Long-Term Efficacy of Biomodeled Polymethyl Methacrylate Implants for Orbitofacial Defects

ORIGINAL ARTICLE Long-term Efficacy of Biomodeled Polymethyl Methacrylate Implants for Orbitofacial Defects

Michael J. Groth, MD; Aparna Bhatnagar, MD; William J. Clearihue, PhD; Robert A. Goldberg, MD; Raymond S. Douglas, MD, PhD

Objective: To report the long-term efficacy of custom between injury and presentation ranged from 1 month to polymethyl methacrylate implants using high-resolution 40 years. There were no significant complications, includ- computed tomographic modeling in the reconstruction of ing infection, extrusion, or displacement of the implant. complex orbitofacial defects secondary to trauma. In all of the patients, wound healing was uneventful, with antibiotic drugs administered perioperatively. Mean fol- Methods: Nine patients with complex orbitofacial bone low-up was 4.3 years from the first visit (range, 6 months defects after trauma were evaluated for this retrospective, to 10 years). nonrandomized, noncomparative study. All the patients underwent reconstruction using custom, heat-cured polymethyl methacrylate implants. Patients were followed up Conclusions: Computed tomographic biomodeled, pre- postoperatively and evaluated for complications. fabricated, heat-cured polymethyl methacrylate implants are well tolerated in the long term. Their advantages in- Results: Nine consecutive patients (5 men and 4 wom- clude customized design, long-term biocompatibility, and en) aged 28 to 63 years who underwent surgical recon- excellent aesthetic results. struction using prefabricated, heat-cured polymethyl methacrylate implants were included in the study. The interval Arch Facial Plast Surg. 2006;8:381-389

HE ACCURATE REPLICATION report the successful long-term efficacy of of complex human anatomy custom polymethyl methacrylate (PMMA) has long been sought for implants using high-resolution computed patients with severe orbito- tomographic (CT) modeling in the recon- facial defects. These abnor- structionofcomplexorbitofacialdefectssec- malitiesT could result from trauma, congen- ondary to trauma. ital defects, or iatrogenic defects such as tumor removal. The main objective of re- METHODS construction of orbitofacial defects is to restore anatomical integrity, providing proper eyelid and facial function and cos- PATIENTS metic improvement. Secondary reconstruc- Nine consecutive patients who underwent re- tions pose a particular challenge to the construction of orbitofacial defects secondary to surgeon. Severe trauma and the resultant trauma using CT biomodeled implants were in- multicontoured disruption of tissues causes cluded in the study. Criteria for the use of a cus- extensive scarring, loss of anatomical land- tom CT biomodel included severe bony trauma marks, and loss of functional tissue. Sec- with multicontoured orbitofacial defects and un- ondary reconstruction can exacerbate all of satisfactory primary reconstruction. Preopera- tive considerations included the degree of trauma, Author Affiliations: Orbit and these conditions. Many autologous and allogenic implant previous surgery, tissue volume, and func- Ophthalmic Plastic Surgery tional deficits. Measurements of the pupillary dis- Division, Jules Stein Eye materials have been used with varying suc- tance, degree of enophthalmos, displacement of Institute, Los Angeles cess and indications. In general, autologous zygoma, and orbital rim were included. In all of (Drs Groth, Bhatnagar, and alloplastic materials, which are mod- the cases, patients underwent 3-D CT of the or- Goldberg, and Douglas), eled intraoperatively, have failed to create bits and construction of a custom PMMA im- Brighton Laser and Surgery ideal 3-dimensional (3-D) facial and orbital plant to duplicate the anatomical defect. Institute, Beverly Hills contours. In contrast, high-resolution pre- (Dr Groth), and Orbital and operative modeling facilitates precise im- Ophthalmic Plastic and HIGH-RESOLUTION CT Reconstructive Surgery, Greater plant construction and placement, thus pro- BIOMODELED CUSTOM Los Angeles Veterans viding improved facial contour and implant PMMA IMPLANTS Administration Hospital, West stability. Concerns regarding alloplastic ma- Los Angeles (Drs Clearihue and terial placement include long-term implant Acquisition by CT and transfer and evalua- Douglas), Calif. stability and risk of infection.1 Herein we tion of patient data were performed according

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©2006 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 09/23/2021 Figure 1. Computed tomographic scan showing all 3 dimensions (sagittal, coronal, and axial) of the orbitofacial defect as a preliminary step in the formation ofa biomodel.

