Materials and methods

Indications for using the technique included severe comminution, large defects with little or no posterior bony support and secondary reconstruction.

Patients were scanned using high resolution CT with a slice thickness of 0.5 mm. The raw CT information obtained was imported in DICOM (Digital Imaging and Communications in Medicine) file format and processed to create a 3D image using Mimics software (Materialise NV, Leuven, Belgium). Despite the ultra-thin CT slices, the orbital floor may, in some areas, be less than 0.5 mm thick . This is too thin to be captured by the scan, resulting in the phenomenon of pseudo-foramina when viewed in 3D format on both the injured and unaffected orbital floors. To overcome this obstacle, the captured air volume of the contralateral maxillary sinus was identified to create a virtual 3D image of that sinus. This modified CT was exported as an STL file into another software package, Freeform ^® (SensAble, USA) which allowed intuitive 3D digital manipulation with biofeedback. The position of the mid sagittal plane was then established in order to be able to mirror image the sinus morphology to the defect side ( Fig. 1 ). The superior contour of the 3D sinus volume thus recreates the shape of the orbital floor .

the process of virtual reconstruction of the orbital floor using the shape and position of the opposite maxillary sinus. (A) Capturing the air in the contralateral maxillary sinus. (B) Establishing a mid-sagittal plane. (C) Mirroring the maxillary sinus onto the defect side. (D) A 3D image with the virtually reconstructed orbital floor.

The resulting virtual model was used to construct a stereolithographic model ( Fig. 2 ) using rapid prototyping. This model was used to enable the shaping of the titanium mesh in the laboratory to the required contours to fit the virtually repaired orbital defect. The pre-shaped titanium mesh was then sent to be sterilized for use in the operating theatre. Alternatively the model was used to make an implant of the desired shape and size using titanium sheet as previously described . This was carried out by taking an impression of the affected orbit on the stereolithographic model with the now reconstructed orbital wall defect. A hard stone plaster model was poured, which was subsequently used to fabricate the customized implant from commercially pure titanium using pressure flasks. Two different titanium thicknesses of 0.25 and 0.5 mm were available, pressed over the cast using 6000 PSI for 24 or 48 h, respectively. The resulting plate was trimmed, smoothed and polished. Multiple venting holes were created in some cases, according to the designing surgeon’s preference, and a flange was extended over the orbital rim to facilitate implant positioning and to prevent it from being displaced posteriorly, with a hole for subsequent screw fixation. The implant was pacified overnight in concentrated nitric acid for decontamination. The final plate was sent for sterilisation to be used in the operating room. The shortest achievable time from the decision to operate to the implant being sterile and ready to use was 4 days with the rate-limiting step being mainly the logistic problems of the construction of the stereolithographic model at another offsite institution.

(A) Stereolithographic model with the customized titanium plate in position prior to sterilisation. (B) 3D reformatted image of a postoperative CT scan with the titanium plate highlighted.

The two alternative incisions used for access were the mid-eyelid blepharoplasty or the conjunctival incision, depending on operator preference. Where the conjunctival incision was used in the presence of floor and medial defects, a post-caruncular extension was performed to access the medial wall. Orbital dissection was performed in the normal way, exposing and delineating the defect. Herniated orbital contents were retrieved and the plate was inserted and anchored with one or more screws depending on plate design and position. Forced duction testing was performed in all cases and closure was performed after confirming that there was no restriction or tethering of the globe.

A retrospective review of 22 cases treated at the authors’ institution using customized titanium implants for orbital wall reconstruction was carried out. A form was designed for data collection and patients’ case notes were examined, looking at emergency cards, outpatient clinic notes, operating records and correspondence. The collected information was entered into a spreadsheet programme (MS Excel ^® , Microsoft USA) for further processing. The results were reviewed and analysed.

Results

Twenty-two patients were treated using this technique between 2003 and 2008 ( Figs 3 and 4 ). A summary of the results is presented in Table 1 . Seventeen patients presented with diplopia, nine of whom also had enophthalmos. Two patients had enophthalmos with hypoglobus but no diplopia. Postoperatively, 10 patients reported early resolution their diplopia. Six patients noticed significant improvement of their symptoms with mild residual diplopia, in one direction only and at the extremes of gaze, at final review. One patient required ocular muscle surgery. Enophthalmos resolved in eight of the nine cases. No patients developed enophthalmos or diplopia as a postoperative complication.

