Implants and spacers for paralytic ectropion: Literature review and assessment of a thin-profile porous polyethylene implant

Purpose: There is no ideal treatment paradigm for paralytic ectropion. This study evaluated lower eyelid spacers and the efficacy of a novel lower eyelid thin profile, bio?integratable, porous polyethylene. Methods: A retrospective review of 15 consecutive patients who underwent thin?profile porous polyethylene implantation and canthoplasty for paralytic ectropion was carried out. A comprehensive literature review of spacers for paralytic ectropion and retraction using the Pubmed database with search terms “[implant or graft or spacer] and [paralytic ectropion or paralytic retraction],” “graft and paralysis and ectropion,” “implant and paralysis and ectropion,” “graft and paralysis and retraction,” and “implant and paralysis and retraction” was carried out. Results: The mean patient age was 69 years (range: 50–88). Lagophthalmos improved from a mean of 5.7 mm (SD = 3.3, range 3–14 mm) to 1.4 mm (SD = 1.1, range 0–3.5 mm), P < 0.0001. MRD 2 improved from a mean of 6.7 mm (SD = 2.3, range 2–12 mm) to 4.2 mm (SD = 0.9, range 3–6 mm), P = 0.0005. No patients needed additional lower eyelid surgery. There were no implant exposures at a mean follow?up of 7.6 months (SD = 7.9, range 0.7–21.6 months). Detailed literature review revealed that hard palate and ear cartilage are the most reported spacers, each with unique disadvantages. Conclusion: The thin?profile porous polyethylene implant is a useful addition to the management of symptomatic paralytic ectropion. Meaningful comparison of lower eyelid spacers is difficult because of variations in surgical technique, spacer size, and poorly reported outcome data. No spacer proves superior

PPE tube filled with autologous fat in the repair of peripheral nerve: a new proposal / Tubo PPE relleno con grasa autóloga en la reparación de los nervios periféricos: una nueva propuesta

This study proposes the use of a porous polyethylene (PPE) tube as the conductive element in the regeneration in the sciatic nerve sectioning and evaluates the use of fill with autologous fat. The subject was divided randomly into five groups, 3 control and 2 experimental (PPE tube graft with/ without autologous fat). Each group was selected for functional, histological and morphometric evaluation of the sciatic nerve. Functional analysis of the sciatic nerve occurred through the "footprint" values near -100 refer sectioned sciatic nerve, near 0 (zero) refer to control group. On histological analysis of the experimental groups lots of dense connective tissue replacing nerve tissue was observed. In morphometric analysis the group EGPGf got higher performance in all of variables. The use of PPE has shown promise in nerve regeneration with favorable results when associate with fat as a trophic factor in the regeneration.

Este estudio propone el uso de un tubo de polietileno poroso (PPE) como elemento conductor en la regeneración del nervio ciático seccionado y evaluar el uso de relleno con grasa autóloga. Al azar se formaron cinco grupos, 3 y 2 de control experimental (PPE prótesis tubular con / sin grasa autóloga). Cada grupo fue seleccionado para estudiar la forma funcional, histológica y evaluación morfométrica del nervio ciático. Un análisis funcional del nervio ciático se produjo a través de los valores de "huella", cerca de -100 se refiere al nervio ciático seccionado; cerca de 0 (cero) se refiere al grupo control. En el análisis histológico de los grupos experimentales se observó una gran cantidad de tejido conjuntivo denso que sustituye el tejido nervioso. En el análisis morfométrico, el grupo experimental de injerto de polietileno lleno de grasa (EGPGf) obtuvo un mayor rendimiento en todas las variables. El uso de PPE ha mostrado ser prometedor en la regeneración del nervio, con resultados favorables cuando se asocia con la grasa como un factor trófico en la regeneración.

