Bony realignment after surgical removal of orbital implantation cysts: A case series

Abstract

Orbital cyst formation following previous orbital fracture surgery is an uncommon complication, yet it poses a significant concern related to permanent implant use. This complication may result in a pronounced mass effect that leads to deformation of the orbital bony walls. We present the three cases of orbital implantation cysts associated with orbital wall deformity, where bony alignment normalized after complete cyst removal. Patients exhibited ocular symptoms, including proptosis, diplopia, and hyperglobus. Surgical management involved total resection of the orbital cyst, removal of the prior implant, and placement of a new absorbable implant. Serial orbital computed tomography imaging performed over a 2-year postoperative period revealed progressive restoration of the orbital wall contour through ongoing bony realignment, with no evidence of implant migration or cyst recurrence. To the best of our knowledge, these cases provide the first documented radiological proof that bony remodeling after mass effect from an orbital implantation cyst is reversible, indicating that bone deformation caused by chronic compression can return to normal anatomy. This series underscores the necessity of thorough cyst excision and highlights the potential for anatomical correction following surgical intervention.

Introduction

Alloplastic implants are frequently utilized in orbital reconstruction procedures after orbital wall fractures, and formation of cysts related to these implants – designated as orbital implantation cysts – can complicate recovery. The most prevalent forms are hemorrhagic or hematic cysts, while some cases may also develop epithelial cysts.[1,2,3] Cystic complications following orbital wall fracture repair are rare events, so incidence data are limited to case reports and small case series. These cysts may present with symptoms such as pain, proptosis, or diplopia, and management typically involves surgical excision of the cyst and removal of the implicated implant.

Cyst formation after orbital implantation procedures may exert a mass effect on surrounding structures, and these expanding lesions can subject adjacent tissues to chronic pressure, leading to gradual remodeling of the bony anatomy and distortion of the normal orbital contour.[2,4] Nevertheless, their long-term radiologic changes remain poorly defined. Earlier research has described the potential for bony realignment during the healing process in orbital fracture cases, both with conservative treatment[5] and after surgical intervention.[6,7] However, realignment of the bone following the removal of implantation cysts has not previously been documented.

In our cohort of orbital implantation cyst cases, we identified orbital wall deformation attributable to cystic lesions. We present the cases in which patients underwent cystectomy with simultaneous implant removal, followed by serial radiological assessment.

Case Presentation

Case 1

A 23-year-old male presented with 1 month of left eye proptosis. He had sustained blunt trauma to the left eye 14 years earlier, which required repair of an inferior wall blowout fracture using an alloplastic implant. On ophthalmic examination, the best-corrected visual acuity (BCVA) was 1.0 in both eyes. Intraocular pressure (IOP), measured by noncontact tonometry (NCT), was 13 mmHg in the right eye and 16 mmHg in the left eye. Anterior chambers were deep and clear, and the lenses were clear bilaterally. Exophthalmometry revealed 12 mm in the right eye and 13 mm in the left eye. Assessment of extraocular motility showed a 15-prism diopter left hypertropia in primary gaze and restricted downward movement.

Orbital computed tomography (CT) demonstrated a 25-mm cystic lesion surrounding the inferior orbital implant, with associated bony distortion indicated by downward protrusion of the inferior orbital wall [Figure 1a and b]. The patient underwent complete cystectomy and removal of the previous implant, which appeared to be a porous polyethylene sheet; the orbital wall was reconstructed using an absorbable implant (OSTEOTRANS™-MX, Takiron Co., Ltd., Japan). The cyst exhibited findings consistent with a hematic cyst from previous hemorrhage and contained viscous, greenish material [Figure 1c and d].

Figure 1.

Coronal (a) and sagittal (b) images from preoperative orbital computed tomography (CT) scans demonstrate a 25 mm cystic mass encasing the orbital implant, with associated distortion of the adjacent bone. The previously inserted alloplastic implant (c) is shown after removal together with the cyst (d). Sequential orbital CT images: (e) Preoperative findings displayed downward protrusion of the inferior orbital wall. (f) On postoperative day 1, the inferior wall was reconstructed using a new implant. (g) At 1-year follow-up, the orbital wall contour showed gradual recovery. (h) By 2 years, complete normalization of bony anatomy was observed

During the 2-year postoperative follow-up period, the patient experienced a complete resolution of preoperative symptoms, including proptosis, extraocular movement limitation, and diplopia. Serial postoperative orbital CT scans over the 2 years documented gradual normalization of the inferior orbital wall contour through ongoing bony remodeling [Figure 1e-h].

