Because of the recent trend for total hip arthroplasty in younger patients, more bone-preserving implants have been designed, based partly on the premise that maintenance of more bone stock would allow revision with standard primary implants. Another possible advantage of an implant that retains the femoral neck is that it may allow anatomical recreation of the center of the femoral head, femoral neck anteversion, anterior tilt, and caput-collum-diaphysis (CCD) angle, as well as femoral offset and leg length, without the use of modular implants. To determine whether the proximal femoral anatomy could be recreated, this study used computed tomography data and 3-dimensional modeling from 10 cadaver hips in 6 whole body specimens. Three femoral neck resection levels were investigated: 2 mm, 5 mm (recommended resection), and 10 mm from the base of the femoral neck. Results showed that the center of the femoral head, femoral neck anteversion, and CCD angle could all be recreated with available implant sizes, without modularity, within 2° and 1 mm on average. The addition of a modular neck provided no advantage in recreation of the hip center or other anatomical parameters. Use of a short metaphyseal femoral neck retaining-type of stem should allow restoration of anatomical parameters without the use of an exchangeable modular femoral neck.

This chapter begins with providing an overview of the history and development of various orthopedic trauma devices, including dynamic compression plates, limited contact dynamic compression plates, and intramedullary nails. It then transitions into a discussion of the specific biomechanical properties of each design and how this allows each device to perform its necessary task effectively, as well has how these properties could potentially lead to failure. Understanding the biomechanics of each device may be helpful when choosing which devices best address the fracture being dealt with. Although all orthopedic trauma devices have a finite lifespan, this chapter documents the advantages and shortcomings of each device in order to help understand which devices may be most useful in specific types of fractures. Finally, retrieval studies for various devices are summarized to better understand the modes of failure for each type of device. Learning from failures and studying these retrievals may help to better understand these devices and could lead to development of better devices in the future.