Takeaways
Question : What was the precision of the lateral fixation PSI in orbital wall fractures without posterior bone edge and standard fixation point defect including malunion zygomaticomaxillary complex and comminuted mid-facial fracture reconstruction?
Findings: The difference of orbital volume and exophthalmometry value between affected and unaffected eyes of 16 patients with complex orbital fractures was reduced. The values between affected and unaffected eyes were not different after reconstruction.
Meaning: The novel designed-PSI enables precise reconstruction and should be considered as a cost-effective alternative.
INTRODUCTION
Reconstruction of complex orbital fractures involving both multiple wall fractures with posterior edge and inferior orbital rim defects is challenging due to the intricate and complex 3D shapes with limited intraoperative view and no standard implant fixation point. Titanium mesh is a preferred implant in this situation due to its ability of rigid fixation with screw. Before the 3D printing technology era, individualization of implant contour and fixation point were impossible. Free-hand bending and preformed standard plates could be poorly-fitted and could lead to visual disturbance and unaesthetic results such as enophthalmos and displacement of the implant.1 , 2 3–5
The purposes of this study were to evaluate the results of a newly designed lateral fixation titanium PSI in complex orbital wall reconstruction and to demonstrate its effectiveness by measuring orbital volume change and distance from the tip of the posterior clinoid process to the posterior corneal surface of the globe conveying correction of enophthalmos.
MATERIALS AND METHODS
Patients
The prospective noncomparative case series design of this study was approved by the institutional review board and ethics committee, Faculty of Medicine, Chulalongkorn University. All patients who had a unilateral complex orbital wall fracture with inferior orbital rim defect were recruited and underwent an orbital reconstruction using PSI performed by a single surgeon (PS) at King Chulalongkorn Memorial Hospital, Bangkok, Thailand between November 2018 and March 2021.
Indications for orbital reconstruction are as follows: (1) persistent diplopia with limitation of eye movement within 30 degrees of the primary position; (2) significant enophthalmos which exceeds 2 mm and is cosmetically unacceptable; (3) large fractures involving at least half of the orbital floor. Only multiple wall fracture cases with posterior edge and inferior orbital rim defects, including those with comminuted mid-facial fracture and malunion of zygomaticomaxillary complex, were selected for PSI placement. Bilateral cases and patients who had PSI placement for volume augmentation in anophthalmic socket were excluded from the study.
Informed consent was obtained from all patients. Pre and postoperative CT scans with image-guided surgery protocol for craniomaxillofacial scanning parameters were performed. Data of baseline characteristics (including age, gender, baseline ophthalmic examination and duration from time of injury to surgery) were gathered. Some distinct characteristics of the cases were also observed (eg, diplopia and concomitant orbital foreign body). All cases were late surgical repair.
Preparation of 3D-printed PSI
To fabricate the PSI, imaging data from the CT scan were transformed into a 3D file with a segmentation process in the anatomical bone region of interest. Three-dimensional reconstruction of the affected orbit was performed by using the mirrored nonaffected orbit as a template. The extent of the PSI was lined along with the fractured site but was limited anterior to the inferior orbital fissure, and maximal implant size was recommended by the surgeon (Fig. 1 ). The mirroring technique was based on the use of the mid-sagittal plane as a reference. The anatomical mesh implant with screw hole fixation at maxillary or zygomatic bone was then created using mirrored and nonmirrored bone as a guide. The PSI was manufactured by selective laser melting using titanium alloy Ti-6Al-4V (Meticuly Co., Ltd., Thailand) with a plate thickness of 0.45 mm and a screw hole diameter of 0.16 mm. A rapid prototype model of the affected orbit with position of the fixation point was also created for intraoperative guidance.
Fig. 1.: Illustration of the maximum recommended size of PSI for orbital reconstruction. It should be noted that the size of PSI was limited by the feasibility of transconjunctival placement.
Surgical Procedure
The orbital floor was approached through a preseptal transconjunctival or swinging eyelid incision. Medial orbital wall was approached through a transcaruncular incision. Patients who previously underwent orbital repair with transcutaneous incision (subcilliary or subtarsal) were exposed to the defected field via the previous incision. Orbital foreign bodies and pre-existing orbital floor implants including any plate and screws at inferior orbital rim, if present, were removed. Herniated orbital contents were repositioned, and orbital wall defects were reconstructed using the PSI implant. The anterolateral aspects of the PSI were secured to the remaining orbital rim of the maxillary or zygomatic bone using a titanium screw. The screw fixation point was at maxillary bone, if present, and at zygomatic bone when there was a complete inferior orbital rim defect. Sub-orbicularis oculi fat, malar fat, and pre-existing scars were transposed to cover the anterior edge of the implant. Periosteum and the conjunctival wound were closed with interrupted 5-0 and 7-0 vicryl sutures, respectively.
