Coralline hydroxyapatite as an ocular implant.

Fifty patients received a coralline hydroxyapatite sphere as a buried integrated ocular implant after enucleation or evisceration surgery. The surgical technique is described and the results discussed. All patients obtained final prosthetic motility superior to that possible with simple spherical methylmethacrylate implants. After a follow-up of 2 to 27 months (mean, 10.4 months) there have been no cases of migration or extrusion. Complications have been minimal and easily managed. The hydroxyapatite implant appears to offer excellent cosmetic reconstruction without the unacceptable infection and extrusion rates seen with other integrated implants.     

兔眶内植入国产珊瑚羟基磷灰石的实验研究

目的：探讨国产珊瑚羟基磷灰石（ＨＡ）眶内植入物的生物相容性以及植入兔眶内后纤维血管化情况。方法：在１８只兔眶内植入国产珊瑚ＨＡ,于术后定期取出植入物作光镜与透射电镜检查,结果：１８例中有２例出现植入物暴露,无发生植入物暴露的组织学改变显示;术后６周时植入物已全部纤维血管化,公有少许为症细胞;发生植入物暴露的组织学改变显示;植入物外围少许纤维血管长进,内围大量炎症细胞浸润。结论：①国产珊瑚ＡＨ具有良     

Osseous metaplasia with functioning bone marrow in hydroxyapatite orbital implants

Background: Bone formation within the hydroxyapatite implant has been reported in explanted spheres in humans. Bone-specific differentiation was observed to occur earlier in the pores of spherical hydroxyapatite implants enhanced with osteogenin within the rabbit socket. We observed previously unreported bone marrow formation in a coralline hydroxyapatite implant placed into the rabbit orbit after evisceration. Methods: One eye of each of 10 New Zealand white rabbits weighing between 2 and 3 kg was eviscerated and implanted with hydroxyapatite spheres. The explanted hydroxyapatite spheres 20 weeks after surgery were examined under the microscope. Results: Histopathologic examination of the excised implants showed the presence of trabeculae of mature bone with fatty marrow and hematopoietic elements. Scattered throughout the fatty tissue were bone marrow elements consisting of precursors of the granulocytic and erythroid series and also megakaryocytes. Conclusion: The osseous metaplasia with functioning bone marrow was incidentally observed in the coralline hydroxyapatite implant without the addition of any osteogenesis-inducing agents. Received: 21 July 1999 Revised version received: 3 November 1999 Accepted: 4 November 1999     

Rate of vascularization of coralline hydroxyapatite ocular implants.

Twelve patients received a coralline hydroxyapatite sphere as a buried integrated ocular implant after enucleation surgery. The implant was modified by drilling 5 access holes, 1 mm in diameter, to the center of the sphere to allow more rapid host tissue ingrowth. 99Tc MDP static and dynamic bone scan studies were performed at various intervals after implantation to confirm the time course for vascularization. Complete vascularization was noted in 1 of 2 patients at 8 weeks after surgery, in 7 of 7 patients at 10 to 12 weeks, and in 3 of 3 patients at 16 weeks. This modified technique allows the hydroxyapatite ocular implants to be drilled for the final motility peg at an earlier time than currently possible, thereby resulting in more rapid cosmetic rehabilitation and obviating the need for secondary modification or replacement of the prosthesis.     

Primary placement of a titanium sleeve in hydroxyapatite orbital implants

BACKGROUND: To study a new surgical option of primary placement of a titanium sleeve into hydroxyapatite implants during enucleation or evisceration. METHODS: A standard enucleation or cornea preserved evisceration was performed, followed by preplacement of a titanium sleeve into the hydroxyapatite implant by a hand drill sleeve driver. Care must be taken to ensure that the titanium sleeve is positioned centrally when the implant is put inside the orbital socket or eviscerated shell. The Tenon capsule and conjunctiva were meticulously closed with minimal tension. Complications such as sleeve exposure, coralline exposure, and infection of the titanium sleeve were closely observed. RESULTS: In all, 30 patients were treated in the above fashion with 10 enucleation and 20 evisceration procedures. The follow-up period ranged from 9 to 24 months. Three of the sleeves were found to have exposed spontaneously at 5 and 7 weeks following original surgery. They had no further complication except one sleeve loosening. The remaining 27 sleeves that did not spontaneously expose pursued secondary exposure of the titanium sleeve and peg insertion by conjunctival cutdown procedure 3 months after original surgery. Two sleeves were found to be oblique positioned after the conjunctival cutdown procedure. Fortunately, all the 30 patients were successfully fit with a peg-coupled prosthesis with good motility. CONCLUSION: Primary placement of a titanium sleeve into hydroxyapatite implants has several advantages, including high patient acceptance, technical simplicity, and office-based conjunctival cutdown pegging procedure. By avoiding the expense of postoperative imaging study and additional prosthetic modification, a more rapid and efficient rehabilitation is possible.     

