gms | German Medical Science

Objectives: Arthrodesis of the Os naviculare, Os cuneiforme I and Os metatarsale I (medial column) is performed for reasons such as Charcot arthropathy, arthritis, posttraumatic reconstruction or severe pes planus. The complication rate is still high and mainly resulting from inadequate fixation. Special plates, designed for medial column arthrodesis, seem to offer potential to reduce the complication rate. The aim of this study was to compare biomechanically plantar and dorsomedial fusion of the medial column using two new plating systems.

Methods: Eight matched pairs of human cadaveric legs were randomized in two groups and medial column fusion was performed using either plantar or dorsomedial variable-angle locking compression plates. The specimens were then biomechanically tested under cyclic progressively increasing axial loading with physiological profile of each cycle (Figure 1 [Fig. 1]).

In additiona to the machine data, anteroposterior x-rays were taken every 250 cycles and motion tracking was applied to determine movements at the arthrodesis side. Statistical evaluation of the parameters of interest was performed at a level of significance p=0.05.

Results and Conclusion: Angular and torsional deformations increased significantly in each group between 1000, 2000 and 4000 cycles (p≤0.034). Displacement of the talonavicular joint was significantly lower for plantar plating (p≤0.016) while there was significant less movement in the navicular cuneiform and tarsometatarsal I joints for dorsal plating (p<0.001). The two plating systems did not differ significantly with regard to stiffness and cycles to failure (p≥0.201) .

Generally, dorsomedial plating showed less movement than plantar plating in this setup under dynamic loading. However, there was no difference between the two plating systems with regard to stiffness and cycles to failure. Thus, other considerations, such as access morbidity, associated deformities / ulcers or surgeon's preference, may also guide the choice of plating pattern. Further clinical studies are necessary before definitive recommendations can be given.