Arthrodesis of the first metatarsocuneiform joint: a comparative cadaveric study of external and internal fixation

Arthrodesis of the first metatarsocuneiform joint for the treatment of severe hallux abductovalgus with or without hypermobility of the first ray has gained popularity in recent years. The purpose of the current study was to compare the strength of external fixation to internal fixation for arthrodesis of the first metatarsocuneiform joint in a cadaveric model. Ten pairs of fresh frozen lower extremity cadaver specimens were used, and randomly assigned to fixation at the first metatarsocuneiform joint with crossed cannulated screws or a monorail uniplanar external fixator. Test specimens were then loaded to failure, which was defined as 3 mm or more of displacement at the arthrodesis site. Because of complications encountered during testing, 4 pairs of specimens were excluded from the final results. In the remaining 12 specimens (6 pairs of cadaver limbs), the mean maximal load to failure was 2300.02 +/- 711.86 N for the external fixator and 1666.38 +/- 1072.75 N for the internal fixation construct, and although this difference was not statistically significant (P = .2557), it was likely to have been clinically significant since approximately 27.55% more force was required to disrupt the external fixation construct in comparison with the internal fixation construct. Given these findings, further research into the mechanical and clinical properties of internal and external fixation for first metatarsocuneiform joint arthrodesis is warranted.

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