The Effects of Commodified Growth Factor Products on the Fibrovascularization of Porous Polyethylene Orbital Implants

PURPOSE: To investigate the effects of commodified growth factor products used clinically on fibrovascular ingrowth into porous polyethylene orbital implants. METHODS: Porous polyethylene orbital implant sheets (Medpor(R)) soaked with Nepidermin (Easyef(R)), Trafermin (Fiblast(R)), and normal saline were implanted into the backs of 18 Sprague-Dawley rats. The degree of fibrovascular ingrowth as observed using a light microscope was compared 1 and 2 weeks after implantation and was calculated as a percentage of the fibrovascular ingrowth length. RESULTS: One week after implantation, the percentage of fibrovascular ingrowth length was 25.33 +/- 5.43%, 22.56 +/- 5.30%, and 21.78 +/- 4.66% in the Easyef(R)-, Fiblast(R)- and normal saline-soaked groups. The degree of fibrovascularization was higher in the Easyef(R)-soaked group than in the other groups (p = 0.020, 0.012). Two weeks after implantation, the degree of fibrovascularization was 98.33 +/- 5.00%, 100.00 +/- 0.00%, and 95.89 +/- 4.57%, which was significantly higher in the Easyef(R)-, and Fiblast(R)-soaked groups than in normal saline-soaked group (p = 0.019, <0.001). CONCLUSIONS: Commodified growth factor products used in other areas selectively enhanced fibrovascular ingrowth to a greater degree and earlier in ophthalmic plastic and reconstructive surgery.

Pathogenetic analysis and treatment of bone resorption after chin augmentation with prostheses / 中华医学美学美容杂志

Objective To analyze and discuss the possible reasons of the bone resorption beneath the prostheses after chin augmentation.Methods Twelve patients were admitted to our department for further correction after chin augmentation with materials.The bone resorption was observed through the clinical research and X-ray examination.Results All the patients were underwent the removal of the materials,genioplasty was performed in 8 patients,and two patients were treated by chin augmentation with polyethylene.All the patients were satisfied with their facial contouring.Mild bone resorption was found in seven patients (depth of bone resorption ≤2 mm),in which five patients were used with silicone materials,two patients were performed with expanded polytetrafluoroethylene implants.Moderate bone resorption was seen in three cases.All of them were used with silicone implants (2 mm ＜ depth of bone resorption ≤4 mm).Severe bone resorption happened in two patients (depth of bone resorption ＞4 mm).One was used with silicone implant,and the other one was carried out with expanded polytetrafluoroethylene implant.Conclusions The imbalance among mentalis muscle,materials and underlying bone might be one of the key reasons.Thus for mild and moderate microgenia cases,chin augmentation with material is suitable,while long-term fellow-up study is necessary.But for the cases of severe mirogenia or microgenia and micrognathia with dentofacial deformity or mentalis muscle hyperactivity,genioplasty might be performed as well to correct their deformities.

The Reconstruction of Nasal Septal Perforation with High Density Porous Polyethylene Covered with Fascia Lata: An Experimental Study on Rabbit Model

OBJECTIVES: Evaluation of a new material, high-density porous polyethylene (HDPP), which is covered with fascia lata, for experimental nasal septal perforation closure. METHODS: Twenty New Zealand albino rabbits were included and divided into study and control groups. A lateral incision was made from the lateral aspect of the left nares to the incisura nasomaxillaris. After exposure of the cavum nasi, the nasal mucoperichondrium was elevated bilaterally. A full-thickness 0.5x0.5-cm perforation was created over the septum nasi with a No. 11 surgical blade. A fascia lata graft was used for the study group. The HDPP was covered with fascia lata and placed under the elevated mucosa. HDPP without a fascial covering was used in the control group. Four months after the procedure, magnetic resonance imaging was performed to evaluate resorption of the material. The animals were sacrificed, and the nasal septum was completely removed. Macroscopic and histopathological examinations were performed on the nasal septum. RESULTS: All rabbits had survived after the 4-month period. Macroscopically, nine of 10 (90%) perforations were closed in the fascia lata-covered HDPP group. Histopathological examination of these nine rabbits revealed that the continuity of cartilage was disturbed in the perforation areas. Granulation tissue was inverted in areas in which the cartilage continuity was disturbed. The HDPP had remained intact at the edge of the perforation. In the HDPP group, six of 10 implants were still perforated (60%) and four (40%) were closed. The fascia lata-covered HDPP implant had a significantly higher perforation closure rate than that of the HDPP implant alone (P<0.05). CONCLUSION: In cases of septal perforation, it is better to cover the HDPP implant with fascia lata. This covered implant can be used for the repair of nasal septal perforations. HDPP implants are easy to work with and avoid the increased operative time and morbidity associated with harvesting autografts.

