The sphenozygomatic suture as a key site for osteosynthesis of the orbitozygomatic complex in panfacial fractures: a biomechanical study in human cadavers based on clinical practice

Abstract

The aims of this study were to determine the forces required for fracturing the intact orbitozygomatic complex and to evaluate the strength of the orbitozygomatic complex-fixation, especially with regard to the sphenozygomatic suture as a fixation point. In severe midfacial and panfacial fractures, the sphenozygomatic suture is routinely used in the authors' practice as a key site for fixation of the orbitozygomatic complex, thus establishing a stable outer frame as a basis for subsequent reconstruction. However, this has never been formally described, nor has it been biomechanically tested. Eight human cadaver heads were subjected to forces applied in a standard fashion to the orbitozygomatic complex on both sides (n = 16) using a servohydraulic testing machine. The force required to break the intact orbitozygomatic complex was measured on both sides. Subsequently, fracture patterns were noted and each orbitozygomatic complex (n = 16) was assigned to one of four groups: four-point fixation (zygomatic arch, frontozygomatic suture, infraorbital rim, zygomaticomaxillary buttress) using a 1.3/2.0-mm titanium system (group 1) and a 2.0-mm bioresorbable system (group 3); or three-point fixation (zygomatic arch, frontozygomatic suture, sphenozygomatic suture) using 1.3/2.0-mm titanium system (group 2) and a 2.0-mm bioresorbable system (group 4). Forces for failure of the constructs were measured. The force for failure of the intact orbitozygomatic complex was 1826 +/- 852 N. The mean force required for failure of the reconstructed orbitozygomatic complex was 504 +/- 178 N for group 1, 620 +/- 304 N for group 2, 93 +/- 22 N for group 3, and 133 +/- 31 N for group 4. The titanium constructs provided 27.7 percent (four-point fixation) and 31.7 percent (three-point fixation) of the intact breaking strength of the orbitozygomatic complex, which was significantly higher (p < 0.05) compared with 5.4 percent (four-point fixation) and 7.7 percent (four-point fixation) for the bioresorbable system. Plate bending (91 percent) was the primary cause for failure in the titanium plating system, whereas plate and screw breakage (57 percent) was responsible for failure of the resorbable system. The fixation of the sphenozygomatic suture was a key site in the fixation of the orbitozygomatic complex, which could be demonstrated with superior results in the three-point fixation group compared with the four-point fixation group. The bioresorbable system showed the lowest values in this cadaver study. Further experimental and clinical studies might determine whether the bioresorbable materials are sufficient for the treatment of complex fractures of the orbitozygomatic complex.