异形羟基磷灰石义眼台的临床应用

目的:观察异形羟基磷灰石义眼台植入术并发症及手术效果,探讨异形义眼台的适应证及其临床应用价值。方法:设计不同体积的异形羟基磷灰石义眼台,治疗眼球萎缩、眼内容物摘除及眼球摘除术后患者共30例。对照组植入常规圆球形羟基磷灰石义眼台共30例。异形义眼台组与对照组间性别、年龄、眼部情况相似。手术后随访时间6mo以上,观察患者义眼台植入术后球结膜愈合时间、义眼台暴露、感染等并发症、义眼台活动度、位置以及与义眼片适合程度的差异。结果:异形羟基磷灰石义眼台组没有发生义眼台暴露、感染等严重并发症,球结膜愈合时间短,义眼台植入后前表面呈圆弧形,能与义眼片很好的吻合,义眼台活动度及位置均好于对照组。对照组有2例(7%)发生早期球结膜裂开的并发症,经过治疗后均愈合。结论:异形义眼台可以降低义眼台植入后引起的并发症,可以有效适应患者眼部病变的情况,获得良好的手术效果,适应证更广,安全性更好。     

Comparative motility of hydroxyapatite and alloplastic enucleation implants

OBJECTIVE: To compare the motility of scleral-covered hydroxyapatite and alloplastic enucleation implants. DESIGN: Retrospective, nonrandomized comparative trial. PARTICIPANTS: Measurements were obtained after surgery in 76 anophthalmic patients who had received either hydroxyapatite or alloplastic enucleation implants. METHODS/MAIN OUTCOME MEASURES: Horizontal and vertical excursions of the enucleation implants. RESULTS: There is no clinically important difference between the movement of hydroxyapatite and alloplastic enucleation implants. Implant movement appears to decline with advancing age. CONCLUSION: Scleral-covered alloplastic and hydroxyapatite enucleation implants show similar movement. Although directly coupling hydroxyapatite implants to the prosthesis via the motility peg provides enhanced prosthetic movement, there appears to be no motility benefit of nonpegged hydroxyapatite over spherical alloplastic implants.     

Porous implant exposure: Incidence, management, and morbidity

PURPOSE: To identify what factors may predispose patients to exposure of porous anophthalmic implants and to determine the outcome of exposed porous implants. METHODS: Examination of pooled data obtained through a PubMed literature search of English-language publications from 1989 through 2004 using the key words enucleation, evisceration, and socket reconstruction. RESULTS: Porous implants were inserted in 80% (3012 of 3777) of the cases identified from 49 publications. The difference in exposure rate between coralline hydroxyapatite (4.9%) and porous polyethylene (8.1%) implants is primarily related to a higher reported complication rate of uncovered porous polyethylene implants, particularly in retinoblastoma patients. Other techniques associated with increased exposures include wrapping implants with bovine pericardium or polyglactin mesh. Evisceration and secondary procedures did not have statistically different complication rates compared with enucleation. There are more late exposures of porous polyethylene than coralline hydroxyapatite implants. Spontaneous healing of exposures occurred in 13% (19 of 145) of cases. Covering exposures with patch grafts underneath vascularized conjunctival flaps was the most successful method of surgical repair. Implant removal was necessary after 29% (42 of 145) of exposures. CONCLUSIONS: Although the published literature between 1989 and 2004 reports higher complication rates for uncovered porous implants and implants wrapped with bovine pericardium or polyglactin mesh, pooling data from different studies may mask very good or poor results obtained by individual surgeons. Spontaneous healing of exposed porous implants is relatively uncommon. However, many exposed porous implants can be salvaged with secondary repair.     