A B

Figure 2. Photographs of a 3-dimensional (3-D) computed tomographic biomodel with a polymethyl methacrylate (PMMA) implant. A, Front view of the biomodel (shown in violet) with the PMMA implant (shown in green) covering the orbital defect. B, Diagonal view of the same biomodel and implant demonstrating the 3-D effect and showing depth and dimension of the implant, which is fitted into the defect. The prefabricated PMMA implant (front [a] and diagonal [b] view) is constructed using computer-generated data and the biomodel. The generation of the 3-D biomodel is crucial, as it determines the exact shape and dimension of the future prefabricated PMMA implant.

to principles established in preliminary studies on geometri- DATA TRANSLATION cally standardized models and the production of implants for bony models.2 Generation of a physical model (BMI Biomedi- The technician identified the 3-D region of data describing the cal Modeling Inc, Boston, Mass) from CT data required 4 ba- model, and the slices were reconstructed into a 3-D object. The sic steps. The first step was acquisition of CT data using speci- reconstruction also interpolated between the slices, filling in the fied protocols (Figure 1). The second step was delineation of “gaps” within each single slice and producing a smoother model. a CT data subset, which described the model itself (Figure 2). The third step involved data translation into a rapid prototyp- ing machine to form the 3-D model. Using these data, an ac- IMPLANT FABRICATION TECHNIQUE curate prefabricated PMMA implant was constructed using a 6-step process.2 For best results, strict protocols on patient move- Generation of an accurate PMMA implant from the 3-D CT ment and technical considerations were followed (a copy of the model required several steps. Briefly, a thin layer of dental die BMI Biomedical Modeling Inc protocol can be obtained via e-mail stone was painted on the bony tissue side of the wax. After the at http://www.biomodel.com). Actual scanning time was kept die stone hardened, the mold was separated and the cavity was as short as possible, with 0.5- to 1.0-mm slices. thoroughly cleaned. The PMMA non–cross-linked acrylic mono-

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Figure 3. Intraoperative photographs showing accuate placement of the prefabricated polymethyl methacrylate (PMMA) implant. A, Formation of a thin meniscus of fluid between the bone implant interface is seen, which confirms proper placement of the PMMA implant over the anatomical defect. B, Clear distribution of fluid is seen over the bone under the transparent PMMA implant.

