Comparison between local-made and imported porous polyethylene orbital implant:a randomized controlled equivalence trial and multicenter study

AIM:To compare the exposure rate,infection rate,percentage of enhancement,and success rate between Medpor and the three-dimensional printed polyethylene(3DP-PE)orbital implant in a preliminary report.METHODS:This prospective,randomized,equivalence,controlled trial was conducted at two institutes.The equivalent margin was±10%.The sample size for the equivalence trial was 174 participants per group.Patients who were eligible for enucleations received either Medpor or 3DP-PE implants based on a randomized block of six.The surgeries were performed by five oculoplastic surgeons.The assessor and patients were masked.The magnetic resonance imaging(MRI)of the orbit was performed at least 6mo after operation and the fibrovascular ingrowth was analyzed using the Image J software.Follow-up continued at least 1y after surgery.The intention to treat and per protocol approaches were used.RESULTS:Totally 128 patients met the criteria in the report.Fifty Medpor and 553DP-PE cases completed the trial.The most common cause of blindness was trauma.The mean follow-up times of Medpor and 3DP-PE were 33 and 40mo respectively.The exposure rate was not statistically significant between two groups(6.0%and 7.3%),P<0.05,95%CI(-9.8%,+12.0%).The success rates were 94%(Medpor)and 92.7%(3DP-PE).No postoperative infection was reported.Nine patients had MRI tests and two had implant exposures with 66.3% enhancement at 75mo(Medpor)and 58% enhancement at 57mo(3DP-PE)postoperatively.CONCLUSION:There is no statistically significant difference in exposure rate and success rate between Medpor and 3DP-PE in enucleation in the report.However,we cannot conclude that they are equivalent in terms of the exposure rate and success rate because the 95%CI is wider than±10%.The infection rate is equivalent in both groups.

Effect of basic fibroblast growth factor(bFGF) on the treatment of exposure of the orbital implants

Objective: To evaluate the efficacy and the indication of basic fibroblast growth factor (bFGF) in the treatment of exposure of orbital implants. Design: Retrospective and observational case series. Methods: We reviewed 41 patients (41 eyes) suffering exposure of orbital implants from Jan. 2000 to June 2006. The study group patients with mild exposure received com-bined treatment with bFGF and antibiotic drops, and while the control group patients with mild exposure were treated with anti-biotic drops only. The study group patients with moderate and severe exposure received combined treatment with bFGF and antibiotic drops, and after 2 months they were subjected to amniotic membrane transplantation, while the control group patients with moderate and severe exposure underwent amniotic membrane transplantation after using antibiotic drops. Observation of the growth of conjunctival epithelium and comparison of the healing rate of the two groups. Results: The healing rates of the mild, moderate and severe exposure study group were 100% and 92.3%. The healing rates of the mild, moderate and severe exposure control group were 55.6% and 66.7% respectively. The difference of the healing rates of the mild exposure study group and the control group was significant (P=0.033). And the difference of the healing rates of the moderate and severe exposure study group and the control group was not significant (P=0.167). Conclusion: bFGF may promote obviously the healing of orbital implant exposure, particularly it can be the first choice for the treatment of mild degree exposure. For the moderate and severe cases, it can be administered before surgical repair to enhance neovascularization and will tend to increase the success rate of surgical repair.

Amniotic membrane transplantation for porous sphere orbital implant exposure

Objective: This study is aimed at describing the clinical outcome of amniotic membrane transplantation for exposure of porous sphere implants. Methods: A retrospective review of consecutive cases of porous sphere orbital implant exposure was carried out. Eight cases were presented between May 2004 and Oct. 2006 (5 males, 3 females; mean age 44.5 years). Six had enucleation and two had evisceration. Exposure occurred in two primary and six secondary. Orbital implant diameter was 22 mm in seven cases and 20 mm in one case. Six patients are with hydroxyapatite and two with high-density porous polyethylene (Medpor) orbital implants. The mean time from implantation to exposure was 1.1 months (range 0.8~2 months). All patients required surgical intervention. Results: The time of follow-up ranged from 3.0 to 28.0 months (mean 16.5 months). Amniotic membrane grafting successfully closed the defect without re-exposure in all of these patients. The grafts were left bare with a mean time to conjunctiva of about 1 month (range 0.8~1.5 months). Conclusion: Exposed porous sphere implants were treated suc-cessfully with amniotic membrane graft in all of patients. The graft is easy to harvest. This technique is useful, dose not lead to prolonged socket inflammation and infection, and it is valuable application extensively.

