Use of bovine pericardium as a wrapping material for hydroxyapatite orbital implants

Tendon elongation with bovine pericardium in strabismus surgery-indications beyond Graves' orbitopathy

BACKGROUND

For some patients with complex ocular motility disorders, conventional strabismus surgery is insufficient. Surgery with tendon elongation allows correction of larger angles and maintains a sufficient arc of contact for rectus muscles. This study reports results for tendon elongation with bovine pericardium (Tutopatch®) in indications other than Graves' orbitopathy in which it is already widely used.

METHODS

We reviewed the records of all patients who underwent surgery with Tutopatch® in our institution. Angles of squint and head postures were analyzed preoperatively, on the first postoperative day, and in the long term (median 9 weeks after the operation). Patients with Graves' orbitopathy were excluded.

RESULTS

From 2011 to 2018, the procedures on 58 eyes of 54 patients (35 females, median age 35 years (3-75)) met the inclusion criteria. Horizontal rectus muscle surgery (53 eyes) was conducted on patients with residual strabismus (13), Duane's retraction syndrome with eso- (type I: 16)/exodeviation (type II: 2, type III: 1), 6th (7)/3rd nerve palsy (7), Möbius syndrome (2), congenital fibrosis of the extraocular muscles type 3A (CFEOM3A, TUBB3 mutation) (4), and orbital apex syndrome (1). Vertical rectus muscle surgery (5 eyes) was conducted on patients with myasthenia (1), vertical tropia after orbital floor fracture (1), CFEOM1 (2), and Parry-Romberg syndrome (1). 42 eyes had prior eye muscle surgery (1-5 procedures, median 1). Out of 45 patients with postoperative long-term data, 43 showed an angle reduction. Fifty-one percent had an angle of 10Δ (prism diopter) or less, one had a significant over-effect, and 10 had revision surgery. For the heterogeneous group of residual eso- and exotropias, the median absolute horizontal angle was reduced from 35Δ (16 to 45Δ) to 9Δ (0 to 40Δ), for Duane's retraction syndrome from 27.5Δ (9 to 40Δ) to 7Δ (0 to 40Δ), and for sixth and third nerve palsies from 43Δ (20 to 75Δ) to 18Δ (4 to 40Δ). For 3 patients with vertical rectus muscle surgery, the median absolute vertical angle was reduced from 30Δ (20 to 45Δ) to 4Δ (1 to 22Δ). The motility range was shifted in the direction contrary to the elongated muscle in all subgroups. A considerable reduction of the excursion into the field of action of the elongated muscle had to be registered.

CONCLUSIONS

Strabismus surgery with bovine pericardium introduces new surgical options for complicated revisions and for rare and complex oculomotor dysfunctions. Yet, it has to be recognized that this type of surgery aiming at maximum effects, despite preservation or restitution of the arc of contact, leads to reduction of the excursion into the field of action of the elongated muscle. Furthermore, dose finding can be difficult depending on the underlying pathology and more than one intervention might be necessary for optimal results.

Mammalian Pericardium-Based Bioprosthetic Materials in Xenotransplantation and Tissue Engineering

Bioprosthetic materials based on mammalian pericardium tissue are the gold standard in reconstructive surgery. Their application range covers repair of rectovaginal septum defects, abdominoplastics, urethroplasty, duraplastics, maxillofacial, ophthalmic, thoracic and cardiovascular reconstruction, etc. However, a number of factors contribute to the success of their integration into the host tissue including structural organization, mechanical strength, biocompatibility, immunogenicity, surface chemistry, and biodegradability. In order to improve the material's properties, various strategies are developed, such as decellularization, crosslinking, and detoxification. In this review, the existing issues and long-term achievements in the development of bioprosthetic materials based on the mammalian pericardium tissue, aimed at a wide-spectrum application in reconstructive surgery are analyzed. The basic technical approaches to preparation of biocompatible forms providing continuous functioning, optimization of biomechanical and functional properties, and clinical applicability are described.

Multiparametric Optical Bioimaging Reveals the Fate of Epoxy Crosslinked Biomeshes in the Mouse Subcutaneous Implantation Model

Biomeshes based on decellularized bovine pericardium (DBP) are widely used in reconstructive surgery due to their wide availability and the attractive biomechanical properties. However, their efficacy in clinical applications is often affected by the uncontrolled immunogenicity and proteolytic degradation. To address this issue, we present here in vivo multiparametric imaging analysis of epoxy crosslinked DBPs to reveal their fate after implantation. We first analyzed the structure of the crosslinked DBP using scanning electron microscopy and evaluated proteolytic stability and cytotoxicity. Next, using combination of fluorescence and hypoxia imaging, X-ray computed microtomography and histology techniques we studied the fate of DBPs after subcutaneous implantation in animals. Our approach revealed high resistance to biodegradation, gradual remodeling of a surrounding tissue forming the connective tissue capsule and calcification of crosslinked DBPs. These changes were concomitant to the development of hypoxia in the samples within 3 weeks after implantation and subsequent induction of angiogenesis and vascularization. Collectively, presented approach provides new insights on the transplantation of the epoxy crosslinked biomeshes, the risks associated with its applications in soft-tissue reconstruction and can be transferred to studies of other types of implants.

