The bioceramic orbital implant: a new generation of porous implants

The Evolution of Orbital Implants and Current Breakthroughs in Material Design, Selection, Characterization, and Clinical Use

It is occasionally essential to surgically remove the damaged eye of the patient in the case of serious oculoorbital injuries, intraocular cancers, and other life-threatening diseases. An orbital implant is placed into the anophthalmic socket after the eye is removed to provide adequate volume reinstatement and revamp the cosmetic look of a normal eye. In the previous few decades, implant design and material selection criteria have progressed from basic nonporous polymeric spheres to devices with more complicated shapes and functions to ensure improved long-term clinical results. Because of their highly interconnected porous design, ceramic and polymeric porous implants have found popularity as a passive framework for fibrovascular ingrowth, with lower obstacle rates and the option of setting to improve prosthetic eye mobility. These materials, however, are not without flaws. The danger of migration and extrusion, infections after surgery, and poor motility transferred to the cosmetic ocular prosthesis are important elements of orbital implants of today. As a result, the development of novel biomaterials with improved functionalities (i.e., antibacterial effect, angiogenesis, and in situ moldability) that allow better eye replacement is more desirable than ever, highlighting one of the most challenging aspects of research topics in the field of ocular implants. This study highlights the history of orbital implants. It gives an outline of current advancements in the area, over and above some essential observations for materials design, selection, characterization, and transformation to clinical applications.

"Hard" ceramics for "Soft" tissue engineering: Paradox or opportunity?

Tissue engineering provides great possibilities to manage tissue damages and injuries in modern medicine. The involvement of hard biocompatible materials in tissue engineering-based therapies for the healing of soft tissue defects has impressively increased over the last few years: in this regard, different types of bioceramics were developed, examined and applied either alone or in combination with polymers to produce composites. Bioactive glasses, carbon nanostructures, and hydroxyapatite nanoparticles are among the most widely-proposed hard materials for treating a broad range of soft tissue damages, from acute and chronic skin wounds to complex injuries of nervous and cardiopulmonary systems. Although being originally developed for use in contact with bone, these substances were also shown to offer excellent key features for repair and regeneration of wounds and "delicate" structures of the body, including improved cell proliferation and differentiation, enhanced angiogenesis, and antibacterial/anti-inflammatory activities. Furthermore, when embedded in a soft matrix, these hard materials can improve the mechanical properties of the implant. They could be applied in various forms and formulations such as fine powders, granules, and micro- or nanofibers. There are some pre-clinical trials in which bioceramics are being utilized for skin wounds; however, some crucial questions should still be addressed before the extensive and safe use of bioceramics in soft tissue healing. For example, defining optimal formulations, dosages, and administration routes remain to be fixed and summarized as standard guidelines in the clinic. This review paper aims at providing a comprehensive picture of the use and potential of bioceramics in treatment, reconstruction, and preservation of soft tissues (skin, cardiovascular and pulmonary systems, peripheral nervous system, gastrointestinal tract, skeletal muscles, and ophthalmic tissues) and critically discusses their pros and cons (e.g., the risk of calcification and ectopic bone formation as well as the local and systemic toxicity) in this regard. STATEMENT OF SIGNIFICANCE: Soft tissues form a big part of the human body and play vital roles in maintaining both structure and function of various organs; however, optimal repair and regeneration of injured soft tissues (e.g., skin, peripheral nerve) still remain a grand challenge in biomedicine. Although polymers were extensively applied to restore the lost or injured soft tissues, the use of bioceramics has the potential to provides new opportunities which are still partially unexplored or at the very beginning. This reviews summarizes the state of the art of bioceramics in this field, highlighting the latest evolutions and the new horizons that can be opened by their use in the context of soft tissue engineering. Existing results and future challenges are discussed in order to provide an up-to-date contribution that is useful to both experienced scientists and early-stage researchers of the biomaterials community.

[Long-term results of the compatibility of a coralline hydroxyapatite implant as eye replacement]

BACKGROUND

Coralline hydroxyapatite has been used since 1983 as volume replacement. Through 2001, a total of 200 hydroxyapatite implants were used in our department.

OBJECTIVE

This prospective study was undertaken to measure the subjective and objective long-term tolerance of this implant.

MATERIALS AND METHODS

In 2012, a total of 20 patients were examined, who were enucleated or eviscerated between 1993 and 2001 (average follow-up 16.2 years) and had an hydroxyapatite implant placed with a scleral sheath. We evaluated the subjective tolerance and measured the motility, the prominence of the globe, lid positions, changes of the conjunctiva and postoperative complications.

RESULTS

The subjective long-term tolerance was reported to be good. All patients had a ptosis; an ectropion was found in 50% of patients. In 40% of the patients additional surgery was performed. The motility was better in primary than in secondary placed implants. Volume replacement was successful in 10 patients, 9 patients had a retraction and 1 patient a prominent prosthesis.

DISCUSSION

Hydroxyapatite implants with sclera sheathing were well tolerated and showed good motility on long-term follow-up over more than 16 years. Lid malpositions such as ptosis or ectropion are common but might be due to mechanical stress through the prosthesis and atrophy of the orbital fat.

Integrated versus non-integrated orbital implants for treating anophthalmic sockets

BACKGROUND

Anophthalmia is the absence of one or both eyes, and it can be congenital (i.e. a birth defect) or acquired later in life. There are two main types of orbital implant: integrated, whereby the implant receives a blood supply from the body that allows for the integration of the prosthesis within the tissue; and non-integrated, where the implant remains separate. Despite the remarkable progress in anophthalmic socket reconstruction and in the development of various types of implants, there are still uncertainties about the real roles of integrated (hydroxyapatite (HA), porous polyethylene (PP), composites) and non-integrated (polymethylmethacrylate (PMMA)/acrylic and silicone) orbital implants in anophthalmic socket treatment.

OBJECTIVES

To assess the effects of integrated versus non-integrated orbital implants for treating anophthalmic sockets.

SEARCH METHODS

We searched CENTRAL (which contains the Cochrane Eyes and Vision Trials Register) (2016, Issue 7), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to August 2016), Embase (January 1980 to August 2016), Latin American and Caribbean Health Sciences Literature Database (LILACS) (1982 to August 2016), the ISRCTN registry (www.isrctn.com/editAdvancedSearch), ClinicalTrials.gov (www.clinicaltrials.gov), and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 8 August 2016.

SELECTION CRITERIA

Randomised controlled trials (RCTs) and quasi-RCTs of integrated and non-integrated orbital implants for treating anophthalmic sockets.