Treatment of Blow-out Fractures Using Both Titanium Mesh Plate and Porous Polyethylene (Medpor(R))

PURPOSE: The goals of a blow-out fracture reconstruction are to restore the osseous continuity, provide support for the orbital contents and prevent functional and anatomic defects. Over the past several years, a range of autogenous and synthetic implants have been used extensively in orbital reconstructions. None of these implants have any absolute indications or contraindications in certain clinical settings. However, in extensive blow-out fractures, it is difficult to restore support of the orbital contents, which can cause more complications, such as enophthalmos. This study examined the clinical outcomes of extensive or comminuted blow-out fractures that were reconstructed by the simultaneous use of a titanium mesh plate and Medpor(R). METHODS: Eighty six patients with extensive orbital fractures, who were admitted between March 1999 and February 2007, were reviewed retrospectively. The patients' chart and CT were inspected for review. Twenty three patients were operated on with both a titanium mesh plate (Matrix MIDFACE pre-formed orbital plate, Synthes, USA) and Medpor(R) (Porex, GA, USA). The patients underwent pre-operative CT scans to evaluate the fracture site and measure the area of the fracture. A transconjunctival approach was used, and titanium mesh plates were inserted subperiosteally with screw fixation. Medpor(R) was inserted above the titanium mesh plate. The patients were evaluated post-operatively for enophthalmos, diplopia, sensory disturbances and eyeball movement for a period of at least 6 months. RESULTS: No implant-related complications were encountered during the follow-up period. Enophthalmos occurred in 1 patient, 1 patient had permanent sensory disturbance, and 3 patients complained of ocular pain and fatigue, which recovered without treatment. Although there were no significance differences between groups, the use of 2 implants had fewer complications. Therefore, it can be an alternative method for treating blow out fractures. CONCLUSION: The use of both a titanium mesh plate and Medpor(R) simultaneously may be a safe and acceptable technique in the reconstruction of extensive blow-out fractures.

CT Observation of Alloplastic Materials Used in Blow Out Fracture

PURPOSE: Distinguishing different types of implants and assessing the position and size of implants by radiologic exam after orbital wall reconstruction is important in determining the surgery outcome and forecasting prognosis. We observed time-dependent density changes in three types of implants(porous polyethylene, resorbing plate and titanium mesh plate) by performing facial bone CT after orbital wall reconstructions. METHODS: A total of 32 patients, who had underwent orbital wall fracture surgery from October 2006 to March 2009 and received facial bone CT as outpatients at 1 post-operative year were included in the study. Follow-up facial bone CT was performed on the patients pre-operatively, 1 month post-operatively, and 1 year post-operatively to observe the status of the orbital implants. Medpor(R)(Porex Surgical, Inc., Newnan, Ga.) was used as porous polyethylene and followed-up in 14 cases; for resorbing plate, Synthes mesh plate(Synthes, Oberdorf, Switzerland) was used in the reconstruction, and followed-up in 11 cases; and titanium mesh plate usage was followed-up in 7 cases. Computed tomographic scan(CT) and water's view were done for radiography, and hounsfield unit(HU) was used to compare density of those facial bone CT. Wilcoxon signed rank test was applied to statistically verify measurement difference in each group of hounsfield units. RESULTS: Facial bone CT examination performed in 1 month post-operative showed that the density of porous polyethylene, resorbing plate and titanium mesh plate were -42.07, 105.67 and 539.48 on average, respectively. Among the three types of implants, titanium mesh plate showed the highest density due to its radiopaque feature. Following up the density of three types of implants in CT during 1 year after the orbital wall fracture surgery, the density of porous polyethylene increased in 10.52 House Field Units and the resorbing plate was decreased in 26.87 HouseField Units. There were no significant differences between densities in 1 month post-operatively and 1 year post-operatively in each group(p> or =0.05). CONCLUSION: We performed facial bone CT on patients with orbital fractures during follow-up period, distinguishing the types of implants by the different concentration of implant density, and the densities showed little change even at 1 year post-operative. To observe how implant densities change in facial bone CT, further studies with longer follow-up periods should be carried out.