mer and polymer were processed and packed into the stone teristicsanddetailsoftheirinjuriesaresummarizedinTable1. mold. The mold was subjected to a 3-stage water bath heat- Ocular and orbital examination revealed decreased visual curing unit for 15 hours. Finally, the newly custom- acuity in 6 of 8 patients, hypoglobus in 6, restrictive stra- fabricated, accurate PMMA implant and the 3-D CT biomodel bismus in 5, lower eyelid ectropion in 5, and enophthalmos were sterilized using ethylene oxide gas followed by aeration for at least 72 hours to remove residual ethylene oxide. in 4. Upper eyelid ptosis was present in 3 patients, superior sulcus deformity in 2, and exposure keratopathy in 2. One SURGERY patient had traumatic mydriasis, aphakia, retinopathy and optic neuropathy, and frontal nerve hypoesthesia (Figure 4). All the procedures were performed by 2 of us (M.J.G. and R.A.G.). After reconstruction using custom PMMA implants, no sur- The goal of surgery was to restore anatomical function, orbital gical complications were reported. Two procedures required volume, and facial contour. During reconstruction of the orbi- minor intraoperative modification, such as grinding off ex- tofacial defects, care was taken to ensure precise implant place- cessive PMMA implant or cutting high points of bone. All ment. It was important that the implant did not rest on any high of the implants were fixed using screws that were counter- points of bone because this could dramatically alter orbital vol- fitted (below the level of the implant).This prevents any pro- ume or contour. Appearance of a thin meniscus of fluid be- jection of the screws, thus eliminating palpation externally. tween the bone implant interfaces was indicative of proper placement of the implant (Figure 3A), with an even distribution of The surgical details are included in Table 2. fluid over the entire surface of the bone under the clear implant Figure 5 demonstrates signs of orbitofacial deformity (Figure 3B). If any high points were noted from either the PMMA and scarring secondary to a boating accident 3 years ear- implant or the bone, these were trimmed down at the time of lier. Orbital trauma included a right blowout fracture, a surgery. After surgery, patients were observed for any signs of right tripod fracture, and lateral bowing of the medial wall complications, including orbital hemorrhage, severe pain, dis- of the maxillary antrum with the absence of its superior charge, displacement, and extrusion of the implant. wall, in addition to multiple facial injuries. Previous surgical reconstruction included multiple eyelid operations RESULTS and scleral buckling for retinal detachment. Preoperative assessment demonstrated 2 mm of right enophthalmos. Nine consecutive patients with complex orbitofacial bone Eyelid examination revealed 1 mm of right lower eyelid and soft tissue injuries secondary to trauma were evalu- ectropion, with 2 mm of inferior displacement of the right ated for reconstructive surgery. Their ages ranged from 28 lateral canthal angle, superior sulcus deformity, and ci- to 63 years (mean, 48.7 years). There were 5 men and 4 catricialorbitopathy.Thepatientunderwenthigh-resolution women. The interval between injury and presentation was CT biomodeling and custom implant construction. Sur- 1 month to 40 years (Table 1), during which time all of gical reconstruction using a PMMA implant included right the patients underwent surgical reconstruction else- orbital reconstruction with repair of the orbital blowout where. Procedures before reconstruction with PMMA in- fracture and orbital rim fracture. Additional procedures cluded the use of autologous bone graft (2 patients), po- included right upper eyelid ptosis repair and right infe- rous polyethylene implants (2 patients), titanium plate rior conjunctivoplasty using a free hard-palate mucous implants (2 patients), and soft tissue reconstruction with membrane graft with right canthoplasty. Intraoperatively, hard-palate eyelid grafting and silicone injection (1 pa- constant comparison was made between the patient’s tient each) (Table 2). anatomy and that of the model, which was placed on the All of the patients demonstrated signs and symptoms of table adjacent to the operating field. The implant fit well, severeorbitaltraumaandcicatrisation,includingfacialasym- with minor modification necessary along the posterior and metry (3 patients), orbital asymmetry including hypoglo- medial aspects of the orbital floor. The motility of the eye bus (6 patients), and diplopia (5 patients). Patient charac- was constantly checked during the procedure to prevent

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©2006 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 09/23/2021 Table 1. Characteristics of Patients Who Underwent Reconstructive Procedures Using Custom, Prefabricated PMMA Implants

Interval Patient Between No./Sex/ Year of Trauma and Eye Age, y Trauma Type of Trauma First Visit Symptoms Affected Injuries 1/F/28 1991 Boating accident 3 y Facial symmetry and loss of vision Right Blowout fracture, tripod fracture, penetrating injury to the orbit, retinal detachment, and eyelid laceration 2/F/42 1977 Motor vehicle crash 16 y Diplopia Right Fractures (orbital rim, floor, zygoma, maxilla) and crush injuries, right side of face 3/M/28 1997 Snowboarding accident 10 mo Diplopia and sunken eye Right Fractures (orbital rim and floor) 4/M/41 1992 Fall from 50-ft height 1 mo Diplopia and asymmetry of eyes Right Fractures (orbital rim and floor), eyelid laceration, and contusive injuries to the brain 5/F/48 1998 Motor vehicle crash 1 y Diplopia, asymmetry of eyes, Right Fractures (orbital rim, floor, maxilla, and malar), sunken eye, and drooping of the bilateral fracture zygoma, and severe midface upper eyelid contusion 6/F/62 1964 Fall on left side of face 40 y Improper eye closure and severe Left Fractures (zygoma and malar complex) and deformity of the lower eyelid midface deformity with concavity of the and left cheek maxilla 7/M/63 1990 Blunt injuries 9 y Facial asymmetry Left Fractures (orbital rim and zygoma) 8/M/59 1995 Motor vehicle crash 2 y Diplopia and facial asymmetry Right Fractures (orbital floor, zygoma, and malar complex) 9/M/48 2002 Motor vehicle crash 1 y Facial asymmetry, numbness, Right Blowout fracture and collapsed fracture of the and tingling maxilla

Abbreviation: PMMA, polymethyl methacrylate.