Treatment of intractable orbital implant exposure with a large conjunctival defect by secondary insertion of the implant after preceding dermis fat graft

AIM: To report a procedure and results of a two-stage operation to manage intractable extensive orbital implant exposure with a large conjunctival defect which was difficult to treat with dermis fat grafts due to repeated graft necrosis. METHODS: A retrospective chart review of four patients who had extensive orbital implant exposures with large conjunctival defects and had past histories of repeated autologous or preserved dermis graft failures was done. As a first-stage operation, the problematic pre-existing orbital implants were removed and autologous dermis fat grafts alone were performed on the defect area. Four months later, new orbital implants were secondarily inserted after confirmation of graft survival. The size of the conjunctival defects and state of the extraocular muscles were checked preoperatively. Success of the operations and complications were investigated.RESULTS: The mean size of the conjuctival defects was 17.3mm×16.0mm, and the mean time from the initial diagnosis of orbital implant exposure to implant removal and autologous dermis fat graft was 20.8 months. After implant removal and autologous dermis fat graft, no graft necrosis was observed in any patients. Also, implant exposure or fornix shortening was not observed in any patients after new orbital implant insertion. CONCLUSION: The secondary insertion of a new orbital implant after pre-existing implant removal and preceding dermis fat graft is thought to be an another selective management of intractable orbital implant exposure in which dermis fat grafts persistently fail.

Effects of Vascular Endothelial Cell Growth Factor on Fibrovascular Ingrowth into Rabbit's Hydroxyapatite Orbital Implant

Summary: The effects of different concentrations of vascular endothelial cell growth factor (VEGF) on the fibrovascular ingrowth into rabbits hydroxyapatite orbital implant were investigated. Twelve New Zealand white rabbits were divided into 3 groups and received hydroxyapatite orbital implant surgery in their right eyes. Before and after the operation, the implants were treated with 10 ng/ml VEGF, 100 ng/ml VEGF, or normal saline as control group. The animals received technetium bones scan at 2, 4, and 6 weeks postoperatively. The mean radioactivity counts within region of interest (ROI) of the surgery eye (R) and the non-surgery eye (L) in the same animal were tested, and the R/L ratios were calculated. The implants were harvested at 6th weeks and examined histopathologically. The results showed that at second week, there was no significant difference in mean R/L ratios between VEGF group and control group (F=2.83, P=0.111); At 4th week (F=7.728, P=0.011) and 6th week (F=7.831, P=0.011) postoperatively, the mean ratios in VEGF groups were significantly higher than that in control group. At 6th week postoperatively, the fibrovascularization rates in VEGF groups were higher than in control group significantly (F=8.711, P=0.008). It was suggested that VEGF could promote the fibrovascular ingrowth into hydroxyapatite orbital implant, thus might shorten the time required for complete vascularization of the HA orbital implant.

High density porous polyethylene material (Medpor) as an unwrapped orbital implant

Objective: To introduce the clinical effect among patients who received an unwrapped orbital implant with high density porous polyethylene material (Medpor) after enucleation or evisceration. Methods: Retrospective analysis of a series of 302 patients with anophthalmia who underwent placement of an unwrapped high density porous polyethylene orbital implant. We compared the patients (n=180) who accepted primary implant placement with those (n=122) who accepted secondary implant placement. Parameters evaluated included: age at time of surgery, date of surgery, sex, implant type and size, surgery type, the surgical procedure and technique performed, and complications. Results: The time of follow-up ranged from 2.0 to 58.0 months (mean 32.5 months). A total of 5 of 302 (1.66%) cases had documented postoperative complications. The following problems were noted after surgery: implant exposure, 3 patients (0.99%); implant removed due to orbital infection, 1 patient (0.34%); ptosis, 1 patient (0.34%). There were no significant complications observed in other 297 cases and all implants showed good orbital mo- tility. The clinical effect of primary implant placement is better than that of secondary placement. Conclusion: High density porous polyethylene material can be used successfully as an unwrapped orbital implant in anopthalmic socket surgery with minimal complications. The material is well tolerated, nonantigenic and has low rate of infection and migration.