Porous Polyethylene/Titanium Implants in the Treatment of Large Orbital Fractures

PURPOSE: We present our experience with porous polyethylene/titanium implants in large orbital fractures that are difficult to repair with conventional orbital implants. METHODS: A retrospective analysis was performed on seven patients who underwent repair of orbital fractures using porous polyethylene/titanium implants from September 2005 to December 2007. RESULTS: The average age of the seven patients was 33.3 years, including two males and five females. The mean follow-up period was 5.4 months. Six cases had combined medial and inferior wall fractures, and one case had a large inferior wall fracture. Fractures were all large enough to encompass over 50% of the associated walls. After surgery, ocular motility disturbance and diplopia improved significantly. Enophthalmos improved from a mean of 2.9 mm to 0.6 mm postoperatively. No complications occurred such as visual loss, implant exposure or migration, or orbital infection. CONCLUSIONS: Porous polyethylene/titanium implants are effective and safe for the repair of large orbital fractures without the help of microscrews or microplates.

Five-year Study of 120 Endoscopic Conjunctivodacryocystorhinostomy Using Porous Polyethylene-Coated Tear Drain

PURPOSE: To evaluate the long-term surgical results of 120 endoscopic conjunctivodacryocystorhinostomy (CDCR) procedures using a porous polyethylene (MEDPOR(R)) coated tear drain (MCTD(R)). METHODS: From 2002 to 2007, 120 patients who had been treated with endoscopic CDCR using MCTD(R) were investigated for its success rates and complications. After an osteotomy was made under nasal endoscopy, a tunnel was created from the caruncle in the conjunctival sac to the nasal cavity through the newly created ostium, and then the tunnel was enlarged to allow the insertion of the MCTD(R) The length of the tube to be inserted was determined under endoscopic examination. An anchoring suture was placed at the medial canthus to both the conjunctiva and the skin using a 5-0 Vicryl suture in the fashion of a purse string suture. RESULTS: Causes of obstruction included failed dacryocystorhinostomy (DCR) (74 cases) and idiopathic obstruction (22 cases). Postoperative complications were encountered in four cases with tube loss, 21 cases with a buried tube, 8 cases of extrusion to the conjunctival side, and 11 cases with obstruction caused by conjunctival incarceration or granuloma. The postoperative success rate was 89.1%. CONCLUSIONS: The authors concluded that endoscopic CDCR using MCTD(R) is an alternative to the standard conventional method for preventing dislodgement of the tube postoperatively. However, surgeons should consider that it may be challenging to insert the MCTD(R) and that in cases requiring removal, the tube can be difficult to remove due to adhesions.

Clinical study of augmentation malarplasty with porous polyethylene

Expanded Polytetrafluoroethylene as a Wrapping Material for Porous Polyethylene Orbital Implant

PURPOSE: To investigate the possibility of expanded polytetrafluoroethylene (e-PTFE) as a wrapping material for porous polyethylene orbital implant. METHODS: Two groups of 6 female New Zealand albino rabbits underwent enucleation with placement of a 12 mm porous polyethylene orbital implant wrapped in simple e-PTFE in one group (group 1) and macro-porous e-PTFE in the other group (group 2). Histopathologic sections of the implants obtained at 4, 6, 8 weeks were compared on the extent of fibrovascular ingrowth, percentage of the area of proliferated vessel, and grade of fibrosis between the two groups. RESULTS: There was no implant exposure or severe inflammation in group 1 and 2 during the observation. The extent of fibrovascular ingrowth differs only at 4 weeks. Group 1 showed less fibrovascular ingrowth (until outer 1/3) at anterior half compared with posterior one, but there was no difference between anterior and posterior half in group 2 (until middle 1/3). The percentage of the area of the proliferated vessels was higher in group 2 than group 1 at both anterior and posterior half, and the anterior/posterior ratio of the area of vessels was also higher in group 2 than group 1. The grade of fibrosis was higher in group 2 than group 1 at 4, 6, and 8 weeks. CONCLUSIONS: Macro-porous e-PTFE almost didn't disturb fibrovascular ingrowth into the orbital implant, so macro-porous e-PTFE can be used safely as a wrapping material for porous polyethylene orbital implant.