DATA COLLECTION AND ANALYSIS

Two authors independently selected relevant trials, assessed methodological quality and extracted data.

MAIN RESULTS

We included three studies with a total of 284 participants (250 included in analysis). The studies were conducted in India, Iran and the Netherlands. The three studies were clinically heterogenous, comparing different materials and using different surgical techniques. None of the included studies used a peg (i.e. a fixing pin used to connect the implant to the prosthesis). In general the trials were poorly reported, and we judged them to be at unclear risk of bias.One trial compared HA using traditional enucleation versus alloplastic implantation using evisceration (N = 100). This trial was probably not masked. The second trial compared PP with scleral cap enucleation versus PMMA with either myoconjunctival or traditional enucleation (N = 150). Although participants were not masked, outcome assessors were. The last trial compared HA and acrylic using the enucleation technique (N = 34) but did not report comparative effectiveness data.In the trial comparing HA versus alloplastic implantation, there was no evidence of any difference between the two groups with respect to the proportion of successful procedures at one year (risk ratio (RR) 1.02, 95% confidence interval (CI) 0.95 to 1.09, N = 100, low-certainty evidence). People receiving HA had slightly worse horizontal implant mobility compared to the alloplastic group (mean difference (MD) -3.35 mm, 95% CI -4.08 to -2.62, very low-certainty evidence) and slightly worse vertical implant motility (MD -2.76 mm, 95% CI -3.45 to -2.07, very low-certainty evidence). As different techniques were used - enucleation versus evisceration - it is not clear whether these differences in implant motility can be attributed solely to the type of material. Investigators did not report adverse events.In the trial comparing PP versus PMMA, there was no evidence of any difference between the two groups with respect to the proportion of successful procedures at one year (RR 0.92, 95% CI 0.84 to 1.01, N = 150, low-certainty evidence). There was very low-certainty evidence of a difference in horizontal implant motility depending on whether PP was compared to PMMA with traditional enucleation (MD 1.96 mm, 95% CI 1.01 to 2.91) or PMMA with myoconjunctival enucleation (-0.57 mm, 95% CI -1.63 to 0.49). Similarly, for vertical implant motility, there was very low-certainty evidence of a difference in the comparison of PP to PMMA traditional (MD 3.12 mm 95% CI 2.36 to 3.88) but no evidence of a difference when comparing PP to PMMA myoconjunctival (MD -0.20 mm 95% CI -1.28 to 0.88). Four people in the PP group (total N = 50) experienced adverse events (i.e. exposures) compared to 6/100 in the PMMA groups (RR 17.82, 95% CI 0.98 to 324.67, N = 150, very low-certainty evidence).None of the studies reported socket sphere size, cosmetic effect or quality of life measures.

AUTHORS' CONCLUSIONS

Current very low-certainty evidence from three small published randomised controlled trials did not provide sufficient evidence to assess the effect of integrated and non-integrated material orbital implants for treating anophthalmic sockets. This review underlines the need to conduct further well-designed trials in this field.

Experimental acrylonitrile butadiene styrene and polyamide evisceration implant: a rabbit clinical and histopathology study

ABSTRACT The purpose of this study was to evaluate acrylonitrile butadiene styrene (ABS) and polyamide implants in rabbits submitted to evisceration at the macroscopic and microstructure level and to assess clinical response and histopathological changes as well. For the experimental study implants of 12mm diameter were prepared by rapid prototyping, weighed and the outer and inner surfaces evaluated macroscopically and by electron microscopy. In addition, a compression test was performed and ultrastructural damage was then determined. After evisceration of the left eyeball, nine New Zealand rabbits received ABS implants and nine others received polyamide implants. The animals were assessed daily for 15 days after surgery and every seven days until the end of the study (90 days). Histopathological evaluation was performed at 15, 45 and 90 days after surgery. The ABS implants weighed approximately 0.44g, while the polyamide ones weighed 0.61g. Scanning electron microscopy demonstrated that the ABS implants had regular-sized, equidistant micropores, while the polyamide ones showed micropores of various sizes. The force required to fracture the ABS implant was 14.39 ±0.60 Mpa, while for the polyamide one, it was 16.80 ±1.05 Mpa. Fifteen days after surgery, we observed centripetal tissue infiltration and scarce inflammatory infiltrate. Implants may be used in the filling of anophthalmic cavities, because they are inert, biocompatible and allow tissue integration.

Orbital implants: State-of-the-art review with emphasis on biomaterials and recent advances

In the treatment of severe oculo-orbital traumas, intraocular malignancies or other life-threatening conditions it is sometimes necessary to surgically remove the patient's diseased eye. Following the removal of the eye, an orbital implant is inserted into the anophthalmic socket in order to provide satisfactory volume replacement and restore the aesthetic appearance of a normal eye. Over the last decades, the implant design and the criteria of materials selection evolved from simple non-porous polymeric sphere to devices with more complex shape and functionalities for ensuring better clinical outcomes in the long-term. Polymeric and ceramic porous implants have gained prominence since their highly interconnected porous architecture allows them to act as a passive framework for fibrovascular in-growth offering reduced complication rates and the possibility of pegging to enhance the motility of the artificial eye. However, there are still drawbacks to these materials. Some critical aspects of today's orbital implants include the risk of migration and extrusion, postoperative infections and low motility transmitted to the aesthetic ocular prosthesis. Hence, the development of novel biomaterials with enhanced functionalities (e.g. angiogenesis, antibacterial effect, in situ mouldability) which enable an improved outcome of eye replacement is more than ever desirable and represents one of the most challenging topics of research in the field of ocular implants. This review summarizes the evolution of orbital implants and provides an overview of the most recent advances in the field as well as some critical remarks for materials design, selection, characterization and translation to clinical applications.

[Porous orbital implants]

Since the introduction of the first coralline hydroxyapatite porous orbital implant as eye replacement in the early 1980s, numerous other modified porous implants have been developed. Due to the different design of the existing studies concerning long-term safety with, in some cases, relatively short follow-up, a comparison is difficult and none of the implant types can be clearly identified as being superior. Factors affecting the exposure rate of the implant seem to be the implant coating, the surgical technique and the condition of the patient's tissue at the beginning of surgery.

