Chronic exposure of hydroxyapatite orbital implants: cilia implantation and epithelial downgrowth

Chronic Orbital Inflammation Associated to Hydroxyapatite Implants in Anophthalmic Sockets

Purpose

We report 6 patients who received a hydroxyapatite (HA) orbital implant in the socket and developed chronic orbital inflammation unresponsive to conventional medical therapy.

Case Reports

We assisted 6 cases (4 males, 2 females) who received an HA orbital implant in the socket between 2015 and 2016 at King Khaled Eye Specialist Hospital, Riyadh, Saudi Arabia, and developed chronic orbital inflammation with chronic discharge, redness, and pain (onset from weeks to over 2 decades after surgery). Computed tomography evaluation indicated inflammation in the orbital tissues, and histological examination showed a foreign body granulomatous reaction mainly localized around and blanching the HA implant. The condition was unresponsive to usual medical treatment and was resolved immediately after implant removal.

Conclusions

Chronic inflammation can occur decades after placement of an HA implant in the orbit and can be successfully treated with implant removal.

Porous orbital implant after enucleation in retinoblastoma patients: indications and complications

This study aims to identify risk factors associated with complications in retinoblastoma patients following primary and secondary enucleations with porous implant placement. A retrospective case-control study was performed between 2010 and 2015. Data pertaining to subjects' demographics, medical history, clinical, and pathological findings, implant characteristics and complications were collected. The analysis included 103 eyes of 101 patients age 27.8 ± 21.9 months undergoing enucleation for retinoblastoma. Postoperatively, 19/103 (18%) eyes developed exposure, extrusion, or hematoma requiring subsequent surgery. Exposure was the most common postoperative complication (12/19, 63%). Age at enucleation 24 months or younger, Hispanic ethnicity, female gender, and intravenous chemotherapy prior to enucleation were associated with increased odds of implant complications. In contrast, patients who were given intravitreal melphalan (IM), subtenons carboplatin (SC), or external beam radiation therapy (EBRT) did not demonstrate an increased risk of complications. In this cohort of retinoblastoma patients undergoing primary or secondary enucleation with porous implants, implant exposure was the most common postoperative complication. Our findings suggest that female gender, Hispanic ethnicity, age at enucleation 24 months or younger, and intravenous chemotherapy prior to enucleation may increase the risk of complications.

Improved fibroblast functionalities by microporous pattern fabricated by microelectromechanical systems

Fibroblasts, which play an important role in biological seal formation and maintenance, determine the long-term success of percutaneous implants. In this study, well-defined microporous structures with micropore diameters of 10-60 µm were fabricated by microelectromechanical systems and their influence on the fibroblast functionalities was observed. The results show that the microporous structures with micropore diameters of 10-60 µm did not influence the initial adherent fibroblast number; however, those with diameters of 40 and 50 µm improved the spread, actin stress fiber organization, proliferation and fibronectin secretion of the fibroblasts. The microporous structures with micropore diameters of 40-50 µm may be promising for application in the percutaneous part of an implant.

Increased fibroblast functionality on CNN2-loaded titania nanotubes

Infection and epithelial downgrowth are major problems associated with maxillofacial percutaneous implants. These complications are mainly due to the improper closure of the implant–skin interface. Therefore, designing a percutaneous implant that better promotes the formation of a stable soft tissue biologic seal around percutaneous sites is highly desirable. Additionally, the fibroblast has been proven to play an important role in the formation of biologic seals. In this study, titania nanotubes were filled with 11.2 kDa C-terminal CCN2 (connective tissue growth factor) fragment, which could exert full CCN2 activity to increase the biological functionality of fibroblasts. This drug delivery system was fabricated on a titanium implant surface. CCN2 was loaded into anodized titania nanotubes using a simplified lyophilization method and the loading efficiency was approximately 80%. Then, the release kinetics of CCN2 from these nanotubes was investigated. Furthermore, the influence of CCN2-loaded titania nanotubes on fibroblast functionality was examined. The results revealed increased fibroblast adhesion at 0.25, 0.5, 1, 2, 4, and 24 hours, increased fibroblast viability over the course of 5 days, as well as enhanced actin cytoskeleton organization on CCN2-loaded titania nanotubes surfaces compared to uncoated, unmodified counterparts. Therefore, the results from this in vitro study demonstrate that CCN2-loaded titania nanotubes have the ability to increase fibroblast functionality and should be further studied as a method of promoting the formation of a stable soft tissue biologic seal around percutaneous sites.

Current management strategies for intraocular retinoblastoma

Survival rates for retinoblastoma patients have increased dramatically over the last century, with documented 5-year survival figures reaching 87-99% in developed countries. During the last decade, there has been a dramatic paradigm shift in the treatment approach for intraocular retinoblastoma, emphasising chemoreduction protocols and minimising the use of external beam radiation. The recognition of the increased risk for second non-ocular cancers with external beam radiation contributed to the growing emergence of chemotherapy. Although chemoreduction protocols vary slightly between institutions, many centres are currently treating intraocular retinoblastoma with carboplatin, vincristine and etoposide as a three-drug regimen given in two to six cycles. Clinical studies have demonstrated that systemic chemotherapy must be combined with other modalities, such as laser treatment and cryotherapy, for adequate tumour control and many eyes with advanced intraocular disease require salvage therapy with radiation or enucleation. Therefore, modern centres treating retinoblastoma continue to manage patients with a variety of modalities, individualising the therapy according to the patient's presentation and clinical course.