Auricular cartilage versus donor sclera as a wrapping of hydroxyapatite orbital implants

AIM: To retrospectively compare postoperative outcomes after primary enucleation and placement of a hydroxyapatite(HA) implant without wrapping, wrapped with auricular cartilage or donor sclera. METHODS: Medical records of patients presented as intraocular tumor or severe ocular injury were identified from the electronic medical record system. Cases underwent enucleation and HA orbital implantation were enrolled in this study and were divided into 3 groups according to the wrapping material of HA implant. Cases with autogenous cartilage caps were enrolled in group A(n=11), with donor sclera caps in group B(n=12), and without any wrapping material in group C(n=9). Follow-ups were set at 1, 2 wk, 1, 3, 6, and 12 mo after surgery.RESULTS: Altogether 32 cases finished the followup and were enrolled in this study. Three cases(27.27%) in group A, 4 cases(33.33%) in group B, and 4 cases(44.44%) in group C developed one complication each after surgery. In group A, no HA exposure occurred, but conjunctival inclusion cyst occurred in one and severe conjunctive chemosis in two cases. In group B, one HA exposure occurred, conjunctive inclusion cysts occurred in one, severe conjunctive chemosis occurred in one, and conjunctival granuloma occurred in one case. In group C, one HA exposure occurred, severe conjunctive chemosis occurred in two cases, and conjunctival granuloma occurred in one case. The case of exposure of none-wrapped implant was noted in the first 6 mo after placement of the orbital implant. The case of exposure of donor sclerawrapped implant was noted at the 12 mo after placement of the orbital implant. Both exposure cases were treated successfully with conservative treatment.CONCLUSION: With low incidence of implant exposure and mild complications, auricular cartilage can be a good choice of alternative wrapping material of orbit implant with satisfied outcome.

Comparative study of modified and conventional secondary hydroxyapatite orbital implantations

AIMTo compare the clinical effects of the modified and conventional secondary hydroxyapatite orbital implantations.

Effects and complications of placement of motility coupling post in porous polyethylene orbital implants

Objective： To investigate the effects and complications of primary and secondary placements of motility coupling post （MCP） in the unwrapped porous polyethylene orbital implant （PPOI） following enucleation. Methods： We investigated 198 patients who received PPOI implantation following the standard enucleation procedure in the First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China, from 2002 to 2004. These patients were subgrouped into PPOI-only patients （112 cases, received PPOI following enucleation）, primary MCP patients （46 cases, received primary placement of MCP during PPOI operation）, and secondary MCP patients （40 cases, received secondary placement ofMCP 6 months after the initial surgery）. Effects and complications among these three groups were compared. Results： The PPOI-only patients took shorter treatment course when compared with other two MCP groups （P〈0.001）, without significant difference noted between the two MCP groups. However, the two MCP groups had better prosthetic motility than PPOI-only group （P〈0.001）, without significant difference between the two MCP groups. In the early stage, 2 eyes in the PPOI-only group and l eye in the primary MCP group had PPOI infection. In PPOI-only group, 3 （2.68%） eyes had PPOI exposure, which occurred after fitting the prostheses; 4 eyes （8.70%） in primary MCP group and 1 eye （2.50%） in secondary MCP had PPOI exposure, which occurred before fitting the prostheses. After prosthesis was fit successfully, the excessive discharge and granuloma were 33.9% and 1.79% in PPOI group-only, 53.3% and 8.9% in primary MCP group, and 52.5% and 7.5% in secondary MCP group, respectively. Conclusion： Both primary and secondary placements of MCP into the PPOI following enucleation can help patients to obtain desirable prosthetic motility, but may be associated with more complications. The primary placement of MCP with skilled operation in selected patients is more recommendable than secondary placement.

Clinical analysis of hydroxyapatite orbital implantation after ocular trauma in 211 cases

Objective： To evaluate the therapeutic effects and complications of hydroxyapatite （HA） orbital implantation on patients after trauma-related surgeries. Methods ： Retrospective analysis was made from 211 cases （211 eyes ） who underwent HA orbital implant placement after trauma-related enucleation or evisceration, including 68 cases of evisceration and primary HA implant placement, 77 cases of enucleation and HA implant placement wrapped with multi-windowed sclera, 66 cases of enucleation and HA implant placement free of wrapping. All the cases were followed up for 1-5 years to observe the therapeutic effects and major complications. Results： Five of 211 cases had wound dehiscence. Ten cases had HA implants exposure, including 1 case suffering severe orbital infection and requiring HA implant removal. The implants exposure incidences by the three surgical methods were from 1.30% to 10.06% and averaged 4.74%. Significant difference was found in late exposure incidence and total incidence from the three methods （ X^2 = 13. 372, P 〈 0.01 and X6^2 = 7. 540, P 〈 0.05 ）. Two cases had shrinkage of the lower fornix. Enophthalmos occurred in 1 case treated by method 1 and was corrected by implanting porous polyethylene （Medpor） plate into the bottom of orbit. In 210 cases, the artificial eye moved well and the cosmetic results were satisfactory. Conclusions- Different surgical methods have their own merit and disadvantage. Enucleation and placement of HA implant wrapped with multi-windowed sclera has corroborated fewer complications than others.