Bioceramics in ophthalmology

The benefits of ceramics in biomedical applications have been universally appreciated as they exhibit an extraordinarily broad set of physico-chemical, mechanical and biological properties which can be properly tailored by acting on their composition, porosity and surface texture to increase their versatility and suitability for targeted healthcare applications. Bioceramics have traditionally been used for the repair of hard tissues, such as bone and teeth, mainly due to their suitable strength for load-bearing applications, wear resistance (especially alumina, zirconia and composites thereof) and, in some cases, bone-bonding ability (calcium orthophosphates and bioactive glasses). Bioceramics have been also applied in other medical areas, like ophthalmic surgery; although their use in such a context has been scientifically documented since the late 1700s, the potential and importance of ceramic ocular implants still seem to be underestimated and an exhaustive, critical assessment is currently lacking in the relevant literature. The present review aims to fill this gap by giving a comprehensive picture of the ceramic-based materials and implants that are currently used in ophthalmology and pointing out the strengths and weaknesses of the existing devices. A prospect for future research is also provided, highlighting the potential of new, smart bioceramics able to carry specific added values which could have a significant impact on the treatment of ocular diseases.

Adverse events associated with biodegradable lactide-containing suture anchors

PURPOSE

To evaluate the occurrence of adverse events and inflammatory reactions related to the use of biodegradable anchors.

METHODS

A retrospective review of a consecutive series of arthroscopic shoulder procedures using biodegradable suture anchors performed by a single surgeon was undertaken. The database was purged of patient identifiers. The blinded data were analyzed for procedure type, anchor type and composition, associated procedures, and general demographic data. Anchor composition and number were recorded. A shoulder procedure after the index operation was considered an adverse event. The nature of these procedures was evaluated using medical records, operative images, and video, looking specifically for inflammatory reactions. Any anchor-related issues were documented.

RESULTS

Three hundred sixty cases met the inclusion criteria. The procedure was a tendon repair (rotator cuff or biceps) in 265 cases and a labral repair (instability or SLAP) in 97, 2 of which were combined instability and tendon repairs. Nine different biodegradable anchors were identified, possessing 4 different polymer combinations. Adverse events (reoperations) were identified in 18 of 360 patients (5%): 13 tendon repairs and 5 labral/instability repairs. Only 2 were anchor related. In 1 tendon repair case, the anchor broke and an anchor fragment required removal. In 1 labral repair case, the anchor eyelet (a suture) loosened from the anchor body and eroded the humeral head. No cases of inflammatory synovitis were observed. No statistical difference in adverse event rates existed between tendon and labral repairs (P > .05).

CONCLUSIONS

Anchor-specific adverse events occurred in 2 of 360 procedures (0.5%). One was anchor design related (the prominent head containing the suture eyelet broke off) in a poly-L-lactic acid (PLLA) anchor. One was anchor material related and occurred when the poly-levo (70%)/dextro (30%)-lactide anchor body reabsorbed, loosening the encased eyelet suture and allowing this suture to migrate into the joint. No inflammatory reactions were documented in the slowly degrading pure PLLA or more rapidly degrading biocomposite PLLA/β-tricalcium phosphate-based anchors.

LEVEL OF EVIDENCE

Level IV, retrospective review, therapeutic study.

Biomaterials for orbital implants and ocular prostheses: overview and future prospects

The removal of an eye is one of the most difficult and dramatic decisions that a surgeon must consider in case of severe trauma or life-threatening diseases to the patient. The philosophy behind the design of orbital implants has evolved significantly over the last 60 years, and the use of ever more appropriate biomaterials has successfully reduced the complication rate and improved the patient's clinical outcomes and satisfaction. This review provides a comprehensive picture of the main advances that have been made in the development of innovative biomaterials for orbital implants and ocular prostheses. Specifically, the advantages, limitations and performance of the existing devices are examined and critically compared, and the potential of new, smart and suitable biomaterials are described and discussed in detail to outline a forecast for future research directions.

Long-term outcomes of pegged and unpegged bioceramic orbital implants

PURPOSE

To evaluate the long-term outcomes of pegged and unpegged bioceramic orbital implants.

METHODS

A retrospective analysis of 101 cases of evisceration, enucleation, or secondary implant surgery with placement of a bioceramic porous implant was conducted. Type of surgery, existence of a peg, peg system used, time of pegging, problems encountered before and after pegging, treatment methods, and final status were recorded.

RESULTS

Evisceration was performed on 74, enucleation on 16, and secondary implant surgery on 11 patients. The patients were observed for a mean of 68.4 months (3 months-12 years). Fifty-three of the 101 patients were pegged. Patients were pegged at a mean of 9.3 months (6-23 months). Hydroxyapatite-coated, titanium-sleeved, titanium pegs were used in 43 patients, and titanium peg and sleeve system was used in 10 patients. Major complications were exposure and infection. Three patients presented with early exposure and late exposure developed in 14 of pegged and 4 of unpegged patients. The difference in late-exposure rates between pegged and unpegged group was statistically significant (p < 0.05). Implant infection developed in 9 of the pegged and in 1 of the unpegged patients. Implant exposure was noted in 6 of these 10 patients with infection. The difference in infection rates between the pegged and unpegged patients was statistically significant (p < 0.05). In 2 of the pegged patients, removal of bioceramic implant was required and after resolution of infection, another type of porous implant was implanted and repegged. The peg system was removed in 6 patients for the management of either exposure, infection, extrusion, hypermobility of sleeve, or peg falling out. Four patients were repegged. The time period between peg insertion and development of complications ranged from 15 days to 10 years. 86.8% of pegged patients were free of major complications and satisfied with the result at the last follow-up visit.

CONCLUSION

Despite potential complications that can occur as late as 10 years, bioceramic porous implants yield satisfactory long-term results. Existence of a peg system appears to play a role in the increased rate of late-onset complications. Further investigations on new and safer pegging systems should be conducted.

Standard enucleation with aluminium oxide implant (bioceramic) covered with patient's sclera

Purpose. We describe in our study a modified standard enucleation, using sclera harvested from the enucleated eye to cover the prosthesis in order to insert a large porous implant and to reduce postoperative complication rates in a phthisis globe. Methods. We perform initially a standard enucleation. The porous implant (Bioceramic) is then covered only partially by the patient's sclera. The implant is inserted in the posterior Tenon's space with the scleral covering looking at front. All patients were followed at least for twelve months (average followup 16 months). Results. We performed nineteen primary procedures (19 patients, 19 eyes, x M; x F) and secondary, to fill the orbital cavity in patients already operated by standard evisceration (7 patients, 7 eyes). There were no cases of implant extrusion. The orbital volume was well reintegrated. Conclusion. Our procedure was safe and effective. All patients had a good cosmetic result after final prosthetic fitting and we also achieved good prothesis mobility.