Experience with orbital implants in particular with porous hydroxyapatite materials

PURPOSE: Various materials have been developed since the first implantation of a hydroxyapatite sphere in 1985. They are similar to the porous basic structure and imitate the biological behavior of coralline implants. This article presents own clinical experience with hydroxyapatite implants from 1993 to 2003 and compares own results and other porous orbital implants in the international scientific literature. RESULTS: The original hydroxyapatite implant is well tolerated and implant extrusion is rare. A retrospective analysis of 357 patients regarding this complication shows an extrusion rate of 2.6% over 10 years. The subjective positive tolerance of 71.2% corresponds to the results of international studies. After several stages of development the synthetic product (FCI3) is now comparable with the original product with regard to operative complications and subjective compatibility. Both orbital implants should be used with a protective covering to avoid premature extrusion and to facilitate suturing the extraocular muscles anterior. When using material from humane donors the material must be guaranteed to be completely sterile. The use of vicryl as an orbital plomb wrapping leads to contradictory reports in the literature. Hydroxyapatite ceramics in combination with silicone india rubber represent an alternative to the materials listed above and in this case a wrapping of the orbital plomb is unnecessary. Spherical orbital implants made of aluminum oxide (bioceramic implant) are an alternative to corraline hydroxyapatite implants. Because of their porous,crystalline structure bioceramic implants vascularize well. Porous polythylene orbital implants,which are not available in Germany, are economical, but due to their porosity and vascularization properties they are not comparable with pure hydroxyapatite or hydroxyapatite ceramics. FUTURE VIEW: The dynamic development of the infant anopthalmus adapted to the size growth of the orbita and the exact volume replenishment of the adult orbita cannot yet be fulfilled with the presently available porous hydroxyapatite materials and is the subject of future research.     

羟基磷灰石义眼台纤维血管化的MRI实验研究

目的用磁共振成像（MRI）研究兔眼眶内植入羟基磷灰石（HA）义眼台血管化过程，探讨义眼台血管化MRI的表现和特点。方法12只新西兰白兔眼眶内植入直径12mm天然HA义眼台，于术后第1、2、3、4、5、6周对所有手术兔行双眼磁共振（MR）平扫及Gd—DTPA增强扫描，计算义眼台强化区体积与义眼台体积比值（VE／VHA），对结果用方差分析（q检验）。并于第2、4周随机抽取2只，第6周对剩余动物义眼台行组织病理学检查。结果术后第1、2、3、4周VE／VHA值逐渐增加，均数间比较差异有统计学意义（F=240．654，P=0．000），第4周与第5、6周比较差异无统计学意义（F=0．686，P=0．520）。术后第2周病理显示义眼台周边有纤维血管生长，第4、6周整个义眼台完全血管化。结论MRI可直观、准确地评价义眼台血管化的程度和范围。     

Polytetrafluoroethylene as a wrapping material for a hydroxyapatite orbital implant

PURPOSE: Porous coralline hydroxyapatite orbital implants have been used with great success in anophthalmic sockets. We used a substitute for donor sclera as a wrapping tissue. METHODS: Orbital implants were wrapped with polytetrafluoroethylene (PTFE) instead of homologous donor tissue in five patients after enucleation. RESULTS: The postoperative course was uneventful in three cases. Complications occurred in two cases: one with implant exposure, and one with severe implant infection leading to its eventual removal. CONCLUSIONS: PTFE is inferior to other wrapping tissue.     

Surgical coverage of exposed hydroxyapatite implant with retroauricular myoperiosteal graft

BACKGROUND: With the increasing use of hydroxyapatite orbital implants, the complication of exposure has become apparent to oculoplastic surgeons. Many kinds of patch grafts, such as sclera, dermis, and hard palate mucosa, have been used to cover exposed hydroxyapatite implants with inconsistent results. In this study, the authors use a newly developed technique, autogenous retroauricular myoperiosteal graft, and the results are reported. METHODS: A piece of retroauricular muscle together with its underlying periosteum was carefully harvested. This myoperiosteal graft was patched to the debrided hydroxyapatite exposure area with the periosteal surface facing outward. The margin of periosteal surface was secured with conjunctiva and left uncovered for the surrounding conjunctiva to epithelialise. RESULTS: Nine eyes with hydroxyapatite exposure more than 3 mm were managed with autogenous retroauricular myoperiosteal grafts. Seven cases were successfully treated with single graft surgery. The other two cases needed an additional graft surgery, and there was no re-exposure noted thereafter. Five patients received a successful insertion of the motility peg. All nine patients have been fitted with prosthesis with reasonable motility. There were no complication noted during more than 1 year of follow up. CONCLUSION: The thick composite nature of the myoperiosteal graft provides a durable and vascularised coverage for exposed hydroxyapatite implants. This technique offers an encouraging alternative for the management of exposed hydroxyapatite implants.     