[Porous orbital implants]

Since the introduction of the first coralline hydroxyapatite porous orbital implant as eye replacement in the early 1980s, numerous other modified porous implants have been developed. Due to the different design of the existing studies concerning long-term safety with, in some cases, relatively short follow-up, a comparison is difficult and none of the implant types can be clearly identified as being superior. Factors affecting the exposure rate of the implant seem to be the implant coating, the surgical technique and the condition of the patient's tissue at the beginning of surgery.

Alphasphere as a successful ocular implant in primary enucleation and secondary orbital implant exchange

PURPOSE

To describe the surgical technique for a novel poly-HEMA (2-hydroxyethyl methacralate)[PHEMA] implant (Alphasphere, Addition Technology, Des Plaines, IL) in primary enucleation and placement of secondary orbital implant.

METHODS

Retrospective chart review of all patients receiving an Alphasphere implant for primary enucleation or secondary implant exchange from October 2009 to 2011. Interval follow-up was performed again on January 2013. Patient demographics, indications for surgery, and post-operative complications were reviewed.

RESULTS

Twelve patients received an Alphasphere implant for primary enucleation (n = 10) or secondary exchange (n = 2), with follow-up that ranged from 2 weeks to 14 months. The study included 9 adult and 3 pediatric patients with a mean age of 40 years, range 8-82 years. The indication for enucleation included: painful blind eye (n = 9), enophthalmos with difficult prosthesis fit in cases of secondary implant exchange (n = 2), and prophylaxis for sympathetic ophthalmia (n = 1). Only one patient required removal of the implant, due to a sinus infection with subsequent extrusion of the implant. Otherwise, the only other complication experienced was slight implant migration (n = 1).

CONCLUSION

This initial report indicates that Alphasphere can be successfully used in the management of an anophthalmic socket. The advantages of the Alphasphere implant include: it does not require tissue wrapping, extraocular muscles can be directly sutured to the implant, it maintains a smooth surface to limit risk of exposure due to conjunctival breakdown, and undergoes anterior orbital fibrovascular ingrowth which optimizes prosthesis location and socket motility.

Orbital implants in enucleation surgery

OBJECTIVE

To compare prosthetic and implant motility and the incidence of complications associated with porous and nonporous enucleation implants.

METHODS

Literature searches conducted in January 2002 for 1985 to 2001 and May 2002 for October 2001 to 2002 retrieved relevant citations. The searches were conducted in MEDLINE and limited to articles published in English with abstracts. Panel members reviewed the articles for relevance to the assessment questions, and those considered relevant were rated according to the strength of the evidence.

RESULTS

A randomized clinical trial and a longitudinal cohort study detected no difference in implant or prosthetic movement between nonpegged hydroxyapatite porous and spherical alloplastic nonporous implants. No controlled studies were retrieved that investigated whether pegging porous implants improves prosthetic movement. Several case series indicate that patients with pegged hydroxyapatite implants have some degree of improved prosthetic motility. Longitudinal cohort studies show that sclera-covered hydroxyapatite implants have higher exposure rates than sclera-covered silicone implants, and unwrapped porous polyethylene implants have higher exposure rates than unwrapped acrylic implants. There are numerous case series that document a wide range of implant exposure rates in patients with various enucleation implants. It is difficult to compare complication rates among implant types because patient populations vary, surgical techniques differ, and follow-up periods are often limited.

CONCLUSIONS

Based on one randomized clinical trial, spherical alloplastic nonporous and nonpegged porous enucleation implants provide similar implant and prosthetic motility when they are implanted using similar surgical techniques. Coupling the prosthesis to a porous implant with a motility peg or post appears to improve prosthetic motility, but there are few available data in the literature that document the degree of the improvement. There is a widely variable incidence of porous implant exposure, but certain surgical techniques and the type of wrapping material seem to reduce the exposure rate. Additional research is needed to document the long-term incidence of complications related to porous enucleation implants and associated surgical techniques. This includes the use of wrapping materials and what procedural modifications, both surgical and prosthetic, are most effective in reducing these complications.

Conjunctival melting syndrome associated with the use of bovine pericardium wrapping material

PURPOSE

To report 18 cases of unusually large, early conjunctival breakdown occurring with the use of bovine pericardium wrapping material for orbital implants.

METHODS

Retrospective case series. The clinical course and histopathologic features of 18 cases of early conjunctival breakdown in patients who had undergone orbital implantation of bovine pericardium-wrapped hydroxyapatite or porous polyethylene are reviewed.

RESULTS

Eighteen patients presented with unusually large (average 13.44 mm) conjunctival defects over bovine pericardium-wrapped implants. The average time from enucleation to exposure was approximately 4 months. Implants had to be removed in 8 of 18 cases. There was clinical and histologic evidence of tissue inflammation and conjunctival melting.

CONCLUSIONS

The conjunctival melting phenomenon we report herein is alarming. We have abandoned the use of bovine pericardium as a wrapping material for implants after enucleation because of the unfavorable results.