MR imaging of progressive enhancement of a bioceramic orbital prosthesis: an indicator of fibrovascular invasion

The physical properties of bioceramics have made them ideal for a variety of prosthetic devices. Their porous structure allows fibrovascular tissue to invade the implant and secure it and provides a surface for muscular attachment. This process has been well-documented in animal studies; however, this case report describes the periodic imaging changes seen in a 67-year-old man following placement of a bioceramic orbital prosthesis.

Late exposure of the bioceramic orbital implant

PURPOSE

To investigate the long-term outcome of the Bioceramic orbital implant.

DESIGN

A retrospective, comparative, nonrandomized study.

METHODS

Data were collected from the patients receiving Bioceramic orbital implants at National Taiwan University Hospital between June 1, 2001 and November 1, 2005. The implant was wrapped with Vicryl mesh, adding anteriorly with a scleral patch graft following enucleation with primary or secondary implantation. The unwrapped implant was inserted into an eviscerated globe with posterior sclerotomy and cornea preserved. Primary or secondary placement of sleeve was performed in some patients.

RESULTS

A total of 112 cases were reviewed. Four patients were excluded attributable to insufficient follow-up. The other 108 patients had a mean follow-up period of 35.8 +/- 10.6 months (range, 24 to 70 months). Fifty patients (46.3%) received the pegging procedure. Eight of 108 (7.4%) cases of late exposure were identified on average 20.7 months after implantation. We identified no cases of implant exposure in 30 cases of enucleation and eight cases of secondary implant when the implant was wrapped in Vicryl mesh and an anterior scleral cap was used. All exposures developed in eviscerated patients (70 cases): two without pegging, three with primary placement, and three with secondary placement of the sleeve. The exposure rate was higher in patients with eviscerated globes, pegged implants, and prior ocular operations (P < .005).

CONCLUSIONS

Late exposures of Bioceramic implants were found after long-term follow-up, associated with evisceration, pegging, and prior ocular surgeries. The modified wrapping technique can prevent exposure following secondary implantation and enucleation.

Biomatériaux de reconstruction et de comblement osseux en ORL et chirurgie cervicofaciale

INTRODUCTION

Position of medical devices has increased for last 30 years in otorhinolaryngology. Legal directive of use, main indications and perspectives are presented.

RESULTS AND DISCUSSION

Biomaterials are medical devices planned for tissue reconstruction or substitution. The approval labelling are planned in Europe by the European Community certification (marquage CE) and overseen by a postmarket medical device safety (matériovigilance), that are completely independent from the Food and Drug Administration certification. Indications of biomaterials are likely competitive to those of autografts; their advantage is to limit the morbidity due to autograft harvesting. Benefits are aesthetics, functional or complementary. Main indications are presented in otology, rhinology, face traumatology, laryngology, anti-aging surgery, implants and epithesis. Research fields are scanned (increased therapeutic properties, drug delivery systems, tissue engineering...).

CONCLUSION

Biomaterials are increasingly implanted in ENT surgery. The surgical success of their use require a strict legal label and well-defined indications.

Perspective on Orbital Enucleation Implants

The philosophy and design of orbital enucleation implants have evolved significantly over the past 50 years. Animal studies and improved imaging techniques have changed our understanding about the physiology and anatomy of the post-enucleation orbit. Changes in implant design and biomaterials have reduced complication rates. It is our impression that for many ophthalmic professionals in training, the rational behind the current thinking in implant design and biomaterials is unclear. This is in part related to the older literature on orbital enucleation implants, which is scattered and at times contradictory. This review aims to present the historical information in a coherent and concise form; provide evidence based review of changes in the practice patterns of enucleation; identify areas of continuing controversy; and highlight gaps in the scientific literature about orbital implants, in particular, the poor understanding of implant and prosthesis motility.

Porous Orbital Implants in Enucleation: A Systematic Review

Orbital implants have been used for cosmesis following surgical removal of the eyeball, or enucleation, for over a century. Implant design has progressed significantly in recent years with the use of porous devices, with the theoretical advantages of reduced complications and improved cosmesis. However, in some cases the theoretical benefits have not fully translated into clinical results. In this article the use of orbital implants in enucleation, with a particular focus on the newer porous biomaterials that have gained prominence over the last 15 years, is reviewed. Specific factors identified as affecting the performance of porous orbital implants include the material used, pore size, and morphology. Mechanical factors have received little consideration in the past and may form a basis for the use of higher compliance porous materials in the future. Of the porous materials in use, current clinical evidence is not sufficient to suggest either that porous implants are superior to non-porous implants, or that one material is more suited to the application than another. Future developments in this field require randomized controlled clinical trials with extensive follow-up as complications may not become evident until over 5 years post-implantation.

Prevention of exposure of porous orbital implants following enucleation

PURPOSE

To investigate effectiveness of adding a scleral patch graft on a Vicryl mesh-wrapped porous orbital implant to prevent exposure following enucleation.

DESIGN

A retrospective, comparative, nonrandomized study.

METHODS

From October 1996 to February 2006, 74 consecutive patients (74 sockets) who received porous orbital implants primarily or secondarily after enucleation at National Taiwan University Hospital (72 cases) and at Far Eastern Memorial Hospital (2 cases) were collected. Patient demographics, ocular diagnosis, the surgical technique, prior ophthalmic surgery, type, covering, and size of the implant, follow-up periods, and complications associated with pegs and implants were recorded. Group 1 patients received a Vicryl mesh-wrapped implant without a scleral patch graft. Group 2 patients received anterior capping with a scleral patch on the Vicryl mesh-wrapped implant.

RESULTS

Of 74 identified cases, 12 were excluded for insufficient follow-up. The 62 remaining cases had more than a two-year follow-up. There were two implant exposures (12%, two of 17) in group 1. Retroauricular myoperiosteal graft and scleral patch were used to repair exposed implants successfully. No exposure was noted in group 2 (n = 45). A significant between-group difference in exposure rate was found (P = .02). Early conjunctival dehiscence followed by spontaneous healing occurred in three group 2 patients.

CONCLUSIONS

Scleral patch graft and Vicryl mesh can act as duplicate barriers between anterior surface of implants and overlying soft tissue. The modified wrapping technique prevents porous implants from exposure effectively.

Evaluation of a double-setting alpha-tricalcium phosphate cement in eviscerated rabbit eyes

PURPOSE

To evaluate the macroscopy, microstructure, and tissue reaction of a double-setting alpha-tricalcium phosphate bone cement used as an intraocular implant in rabbits.

METHODS

The internal and external surface of the double-setting alpha-tricalcium phosphate implant was analyzed macroscopically and by scanning electron microscopy. Twelve New Zealand rabbits received 12-mm implants made of double-setting alpha-tricalcium phosphate cement after unilateral evisceration. Clinical evaluation was performed daily for the first 15 days after surgery and at 15-day intervals until the end of the study period. For histopathologic analysis, 3 animals per experimental period were submitted to enucleation at 15, 45, 90, and 180 days.