Table 2. Surgical Data of Patients Who Underwent Reconstruction Using PMMA Implants*

Date of Patient Surgery, Intraoperative No. Previous Procedures Previous Implant mo/d/y Surgical Procedure† Adjustments Follow-up, y 1 Scleral buckling and eyelid No 9/5/1995 Roof ϩ rim ϩ facial implant None 10 procedures 2 Multiple orbital reconstructive Bone grafts 8/1/1994 Floor ϩ rim None 4 procedures and strabismus correction 3 Multiple orbital reconstructive No 6/29/1998 Floor ϩ rim Trimming of the implant 1 procedures 4 Eyebrow laceration repair No 7/27/1993 Floor ϩ rim Grinding off of 6 excessive PMMA 5 Orbital floor implantation and Titanium mesh and 2/14/2000 Floor ϩ rim ϩ facial None 4 eyelid reconstruction Medpore and hard ϩ removal of old palate mucous implant membrane graft 6 Midface reconstruction and Cheek implant, 5/31/2005 Floor ϩ facial ϩ removal None 0.5 orbital rim and floor silicone injection, of old implant implantation and titanium implant 7 Reconstruction of the left eyelid No 8/5/1999 Floor ϩ volume enhancer None 6 and left midface 8 Multiple orbital reconstructive Autologous bone and 2/6/1997 Roof ϩ floor ϩ removal None 5 procedures Medpore implant of old implant 9 Upper eyelid laceration repair No 5/14/2003 Floor ϩ zygoma ϩ maxilla None 2

Abbreviation: PMMA, polymethyl methacrylate. *All of the patients had placement of screws and no complications. †Reconstruction of the orbitofacial defect using custom PMMA implants.

entrapment of the septae or extraocular muscle. The post- bital trauma included fractures of the right frontal bone, or- operative photograph demonstrates good improvement bital floor, and zygomatic arch (posterior and lateral dis- of the superior sulcus defect and improvement of enoph- placement consistent with trimalar fracture) and inferior thalmos and eyelid contour and function (Figure 6). displacement of orbital soft tissue. Preoperative assessment Figure 7A shows a patient with severe facial and or- of the right eye revealed 3.5 mm of hypoglobus, with de- bital trauma after a fall from a 50-ft height. Extensive or- pression of malar eminence, superior sulcus deformity, and

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4 Patients, No.

0 Decreased VA Hypoglobus EnophthalmosRestrictive Lower Eyelid Upper Eyelid SS Deformity Exposure Others Strabismus Ectropion Ptosis Keratopathy

Figure 4. Clinical features of the 9 patients who underwent surgical reconstruction of traumatic orbitofacial defects using polymethyl methacrylate implants. “Others” includes traumatic mydriasis, aphakia, retinopathy with optic neuropathy, and hypoesthesia over the frontal nerve region. VA indicates visual acuity; SS, superior sulcus.

Figure 5. Photograph demonstrating significant posttraumatic Figure 6. Postoperative photograph showing significant correction of the enophthalmos, superior sulcus deformity, and cicatricial orbitopathy. This superior sulcus deformity, hypoglobus, and resolving enophthalmos. The patient underwent high-resolution computed tomographic biomodeling, patient was followed up for 10 years and showed no signs of any construction of a prefabricated polymethyl methacrylate implant, and complication. reconstructive surgery with implantation.