Repair of Large Posterior Inferior Wall Fracture Using Medpor(R) Channel Sheet Implant

PURPOSE: To evaluate the effectiveness of a Medpor(R) (porous polyethylene) channel sheet in large posterior and inferior orbital wall fracture repair. METHODS: We retrospectively analyzed the clinical features and postoperative outcomes of 52 patients who had undergone orbital wall reconstruction with a Medpor(R) (porous polyethylene) channel sheet between February 1999 and December 2005. RESULTS: Among 52 patients, 44 were men and 8 were women, with average age of 30.8 years and average follow-up period of 6.3 months. The surgery was performed on average at15 days after injury in 44 patients, except for in 8 reoperated cases. Miniplate or microplate fixation on the orbital rim with a Medpor(R) channel was required in all 52 patients for large posterior inferior wall fracture. Preoperatively, 43 patients had symptomatic diplopia, which resolved completely in 32 patients and decreased in 11 following surgery. No patients had induced diplopia or exacerbation of preoperative diplopia, except the primary gaze of 2 patients with hypertropia remained, requiring strabismus correction. The mean difference in preoperative enophthalmos between both eyes was 2.8 mm, which improved to 0.8 mm at the last follow-up. There were no instances of orbital infection, implant exposure or migration, or visual loss during follow-up. CONCLUSIONS: Medpor(R) channel implant provided optimal reconstruction of large inferior orbital wall fracture with posterior defect that lacked structural support.

Evisceration Using Scleral Capping Technique for Severe Phthisis Bulbi

PURPOSE: To introduce a new technique, involving the creation of a circumferential 360 degrees scleral relaxing incision, using an implant as large as 20 mm in diameter, and report on the surgical results in the treatment of severe phthisis bulbi, which are not indicated for classic evisceration. METHODS: The medical records of 20 patients with 20 phthisis bulbi who had undergone evisceration and placement, using the scleral capping technique, of porous polyethylene orbital implants as large as 20 mm in diameter between September 2002 and February 2006 were reviewed. For each patient, after evisceration, a circumferential 360 degrees equatorial scleral relaxing incision was made posterior to insertion of 4-recti muscles, and a porous polyethylene orbital implant was implanted. Each circumferential scleral relaxing incision wound was loosely sutured in the mattress fashion, using 5-0 braided polyester (Ethibond). RESULTS: The average of preoperative axial length, obtained using A scan and orbital computed tomography scan, was 16.8 mm. Orbital implants of 20 mm in diameter were implanted in all patients. The average of postoperative follow-up interval was 29.1 months. Orbital implant showed good motility to the satisfaction of all of patients. And the scleral capping technique could prevent complications, such as exposure of orbital implant, enophthalmos, and superior sulcus deformity. CONCLUSIONS: Scleral capping technique is safe and useful for evisceration in patients with severe phthisis bulbi. This technique can provide adequate space for the placement of and implant as large as 20 mm in diameter without generating any tension on wound. Consequently, this technique provided cosmesis and prosthesis motiliy, even without the use of a Medor coupling peg, with which patients were satisfied.

Cranioplasty with the Porous Polyethylene Implant(Medpor) for Large Cranial Defect

OBJECTIVE: This paper describes our experience and implant technique for cranioplasty of a large cranial defects using a porous polyethylene implant(Medpor) and compares the results with polymethylmethacrylate(PMMA). METHODS: Sixteen cranioplasties were performed using Medpor(n=10) and PMMA(n=6) implants between June 2003 and January 2005. The criterion for patient enrollment was a defect larger than 10cm in diameter. This study compared the operation times and complications. RESULTS: The operation times ranged from 105 to 250minutes(Mean 180 degrees +/-44minutes) in Medpor and from 185 to 460minutes (mean 128minutes) in PMMA. The absolute operation times were shorter using the Medpor implant and the differences were statistically significant(P=0.030). Satisfactory cosmetic results were obtained in all cases using the Medpor implant and with no implant-related complications. Bone ingrowth to the medpor implant was presumed to be the result on an increase in Houndsfield units of the implant, particularly at the marginal areas in the serial follow-up brain computed tomography images. CONCLUSION: It is believed that the properties of a Medpor implant make this implant an good alternative to the existing methods of a cranial contour correction. However, a further follow-up study will be needed.