RESULTS

On gross inspection, the external surface of the implant was solid, smooth, and compact. The microarchitecture was characterized by the formation of columns of hexagonal crystals with interconnecting channels forming micropores. No wound dehiscence, signs of infection, or implant extrusion were observed in any animal throughout the study period. Histologic examination revealed the formation of fibrovascular tissue surrounding the implants, and there were signs of minimal integration of the surface limiting the fibrocellular cap with the space previously occupied by the implant.

CONCLUSIONS

The double-setting alpha-tricalcium phosphate implant behaved as an inert and non-integratable material. The lack of incorporation of this material by fibrovascular tissue is related to its characteristics of compactness and high resistance.

Individual CAD/CAM Fabricated Glass-Bioceramic Implants in Reconstructive Surgery of the Bony Orbital Floor

BACKGROUND

The aim of the study was to present a set of preliminary cases from an ongoing program of reconstructive procedures using a new technique in the treatment of severe enophthalmos and diplopia after the primary treatment of orbital floor fractures had rendered insufficient results.

METHODS

Glass-bioceramic implants were shaped from computed tomography coordinates with computer-assisted design and computer-assisted manufacturing. In this prefabrication process, the implants were milled individually out of a solid block of Bioverit II (3di Gmbh, Jena, Germany). The adequacy of this reconstruction for treating malfunction and aesthetic deficits was evaluated.

RESULTS

Eight patients with orbital floor fractures underwent successful surgery. The results were encouraging, with all patients showing a good functional and aesthetic outcome.

CONCLUSIONS

Computer-assisted design/computer-assisted manufacturing implants made of Bioverit II can be used for a very accurate and successful secondary reconstruction of the orbital floor. However, it addresses only a few aspects of the treatment of orbital floor fractures and should be considered as an equal alternative to other reconstruction methods.

Infected Aluminum Oxide Orbital Implant

Porous orbital implant infection is rare. The diagnosis may be delayed as the initial symptoms and signs are not always indicative of implant infection. It is often only with time, a persistence of symptoms and signs, and additional symptoms and signs that implant infection is suspected.

Traitement chirurgical des expositions d’implants d’éviscération en hydroxyapatite par greffe d’aponévrose temporale

Using hydroxyapatite porous implants improves the functional and cosmetic results for patients after evisceration. However, exposure is still the most frequent complication and requires various surgical treatments. We present four patients who had an autologous temporalis fascia graft for an exposed hydroxyapatite implant 6 months to 5 years after the first evisceration. Mean follow-up was 17 months. We describe our surgical procedure and its results, and we discuss its advantages and its place in the management of exposed porous implants.

Behavior of Various Orbital Implants Under Axial Compression

PURPOSE

To determine and compare the amount of force required to disrupt the integrity of various orbital implants.

METHODS

Compression tests were carried out by using a servo-electrical universal testing system on orbital implants including aluminum oxide (Bioceramic implant, FCI, Issy-Les-Moulineaux, France), coralline hydroxyapatite (HA) (Bio-Eye, Integrated Orbital Implants, Inc., San Diego, CA, U.S.A.), bovine HA (Molteno M-Sphere, IOP Inc., Costa Mesa, CA, U.S.A.), synthetic HA (FCI3, FCI, Issy-Les-Moulineaux, France), Chinese HA (H + Y Comprehensive technologies, Philadelphia, PA, U.S.A.), polylactic acid (Kinsey Nash Corporation, Duluth, MN, U.S.A.), porous polyethylene (Medpor, Porex Surgical Inc., College Park, GA, U.S.A.), and polymethylmethacrylate.

RESULTS

Two basic groups of implants were identified: those that eventually reach a critical compression point and collapse (coralline HA, aluminum oxide, synthetic FCI3 HA, bovine HA, Chinese HA, and polymethylmethacrylate), and those that do not collapse but gradually compress with increasing load (porous polyethylene, polylactic acid). For similar-sized implants, the critical collapse point was earliest for the FCI3 HA implant, followed by the coralline HA, aluminum oxide, and polymethylmethacrylate implants. Smaller-sized collapsible implants showed earlier critical collapse points than larger-sized implants of similar material.

CONCLUSIONS

A technique was established to assess the force required to disrupt the integrity of various orbital implants that is reliable, unbiased, and repeatable with any orbital implant. Orbital implants of different materials and sizes demonstrate different degrees of integrity. It is important to use similar-sized implants when comparing the integrity of different implant materials because size influences the force required to overcome the structural integrity of the implant.

Primary placement of a hydroxyapatite-coated sleeve in bioceramic orbital implants

PURPOSE

To study a new surgical option of primary placement of a hydroxyapatite-coated sleeve into the Bioceramic implant during enucleation or evisceration.

DESIGN

Retrospective, observational case series.

METHODS

A standard enucleation or evisceration was performed, followed by the preplacement of a hydroxyapatite-coated sleeve into the Bioceramic implant. Care must be taken to ensure the sleeve has been positioned centrally when the implant is put inside the orbital socket. Complications such as sleeve exposure, Bioceramic implant exposure, and infection were closely observed.

RESULTS

Twenty-seven patients were treated in above fashion with five enucleation and 22 evisceration procedures. Five of the sleeves have exposed spontaneously during 1 to 4 months after original surgery. They had no further complication, except for one sleeve around which there were visible Bioceramic spicules attributable to long-term corticosteroid usage. The remaining 22 sleeves that did not spontaneously expose pursued secondary exposure of the sleeve and peg insertion by the conjunctival cutdown procedure 3 months postoperatively. One sleeve was medially positioned far away from the implant center. Re-insertion of new sleeve and peg was scheduled 2 weeks later. One additional sleeve was obliquely positioned after conjunctival cutdown procedure. Fortunately, all 27 patients were successfully fitted with a peg-coupled prosthesis with good motility.

CONCLUSIONS

Primary placement of a hydroxyapatite-coated sleeve into the Bioceramic implants has several advantages, including high patient acceptance, technical simplicity, and an office-based conjunctival cutdown pegging procedure. By avoiding the expense of postoperative imaging studies and additional prosthetic modification, a more rapid and efficient rehabilitation is possible.

