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

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.

Endoscopic orbital floor decompression with preservation of the inferomedial strut

BACKGROUND

Medial and inferior orbital decompression is most commonly performed in the setting of dysthyroid orbitopathy. Diplopia represents the most common complication and may be minimized through the preservation of a bony inferomedial strut (IMS). Historically, this has required a transconjunctival approach due to the technical demands of performing an isolated orbital floor decompression using endoscopic instrumentation. Here we describe a novel technique of a purely endoscopic orbital floor decompression with reliable preservation of the IMS.

METHODS

Description of a novel surgical technique for endoscopic orbital floor decompression with IMS preservation using frontal sinus instrumentation visualized by a 70-degree endoscope.

RESULTS

We have successfully used this technique in 12 orbits with 100% preservation of the bony inferomedial strut and no complications. The extent of decompression and width of the residual strut may be fine tuned as needed to optimize results.

CONCLUSION

Orbital floor decompression with IMS preservation may be reliably performed using purely endoscopic techniques. Successful completion of this procedure requires the adaptation of standard frontal sinus instrumentation to the maxillary sinus roof and thus may be readily mastered by any endoscopic surgeon comfortable with frontal sinus techniques.