Acrylic Implantation Research Articles

Posterior capsule opacification (PCO) in pediatric eyes with and without traumatic cataract surgery with in-the-bag single-piece hydrophobic acrylic IOL implantation

Posterior capsule opacification (PCO) in pediatric eyes with and without traumatic cataract surgery with in-the-bag single-piece hydrophobic acrylic IOL implantation

Complications due to bovine pericardium used to cover acrylic implants after enucleation and tubes of aqueous devices

Complications due to bovine pericardium used to cover acrylic implants after enucleation and tubes of aqueous devices

An Ultrasound Biomicroscopy Study of Filtering Blebs after Deep Sclerectomy with a New Acrylic Implant

To identify the clinical and anatomic characteristics of filtering blebs after nonpenetrating deep sclerectomy (NPDS) using ultrasound biomicroscopy, and to evaluate its influence on intraocular pressure (IOP) control. We conducted a prospective interventional case series in 18 eyes of 18 patients who had undergone nonpenetrating deep sclerectomy with Esnoper® implant. A complete ophthalmic examination and ultrasound biomicroscopy (UBM) exploration were performed at 1, 3, and 6 months postoperatively. Intraocular pressure significantly decreased from a mean of 23.5 mmHg (SD 3.5) preoperatively to a mean of 13.1 mmHg (SD 7.6), 13.2 mmHg (SD 4.3), and 13.3 mmHg (SD 3) at 1, 3, and 6 months postoperatively, respectively. At 6 months, lower IOP levels significantly correlated with hyporeflective blebs (r=-0.82, p=0.000), with the presence of hyporeflective suprachoroidal space (r=-0.67, p=0.003) and with the presence of hyporeflective area around the scleral lake (r=-0.55, p=0.02). The presence of these 3 filtration signs together correlated with lower IOP levels compared with the presence of only 1 or 2 (p=0.000, p=0.004, p=0.0005) at 1, 3, and 6 months postoperatively, respectively. A thinner trabeculo-descemetic membrane (TDM) was significantly correlated with lower postoperative IOP value at the first postoperative month (r=0.45, p=0.05). Intraocular pressure mean values and UBM characteristics were not significantly different between eyes with single NPDS and eyes following combined NPDS-phacoemulsification. At 6 months, eyes without goniopuncture had lower IOP values (p=0.02), higher bleb (p=0.015), and thinner TDM (p=0.01) than those needing goniopuncture. Ultrasound biomicroscopy is a useful method to evaluate outflow mechanisms after NPDS and their correlation with postoperative IOP control.

Implante orbital misto para reconstrução de cavidade anoftálmica: relato de caso

A new model of orbital implant, matching the low cost of acrylic implants (PMMA) with the advantages of medpor (Porex) is presented herein. The new implant model consists of a PMMA implant with a dura mater scrap adhered on its anterior face of the same diameter of the acrylic implant and a medpor snip adhered on its posterior face by sterile cyanoacrylate. Dura mater was fixed to medpor with 6.0 mono-nylon. One patient who presented previous extrusion of the implant was submitted to surgery and was evaluated on the 1st, 7th, 15th, 30th postoperative days, and 3 and 6 months after surgery when a computed tomography was performed. A good cosmetic, mobility and volume result was noted after an escleral prosthesis was adapted, with no infection, migration or extrusion of the implant until this moment. This case showed us that it is possible to use a more economic implant model with the same results of medpor (Porex).

Giant cell tumor of bone

This retrospective study analyses 67 patients with 69 giant cell tumors of bone staged according to the Surgical Staging System of benign and malignant lesions of Enneking (1980, 1986). A significant correlation between Stage 2 and Stage 3 benign lesions in respect to local recurrence as well as between the therapeutic procedures and recurrence was found. Intralesional excision with temporary acrylic cement implantation showed to be the preferable initial treatment of these tumors. Special attention to surgical staging, surgical techniques and a supervised rehabilitation program minimize the incidence of recurrence and at the same time giving am maximum of joint function.