(A) Preoperative coronal CT scan image demonstrating a left-sided medial orbital wall defect. (B) Postoperative coronal CT scan of the same patient showing the customized titanium plate in position. (C) 3D reformatted postoperative CT scan demonstrating the medial wall titanium plate.

Extensive orbital floor defect reconstructed with a customized titanium mesh. (A) Sagittal view of the preoperative CT scans showing the unaffected side. (B) Sagittal view of the preoperative CT scans showing the orbital floor defect. (C) Sagittal view of the postoperative CT scans showing the titanium mesh reconstruction of the orbital floor defect.

Table 1

Results of post-traumatic orbital wall reconstruction using customized titanium implants in 22 patients.

	Age	Sex	Diagnosis (site and indication)	Aetiology	Preop enophthalmos	Preop diplopia	Time from trauma to surgery in days	Incision	Implant profile	Postop enophthalmos	Postop diplopia	Complications	Follow-up in months
1	23	M	Floor comminution with malar fracture	Assault	Yes	Yes	12	Lower blepharoplasty	0.5 mm plate	No	Resolved 30/7	Scleral show, settled later	16
2	30	M	Large floor defect with malar fracture	Assault	No	No	7	Lower blepharoplasty	Mesh	No	No	Scleral show	19
3	29	M	Floor comminution	Sports	No	Yes	13	Lower blepharoplasty	Mesh	No	Resolved 8/12	None	8
4	18	F	Floor and medial wall secondary reconstruction	RTA	Yes	Yes	114	Lower blepharoplasty	0.5 mm plate	Resolved	Improved	Mild residual diplopia	3
5	18	M	Large floor defect	Assault	No	yes	31	Conjunctival	Mesh	No	Improved	None	2
6	64	M	Floor and malar fracture	Work-related	No	No	17	Lower blepharoplasty	Mesh	No	No	None	5
7	24	F	Large floor defect	Assault	No	Yes	37	Lower blepharoplasty	Mesh	No	Improved	None	2
8	27	M	Large floor defect	Assault	No	Yes	20	Lower blepharoplasty	Mesh	No	Resolved 1/7	None	3
9	36	M	Large floor and medial wall defect	RTA	Yes with hypoglobus	No	62	Lower blepharoplasty	0.5 mm plate	Resolved	No	Ectropion (also had severe lid injuries)	5
10	15	M	Large floor defect	Sport	No	Yes	10	Lower blepharoplasty	0.5 mm plate	No	Resolved 1/7	None	20
11	29	M	Large medial wall defect	Sport	No	Yes	34	Lower blepharoplasty and medial ethmoidotomy	0.25 mm plate	No	Resolved 1/7	Temporary ectropion, resolved	6
12	32	F	Floor and medial wall secondary reconstruction	RTA	Yes with hypoglobus	Yes	2 years	Lower blepharoplasty	0.5 mm plate	Improved	Improved	Discomfort and palpable plate rim	38
13	44	M	Large floor defect	Sports	Yes	Yes	73	Conjunctival	0.25	Resolved	Required ocular muscle surgery	None	24
14	49	M	Large floor and medial wall defect	Assault	Yes with hypoglobus	Yes	253	Conjunctival with lateral canthotomy	Mesh	Resolved	Resolved	None	6
15	49	M	Large floor and medial wall defect	Assault	Yes with hypoglobus	No	68	Lower blepharoplasty	2 × 0.25 mm plates	Resolved	No	None	10
16	17	M	Large floor defect	Assault	Yes with hypoglobus	Yes	164	Conjunctival	0.25 mm plate	Resolved	Resolved 5 days postop	None	8
17	40	M	Large floor defect	Assault	Yes	Yes	234	Conjunctival	0.25 mm plate	Resolved	Resolved	Mild right globe elevation, subsequently settled	15
18	30	M	Comminution	Assault	No	Yes	27	Lower blepharoplasty	0.25 mm plate	No	Resolved	Deterioration in vision postop, resolved later	5
19	25	M	Large floor and medial wall defect	Fall	No	Yes	24	Lower blepharoplasty	0.25 mm plate	Resolved	No	None	6
20	29	M	Large floor defect	Sports	yes	Yes	90	Conjunctival	0.25 mm plate	Resolved	Resolved 7/7	None	3
21	19	M	Large floor defect	Assault	No	No	27	Lower blepharoplasty	0.25 mm plate	No	No	None	2
22	32	M	Delayed primary reconstruction	Assault	yes	Yes	331	Lower blepharoplasty	0.25 mm plate	Improved	Improved	None	4

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