Radiation absorption properties of orbital implants

PURPOSE: To determine the radiation absorption properties (RAP) of three commonly used orbital implant materials, namely, methylmethacrylate (MM), hydroxyapatite (HA), and porous polyethylene (PP). METHODS: Eighteen (18)-mm spheres of MM, HA and PP were tested with 1.25 MV gamma-rays from cobalt-60, 6 MV X-rays, and 9 MeV, 12 MeV, and 16 MeV electron beams. The implants were immersed in a water phantom, and the measurements were obtained on X-omat V(R) film; the scanning was done with a computerized laser densitometer, CADSCAN(R). RESULTS: The RAP of all three materials appeared to be very close to those of water. The density of the MM implant was calculated to be the closest to that of water at all photon and electron energies. PP had a higher transmission than water at all electron energies (9, 12 and 16 MeV); the transmission through HA, however, was lower than through water. CONCLUSION: When postoperative radiation is indicated for an orbit containing an implant, the RAP of the allograft material play a significant role in the planning of the radiation treatment. Our study indicated that MM implants have RAP equivalent to those of water when treatment of orbital tumors is undertaken at the commonly used photon and electron energies. The RAP of the other allografts were either higher or lower, which may lead to unreliability in irradiation planning.     

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.     

Coralline hydroxyapatite orbital implant (bio-eye): experience with 158 patients

PURPOSE: To assess the problems seen in 158 patients with coralline hydroxyapatite (HA) orbital implants (Bio-Eye). METHODS: A consecutive case series of 170 patients receiving coralline HA implanted by two surgeons over a 5-year period were reviewed. The authors analyzed age, type of surgery, implant size, peg system, follow-up duration, time of pegging, problems encountered, and treatment. RESULTS: Twelve patients were lost to follow-up after 5 months, leaving 158 patients who were followed from 6 to 130 months (average, 39 months). Problems in unpegged implants occurred in 36 (22.8%) patients. Discharge occurred in 18 (11.4%) patients, implant exposure in 12 (7.6%), socket discomfort in 1 (0.6%), conjunctival thinning in 3 (1.9%), chronic conjunctival swelling in 2 (1.3%), and implant infection in 3 (1.9%). Problems after pegging occurred in 68 (50.7%) of 134 patients: discharge in 27 (20.1%), pyogenic granuloma in 24 (17.9%), conjunctiva overgrowing the peg in 4 (3.0%), implant exposure around the sleeve in 5 (3.7%), clicking in 6 (4.5%), peg on an angle in 2 (1.5%), loose sleeve in 1 (0.7%), peg falling out in 18 (13.4%), popping peg in 1 (0.7%), poor transfer of movement in 3 (2.2%), pain with movement in 1 (0.7%), and implant infection in 2 (1.5%). CONCLUSIONS: The Bio-Eye orbital implant represents a porous orbital implant that is biocompatible with orbital tissues and allows fibrovascular ingrowth and improved motility when coupled to the overlying artificial eye. It is more expensive than other commercially available porous orbital implants, such as synthetic FCI3 HA, porous polyethylene (Medpor), and aluminum oxide (Bioceramic) implant. Problems encountered with its use are similar to those problems seen in patients with the synthetic FCI3 hydroxyapatite and aluminum oxide orbital implants.     

