Delayed Extrusion of Hydroxyapatite Cement Orbital Floor Implant: A Rare Case Report of Augmentation Failure

Abstract

Introduction

Hydroxyapatite implants are widely used in orbital reconstruction due to their biocompatibility and capacity for osseointegration. Complications such as implant exposure or extrusion typically occur in the early postoperative period, with late-onset cases being exceedingly rare.

Case Presentation

This report presents a 78-year-old female who developed hydroxyapatite implant extrusion 7 years after orbital volume augmentation for an anophthalmic socket. She presented with lower eyelid retraction, ectropion, redness, and a fistula in the inferior fornix. Surgical management included implant removal, placement of a dermis fat graft from the abdomen to restore orbital volume, and correction of eyelid deformities using a tarsal strip and full-thickness skin graft. Postoperatively, the patient achieved successful resolution of symptoms, restoration of orbital volume, and correction of eyelid position.

Conclusion

This case emphasizes the need for long-term surveillance following orbital reconstruction and highlights effective management strategies for rare delayed implant extrusion.

Introduction

Hydroxyapatite spherical implants are frequently used in orbital reconstructive surgeries due to their biocompatibility, integration with surrounding tissues, and low risk of long-term complications [1, 2]. They are favored in orbital volume augmentation and repair of anophthalmic sockets, as they allow for excellent vascularization and minimize the risk of early extrusion when compared to other alloplastic materials [3]. In contrast, hydroxyapatite cement or filler is used as an injectable or moldable material for orbital floor augmentation to further correct volume deficits. However, despite their high success rates, implant exposure and extrusion remain possible complications, though these generally occur in the early postoperative period. Late-onset extrusion of hydroxyapatite cement, particularly several years after implantation, is a rare phenomenon [4].

The incidence of hydroxyapatite spherical implant extrusion is low, with reported rates of spherical ocular implant extrusion ranging between 2% and 6% in various studies [3, 4]. Most complications tend to occur within the first year following implantation, with the early postoperative period being the most vulnerable time for extrusion due to poor wound healing, infection, or improper implant positioning [5]. Late extrusion, defined as occurring more than 1 year postoperatively, is even less common and represents a clinical anomaly. In long-term follow-up studies of patients with hydroxyapatite orbital implants, rates of extrusion beyond the first year have been reported to be significantly lower, likely due to the material’s ability to integrate with host tissues and maintain stability over time.

The precise pathogenesis of these late complications remains unclear, but contributing factors may include progressive scarring, trauma, chronic inflammation, or changes in the peri-implant tissue over time. Given the infrequent nature of these late events, there is a paucity of large-scale studies specifically addressing the incidence and management of late hydroxyapatite implant extrusion. This case report presents a rare instance of late hydroxyapatite filler implant extrusion, occurring 7 years after initial orbital floor augmentation in a patient with an anophthalmic socket. Collection and evaluation of protected patient health information were HIPAA compliant, and this manuscript adhered to the tenets of the Declaration of Helsinki. The CARE Checklist has been completed by the authors for this case report, attached as online supplementary material (for all online suppl. material, see https://doi.org/10.1159/000547670).

Case Presentation

A female in her late 70s presents with significant complications stemming from an orbital floor augmentation procedure performed 7 years prior. She previously underwent enucleation in her left eye during her youth due to an infection. Initially, the patient underwent augmentation of her anophthalmic left orbit with hydroxyapatite cement filler to correct enophthalmos. The procedure was successful at the time, restoring orbital volume and maintaining structural integrity. No immediate postoperative complications were noted, and the patient experienced significant cosmetic and functional improvements in her orbital volume.

Upon presenting physical examination, there was clear evidence of left lower eyelid retraction, redness, swelling, and fistula formation along the inferior fornix. There was obvious exposure and extrusion of the hydroxyapatite filler implant through the lower eyelid. The patient also had left lower lid ectropion secondary to scarring and chronic irritation from the implant extrusion (Fig. 1). Preoperative CT imaging clearly demonstrated the separation between the orbital spherical implant and the hydroxyapatite cement used for floor augmentation, as well as anterior erosion of the maxillary bone (Fig. 2).

Fig. 1.

a, b Preoperative presentation of the patient’s left lower eyelid. The image demonstrates pronounced lower eyelid retraction with marked redness, swelling, and the presence of a fistula along the inferior fornix.

Fig. 2.

a, b Coronal and axial CT images of the left orbit demonstrating the orbital anatomy in an anophthalmic socket. The hyperdense, crescent-shaped hydroxyapatite cement filler is visible along the orbital floor, situated inferior to the pre-existing spherical orbital implant. There is associated erosion of the anterior maxillary wall, consistent with chronic implant extrusion. The relationship between the cement filler, orbital contents, and underlying bone is clearly visualized.

Given the patient’s history and the severity of the implant extrusion, it was agreed that the orbital implant would need to be removed to prevent further damage, infection, or worsening of the ectropion. An incision was made along the inferior fornix and the dissection was carried out to expose the eroded hydroxyapatite implant. The implant was removed in its entirety, and the cicatrix formation and surrounding scar tissue were carefully released. To restore the orbital volume and correct the deformity caused by the implant extrusion, a dermis fat graft from the patient’s abdomen was used. A portion of the dermis and subcutaneous fat was excised, thinned, and shaped to fit the orbital defect. This restored volume and corrected the anterior maxillary erosion caused by the prolonged extrusion of the implant.

