Mechanical evaluation of a new minimum-contact plate for internal fracture fixation

Objective: To determine whether the mechanical properties (stiffness and strength) of a new design of internal fixation plate, with reduced bone-to-plate contact area for reducing disturbance to the bone blood supply at the fracture site, are comparable with those of commonly used fracture fixation plates. Design: Four-point bending and torsion tests were conducted to compare the new minimum contact plate (MCP) with two established internal fixation plates: the dynamic compression plate (DCP) and the limited contact dynamic compression plate (LC-DCP). The bending stiffness and strength were determined according to the International Standards Organization bending test for bone plates, and the torsional stiffness and torque to failure were calculated from torsional loading data with the plates attached to synthetic bones. Results: The new MCP plate was significantly stiffer than the other two plates and stronger than the DCP plate in bending (p < 0.01). In torsion, the MCP plate was marginally stiffer (p < 0.11) and significantly stranger (p < 0.01) than the LC-DCP plate and not as stiff and strong as the DCP plate (p < 0.01). Conclusions: Mechanically, the MCP plate has adequate stiffness and strength for clinical application because it is at least as stiff and strong as one of the commonly used plates under both bending and torsional loading conditions.