Orbital Volume Measurement and Exophthalmometry Measurement by Posterior Clinoid Method
Orbital volume was determined from preoperative and postoperative 3D reconstructed CT scans. Due to the absence or malposition of lateral orbital rim, the posterior clinoid method was chosen for exophthalmometry measurement. It was obtained from the axial plane of the CT scan with single measuring line from tip of the posterior clinoid process to the posterior corneal surface of the globe.6
Descriptive statistics were used to evaluate baseline characteristics with mean and SDs used for quantitative variables and counts and percentage for categorical variables. Continuous parametric data were analyzed by paired sample t test. A P value of less than 0.05 was considered statistically significant, and all analyses were conducted using SPSS software, version 22 (SPSS, Chicago, Ill).
RESULTS
Initially, eighteen patients with complex orbital fractures underwent reconstruction with PSI during the data collection period. Two patients were excluded, one with anophthalmos and the other with bilateral orbital fractures, leaving a total of 16 patients (nine men, seven women) included in the study for data analysis. The mean age of patients was 36 (19–55) years, and all patients had traumatic injury. Seven patients had previous repair with unsatisfactory outcomes using conventional implants. The average time from injury to surgery with PSI was 2.8 years (range 1–4 years).
Compared with preoperative value, there was a significant decrease in postoperative mean difference of orbital volume between eyes (reduction of the mean difference = 2904.40 mm3 , P < 0.001). Similarly, the postoperative mean difference of the exophthalmometry value between eyes was significantly decreased (reduction of the mean difference =2.89 mm, P < 0.001). After reconstructive surgery with PSI, the mean orbital volume and the exophthalmometry value between affected and unaffected eye was not statistically different (2503.82 ± 454.04 mm3 ;P = 0.57 and 1.09 ± 0.26 mm; P = 0.28, respectively) (Table 1 ). During the 6-month follow up period, there was one case of infected wound from retained orbital wooden foreign body that required implant removal and one case of unresolved vertical diplopia that required extraocular muscle surgery.
Table 1. -
Comparison of Preoperative and Postoperative Orbital Volume Differences and Exophthalmometry Value Differences between the Affected and Unaffected Eyes (N = 16)
Mean ± SE (mm3 )
P
Orbital volume
Preoperative difference
5408.22 ± 624.95
<0.001
Postoperative difference
2503.82 ± 454.04
0.57
Exophthalmometry value
Preoperative difference
3.98 ±0.61
<0.001
Postoperative difference
1.09 ± 0.26
0.28
*P based on paired T -test.
DISCUSSION
Orbital wall reconstruction can be performed with various kinds of implant materials7 , 8 3–5 , 9 8 , 10–12 2 3–5
In pure orbital wall fracture, the necessity of PSI is still debated due to its significantly higher cost. However, in cases of malunion zygomaticomaxillary complex and comminuted mid-facial bone fracture for those who lack proper fixation point for standard implant, other implants are not optimal solutions when compared with PSI. From our study, the reconstruction of complex orbital fractures using a lateral fixation designed PSI provides not only stability for the fracture site but also yields precise outcomes. We found no significant difference of the orbital volume and exophthalmometry value between the affected and unaffected orbits after reconstruction. Enophthalmos was improved and cosmetically acceptable in all cases as shown in an example patient (Fig. 2 ).
Fig. 2.: A 49-year-old male patient with right orbital floor, medial wall, lateral wall, nasal, and zygomatic fractures underwent previous orbital rim repair with plate and screws and orbital wall repair with bone graft. Photographs show improvement of enophthalmos from before (A) to after the PSI surgery (B). The figures below show pre and postoperative 3D-reconstruction CT scan illustrating that only old plate and screws at the inferolateral orbital rim were removed.
Late postoperative infection was found in one patient due to retained wooden foreign body, and the removal of the PSI was needed. One case with three previous surgeries had persistent diplopia from hypertropia after PSI orbital reconstruction of four wall fractures. This patient first presented with mark enophthalmos and limitation of eye movement due to poor orbital repair technique with medial and inferior rectus incarceration to the previous implant. Surgeons should be cautious of globe misalignment before placement of PSI implant, aiming for full correction in severe contracted orbital soft tissue and marked limited extraocular movement.
