudofracture, also called a Looser zone, is a diagnostic finding in

osteomalacia Osteomalacia is a disease characterized by the softening of the bones caused by impaired bone metabolism primarily due to inadequate levels of available phosphate, calcium, and vitamin D, or because of resorption of calcium. The impairment of b ...

. Pseudofracture also rarely occurs in Paget's disease of bone, hyperparathyroidism, renal osteodystrophy, osteogenesis imperfecta, fibrous dysplasia, and hypophosphatasia. Looser zones are named after Emil Looser, a Swiss physician.

Structure

A band of bone material of decreased density may form alongside the surface of the bone. Thickening of the

periosteum The periosteum is a membrane that covers the outer surface of all bones, except at the articular surfaces (i.e. the parts within a joint space) of long bones. (At the joints of long bones the bone's outer surface is lined with "articular cartila ...

occurs. The formation of callouses in the affected area is also common. This gives the appearance of a false fracture. Typical sites of involvement are the axillary margins of the

scapula The scapula (: scapulae or scapulas), also known as the shoulder blade, is the bone that connects the humerus (upper arm bone) with the clavicle (collar bone). Like their connected bones, the scapulae are paired, with each scapula on either side ...

, ribs, pubic rami, proximal ends of the

femur The femur (; : femurs or femora ), or thigh bone is the only long bone, bone in the thigh — the region of the lower limb between the hip and the knee. In many quadrupeds, four-legged animals the femur is the upper bone of the hindleg. The Femo ...

and

ulna The ulna or ulnar bone (: ulnae or ulnas) is a long bone in the forearm stretching from the elbow to the wrist. It is on the same side of the forearm as the little finger, running parallel to the Radius (bone), radius, the forearm's other long ...

References

Skeletal disorders {{musculoskeletal-disease-stub