Are hip fractures caused by falling and breaking or breaking and falling? Photoelastic stress analysis

The distribution of stress in the heads of femurs has been assessed using an engineering technique known as photoelastic stress analysis. The aim of the investigation was to locate and evaluate the probable sites of structure failure in femurs with various axes of loading. The analysis shows that the maximum stress in the upper femur occurs in the cervical region during vertical loading. Lateral loading does not produce significant stress patterns at the sites of extracapsular hip fracture. It is concluded that cervical hip fractures in individuals suffering from osteoporosis result from a combination of fatigue damage and axial muscular compression, rather than forces generated by a fall. This has significance for the medico-legal interpretation of the cause of death following femoral neck fracture.