¹Martin-Luther-University Halle-Wittenberg, Halle, Deutschland
²University Witten/Herdecke, Halle, Deutschland

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Objectives: Hallux valgus (HV) is a common forefoot deformity that often leads to foot pain and functional limitations, requiring surgical intervention when conservative treatments fail. Tarsometatarsal arthrodesis is a widely used procedure for severe HV deformities, with plantar plate fixation demonstrating superior biomechanical outcomes. However, the biomechanical equivalence of different plantar plate designs remains unclear. Specifically, there is a lack of biomechanical studies comparing how design variations affect load distribution, durability, and the risk of material failure postoperatively.

Material and methods: This study involved a biomechanical analysis of two widely used plantar Lapidus plating systems: the U-shaped plate from Arthrex™ and the straight plate from Wright Medical™. A total of 20 fresh frozen cadaveric feet from 10 donors were included, ensuring none exhibited prior surgical interventions or deformities. The plates were assigned randomly to each specimen, and tarsometatarsal arthrodesis was performed according to the manufacturers' guidelines. Mechanical testing was conducted using a universal testing machine, focusing on cyclic loading and maximum load capacity to assess the mechanical stability of each system. Cyclic loads were systematically applied in four increments, culminating in a ramp test to ascertain the maximum load to material failure.

Results: The Arthrex™ and Wright Medical™ plantar Lapidus plates demonstrated commendable mechanical stability under cyclic loading, with nearly no significant differences in stiffness across the four cyclic loading force cycles. In the maximum load capacity test, the Wright Medical™ plate showed a higher mean load capacity (540.6 N, SD = 36.09) compared to the Arthrex™ plate (446.6 N, SD = 91.32), with a statistically significant difference (p = 0.03) and a large effect size (Cohen’s d = 1.56). The considerable variability in the Arthrex™ plate’s performance, as indicated by its wider standard deviation, warrants caution in the interpretation of these results, especially given the relatively small sample sizes.

Conclusions: This biomechanical analysis confirms that both the Arthrex™ and the Wright Medical™ plantar Lapidus plating systems provide comparable mechanical performance, despite differences in design. While slight variations in load-bearing capacity were noted, these differences were minimal. The comparable mechanical stability of both systems, especially while cyclic loading, suggests that surgeons can choose either system based on personal preference without compromising the surgical outcome in terms of postoperative plate failure. Further studies involving larger sample sizes and diverse testing conditions is needed to present any nuanced biomechanical differences between the designs of plantar plate systems and their long-term clinical implications.