Biomechanical evaluation of reconstruction of the posterior complex in restorative laminoplasty with miniplates

Abstract

Objective To evaluatethe biomechanical effects of different miniplates on restorative laminoplasty. Methods Assembled restorative laminoplasty models were developed based on 3D printed L4 lamina. Three miniplates models (two-hole, L-shaped and H-shaped miniplates) were constructed. Static and dynamic compression tests were analyzed to investigate the biomechanical effects of different instruments in restorative laminoplasty. Results The “door close” phenomenon and the collapse of lamina occurred in L-shaped and two-hole miniplates, while plate break occurred in the L-shaped miniplates. However, these phenomenons were absent in H-shaped miniplates. The sustainable yield load of H-shaped miniplates was greater than that of L-shaped and two-hole miniplates. No significant difference in yielding-displacement was found between H-shaped and L-shaped miniplates, while both were much less than that of two-hole miniplates. Moreover, the compressive stiffness and the axial displacement under the same mechanical load were arranged as follows: H-shaped > L-shaped > two-hole miniplates. The results of dynamic compression test revealed that the peak load of H-shaped miniplates reached 873 N and was 95% of the average yield load of the static compression, and was better than that in two-hole and L-shaped miniplates. Besides, the dynamic compression results also showed that the ultimate load of H-shaped miniplates was more than twice that of two-hole miniplates or L-shaped miniplates. Conclusions The mechanical strength of H-shaped miniplates was superior to L-shaped and two-hole miniplates in maintaining spinal canal enlargement and spinal stability, and was more excellent in fatigue stability and ultimate load.