In vitro adherence of conjunctival bacteria to different oculoplastic materials

AIM: To investigate the resistance to bacterial adhesion of materials used in oculoplastic surgery, particularly materials used in the manufacture of orbital implants.METHODS: Seven organisms of conjunctival flora(two strains of Staphylococcus epidermidis and one strain each of Staphylococcus aureus, Staphylococcus hominis, Corynebacterium amycolatum, Acinetobacter calcoaceticus, and Serratia marcescens) were selected. A lactic acid bacterium(Lactobacillus rhamnosus) was also included as positive control because of its well-known adhesion ability. Eight materials used to make oculoplastic prostheses were selected(glass, steel, polytetrafluoroethylene, polymethylmethacrylate, silicone from orbital implants, commercial silicone, porous polyethylene, and semismooth polyethylene). Materials surfaces and biofilms developed by strains were observed by scanning electron microscopy. Kinetics of growth and adhesion of bacterial strains were determined by spectrophotometry. Each strain was incubated in contact with plates of the different materials. After growth, attached bacteria were re-suspended and colony-forming units(CFUs) were counted. The number of CFUs per square millimetre of material was statistically analyzed.RESULTS: A mature biofilm was observed in studied strains except Staphylococcus hominis, which simply produced a microcolony. Materials showed a smooth surface on the microbial scale, although steel exhibited 1.0-μm-diameter grooves. Most organisms showed significant differences in adhesion according to the material. There were also significant differences in thetotal number of CFUs per square millimetre from each material(P=0.044). CFU counts were significantly higher in porous polyethylene than in silicone from orbital implants(P=0.038).CONCLUSION: Silicone orbital implants can resist microbial colonization better than porous polyethylene implants.

The use of virtual surgical planning and navigation in the treatment of orbital trauma

Virtual surgical planning （VSP） has recently been introduced in craniomaxillofacial surgery with the goal of improving efficiency and precision for complex surgical operations. Among many indications, VSP can also be applied for the treatment of congenital and acquired craniofacial defects, including orbital fractures. VSP permits the surgeon to visualize the complex anatomy of craniofacial region, showing the relationship between bone and neurovascular structures. It can be used to design and print using three- dimensional （3D） printing technology and customized surgical models. Additionally, intraoperative navigation may be useful as an aid in performing the surgery. Navigation is useful for both the surgical dissection as well as to confirm the placement of the implant. Navigation has been found to be especially useful for orbit and sinus surgery. The present paper reports a case describing the use of VSP and computerized navigation for the reconstruction of a large orbital floor defect with a custom implant.

Next-generation finely controlled graded porous antibacterial bioceramics for high-efficiency vascularization in orbital reconstruction

Eyeball loss due to severe ocular trauma,intraocular malignancy or infection often requires surgical treatment called orbital implant reconstruction to rehabilitate the orbital volume and restore the aesthetic appearance.However,it remains a challenge to minimize the postoperative exposure and infection complications due to the inert nature of conventional orbital implants.Herein,we developed a novel Ca-Zn-silicate bioceramic implant with multi-functions to achieve the expected outcomes.The porous hardystonite(Ca2ZnSi2O7)scaffolds with triply periodic minimal surfaces(TPMS)-based pore architecture and graded pore size distribution from center to periphery(from 500 to 800μm or vice versa)were fabricated through the digital light processing(DLP)technique,and the scaffolds with homogeneous pores(500 or 800μm)were fabricated as control.The graded porous scaffolds exhibited a controlled bio-dissolving behavior and intermediate mechanical strength in comparison with the homogeneous counterparts,although all of porous implants presented significant antibacterial potential against S.aureus and E.coli.Meanwhile,the pore size-increasing scaffolds indicated more substantial cell adhesion,cell viability and angiogenesis-related gene expression in vitro.Furthermore,the gradually increasing pore feature exhibited a stronger blood vessel infiltrating potential in the dorsal muscle embedding model,and the spherical implants with such pore structure could achieve complete vascularization within 4 weeks in the eyeball enucleation rabbit models.Overall,our results suggested that the novel antibacterial hardystonite bioceramic with graded pore design has excellent potential as a next-generation orbital implant,and the pore topological features offer an opportunity for the improvement of biological performances in orbital reconstruction.