Eine biomechanische Untersuchung zur Lapidsarthrodese : Plantare winkelstabile versus dorsomediale winkelstabile Platte
Several different techniques have been used for Lapidus arthrodesis in hallux valgus surgery. To test the hypothesis that a plantarly applied angle-stable, anatomically precontoured plate provides stronger fixation than a dorsomedially applied angle-stable plate we biomechanically compared the two constructs for metatarsocuneiform arthodesis. Materials and methods: Six matched pairs of fresh frozen human cadaver specimens were used. The bone mineral density of each pair was measured with pQCT. One foot of each pair was randomly assigned to receive a plantar plate (DARCO® Plantar Lapidus Plate, Wright Medical Deutschland GmbH, Raisting, Germany) on the TMT joint while the other foot received a dorsomedially applied construct (H-shaped titanium 0-mm-step-off DARCO® LPS locked plate, Wright Medical Deutschland GmbH, Raisting, Germany). Then in turn a quasi-statically, a cyclic loading and load-to-failure test were performed. We obtained stiffness and range of motion (ROM) data in the statically, the constructs' displacement in the cyclic and finally stiffness and maximum load to failure in the load to failure test. Results: There was no difference regarding BMD (p = 0,25) and displacement ( p = 0,14). The plantar construct had greater initial stiffness (p = 0.028) and final stiffness (p = 0.042), ROM (p = 0.028), and load to failure (p = 0.043). Conclusion: The plantar plate combined with a compression screw provides a sturdier, stronger construct than does metatarsocuneiform fusion with a dorsomedially applied plate. Clinical Relevance: The shown biomechanical offers of the plantar plate may help to minimize rates of non-union and to admit earlier resumption of weightbearing.