Mersilene mesh versus sclera in wrapping hydroxyapatite orbital implants

PURPOSE: To compare Mersilene mesh versus sclera in wrapping hydroxyapatite orbital implants used in primary enucleation. METHODS: In a prospective, randomized, interventional comparative case series, 60 eyes from 60 consecutive patients were included and randomly allocated for primary enucleation and either Mersilene mesh-wrapped hydroxyapatite (MHA) orbital implant (30 cases, 50%) or sclera-wrapped hydroxyapatite (SHA) orbital implant (30 cases, 50%) under general anesthesia. Complete socket examination was performed at 1 week, 1 month, and then every 3 months after surgery. RESULTS: Mean age was not significantly different (P = 0.08) between patients with MHA (36.43 years) and SHA (28.50 years) orbital implants. The most common cause of enucleation was trauma in both groups (P = 0.09). Patients with MHA had significantly (P = 0.005) longer follow-up time (mean, 11.40 months) than those with SHA (mean, 9.40 months). No exposure was found at last follow-up in the MHA group, but one patient in the SHA group had a small exposure (1 x 1 mm) 1 month after surgery that was conservatively treated. There were no significant postoperative soft tissue complications in either group. CONCLUSIONS: Sclera and Mersilene mesh could be used as a wrapping material for hydroxyapatite orbital implants without significant complications. Absence of disease transmission, low cost, and availability are the main advantages of Mersilene mesh.     

两种不同术式Ⅰ期羟基磷灰石义眼座植入术的临床研究

目的比较两种不同术式的Ⅰ期羟基磷灰石义眼座植入术的临床疗效。方法将99例有义眼座植入适应证患者分为A、B两组，A组行眼球摘除巩膜包裹法植入义眼座，B组行眼内容剜除巩膜覆盖法植入义眼座，术后观察两组患者配戴义眼后外观改善程度、术后并发症。结果两组患者外观改善程度差异无显著性，但A组结膜裂开发生率高于B组（Х^2=7.380，P〈0.01），义眼座暴露发生率也高于B组（Х^2=5.160，P〈0.05）。结论眼内容剜除巩膜覆盖法是一种较眼球摘除巩膜包裹法简单、安全、方便、疗效确切的义眼座植入手术，值得在临床推广应用。     

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.     

Fibrovascular ingrowth into hydroxyapatite and porous polyethylene orbital implants wrapped with acellular dermis

PURPOSE: Acellular dermis is a frequently used wrapping material for hydroxyapatite (HA) and porous polyethylene (PP) orbital implants. In an animal model, we determined by histology the extent of fibrovascular ingrowth within orbital implants wrapped in acellular dermis at 6 and 12 weeks after surgery. METHODS: Four Yucatan minipigs were used for the study. Two minipigs had HA implants and two had PP implants. Implants were harvested at 6 or 12 weeks after surgery and were examined histologically for fibrovascular ingrowth. RESULTS: There was complete fibrovascularization of HA implants harvested at both 6 and 12 weeks after surgery. The PP implant harvested at 6 weeks had incomplete fibrovascularization, whereas the PP implant harvested at 12 weeks had complete fibrovascular ingrowth. There was no histologic evidence of inflammation seen in any of the orbital implants. On gross and histologic examination, the wraps were found to persist on the surface of all orbital implants, with little histologic evidence of inflammation localized to the acellular dermis. CONCLUSIONS: Acellular dermis wraps support fibrovascularization of both HA and PP orbital implants. Additionally, acellular dermis does not incite significant inflammation in association with HA and PP orbital implants and can persist in situ for at least 12 weeks after surgery.     

Six cases of bacterial infection in porous orbital implants

BACKGROUND: We present 6 cases of bacterial infection that developed after porous orbital implant surgery. CASES: Five patients with hydroxyapatite implants showed lid swelling, discharge, and suppurative granuloma 14 days to 3 years after surgery. The hydroxyapatite implants were removed 14 days to 41 months postoperatively, and synthetic porous polyethylene orbital implants were inserted. Thick discharge and conjunctival melting was noted 14 months after primary Medpor implant surgery in the sixth patient, and the infection was controlled by medical therapy. OBSERVATIONS: The culture of specimens removed with swabs from the conjunctiva of patients and from the hydroxyapatite implants showed growth of Staphylococcus aureus, Staphylococcus epidermidis, alpha-hemolytic streptococcus and peptostreptococcus in 4 patients, whereas Streptococcus pyogenes were cultured from the conjunctiva in the Medpor implant patient. Culture for the remaining patient was negative .CONCLUSIONS: If there is continuous pain, injection, and discharge after porous implant insertion, bacterial infection in the implant should be considered immediately. Systemic antibiotics and topical eye drops should be administered without delay. If no improvement is observed, the implant should be removed and a different approach must be considered.