Restoration of the inferomedial orbital strut using a standardized three-dimensional printing implant

Abstract

The inferomedial orbital strut (IOS) is the thin bony junction of the orbital medial wall and floor. Its fracture is common and leads to serious complications, including enophthalmos, globe dystopia and diplopia. However, anatomical restoration of the IOS is challenging owing to reduced structural support; sound anatomical background and accurate implants are therefore essential. The aim of the present study was to incorporate data from cadaveric orbit anatomy into three-dimensional (3D) printing technology and to reconstruct the complex orbital fracture elaborately. After averaging the data from computed tomography (CT) images of 100 adult cadavers, the dimensions of the IOS were extracted, and a tangent sphere was created using a computer-aided design program. The curves were compared with the CT data of 10 adult patients from the simulation test. Based on these data, a standardized 3D implant, 1.15 mm thick, was designed using polycaprolactone. The implant was placed in five patients with complex orbital fractures. The radius of the sphere in contact with the orbit, measuring 33.54 mm, was confirmed to be appropriate. A comparison between the normal side volume (V0) and the postoperative volume (V_post ) showed that they were statistically similar. Furthermore, a comparison between V0 and the preoperative volume (V_pre ), and V_post compared with V_pre also showed a statistically significant difference (P < 0.05). On follow-up, the preoperative ocular symptoms were resolved. The orbital data obtained from 100 cadavers provided standardized orbital anatomy, and 3D printed implants were created. The implants were anatomically accurate with regard to the orbital cavity and adequately covered the simulation model. The implant also showed satisfactory results when applied clinically in actual patients.

Keywords: 3D printed implants; computer-aided design; inferomedial orbital strut; orbital fracture.

Figure 1

(a) Korean male and female standard skull model. (b) Measurement of the radius of the sphere to contact the orbital wall using standard skull models of males and females. [Color figure can be viewed at https://www.wileyonlinelibrary.com]

Figure 2

(a) Process of visualizing the two‐dimensional data from the computed tomography of the patient as a three‐dimensional (3D) model. (b) Comparison between Korean standardized orbital mesh implant and 3D simulation model. [Color figure can be viewed at https://www.wileyonlinelibrary.com]

Figure 3

(a) Korean standard‐type orbital implant manufactured using a three‐dimensional (3D) printer. (b) Comparison between the Korean standardized orbital implant and 3D model of actual patients. [Color figure can be viewed at https://www.wileyonlinelibrary.com]

Figure 4

Analysis of the differences between the orbital implant and orbital wall among Koreans using triangular points of implant. (a) Colored differences between the Korean orbital mesh implant and orbital wall of actual patients. (b) Differences between Korean orbital mesh implant and orbital wall of actual patients using numerical data. [Color figure can be viewed at https://www.wileyonlinelibrary.com]

Figure 5

Analysis of orbital volume in preoperative and postoperative computed tomography. According to the result of repeated measured one‐way anova, normal side volume (V0) and postoperative volume (V_post) were similar, but differences between V0 and preoperative volume (V_pre), as well as V_pre and V_post were significant (P < 0.05).