The Clinical Feasibility of Newly Developed Thin Flat-Type Bioresorbable Osteosynthesis Devices for the Internal Fixation of Zygomatic Fractures: Is There a Difference in Healing Between Bioresorbable Materials and Titanium Osteosynthesis?

Abstract

Introduction: In recent years, bioresorbable plates have undergone remarkable development. However, there has been no attendant improvement in their strength, because strength requires thickness, and complications such as palpability are related to the thickness of bioresorbable plate systems. In this clinical study, we compared the surgical management of zygomatic fractures using newly developed thinner bioresorbable materials or conventional titanium miniplates.

Methods: Twelve patients with zygomatic fractures were randomly divided equally into 2 groups (6 with new bioresorbable osteosynthesis materials and 6 with standard titanium miniplates). Using computed tomography, we evaluated the thickness of the soft tissue and plate at the zygomaticofrontal sutures in each patient with the help of detailed radiographic computed tomography data at 6 months postoperatively. We compared the amount of soft-tissue volume increase between the uninjured healthy and injured operated sides in each patient.

Results: Both groups eventually achieved satisfactory healing, with a favorable restoration of form and function and without any complications, including palpability. The amount of soft-tissue volume increase at the operated side relative to the uninjured healthy side using new thin bioresorbable plates was 131.1% (range: 101.5-165.8). On the other hand, that of titanium miniplates was 126.4% (range: 102.2-167.6). There was no statistically significant difference (P > 0.05).

Conclusion: This newly developed thinner flat-type bioresorbable plate system could be considered clinically useful in the treatment of zygomatic fractures even in easily palpated areas, such as the infraorbital rim or zygomaticofrontal sutures, without any healing differences in skeleton as compared with conventional titanium miniplates.

FIGURE 1

The new design of the GRAND FIX (Gunze) osteosynthesis device composed of poly-l-lactide. It is available as thin and flat-type bioresorbable plate systems.

FIGURE 2

The 2-point fixation technique for the treatment of zygomatic fractures (bioresorbable osteosynthesis materials group (patient 1): (A and B) frontal and axial views of 3-dimensional computed tomography image showing inferior dislocation of the zygomatic body due to zygomatic fracture; (C) placement of a plate across the frontozygomatic fracture area via a lateral eyebrow incision; (D) placement of a plate across the fracture of the zygomaticomaxillary buttress through the maxillary vestibular approach.

FIGURE 3

The 3-point fixation technique for the treatment of zygomatic fractures (bioresorbable osteosynthesis materials group (patient 4): (A) frontal view of 3-dimensional computed tomography image showing inferior dislocation of the zygomatic body; (B) placement of a plate across the frontozygomatic fracture area via a lateral eyebrow incision; (C) placement of a plate across the infraorbital rim fracture area through a transconjunctival approach; (D) placement of a plate across the fracture of the zygomaticomaxillary buttress through the maxillary vestibular approach.

FIGURE 4

Evaluation of the postoperative computed tomography data using SimPlant 11.04 (Materialise Dental Inc): (A) determination of the midpoint from the medial and distal edges of the frontozygomatic sutures; (B) drawing a vertical line to the zygomatic bone from the midpoint to set the point of intersection with the soft tissue. Then the distance to the soft tissue from the bone was measured.

FIGURE 5

(A) A conventional plate system with a thick plate, further increased by the thickness of the screwhead; (B–D) the thin-type GRAND FIX (Gunze) has a thickness of 0.95 mm, and is characterized by a counterbore system. In the counterbore system, the thickness of the plate is not increased even when fixed using a screw.