Titanium mesh versus bioresorbable plates in orbital floor repair: Implications for blunt‑impact biomechanics.

Abstract

The native orbital floor behaves as a thin "blow‑out fuse," redirecting blunt‑impact energy away from the globe. Whether this protective role is preserved or lost after reconstruction depends largely on the stiffness and thickness of the implant, but quantitative evidence remains sparse. A subject‑specific, CT‑derived head model was analyzed using Abaqus/Explicit. A 20-mm cylindrical impactor struck the reconstructed orbit at 6 m/s. Three clinically used implants were compared: (i) 0.4 mm poly‑L‑lactide‑co‑glycolide / β‑TCP composite plate (CMP), (ii) 0.8 mm poly‑L‑lactide‑co‑glycolide plate (BMP), and (iii) 1.0 mm contoured titanium mesh (Titan fan). Mesh‑density and contact definitions were verified a priori. Peak von Mises stress, absolute maximum principal strain, and internal energy were extracted for the implant and globe. Peak globe stress/strain on the anterior surface was similar across reconstructions (von Mises stress 1.80-1.85 MPa). Implant behavior differed substantially: the titanium mesh reached a peak implant von Mises stress of 87.7 MPa while absorbing 14.2 mJ of internal energy. In contrast, CMP and BMP showed markedly lower peak implant stress (2.83 MPa and 2.75 MPa, respectively) while absorbing more internal energy (16.5 mJ and 44.0 mJ). Globe internal energy was 4332 mJ with titanium versus 4180 mJ with both bioresorbable plates (3.5% reduction). Compliant, bioresorbable plates dissipate a larger fraction of impact energy within the implant itself and modestly reduce the load transmitted to the eye. These results support retaining a degree of orbital‑floor compliance-rather than maximal rigidity-when selecting materials and thicknesses for reconstruction after blow‑out fracture.