Osteoporosis can be literally translated as porous bones, leading to structural deterioration of the bone coupled with a reduction in bone density, increasing the risk of fracture1. With untreated osteoporosis, the quantity and quality of the bone deteriorates and becomes vulnerable to fracture at much lower forces than would normally be expected. Dual energy x-ray absorptiometry (DXA) scanning is widely recognised as the gold-standard imaging modality for the measurement of bone mineral density (BMD) used to aid diagnosis, management and treatment response of osteoporosis medications2.

Atypical femoral fractures are differentiated from these standard fractures by the presence of fracture in the absence of trauma, increased cortical thickness in many cases, and originate in the lateral cortex of the femur. Atypical femoral fracture, is classified as being extracapsular, not affecting the hip joint, and at or distal to the subtrochanteric area.

Atypical femoral fractures (AFFs) have been associated with the long term use of bisphosphonate drugs used to treat osteoporosis and were first described in the seminal paper as being atraumatic and occurring in the presence of long term bisphosphonate therapy3. Numerous subsequent studies have demonstrated similar findings, highlighting the significant morbidity associated with these types of fractures4, 5, 6, 7. However, prior to complete fractures, there are often warning signs. Patients may report persistent groin, thigh or hip pain and on imaging “beaking” can be visualised on the lateral aspect of the femur. These early features provide the potential for opportunistic screening for AFF using dual energy x-ray absorptiometry (DXA) as a low dose imaging technique where patients will be scanned routinely, as a means of monitoring their response to osteoporosis treatment and assessment. Incomplete AFFs have been identified on imaging through thickening of the lateral femoral cortex, presenting as a peak. New DXA scanning software, developed by General Electric (GE) Lunar, presents the ability to routinely scan and assess the full length of the femur and highlight cortical changes as part of routine clinical care. Designed to be used as part of routine DXA scanning to identify changes in the femoral cortex, these scans aid the identification of cortical changes which may signify incomplete atypical femoral fractures.

GE Lunar conducted a study involving extended femur bench phantoms using the new version 17.0 scan software, however an in-vivo precision study offers a true reflection of measurement differences found in human subjects. The motivation for this precision study is the evaluation and assessment, in routine clinical use, of the extended femur scanning software developed by GE, designed to be used as part of routine DXA scanning, to identify changes in the femoral cortex in a clinical population.