orbital volume deficit with 3 mm of enophthalmos. There junctival incision with subperiosteal dissection were was hypoesthesia of the ophthalmic division of the trigemi- used to achieve access to the bony defects (Figure 9 and nal cranial nerve. Motility examination showed limitation Figure 10). Postoperative assessment demonstrates sig- of upgaze and downgaze in the right eye. The patient un- nificant improvement of the hypoglobus, superior sul- derwent CT biomodeling and custom implant construction. cus defect, and enophthalmos (Figure 7B and C). The orbital anatomical reconstructions with implants are Figure 11 demonstrates preoperative and postop- demonstrated in Figure 8A. Because the patient had a su- erative photographs of a patient who underwent PMMA perior orbital rim defect and an inferior orbital floor defect, implant reconstruction of multiple bony injuries and 2 implants were designed (Figure 8B and C). Figure 8D eyelid lacerations after a motor vehicle crash 1 year demonstrates typical lock-and-key fit to anatomical struc- before presentation. On examination, he demonstrated a tures. The same precise fit was achieved intraoperatively. healed malar fracture with hypoglobus and enophthal- A superior eyelid crease incision and an inferior transcon- mos of 2 mm each in addition to some degree of midface

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Figure 7. Photographs of a patient with severe facial and orbital trauma after a fall from a 50-ft height. A, Significant posttraumatic hypoglobus, restrictive strabismus, enophthalmos, and orbital volume defect of the right eye. The patient underwent multiple reconstructive procedures of the face and orbit but still experienced diplopia and facial asymmetry before undergoing reconstructive surgery with implantation of a prefabricated, custom polymethyl methacrylate implant. B, Early postoperative photograph showing minimal orbital inflammation, with sutures at the superior eyelid crease and lateral canthal angle after reconstructive surgery. C, At 1-year follow-up there is improvement of the hypoglobus, superior sulcus deformity, and enophthalmos.

A B

C D

Figure 8. Photographs showing computed tomographic biomodeling of the patient’s anatomical defects using polymethyl methacrylate (PMMA) implants placed over the defect. Two separate PMMA implants were constructed for superior and inferior bony defects (A). Prefabricated custom PMMA implants were designed for the superior orbital rim (B) and the orbital floor (C), with a lock-and-key fit to the anatomical structures (D).

descent and hollowing of the right malar and submalar extrusion or implant infection. None of the patients in regions (Figure 11A). The CT scan demonstrated a com- this study developed significant complications, includ- minuted fracture of the right maxilla involving the ante- ing infection, extrusion, or displacement of the implant. rior ramus of the orbital floor (Figure 12). A CT bio- All of the patients had minimal postoperative pain, and model was designed that clearly illustrated the areas of none developed hematoma or seroma. No surgical bony defect in the orbital floor (Figure 13A). Accord- drains were used. In all of the patients, wound healing ingly, a PMMA implant was constructed (Figure 13A was uneventful, with antibiotics given perioperatively. inset) to fully conceal the fracture site (Figure 13B). The Mean follow-up after reconstruction was 4.3 years patient withstood the surgery well and showed marked (range, 6 months to 10 years). All of the patients had a improvement after surgery (Figure 11B). routine follow-up with complete ophthalmologic evalu- Long-term data demonstrate that placement of ation once a week for a month, followed by once every orbital implants achieves reliable stability and long- 2 months for 6 months and quarterly annual visits term improvement in function with minimal risk of thereafter.

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Figure 9. Intraoperative photographs showing placement of a custom polymethyl methacrylate implant for a superior orbital rim defect. A, A superior eyelid crease incision was used to expose the fracture site. B, Fixation of the polymethyl methacrylate implant with metallic screws.

A B

Figure 10. Intraoperative photographs of a patient who underwent reconstruction of an orbital floor defect after trauma. A, An inferior transconjunctival incision was made with subperiosteal dissection to achieve access to the bony defect. B, Placement of a custom polymethyl methacrylate implant in the orbital floor defect.

A B

Figure 11. Preoperative and postoperative photographs of a patient who underwent reconstruction using a polymethyl methacrylate implant for multiple bony injuries and eyelid lacerations after a motor vehicle crash. A, Preoperative photograph showing right hypoglobus and enophthalmos in addition to midface descent and hollowing of the malar region. B, Postoperative photograph at 8-month follow-up showing improvement of the hypoglobus and facial symmetry.

