Osteoporosis is loss of skeletal bone which may result from a variety of factors. In osteoporosis, the bone mineral density (BMD) is reduced, bone microarchitecture deteriorates, and the amount and variety of proteins in bone are altered. Any person who is immobilized over a prolonged period will experience some degree of osteoporosis. Advanced age is a factor in osteoporosis.
Trabecular bone (inner part of the bone) is more affected than cortical bone (outer part of the bone). Spinal vertebrae are usually affected first. Typically, these are the lower thoracic and upper lumbar (T6-L1). If lesions are higher than this, neoplasm must be considered. Thoracic vertebrae (chest level spinal bone) sustain wedge-shaped fractures, while crush fractures are common in lumbar vertebrae.