Effect of Basic Fibroblast Growth Factor on Fibrovascular Ingrowth into Porous Polyethylene Anophthalmic Socket Implants

To investigate the effect of basic Fibroblast Growth Factor (bFGF) on fibrovascular ingrowth into porous polyethylene orbital implants (Medpor (R) ) and to investigate any differences according to the method of administration. For the treated groups, after evisceration and Medpor (R) implantation, bFGF was administered by soaking Medpor (R) in the bFGF solution, and/or by injecting bFGF into the Medpor (R) 1 week after the operation. Implants were removed 4 weeks after the operation and examined for the degrees of fibrovascular ingrowth by light microscopy. The percentages of the cross-sectional area of the implant occupied by fibrovascular ingrowth and the numbers of proliferated vessels were significantly higher in the bFGF-treated groups (Mann Whitney test, p 0.05). bFGF promoted fibrovascular ingrowth into porous polyethylene orbital implants regardless of the route of administration. Therefore, bFGF might be helpful to prevent complications such as implant exposure.

The Effect of the Synthetic Bone Glass on the Fibrovascularization into Porous Polyethylene Orbital Implant

PURPOSE: To evaluate the effect of the synthetic bone glass particulate (BG) on the fibrovascular ingrowth into porous polyethylene orbital implant (PP). METHODS: Forty eight rabbits were divided into 4 groups according to the surgical techniques and implanted materials. One eye was enucleated one eye and PP was implanted in group 1, was eviscerated and PP was implanted in group 2, was enucleated and BG, containing 30% by weight synthetic bone glass particulate, was implanted in group 3, and was eviscerated and BG was implanted in group 4. All implants of each group were assessed by histologic study at the first, second, fourth, and eighth weeks postoperatively. The area of fibrovascular ingrowth was calculated by histologic examination. RESULTS: There were no statistically significant differences in the fibrovascular ingrowth among these groups. A greater number of vessels per unit area and matured fibrous tissue was found in the more outer zone at longer time after implantation, but there was not statistically significant difference among the four groups. CONCLUSIONS: On the basis of this study, the synthetic bone glass particulate did not significantly increase the rate of fibrovascular ingrowth into porous polyethylene orbital implant in rabbits.

The Use of Porous Polyethylene Implants (Medpor(R)) in Cross Pattern in Case of Extensive Blow Out Fracture

Implants are used in operative reconstruction of bony defect in case of blow-out fracture. If there is a large bony defect, the thin and flexible implants can not sustain intraorbital pressure, so it may be displaced. To prevent postoperative displacement of the implant, we tried reinforcing the center of the implant, where the intraorbital pressure was focused, piling up two pieces of porous polyethylene Implants(Medpor(R)) cross- shaped. 190 patients of large blow out fracture were divided into control group(n=95) who received classic orbital wall reconstruction and study group(n=95) to whom we inserted two small pieces of Medpor(R) one by one and covered a large defect cross shaped. We compared two groups in operative time, duration of postoperative accommodation and re-operation number. Operative time was assessed as shorter in study group(16.73+/-4.24min vs 21.40+/-5.32min, p> or =0.01). Duaration of postoperative accommodation also assessed as shorter in study group (2.05+/-0.70 weeks vs 3.00+/-1.00 weeks, p> or =0.01). There was no specific difference between two groups for re- operation number (3 vs 3, p=1.00). The method to insert two small pieces of Medpor(R) one by one and covered a large defect cross shaped shows shorter operative time and duration of postoperative accommodation than the classic method inserting large one piece of Medpor(R).