Advances in Cranioplasty: A Simplified Algorithm to Guide Cranial Reconstruction of Acquired Defects

The search for a universal reconstructive material and the application of a routine approach leaves the surgeon limited in cranial reconstruction. Facility with a variety of implant materials and approaches helps optimize surgical management. The variability of surgical defects and challenges in cranial reconstruction highlights the importance of a strategic approach to evaluate both the defect and the clinical circumstance. Among the numerous alloplastic materials available, the utility of titanium mesh, hydroxyapatite cement, and prefabricated custom acrylic implants have remained at the forefront. The onus of responsibility remains on the surgeon to evaluate each clinical scenario and select the optimal course for management.

Posteriore Kapselopazifikation nach Phakoemulsifikation bei Patienten mit rheumatoider Arthritis

To assess the posterior capsule opacification (PCO) rate after phacoemulsification with polyacrylic intraocular lens (IOL) implantation in patients with rheumatoid arthritis (RA) compared with the controls, and to assess whether preoperative activity of RA is associated with a higher incidence of PCO. 24 eyes of 20 RA patients operated in a period of 4 years were included in our study. A control group of 20 eyes from 20 health subjects were also included in our study. All procedures were performed by a single surgeon with the same surgical technique and postoperative medication. One year postoperatively in two eyes (8.3%) of RA-patients lens epithelial cells (LEC) migration of grade 1 was observed, in controls also in two eyes (10%). No correlation was observed between age, duration of RA or preoperative activity of RA and the PCO rate. Following acrylic IOL implantation, the PCO rate one year after surgery was 8.3% in RA patients and 10% in controls. RA patients present no higher risk for PCO development than controls.

Optical Coherence Tomography of Intraocular Lens Implants and Their Relationship to the Posterior Capsule: A Pilot Study Comparing a Hydrophobic Acrylic to a Plate-Haptic Silicone Type

Background: Optical coherence tomography (OCT) has been used to examine the anterior as well as the posterior segment and can be used to examine the intraocular lens (IOL) and their relationship to the posterior capsule in vivo. Objectives: To use OCT to examine two of the IOLs and some of the features related to the development of posterior capsular opacification (PCO). Methods: This is a pilot study of a prospective (n = 12) and a retrospective (n = 14) series of patients who had uneventful phacoemulsification and IOL implantation of either hydrophobic acrylic (Acrysof; Alcon) or plate-haptic (PH) silicone (C11UB; Chiron, Bausch & Lomb) IOLs. The outcome of interest was the ability of OCT to clearly delineate the outline of the IOL optics and their appositional relationship to the posterior capsule. Results: OCT showed that hydrophobic acrylic IOLs had a better defined outline than PH silicone IOLs. It also showed close apposition between hydrophobic acrylic optics and the mid-peripheral part of the posterior capsule and the absence thereof with PH silicone IOLs. Conclusions: Hydrophobic acrylic implants have better definition on the OCT scans than PH silicone and they develop close apposition to the posterior capsule. The latter feature is consistent with the ‘no space, no cell, no PCO’ concept and what is known about the effect of the implant material and design on the rate of PCO.

Enucleation with Reverse Replacement of Sclera as an Alternative to Conventional Evisceration

Background and Objective: To objectively review the results of a technique combining enucleation with evisceration in patients listed for traditional evisceration with preservation of the rectus muscles. Materials and Methods: Ten patients who underwent combined enucleation and evisceration with 3 to 36 months of follow-up were identified (average follow-up 14 months). Three eyes were phthisical, 1 microphthalmic, 1 buphthalmic, 1 a secondary implant following conventional evisceration and 4 non-phthisical painful eyes. The technique involved enucleation followed by evisceration of the eye contents. Implants, either coral or acrylic, were wrapped in the eviscerated sclera and replaced in the orbit with the posterior pole of the sclera facing anteriorly. The rectus muscles were then resutured onto the sclera. The patients were subsequently recalled and volume replacement, cosmesis and complications were assessed. Results: Three coral and 7 acrylic implants were placed, 2 of 22 mm, 7 of 20 mm and 1 of 18 mm. No complications were encountered, in particular no implant extrusions. Cosmesis was graded good in 9 out of 10 patients. Conclusion: Combined enucleation and evisceration allows the selection and placement of an appropriately large-sized implant to achieve good volume replacement with no extrusions in our series. This technique is particularly pertinent as an alternative to standard evisceration in phthisical eyes.