All cases in our study had delayed surgery due to unstable condition: seven had previous surgeries, five had concurrent life-threatening injuries requiring medical attention, two had chronic osteomyelitis at the fracture site, and two had globe rupture with ophthalmic complications. We confirmed the results from a prior study that delayed primary surgery did not result in worse outcomes when compared with early surgery.13 14 , 15
Although the PSI is highly precise and offers excellent clinical outcomes with significantly lower revision rates when compared with other orbital implants,2
CONCLUSIONS
It is shown by quantitative assessment that PSI enables precise reconstruction of complex orbital fractures with rim involvement. Individualized shape and fixation point outweigh its high cost in cases with malunion zygomaticomaxillary complex and comminuted mid-facial bone fracture. Implants that are meticulously designed to fit in the exact anatomical position of an orbit can yield excellent outcomes.
PATIENT CONSENT
The patient provided written consent for the use of his image.
REFERENCES
1. Schlittler F, Schmidli A, Wagner F, et al. What is the incidence of implant malpositioning and revision surgery after orbital repair? J Oral Maxillofac Surg. 2018;76:146–153.
2. Schlittler F, Vig N, Burkhard JP, et al. What are the limitations of the non-patient-specific implant in titanium reconstruction of the orbit? Br J Oral Maxillofac Surg. 2020;58:e80–e85.
3. Raisian S, Fallahi HR, Khiabani KS, et al. Customized titanium mesh based on the 3D printed model vs. manual intraoperative bending of titanium mesh for reconstructing of orbital bone fracture: a randomized clinical trial. Rev Recent Clin Trials. 2017;12:154–158.
4. Gander T, Essig H, Metzler P, et al. Patient specific implants (PSI) in reconstruction of orbital floor and wall fractures. J Craniomaxillofac Surg. 2015;43:126–130.
5. Kärkkäinen M, Wilkman T, Mesimäki K, et al. Primary reconstruction of orbital fractures using patient-specific titanium milled implants: the Helsinki protocol. Br J Oral Maxillofac Surg. 2018;56:791–796.
6. Tiong TYV, Sundar G, Young SM, et al. A novel method of CT exophthalmometry in patients with thyroid eye disease. Asia Pac J Ophthalmol (Phila). 2020;9:39–43.
7. Gunarajah DR, Samman N. Biomaterials for repair of orbital floor blowout fractures: a systematic review. J Oral Maxillofac Surg. 2013;71:550–570.
8. Dubois L, Steenen SA, Gooris PJ, et al. Controversies in orbital reconstruction-III. Biomaterials for orbital reconstruction: a review with clinical recommendations. Int J Oral Maxillofac Surg. 2016;45:41–50.
9. Strong EB, Fuller SC, Wiley DF, et al. Preformed vs intraoperative bending of titanium mesh for orbital reconstruction. Otolaryngol Head Neck Surg. 2013;149:60–66.
10. Baumann A, Burggasser G, Gauss N, et al. Orbital floor reconstruction with an alloplastic resorbable polydioxanone sheet. Int J Oral Maxillofac Surg. 2002;31:367–373.
11. Büchel P, Rahal A, Seto I, et al. Reconstruction of orbital floor fracture with polyglactin 910/polydioxanon patch (ethisorb): a retrospective study. J Oral Maxillofac Surg. 2005;63:646–650.
12. Tuncer S, Yavuzer R, Kandal S, et al. Reconstruction of traumatic orbital floor fractures with resorbable mesh plate. J Craniofac Surg. 2007;18:598–605.
13. Scawn RL, Lim LH, Whipple KM, et al. Outcomes of orbital blow-out fracture repair performed beyond 6 weeks after injury. Ophthalmic Plast Reconstr Surg. 2016;32:296–301.
14. Shin HS, Kim SY, Cha HG, et al. Real time navigation-assisted orbital wall reconstruction in blowout fractures. J Craniofac Surg. 2016;27:370–373.
15. Zavattero E, Ramieri G, Roccia F, et al. Comparison of the outcomes of complex orbital fracture repair with and without a surgical navigation system: a prospective cohort study with historical controls. Plast Reconstr Surg. 2017;139:957–965.