Fibrovascularization of Intraorbital Hydroxyapatite-Coated Alumina Sphere in Rabbits

We investigated the fibrovascular ingrowth and fibrovascular tissue maturation of hydroxyapatite-coated, porous alumina sphere (Alumina sphere) in comparison with the hydroxyapatite sphere (HAp sphere) in rabbits. Alumina spheres and HAp spheres were implanted in the left orbits of 42 New Zealand white rabbits after enucleation. Fibrovascular ingrowth and maturation were graded from 1 to 5 at postoperative 1, 2, 3, 4, 8, 12 and 24 weeks. We defined 4 phases: postoperative 1-2 weeks as phase I, 3-4 weeks as phase II, 8-12 weeks as phase III, and 24 weeks as phase IV. The grade was analyzed at each phases. There was no significant difference in fibrovascular ingrowth and maturation between the two groups at all 4 phases, except phase II at which the Alumina sphere showed significantly lower maturation grade (p<0.05). We concluded that the Alumina sphere is an ideal orbital implant material and an ideal substitute for the HAp sphere in clinical practice.

Porous polyethylene orbital implant in the pediatric population

PURPOSE

To determine the incidence of complications of primary insertion of porous polyethylene orbital implant in the pediatric population.

DESIGN

Interventional case series.

METHODS

Prospective nonrandomized case series of 36 eyes of 36 patients under age 15 years who underwent primary placement of an anteriorly wrapped spherical porous polyethylene orbital implant from March 1998 to August 2002, with at least 17 months of follow-up.

RESULTS

The mean age at the time of surgery was 4.6 years. The histopathologic diagnoses after enucleation included intraocular tumor in 22 patients, phthisis bulbi in eight patients, microphthalmos in three patients, Coats disease in two patients, and ruptured traumatic globe in one patient. Twelve patients (33%) had prior ocular surgery. At the time of enucleation, all patients underwent primary placement of spherical porous polyethylene orbital implant anteriorly wrapped with homologous sclera in 30 patients (83%) and autologous sclera in six patients (17%). The spherical implant size was 16 mm in one patient (3%), 18 mm in 10 patients ( 28%), and 20 mm in 25 patients (69%). The prosthesis was fitted after a mean interval of 5 weeks. After a mean follow-up of 44 months (range, 17 to 68 months), there was one case of pyogenic granuloma (3%) and one case of implant exposure (3%). There were no cases of implant extrusion, superior sulcus syndrome, orbital cellulitis, or significant inflammatory response. No porous polyethylene orbital implant was drilled for peg placement.

CONCLUSIONS

Anteriorly wrapped primary porous polyethylene orbital implant in the pediatric population appears to be well tolerated with few complications.

Problems After Evisceration Surgery With Porous Orbital Implants

PURPOSE

To assess the problems associated with the use of 4 types of porous orbital implant (Bio-Eye coralline hydroxyapatite, FCI3 synthetic hydroxyapatite, aluminium oxide [Bioceramic], and porous polyethylene [Medpor]) after evisceration surgery.

METHODS

A retrospective analysis was made of all cases of evisceration with placement of one of four types of porous orbital implants performed between 1991 and 2002 by one surgeon (n = 86). Patient age, implant type and size, surgery type (standard evisceration or evisceration with posterior sclerotomies), peg system used, follow-up duration, time of pegging, problems before and after pegging, and treatment were recorded.

RESULTS

Eight patients had less than 6 months of follow-up. The other 78 patients were followed for 6 to 107 months (average, 31 months). The following problems were noted before peg placement: discharge, 8 patients (10.2%); implant exposure, 6 patients (7.7%); implant fracture at the time of surgery, 1 patient (1.3%); persistent pain, 1 patient (1.3%). Of the 29 patients who had pegging, problems including discharge, exposure, pyogenic granuloma, infection, and peg sleeve problems occurred in 23 (79.3%). Sixteen (55.2%) of the 29 patients required at least 1 additional surgical procedure, 4 required 3 additional procedures, and 2 required 5 additional procedures, including implant removal.

CONCLUSIONS

Although primary evisceration with posterior sclerotomies and placement of a porous orbital implant is an accepted technique for treating a variety of end-stage eye diseases, patients should be cautioned about an increased likelihood of problems and potential need for additional surgeries if pegging is considered.

Clinicopathologic Analysis of 15 Explanted Hydroxyapatite Implants

PURPOSE

To report the clinical findings, treatment, outcomes, and histopathologic findings in patients with suspected orbital implant infection requiring implant removal.

METHODS

Retrospective, observational case series of 14 patients (15 hydroxyapatite orbital implants) undergoing implant removal from September 1994 through December 2002. Patient age, type of surgery, implant type, symptoms, treatment, histopathology of implant, and follow-up course were analyzed.

RESULTS

Of the 14 patients, 7 were female and 7 were male. The mean age at explantation was 42 years. The most common symptoms were discharge and socket tenderness. The most common signs were conjunctival inflammation (edema, hyperemia), discharge, and recurrent pyogenic granuloma. Clinical evidence of infection was documented in 13 patients. Histopathologic assessment of the 15 explanted implants showed acute inflammation and necrosis (abscess) with identification of microorganisms (5 patients), acute inflammation and necrosis without identification of microorganisms (4 patients), chronic inflammation with identification of microorganisms (1 patient), chronic inflammation without identification of microorganisms (3 patients), and a predominant foreign body granulomatous response without identification of microorganisms (2 patients). Osseous metaplasia was seen in 10 implants. Prompt resolution of symptoms and signs occurred in all but one case.

CONCLUSIONS

The clinical course of porous orbital implant infection may be prolonged, and the early symptom of recurrent discharge, a common problem for implant recipients, may delay diagnosis. Implant infection should be suspected when there is persistent conjunctival inflammation and discharge after implant placement despite antibiotic therapy, discomfort on implant palpation, and recurrent pyogenic granuloma (indicative of implant exposure). Implant removal is usually required in these cases. If orbital pain (not necessarily related to implant palpation) is the main complaint, without signs of conjunctival inflammation and with or without discharge, one should consider other reasons for the symptoms.

Current Trends in Managing the Anophthalmic Socket After Primary Enucleation and Evisceration

PURPOSE

To evaluate current trends in the management of the anophthalmic socket after primary enucleation and evisceration.

METHODS

The active membership of the American Society of Ophthalmic Plastic and Reconstructive Surgery (ASOPRS) was surveyed regarding primary enucleations and eviscerations performed between January and December 2002. Survey questions included practice demographics, orbital implant use, wrapping materials, placement of a motility peg, reasons for implant choice, and complications encountered.