COMMENT largely been based on issues concerning biocompatibility and availability. Autogenous materials such as bone grafts Many types of implant materials have been used for recon- provide many advantages, including excellent biocompat- structive orbitofacial surgery. Distinction between the use ibility and low infection and extrusion rates.3 However, these of autogenous bone grafts and alloplastic materials has materials have pertinent limitations, such as the potential

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©2006 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 09/23/2021 for a prolonged operative procedure,4 limited supply, sig- all, PMMA is well suited to custom orbital implantation nificant resorption, donor site morbidity, and minimal mal- and generates minimal thermal, electrical, and mag- leability and customization. Craniofacial implants have been netic conductivity.6 successfully made from materials such as PMMA and sili- Previous literature has raised concerns that alloplas- cone polymers for more than 45 years.5 Prefabrication of tic implants are prone to infection and explantation in PMMA offers customization while using an established bio- the long term. A study by Jordan et al7 reported that the compatible material. In 2 of the present patients, the pre- incidence of early and delayed complications varies from vious autologous bone grafts had to be removed owing to 0.4% to 7.0% with alloplastic implants. A study8 of 37 significant resorption or displacement. Customizing auto- orbital reconstructions using titanium implants re- grafts intraoperatively is difficult, and it is technically im- ported complications such as undercorrection, symp- possible to achieve ideal precision for eyelid and facial sym- tomatically palpable implants, and orbital infection re- metry. Small asymmetries of 1 to 3 mm are not only quiring explantation. In another study,4 a 7% complication aesthetically noticeable but can compromise eyelid func- rate included tight orbital fit, gaze limitation, and even- tion. In the patients described herein, periorbital facial sym- tual development of enophthalmos. Infections usually de- metry was improved, as was eyelid function. Use of CT bio- velop as a sequela to floor and medial wall orbital frac- modeling for alloplastic materials is convenient and provides tures. The proximity and disruption of the paranasal precise and functional reconstruction. sinuses seem too significant for infection.9 Bioactive glass Prefabricated computer-generated implants made from has been used in the reconstruction of the orbital floor. carbon fiber–reinforced polymer and prebent titanium The authors noted complications such as ectropion and plates have also been used for cranioplasty but are ex- infraorbital nerve hypoesthesia in 2 of 28 patients in their pensive. The ideal alloplastic material should be biocom- series.10 Orbital abscess, recurrent infection leading to im- patible, inert, lightweight, rigid, and inexpensive. Over- plant removal, postoperative infraorbital anesthesia, and palpable screws were some of the complications encoun- tered in other studies11,12 using alloplastic implants, such as porous polyethylene and silicone. In addition, 2 case reports described orbital fracture reconstruction using woven polyamide, followed by fistula formation from the maxillary antrum and ethmoid air cells. Both cases were cured by removal of the implant and surrounding tissue.7 In the present study, although the sinuses were involved in 6 of 8 cases, no such complication occurred. The incidence of perioperative infection has been re- markably low for porous hydroxyapatite.13 This resis- tance has been attributed to antibiotic-containing blood filling the pores of the implant, thus preventing normal and pathologic flora from establishing infection in the implant.13,14 However, cases with hydroxyapatite implants have been reported to develop clinically signifi- Figure 12. Coronal computed tomographic scan of the face demonstrating a cant deep-tissue infection.15 Although the number of pa- comminuted fracture of the right maxillary anterior wall with hemorrhagic opacification of the right maxillary sinus. Also seen is the fracture of the right tients in this study is too small to address the issue of orbital floor involving the anterior ramus. infection rate, all of these cases were secondary recon-

A B

Figure 13. Photographs of the computed tomographic biomodel and custom prefabricated implant for reconstruction of an orbitofacial defect. A, Computed tomographic biomodel prepared for the patient with an orbital floor fracture. The polymethyl methacrylate implant is shown in the inset. B, Photograph showing accurate placement of the polymethyl methacrylate implant over the orbital floor defect.