Scleral Eversion Technique for Porous Polyethylene Orbital Implant after Evisceration

PURPOSE: This study is to describe scleral eversion technique as a modification of evisceration to improve its disadvantages for placement of porous orbital implant and to report the results of placement of porous orbital implants with this technique. METHODS: The medical records of 27 patients with 27 eyes who had undergone evisceration and placement of porous polyethylene orbital implant with scleral eversion technique between November 1998 and January 2000 were reviewed. Surgical technique involved the removal of corneal button and the intraocular contents. Optic nerve was severed, scleral shell was everted, and porous polyethylene orbital implant was implanted into the retroscleral and intraconal space. RESULTS: Orbital implants of 20 mm in diameter were implanted in all patients. The average postoperative follow-up interval was 22.4 months. No patient experienced severe complications like exposure of implant. All of patients showed good motility of orbital implant and 19 patients were satisfied with motility of prosthesis. Eight patients (29.6%) got placement of motility coupling post without significant problems to enhance motility. CONCLUSIONS: Scleral eversion technique is safe and useful for evisceration and placement of porous polyethylene orbital implant. This technique can provide adequate space for adequate size of implant without any tension on wound, thick anterior scleral barrier for implant and more vascular source for fibrovascular ingrowth. Therefore, it decrease exposure rate of implant.

The Effect of Amniotic Membrane on the Fibrosis between Orbital Connective Tissue and Porous Polyethylene Sheet Iimplant

PURPOSE: Soft tissue or muscle adhesion to the Porous Polyethylene Sheet Implant (PPSI) can cause postoperative extraocular motility disturbance after orbital fracture repairs using PPSI. This study was designed to examine the efficacy of amniotic membrane transplantation in the suppression of fibrosis between orbital connective tissue and PPSI. METHODS: Twelve New Zealand white rabbits were grouped as A, B, and C and conventional PPSI were implanted between orbital connective tissue and orbital floor in group A; PPSI with a barrier surface (PPSI-B) in group B; PPSI with amniotic membrane transplantation in group C. The implants were harvested at 8 weeks postoperatively, and stained with Masson trichrome and hemaoxylin and eosin staining techniques. RESULTS: In group A, the PPSI demonstrated dense adhesion on both the soft tissue implant and the bone implant interfaces. A lot of fibroblasts were observed on the surface of PPSI. In group B, the PPSI-B demonstrated less fibrosis over the barrier surface, and less fibroblasts than in group A. In group C, the PPSI with amniotic membrane transplantation manifested least fibrous adhesion among three groups. CONCLUSIONS: In orbital fracture repair, amniotic membrane transplantation could reduce the fibrosis between orbital connective tissue and PPSI, and might prevent the postoperative extraocualr motility disturbance.

The Preventive Effect of Porous Polyethylene Sheet on the Slippage of Prolene(R) Loop Placed in the Subcutaneous Tissue of Rabbits

PURPOSE: To investigate the role of porous polyethylene sheet in preventing the recurrence of ptosis after frontalis sling with Prolene(R) and the safety of porous polyethylene sheet. METHODS: Prolene(R) was placed subcutaneously in the thigh of white rabbits. In one group, Prolene(R) was placed with porous polyethylene sheet (treated group) and in the other group, Prolene(R) was placed without porous polyethylene sheet (control group). Prolene(R) was tightened and the loosening of the skin was evaluated at 1, 2, 4 and 8 weeks postoperatively. At the same time, the occurence of complications such as infection, granuloma formation was observed. Histologic examination was done at 2, 4 and 8 weeks postoperatively. RESULTS: In the treated group, skin loosening was progressed significantly for 2 weeks (p<0.05, Mann-Whitney U test) but thereafter there was no significant progression. In control group, skin loosening was progressed for 8 weeks (p<0.05, Mann-Whitney U test). Skin loosening was more severe in the control group at each follow-up evaluation (p<0.05, Wilcoxon signed ranks test). No complication was observed during the follow-up period of 8 weeks. On histologic examination, inflammatory reaction and fibrosis ere seen around Prolene(R) in the control group and fibrovascular ingrowth into the pores of porous polyethylene sheet was seen in the treated group. CONCLUSIONS: This study shows that porous polyethylene sheet can be safely used to prevent the slippage of Prolene(R) and the use of porous polyethylene sheet will be helpful in preventing the recurrence of ptosis after frontalis sling with Prolene(R).