In addition to the volume restoration, the patient’s lower lid ectropion was addressed by performing a tarsal strip procedure. The lower eyelid was reattached to the lateral orbital rim periosteum using 4-0 Vicryl sutures, restoring proper lid positioning and ensuring a functional lid margin. A full-thickness skin graft, harvested from the right upper eyelid, was used to replace cicatricial anterior lamella of the lower eyelid and provide additional support. The graft was secured in place with 6-0 Prolene sutures, and a foam bolster was applied to stabilize the graft during healing.

The procedure was well tolerated and had no notable postoperative complications. Close follow-up showed proper graft healing and restoration of lower lid function (Fig. 3).

Fig. 3.

a, b Postoperative appearance of the patient’s left lower eyelid following surgical intervention, exhibiting successful resolution of the fistula and elimination of implant exposure. The left lower lid position has been restored with correction of ectropion achieved through tarsal strip repair and the placement of a full-thickness skin graft. Notable improvement in eyelid contour and reduction of swelling.

Discussion

It is sometimes necessary to surgically remove a damaged eye from a patient with serious oculo-orbital injuries, intraocular cancers, or other life-threatening diseases. Upon the removal of the eye, a spherical ocular implant is usually placed into the anophthalmic socket to retain the cosmesis of a normal orbit [6]. The spherical ocular implant typically replaces 70–80 percent of the original eyeball volume and offers a substrate for which the cosmetic visual prosthesis may be fitted [7].

In circumstances of anophthalmic enophthalmos, additional material may be implanted into the orbital floor to augment orbital volume by displacing the spherical orbital implant [7]. For these types of additional implants, an ideal material has a porous structure to encourage vascularization, good long-term durability, easily titratable volume and is cost-effective. Vagefi [8] describes different techniques for orbital volume augmentation including using injectable hydroxyapatite filler.

This case report presents a rare instance of injected implant extrusion, occurring 7 years after initial orbital floor augmentation with hydroxyapatite cement to treat anophthalmic enophthalmos. The patient presented with significant complications resulting from an orbital floor augmentation with hydroxyapatite cement 7 years prior, including extrusion with exposure of the hydroxyapatite cement implant through the lower eyelid alongside left lower eyelid retraction, redness, swelling, and fistula formation along the lower lid margin.

While several studies are dedicated to the assessment of hydroxyapatite’s suitability as a spherical orbital implant, fewer are dedicated to the material’s risk for complications as an injectable filler for floor augmentation [3, 4, 9, 10]. Current literature describes peribulbar hemorrhage, anterior implant migration and internal prosthesis extrusion, upper eyelid ptosis, and postoperative eye pain as infrequent complications from hydroxyapatite injection [1, 3, 5].

In contrast, our literature search returned no prior reports of hydroxyapatite filler extrusion. The rarity of this event is likely due to the favorable qualities of hydroxyapatite which resist complication. The biocompatible porous structure of hydroxyapatite maintains a densely interrelated orifice network and therefore acts as a scaffold for fibrovascular ingrowth [6]. Given this ingrowth, the hydroxyapatite implant is less susceptible to migration [10]. Therefore, any minor exposures typically heal before requiring intervention [6].

An understanding of why this patient experienced these complications remains unclear. She suffered from type 2 diabetes and hypertension which can be theorized to be contributing factors, as those conditions may hinder healing and have therefore resulted in less fibrovascular ingrowth with the hydroxyapatite filler implant. However, this is hypothetical in the absence of further study, and true causality may be better elucidated in future longitudinal studies.

Conclusion

Extrusion of injected hydroxyapatite cement, especially years after a successful original injection, is a very rare sequela of orbital floor volume replacement via injected filler. To our knowledge, this is the first report of extrusion and exposure of the injectable hydroxyapatite cement filler itself and one of the first reports of hydroxyapatite fillers causing complications many years after placement.

This case study provides evidence of a rare, but possible, long-term complication of injectable hydroxyapatite cement fillers in ocular floor augmentation procedures. While patients should be educated on the most significant risks of this procedure – that is, extrusion and exposure of their spherical orbital implant, they should also be alerted of the possibility of late-onset extrusion of the filler.

The existence of this case study does not provide sufficient evidence to assess the overall risk versus benefit ratio of injectable hydroxyapatite cement filler for anophthalmic enophthalmos. This study highlights the need for more rigorous research to assess the potential long-term complications of injectable hydroxyapatite cement use for orbital floor volume replacement.

Statement of Ethics

Ethical approval is not required for this study in accordance with national guidelines, as this is a single-patient case report. Written informed consent was obtained from the patient for publication of the details of their medical case and accompanying images.

Conflict of Interest Statement

The authors have no conflicts of interest to declare. This includes financial (e.g., consultancies, stock ownership, grants, royalties) or nonfinancial (e.g., professional or personal) relationships that may have influenced the content or preparation of this manuscript within the past 3 years.

Funding Sources

No funding was received for the preparation, data collection, analysis, or authorship of this study.

Author Contributions

Adam Ayoub contributed to literature review, data collection, manuscript drafting, figure creation, and revisions. Matthew Hartwig contributed to literature search, manuscript editing, and discussion writing. Adam S. Hassan, MD, served as the primary surgeon for the case, contributed surgical details, clinical interpretation, and supervised the manuscript preparation. All listed authors meet the ICMJE criteria for authorship.

Funding Statement

No funding was received for the preparation, data collection, analysis, or authorship of this study.

Data Availability Statement

All data generated or analyzed during this study are included in this article and its online supplementary material. Further inquiries can be directed to the corresponding author.