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©2006 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 09/23/2021 structions. In addition, CT biomodeling and prefabrica- Financial Disclosure: None reported. tion of implants in the present study provided geomet- Previous Presentation: This study was presented as a ric standardization and gapless technical precision and poster at the World Ophthalmology Congress; Febru- guaranteed an exact fit. In the present study, all of the ary 21, 2006; Sa˜o Paulo, Brazil. screws were counterfitted (buried below the bony level) so they could not be palpated. This reflects the safety and effectiveness of the PMMA and ensures its long-term sta- REFERENCES bility without the risk of displacement leading to infection and removal. Polymethyl methacrylate was shown 1. Eufinger H, Wehmoller M, Harders A, Heuser L. Prostheses for the reconstruc- to be well tolerated without presenting biological ad- tion of skull defects. Int J Oral Maxillofac Surg. 1995;24:104-110. verse effects such as foreign body reactions.16 2. Clearihue WJ, Groth MJ, Noel JC. PMMA implant fabrication, utilizing the Photo- In the present study, all of the patients were first seen polymer Solid Ground Forming Process. J Facial Somato Prosthet. 1998;4: 105-118. many years after the trauma and primary reconstruc- 3. Taub PJ, Rudkin GH, Clearihue WJ III, Miller TA. Prefabricated alloplastic im- tion (1 patient presented 40 years after the trauma) with plants for cranial defects. Plast Reconstr Surg. 2003;111:1233-1240. facial asymmetry and deformity. Reconstruction with cus- 4. Janecka IP. New reconstructive technologies in skull base surgery: role of tita- tom biomodeled implants offered a practical alternative nium mesh and porous polyethylene. Arch Otolaryngol Head Neck Surg. 2000; 126:396-401. in complex cases. It requires preoperative CT according 5. Steinhauser EW, Hardt N. Secondary reconstruction of cranial defects. J Maxil- to specific parameters and can be accomplished in al- lofac Surg. 1977;5:192-198. most all radiology centers. Model construction is straight- 6. Chiarini L, Figurelli S, Pollastri G, et al. Cranioplasty using acrylic material: a new forward, with reduced operative time. All of the pa- technical procedure. J Craniomaxillofac Surg. 2004;32:5-9. tients demonstrated long-term sustained improvement 7. Jordan DR, Onge PS, Anderson RL, Patrinely JR, Nerad JA. Complications as- sociated with alloplastic implants used in orbital fracture repair. Ophthalmology. of facial deformities. 1992;99:1600-1608. We conclude that biomodeled PMMA implants are well 8. Rubin PA, Bilyk JR, Shore JW. Orbital reconstruction using porous polyethyl- tolerated in the long term. Although this study is rela- ene sheets. Ophthalmology. 1994;101:1697-1708. tively small, it is the first time long-term data have been 9. McNab AA. Sino-orbital fistula: two case reports. Clin Experiment Ophthalmol. 2000;28:324-325. presented regarding the applicability of biomodeled 10. Kinnunen I, Aitasalo K, Pollonen M, Varpula M. Reconstruction of orbital floor PMMA implants. We believe that the advantages of cus- fractures using bioactive glass. J Craniomaxillofac Surg. 2000;28:229-234. tomization and long-term efficacy reported in this ar- 11. Ng SG, Madill SA, Inkster CF, Maloof AJ, Leatherbarrow B. Medpor porous poly- ticle far outweigh potential complications in complex or- ethylene implants in orbital blowout fracture repair. Eye. 2001;15:578-582. bital reconstruction, which requires precise implant 12. Mauriello JA Jr, Hargrave S, Yee S, Mostafavi R, Kapila R. Infection after inser- tion of alloplastic orbital floor implants. Am J Ophthalmol. 1994;117:246-252. customization to provide function improvement. 13. Rosen HM. Porous, block hydroxyapatite as an interpositional bone graft sub- stitute in orthognathic surgery. Plast Reconstr Surg. 1989;83:985-990. Accepted for Publication: July 26, 2006. 14. Merritt K, Shafer JW, Brown S. Implant site infection rates with porous and dense Correspondence: Raymond S. Douglas, MD, PhD, Or- materials. J Biomed Mater Res. 1979;13:101-108. 15. Rosen HM. The response of porous hydroxyapatite to contiguous tissue infection. bital and Ophthalmic Plastic Surgery Division, Jules Stein Plast Reconstr Surg. 1991;88:1076-1080. Eye Institute, 100 Stein Plaza, Room 2-267, Los Ange- 16. Luparello D, Bruschi S, Verna G, et al. Cranioplasty with polymethylmethacry- les, CA 90095 ([email protected]). late: the clinico-statistical considerations. Minerva Chir. 1998;53:575-579.

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