Licking rate adaptations to increased mandibular weight in the adult rat

In this experiment, chronic mandibular loading was used to study adaptation in licking rate. Twenty-four 115-day-old rats were randomly divided into two groups. The experimental group received 1.791±0.083 g submandibular gold implants, and the control group received 0.179±0.009 g submandibular acrylic implants. The animals were videotaped while lapping on two separate occasions preoperatively, and once every week postoperatively for 12 weeks. The videotapes were used to obtain licking rates for each animal at each taping session. The findings showed that licking rate decreased significantly after surgery for both groups; however, the decrease was similar for both the experimental and control groups. This indicates that licking rate was affected by the experimental design, but not specifically by the weight of the gold implant.

Preformed acrylic cranial implants using fused deposition modeling: A clinical report

Fabrication of acrylic cranial implants by conventional methods of moulage and mold formation may be difficult when the margin of the defect cannot be accurately detected. Three-dimensional anatomic models built by fused deposition modeling can serve as templates for the fabrication of custom acrylic implants for large or complicated cranial defects. Virtual mirror imaging of the contralateral nondefect side can facilitate the restoration of symmetry in appearance-sensitive areas. This clinical report presents a method for the fabrication of cranial implants for 2 patients using anatomic modeling technology.

Exposure rates of wrapped and unwrapped orbital implants following enucleation.

To compare the complication rate of porous polyethylene orbital motility implants with solid acrylic implants following enucleation and identify possible risk factors. The authors retrospectively reviewed the charts of a total of 117 consecutive enucleations performed at the University of Illinois at Chicago between March 28, 1994, and May 28, 1999. Data obtained included patient demographics, surgical indication, implant type, attending surgeon, surgical technique, and any reported complications. The primary outcome was presence or absence of implant exposure at the final recorded visit. Of the 117 identified cases, 29 were eliminated due to insufficient follow-up data. Of the 88 remaining cases, 48 patients received porous implants and 40 received solid acrylic implants. Implant exposure developed in four cases. All exposures occurred in unwrapped porous polyethylene implants (n=2) or porous polyethylene implants wrapped in absorbable material (n=2). All exposures occurred in patients younger than 18 years of age, and 75% occurred early after trauma-associated enucleation surgery. The exposure rate of porous polyethylene implants in this study (9%) was found to be comparable to published rates for hydroxyapatite implants. There were no exposures of unwrapped solid acrylic spheres. Unwrapped porous implants in pediatric patients or following trauma-related enucleation may represent an increased risk for postoperative implant exposure. Absorbable wrapping of porous implants may carry the same risk for exposure as no wrapping. Porous implants wrapped in durable material appear to be as safe as solid acrylic spheres.