RESULTS

A total of 2,779 primary orbital implants were reported, comprising 1,919 (69.1%) enucleations and 860 (30.9%) eviscerations. The high-density porous polyethylene implant was used most frequently for enucleations (42.7%), followed by coralline hydroxyapatite (27.3%) and nonporous alloplastic implants (19.9%). For eviscerations, the high-density porous polyethylene implant was the most commonly used implant (42.3%), followed by hydroxyapatite (25.9%) and nonporous alloplastic implants (25.7%). The top 3 reasons for implant choice were outcome (69.3%), cost (43.6%), and experience (39.5%). Most implants were either not wrapped (59.8%) or were wrapped in donor sclera (25.2%) or polyglactin mesh (7.2%). Pegs were used in 8.1% of all implants reported. The most frequent complications encountered for unpegged implants were exposure (3.2%) and infection (0.4%). For pegged implants, the most common complications reported were pyogenic granuloma (13.7%), exposure (5.7%), and discharge (5.7%).

CONCLUSIONS

In managing the anophthalmic socket, ASOPRS survey respondents preferred to use the porous polyethylene implant after primary enucleation and evisceration. Most orbital implants were not wrapped, and most surgeons preferred not to place a motility post or peg in the implant.

Localization of extraocular muscles during secondary orbital implantation surgery

PURPOSE

To describe a technique for localizing extraocular muscles during secondary orbital implantation and to report the author's experience in 100 consecutive cases.

DESIGN

Retrospective, noncomparative, consecutive case series.

PARTICIPANTS AND METHODS

A retrospective review was performed of the charts from one surgeon's practice of 100 consecutive patients who received a secondary porous orbital implant for anophthalmic socket rehabilitation. The following data were recorded: age, gender, reason for seeking secondary implantation, type of implant used, size and style of implant used, number of muscles localized, follow-up duration, and problems encountered and their treatment. Preoperative and postoperative photographs, implant motility, prosthetic motility, and overall impressions (by patient and physician) of the surgical outcome were analyzed.

RESULTS

The 100 patients (66 males and 34 females, with a mean age of 38.9 years) were followed up for an average of 16.9 months (range, 4-60 months). All 4 rectus muscles were identified in 93 patients, 3 recti were identified in 6 patients, and 2 recti were identified in 1 patient. In 2 patients, the levator muscle mistakenly was thought to be the superior rectus muscle and was connected to the implant. Reconstructive surgical procedures were required in both cases. At final follow-up, 98% of patients believed that they had benefited from surgery, with an improved prosthetic appearance, improved symmetry between the 2 eyes, improved comfort, better prosthetic motility, or a combination thereof. Compared with the results of the preoperative examination, implant and prosthetic motility was improved in 92% to 98% of patients.

CONCLUSIONS

The tunnel technique allows successful localization of extraocular muscles during secondary orbital implant surgery in a high percentage of patients. Surgical outcomes were excellent, with few complications and high patient satisfaction.

Fibrovascularization of Porous Polyethylene (Medpor) Orbital Implant in a Rabbit Model

PURPOSE

To evaluate the porous polyethylene (Medpor) orbital implant in a rabbit model and compare it with three other currently available porous implants: Bio-Eye coralline hydroxyapatite (HA), FCI(3) synthetic HA, and aluminum oxide (Bioceramic).

METHODS

The porous polyethylene implant was examined macroscopically and microscopically (with scanning electron microscopy). Implantation was performed in 10 adult male New Zealand albino rabbits. Each animal underwent enucleation of the right globe under general halothane gas anesthesia, followed by placement of a 12-mm porous polyethylene implant. In 5 animals, the implant was encased in polyglactin 910 (Vicryl mesh); in the other 5, it was left unwrapped. The implants were moistened in saline before placement. Implant vascularization was evaluated by histopathology at 4, 8, 12, 16, and 24 weeks.

RESULTS

The porous polyethylene implant was found to have a smoother exterior surface than the Bio-Eye, FCI(3) synthetic HA, and aluminum oxide implants. Rather than a uniform interconnected porous architecture, there was an extensive system of interconnected channels through the implant, ranging in size from 125 to 1000 microm. On high-power examination there was a more solid, woven appearance without any sign of the microcrystals seen in the other porous implants. One rabbit had a retrobulbar hemorrhage after surgery and was euthanized. All the other rabbits tolerated the implant well, and there were no complications. On histopathologic examination, fibrovascularization gradually increased over time. One implant was completely vascularized at 12 weeks, and both implants harvested at 16 weeks were completely vascularized. The implant harvested at 24 weeks showed only partial vascularization (14%).

CONCLUSIONS

The porous polyethylene orbital implant represents an alternative implant for use after enucleation or evisceration or for secondary implantation. In our rabbit model, the porous polyethylene implant was well tolerated without complication. Complete fibrovascularization was first seen at 12 weeks. Porous polyethylene orbital implants appear to vascularize more slowly than Bio-Eye coralline HA, FCI(3) synthetic HA, and aluminum oxide implants.

The use of vicryl mesh in 200 porous orbital implants: a technique with few exposures

PURPOSE

To report the results of a wrapping technique for porous orbital implants by using polyglactin 910 (Vicryl) mesh (Ethicon Inc., Somerville, NJ, U.S.A.).

METHODS

We retrospectively reviewed the records of 200 consecutive patients from one author's practice who received a polyglactin 910 mesh-wrapped porous orbital implant after enucleation or as a secondary implant between October 1, 1996, and April 15, 2001. We recorded potential problems that might be attributed to polyglactin 910 mesh both before pegging (excessive inflammatory response to the material, conjunctival thinning, and implant exposure) and after pegging (exposure of the implant around the sleeve, conjunctival thinning, and implant exposure other than adjacent to the peg).

RESULTS

One hundred twenty-two men and 78 women underwent placement of a polyglactin 910 mesh-wrapped porous orbital implant. The average age at the time of implantation was 48.9 years (range, 11 to 85 years). The average follow-up interval in the 200 patients was 19.4 months (range, 2 to 80 months). Thirteen of the 200 patients had less than 6 months of follow-up, leaving 187 patients with an average follow-up of 20.5 months (range, 6 to 80 months). There were 76 primary enucleations and 124 secondary orbital implants. Thirty-seven patients received a Bio-Eye hydroxyapatite implant (HA) (Integrated Orbital Implants, San Diego, Calif), 97 received a synthetic FCI hydroxyapatite implant (FCI, Issy-Les-Moulineaux, France), and 66 received a Bioceramic implant (aluminum oxide-Al2O3) (FCI, Issy-Les-Moulineaux, France). One hundred fourteen patients (57%) underwent peg placement. The average time to pegging was 9.9 months (range, 6 to 16 months). Before pegging, 4 of 187 patients (2.1%) had implant exposure. Three of these exposures followed secondary orbital implant placement (2 Bio-Eye HA, 1 synthetic FCI3 HA) and one followed an enucleation (synthetic FCI3 HA). Two patients required a temporalis fascia graft and one required a scleral patch; the remaining defect closed spontaneously. One patient had conjunctival thinning 6 months after orbital implantation, which remained stable with no frank exposure for 36 months. No patient had excess socket inflammation. After peg placement, 3 additional patients had exposure of the implant around the peg site. There were no cases of conjunctival thinning or exposure of the implant other than adjacent to the peg site.

