The X-Bolt: A Biomechanical Study with this New Design Variation of the Dynamic Hip Screw (DHS)

Francis O'Neill, McGloughlin T

Abstract

Objective:The objective of this study was to test a newly developed implant for the treatment of intertrochanteric fractures, the X-Bolt, against the current gold standard, the Dynamic Hip Screw (DHS), by comparing the amount of energy required to cause failure of both of them. Methods:Push out studies were performed with both the dynamic hip screw and the X-Bolt in an artificial bone substrate in the form of polyurethane foam blocks, which have predefined mechanical properties. These push out studies were performed as a means to investigate each implants resistance to ‘cut out’ as this is the most common mode of failure with the DHS. Results: The results demonstrate that the X-Bolt produced a force displacement curve with a different pattern of failure than the DHS. The X-Bolt initially required less energy to move it within the test material, than the DHS. However, the further the X-Bolt advanced within the test material, the greater the resistance and as this was the opposite as to what occurred with the DHS, the X-Bolt eventually required more energy than the DHS to advance through the test material and fail due ‘cut out’. Conclusion:The X-Bolt is a new concept with regard to fixation of intertrochanteric fractures. It produces a different force displacement curve than the dynamic hip screw. However further investigations are necessary before the true potential of this new implant is known.

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