Implant infection in porous orbital implants

PURPOSE

To analyze implant infection in patients with porous orbital implants.

METHODS

A retrospective analysis of 212 patients with one of five types of porous orbital implants (bone-derived hydroxyapatite [HA], coralline HA, synthetic HA, porous polyethylene, and aluminium oxide) was conducted. Reasons for surgery, type of surgery, type of implant, peg system used, time of pegging, problems before and after pegging, treatment, and follow-up duration were recorded for all patients, along with additional data including time of onset of infection, microorganism cultured, antibiotics used, patient response to antibiotic therapy, additional interventions, and final status for patients with infection.

RESULTS

Of the 212 patients with porous orbital implants, 116 (54.72%) were pegged. Implant infection was observed in 11 of 116 patients (9.48%) with pegs, whereas 0% of unpegged implants was infected (p = 0.001). The interval between pegging and the onset of infection was 3 to 83 months (average, 36.27 +/- 29.12 months). Implant exposure was noted in 5 of the 11 patients with infection. Symptoms resolved completely with antibiotic treatment in 7 patients. One patient required implant removal as the result of frequent exacerbations. The remaining 3 patients presented with hemorrhagic, purulent discharge and/or pyogenic granuloma on their last visits after being free of symptoms for 5 to 6 months.

CONCLUSIONS

Implant infection is a serious problem that requires additional patient visits, intensive antibiotic therapy, surgery, or some combination of these. Existence of a peg system appears to play a role in implant infection. Infection may develop as late as 6 to 7 years after pegging, and the patient should be cautioned about potential late-onset problems. It is possible to control the infection with appropriate antibiotic therapy; removal should be reserved for refractory cases.

Hydroxyapatite orbital implant exposure in children

PURPOSE

Hydroxyapatite orbital implants are buried implants that may be integrated into the overlying prosthesis after enucleation. We report problems encountered using these implants during a 14-year period in a pediatric population.

METHODS

Retrospective analysis of a pediatric population from 1987 through 2001.

RESULTS

Indications for enucleation (N = 19) included retinoblastoma (n =17), persistent hyperplastic primary vitreous (n =1), and painful blind eye (n =1). Conjunctival erosion (36.84%) and consequent implant exposure (15.70%) were the main problems identified in this study. There were no cases of orbital infection. Management included resuturing and scleral patching.

CONCLUSION

Conjunctival erosion of hydroxyapatite implants contributed to significant morbidity in 19 children who underwent enucleation and hydroxyapatite orbital implant.

Subcutaneous microfabricated surfaces inhibit epithelial recession and promote long-term survival of percutaneous implants

The long-term success of percutaneous devices is compromised by problems such as infection, mechanical avulsion and epithelial downgrowth. The objective of this study was to test the effects of microfabricated surfaces on tissue integration and long-term survival of percutaneous implants, using a modified implant design and a two-stage surgical method. Hexagonal titanium-coated epoxy implants were constructed with separate subcutaneous and percutaneous components, so that the effects of surface topography on connective tissue could be separated from the effects on epithelium. Subcutaneous components with 30-microm-deep micromachined grooves, 120-microm-deep tapered pits, or smooth control surfaces were secured to the calvarial bone of rats by a titanium pin. After 8 weeks, a percutaneous smooth-surfaced component was secured to the subcutaneous component. Dental impression materials were used to make models of the components and adjacent tissues at weekly intervals and tissue recession around the implants was measured. Some implants were removed at intervals up to 24 weeks and processed for histology. Connective-tissue ingrowth and mineralized tissue were noticed on the micromachined surfaces, whereas a thick capsule and epithelial downgrowth were observed on smooth control surfaces. On all implants, recession occurred most rapidly in the first 3 weeks, but was significantly reduced relative to the smooth controls only on implants with micromachined grooved subcutaneous surfaces (p<0.05). In addition, the time before failure was significantly (p<0.05) longer for implants with grooved subcutaneous surfaces than implants with smooth and pitted subcutaneous surfaces. This study indicated that an impression technique could be used to monitor tissue recession on percutaneous devices, and that micromachined grooved surfaces located subcutaneously improved the performance and longevity of percutaneous devices by promoting tissue integration.

Orbital and periorbital infections

Infections of the orbit and periorbital tissues are not uncommon. Trauma, skin infections, and sinusitis are frequently the underlying cause. Studies have shown changes in epidemiology and pathogens in the last decade. Although classical manifestations are usually present, atypical cases without specific signs and symptoms may confound the diagnosis. A high index of suspicion, aided by ultrasonography, computed tomography, and magnetic resonance imaging, is frequently required for an accurate diagnosis. Prompt diagnosis and treatment may lead to resolution of the infection, thus avoiding ocular sequelae. Orbital infections may spread into the globe, causing endophthalmitis. Some patients may even need an enucleation or evisceration. New materials and techniques may improve the final result of an anophthalmic socket.