Acrylic hydrogel implants after spinal cord lesion in the adult rat

Acrylic hydrogels, like the polymer of 2-hydroxyethyl methacrylate, are biocompatible, mechanically stable, porous materials that can be coated with collagen or laminin acting as bioadhesive substrates. Poly- 2-hydroxyethyl methacrylate sponges have been proposed for restoring the anatomical continuity of damaged neural structures. In the present work, the ability of poly-2-hydroxyethylmethacrylate sponges to provide the injured spinal cord neurons with a conductive substrate for their regenerating axons was investigatedin 32 adultWistar rats. Collagen impregnated poly-2-hydroxyethylmethacrylatesponges were implanted into suction cavities of the dorsal funiculus of the spinal cord. Two to four months after implantation, the spinal cord was removed and processed for histology, and S100 and GFAP immunohistochemistry. To study axonal regeneration into the sponge, the spinal cord or the sensorimotor cortex were injected with 0.05–0.1 ml of an 8% solution of lectin-conjugated horseradish peroxidase or 10% dextran tetramethylrhodamine. The fibroglial reaction, accumulation of mononuclear cells, and angiogenesis at the interface between the spinal cord and the sponge were minimal. Cystic cavitation in the spinal cord was virtually absent. Anterograde labeled axons were seen to penetrate and to elongate the full length of the sponge. These results demonstrate that poly-2-hydroxyethylmethacrylate sponges represent a safe supportive material for regenerating spinal cord axons.

Custom cranioplasty using stereolithography and acrylic

Numerous methods of cranioplasty have been described. Customization and prefabrication have been reported to reduce operating time and improve cosmesis. An original technique for the manufacture of customized cranioplastic implants has been developed and tested in 30 patients.Thirty patients requiring cranioplasties were selected. Data acquired from computed tomography (CT) were used to manufacture exact plastic replicas (biomodels) of craniotomy defects and master cranioplastic implants using the rapid prototyping technology of stereolithography (SL). The three-dimensional (3D) imaging techniques of mirroring and interpolation were used to extrapolate on existing anatomy to design the master implants. The master implants were hand finished to fit the defect in the corresponding cranial biomodel exactly and were then used to create a cavity mould. The mould was used to cast thermally polymerised custom acrylic implants. The surgeons reported that the customized implants reduced operating time, afforded excellent cosmesis and were cost effective. The patients reported that the opportunity to see the biomodel and implant preoperatively improved their understanding of the procedure. Two complications were noted, one infection and one implant required significant trimming. The simultaneous manufacture of the master implant (male) and biomodel (female) components from SL allowed custom accurate implants to be manufactured. Disadvantages identified were the time required for computer manipulations of the CT data (up to 2 h), difficulty in assessing the accuracy of the computer generated master as a 3D rendering, the potential for SL parts to warp, manufacturing time (minimum 2 days) and the cost of approximately $1300 US per case ($1000 for the SL biomodel and $300 for the acrylic casting).

Pathology findings with acrylic implants

We report the pathological findings in cases of acrylic implants obtained by direct intratumoral injection of poly-methyl-methacrylate (PMMA) and N-butyl-cyano-acrylate (NBCA). Direct intratumoral injection of acrylic implants was performed for a variety of primary and secondary bone lesions. These types of treatments have been used at our institution in the last 4 years for 40 vertebroplasty (PMMA) procedures and for nine bone lesions of other locations (PMMA, NBCA). Postmortem histology became available for 1 case of PMMA and for 5 cases with NBCA intratumoral acrylic implants. The pathological findings associated with PMMA and NBCA were evaluated and compared. PMMA exhibited a macroscopic and microscopic rim of tumor necrosis, 6 months after implantation. NBCA exhibited compressive effects on the nearby tumor tissue, however, without signs of significant necrosis outside the acrylic tumor cast. Tumor captured inside the acrylic cast showed extensive to near complete necrosis. Acrylic implants may lead to necrosis when injected directly in tumors. The necrotizing effect may extend beyond the limits of an implant in the case of PMMA. Such an extended effect of PMMA, when compared with NBCA, may be due to the variable toxicity of acrylic implants, including the different degrees of the exothermic reaction during polymerization.