CONCLUSIONS

Polyglactin 910 mesh is an excellent option as a wrapping material for porous orbital implants. It is simple to use, readily available, eliminates the need for donor tissue, does not require a second operative site, and it is less expensive than other currently available wrapping materials. We attribute our high success rate to our technique, which emphasizes proper placement of the implant within the Tenon space, suturing the extraocular muscles anterior to their normal anatomic sites, and meticulous closure of the Tenon capsule and conjunctiva in separate layers.

Accumulation of a black material around some titanium coupling posts

PURPOSE

To report 5 patients with a black material accumulating in the conjunctiva around the titanium peg and sleeve systems.

METHODS

Retrospective small case series. The clinical features of 5 patients were reviewed. Histopathologic analysis was performed on specimens from 3 patients. Neutron activation analysis was performed on 1 sample.

RESULTS

Five asymptomatic patients with black material accumulating in the conjunctiva at the conjunctival-titanium peg interface were evaluated. All patients had a hydroxyapatite-coated titanium sleeve with a titanium peg in position. Histopathologic analysis performed on specimens from 3 patients revealed a mixed inflammatory cell infiltrate with focal areas of a black, foreign-appearing material showing birefringence under polarized light that was predominantly intracytoplasmic. This black material did not respond to bleaching, and in 2 patients, it showed positive staining for iron (Perls method). The material from one patient was evaluated by neutron activation analysis and was found to contain titanium, aluminum, and vanadium. In 18 to 48 months of follow-up, the presence of the material did not appear to be associated with any problems.

CONCLUSIONS

The presence of a black substance accumulating in the conjunctiva around some titanium coupling posts is uncommon and appears to be without any consequence in 18 to 48 months of follow-up. Our analysis revealed this substance to be consistent with titanium alloy (Ti-6Al-4V).

Investigation of a bioresorbable orbital implant

PURPOSE

To analyze a new bioresorbable orbital implant (open-celled polylactic acid, also known as OPLA).

METHODS

The implants were examined macroscopically, with chemical analysis (Fourier transform infrared spectroscopy), and microscopically with scanning electron microscopy. Animal implantation of OPLA implants was carried out in 9 adult male New Zealand albino rabbits. Implant vascularization was evaluated by histopathologic sectioning.

RESULTS

The OPLA implant is porous and lightweight but fragile. Histopathologically it stimulated primarily a multinucleated giant cell granulomatous reaction with little fibrovascular ingrowth seen at 4 and 8 weeks. By 20 and 24 weeks, the implant was replaced predominantly by necrotic debris and peripheral giant cells.

CONCLUSIONS

The OPLA implant is not an acceptable alternative to other currently available orbital implants.

Hydroxyapatite and calcium phosphate coatings on aluminium oxide orbital implants

BACKGROUND

Hydroxyapatite and calcium phosphate have been used as bone graft substitutes as they facilitate and promote tissue ingrowth. We carried out a study to examine uncoated and coated aluminium oxide (alumina) spherical orbital implants and assess whether the coatings influence fibrovascular ingrowth.

METHODS

The aluminium oxide spheres (three coated with hydroxyapatite, three coated with calcium metaphosphate and three uncoated) were manufactured at the School of Materials Engineering, Yeungnam University, Kyongsan, Kyongbuk, Korea. The implants were examined macroscopically and with scanning electron microscopy and were analysed chemically by means of x-ray powder diffraction and x-ray fluorescence spectrophotometry. Implantation of three hydroxyapatite-coated, three calcium metaphosphate-coated and three uncoated aluminium oxide spheres was done in nine adult male New Zealand albino rabbits. Implant vascularization was evaluated at 4, 8 and 12 weeks by means of histopathological sectioning.

RESULTS

All three types of implant had multiple interconnected pores. The coatings increased the size of the trabeculae from 150 microm to 300 microm. As a result, the pores appeared slightly smaller but still ranged in size from 300 microm to 750 microm, compared to 400 microm to 800 microm in the uncoated implants. The coatings also increased the weight of the implants slightly. The implants were all strong mechanically. They were made up primarily of aluminium oxide. The coated implants contained significant amounts of calcium oxide (a contaminant). There was no clinical difference in the socket response between the three groups. Histopathologically, fibrovascularization occurred uniformly throughout each implant at 4, 8 and 12 weeks after implantation.

INTERPRETATION

The hydroxyapatite and calcium metaphosphate coatings did not appear to facilitate or inhibit fibrovascular ingrowth at 4, 8 and 12 weeks. Longer-term studies are need to determine whether the coatings play a role in long-term acceptance and retention of the implants.

Proliferation of human fibroblasts in vitro after exposure to orbital implants

BACKGROUND

Porous orbital implants allow fibrovascular ingrowth and integration with the extraocular muscles. The available implants have different structural characteristics, which may influence orbital response. We studied the proliferation of orbital fibroblasts in vitro after exposure to four different orbital implants.

METHODS

Four orbital implant biomaterials were studied: hydroxyapatite (Bio-Eye), synthetic hydroxyapatite, porous polyethylene (Medpor) (pore sizes 150 microm and 400 microm) and aluminium oxide (Bioceramic implant). Human fibroblasts obtained from orbital fat at the time of elective blepharoplasty were cultured and then exposed to the individual implants. Cell growth was assessed with immunocytochemical analysis using bromodeoxyuridine, a thymidine analogue. After DNA denaturation, the cells were washed, incubated with secondary antibody and visualized.

RESULTS

The fibroblasts growing on the Bio-Eye, synthetic hydroxyapatite, and 150-microm and 400-microm Medpor implants all had debris associated with them. The Bioceramic implant was free of this debris. The Bioceramic implant and the 150-microm Medpor implant had the greatest number of fibroblasts on the coverslips.

INTERPRETATION

The proliferation of fibroblasts, as determined by visualization of actively dividing cells with bromodeoxyuridine, differed on the various implants studied. The lack of debris associated with the Bioceramic implant may be related to the crystalline structure of the implant.