Abstract
Introduction
Metatarsocuneiform (MTC) fusion is a standard treatment for arthritis, instability, and deformity of these joint. The MTC fusion achieves a good clinical outcome, but nonunion rates up to 12% have been reported. There are different methods for fixation of first MTC joint arthrodesis. Our aim was to compare the biomechanical characteristic of internal and external fixation constructs.
Hypothesis
Plantar plate fixation provides higher construct stiffness and endurance stability than intraosseous fixation.
Materials & Methods
Seven pairs of fresh-frozen human specimens were used in a matched pair test. In one foot the MTC joint was supplied with a plantar plate. On the other foot intraosseous-screw fixation was perfomed. The specimen constructs were loaded in a 4 point bending test. Parameters obtained were initial stiffness and number of cycles to failure. Failure was defined as displacement of more than 3 mm plantar gapping.
Results
The intraosseous-screw fixation group showed significantly (p=0.002) less cycles to failure (n=2946) than the plantare plate (n=7517). The initial stiffness was 131 N/mm for the plantare plate and 43 N/mm for the intraosseous implant (p=0.005).
Discussion & Conclusion
Plantar plate fixation of the first MTC fusion created a stronger and stiffer construct than intraosseous fixation. This was likely due to the plantar and dorsal implant position. A stiffer construct can reduce the risk of non-union and shorten the period of nonweight-bearing.