Hydroxyapatite orbital implants Experience with 100 cases

The hydroxyapatite (HA) intraorbital implant is a relatively new implant made from the porous skeleton of a coral species which allows fibrovascular ingrowth and therefore tissue integration. After fibrovascular ingrowth, a hole can be drilled in the implant and a motility peg inserted to increase movements of the prosthesis by coupling the implant to the prosthesis. The records of the first 100 cases of HA intraorbital implants inserted by the one surgeon were analysed for complications, pain and nausea postoperatively, length of hospital stay, and further surgical procedures required. A series of acrylic implants inserted by the same surgeon was used for comparison. Twenty-five primary and 75 secondary HA implants were performed in patients ranging from six to 74 years of age. All were covered in donor sclera. Follow-up was three to 34 months (mean 16.9, median 17.0). Complications occurred in 15 patients and included too large an implant (seven cases) requiring surgical reduction, scleral exposure in three (repair required in one), an early small exposure of the coral in one case, late thinning of the conjunctiva and later exposure of the implant in one, and shallowing of the inferior fornix requiring mucous membrane grafting in three. No implants migrated, extruded or became infected. Of 80 patients beyond six months follow-up, 28 (35%) had insertion of motility pegs, and six (7.5%) of these suffered minor complications related to the peg. Compared to patients having acrylic implants, the postoperative analgesic requirements and length of hospital stay were significantly greater for the HA patients. Hydroxyapatite intraorbital implants represent a significant advance over other implants and offer a more stable, safe alternative. They also offer the possibility of improved prosthesis motility. The additional cost of the implant, prolonged hospital stay and postoperative pain, should be considered in recommending such implants to patients either as primary or secondary implants.

The acrylic-wire option in cervical spine fixation. A retrospective study.

This retrospective study was undertaken to assess the stability of the cervical spine after fixation with acrylic wire implants. Of the 44 patients with various pathological conditions of the cervical spine selected for this treatment in the course of 20 years, 36 were considered suitable for long-term follow-up evaluation. In 30 cases (83%) the stability of the spine was rated good. It is concluded that the acrylic-wire combination is a valuable surgical option in certain conditions i.e. old age, short life expectancy, poor general health, mental disease, in which long confinement in bed or in orthopaedic appliances is poorly tolerated.

Implantation of porous acrylic cement in soft tissues: an animal and human biopsy histological study

Long-term (8 and 24 month) reactions of the (hypo) dermis of the guinea pig to solid and porous (50 vol%) acrylic implants and four human biopsies from porous subcutaneous acrylic implants were studied light microscopically. The solid implants were encapsulated by dense connective tissue. Mobility was evidenced by the loss of 4 out of 36 after 2 yr and was considered the explanation for the occurrence of ectopic cartilage and mineralized material at some solid implants' surfaces after 2 yr. A dense capsule was not evident with the porous implants, instead vascularized collagenous connective tissues penetrated into and filled the pores, thus anchoring the implant to the body. None of these implants, was lost. Notwithstanding the presence of some multinucleated giant cells, scattered inflammatory cells and loosely packed inflammatory foci with both implant materials, the materials were considered well-tolerated by the body. The histology of the human biopsy did not differ significantly from the porous animal implants.

IMPLANTS van Mullem, P. J., and Wijn, J. R. Bone and soft connective tissue response to porous acrylic implants. A histokinetic study. J. Craniomaxillofac. Surg. 16

IMPLANTS van Mullem, P. J., and Wijn, J. R. Bone and soft connective tissue response to porous acrylic implants. A histokinetic study. J. Craniomaxillofac. Surg. 16

Porous Acrylic Cement: Evaluation of a Novel Implant Material

The preparation and some properties of in situ curing porous acrylic cement, a modification of the traditional bone cement, are described. Through numerous animal experiments, the behavior of the porous cement in a biological environment has been studied. The histological evaluation reveals that hard and soft tissues readily grow into the pores of the cement, thus anchoring the implant to the host tissues. Some inflammatory foci, decreasing in number with residence time, together with varying numbers of multinucleated giant cells were found occasionally in the tissues in and around implants. When implanted in soft tissues, the porous cement behaved favorably with respect to solid acrylic implants because of the immobility of the implants and the absence of ectopic hard tissue formation. The biocompatibility of porous acrylic cement is judged to justify clinical trials in plastic and reconstructive surgery.