Case 2

A 23-year-old male presented to our clinic with a 4-year history of progressive left eye proptosis. Eleven years earlier, the patient had undergone surgical repair for a medial wall blow-out fracture using an alloplastic implant after sustaining blunt orbital trauma. Ophthalmic examination demonstrated a BCVA of 0.8 in both eyes. IOPs measured by NCT were within the normal range: 12 mmHg in the right eye and 13 mmHg in the left eye. Both anterior and posterior segment examinations were unremarkable. Exophthalmometry indicated notable asymmetric proptosis, with the values of 21 mm in the right eye and 26 mm in the left eye [Figure 2a]. Prism cover test revealed 15-prism diopters of exotropia and 8-prism diopters of left hypertropia in the primary gaze position. Testing of extraocular movements showed diplopia when the patient gazed upward beyond 20° and on right gaze past 30°, which was associated with discomfort in the left eye.

Figure 2.

(a) Preoperative facial photographs reveal asymmetric exophthalmos (21 mm in the right eye, 26 mm in the left eye). (b) Photograph of the excised cystic mass. Serial postoperative orbital computed tomography scans collected over 2 years (c) Preoperative (d) Postoperative day 1 (e) 1-year postoperative (f) 2-year postoperative documented progressive restoration of the normal medial orbital wall bony structure through ongoing bony remodeling

Orbital CT revealed a 29-mm cystic lesion located in the medial extraconal space of the left orbit, resulting in ipsilateral exophthalmos. The left medial orbital wall was observed to bulge toward the medial side. The patient underwent complete excision of the cyst and removal of the previous porous polyethylene implant, followed by reconstruction of the orbital wall with an absorbable implant (OSTEOTRANS TM-MX, Takiron Co., Ltd, Japan). The excised cyst was found to contain milky fluid [Figure 2b]. Histopathological analysis identified a hematic cyst featuring fibrotic tissue, hemorrhage, and necrosis. Microbiological testing of the cyst contents was negative for both Gram stain culture and fungal culture.

Two years after surgery, the patient maintained excellent clinical outcomes. Exophthalmometry readings had significantly improved to 23 mm in the left eye, with no evidence of ocular motility disorder or diplopia. Serial orbital CT during the 2-year postoperative period consistently demonstrated progressive remodeling of the medial wall bony contour with restoration of normal anatomical features [Figure 2c-f].

Case 3

A 32-year-old male presented with a chief complaint of left lower scleral show that had been identified approximately 3 months earlier. He reported a history of orbital and limb fracture surgery following a traffic accident 9 years prior. On examination, BCVA was 1.0 in the right eye and 0.9 in the left eye. IOP was measured at 13 mmHg in the right eye and 15 mmHg in the left eye. Slit-lamp examination revealed deep and clear anterior chambers and clear lenses bilaterally. The left eye exhibited hyperglobus of approximately 2–3 mm and a lower scleral show of 3.5 mm. Exophthalmometry indicated mild asymmetry, with the values of 17 mm in the right eye and 18 mm in the left eye. Extraocular movements were intact in all the directions. The patient did not experience diplopia in any gaze position.

Orbital CT imaging demonstrated evidence of previous reconstructive surgery involving the left orbital floor to address medial and inferior wall fractures. A well-circumscribed cystic lesion, suggestive of subperiosteal hematoma, was detected at the prior surgical repair site, leading to anterosuperior displacement of the globe on the affected side [Figure 3a and b]. Complete excision of the orbital cystic mass was carried out along with the removal of the previously placed orbital implant [Figure 3c and d]. The orbital floor was reconstructed using an absorbable implant (OSTEOTRANS™-MX; Takiron Co., Ltd., Japan) following total resection of the cyst and removal of the previous implant. Histopathological evaluation of the cyst disclosed organized chronic hemorrhage with associated fibrosis and focal calcification, consistent with a chronic organized hematoma.

Figure 3.

Preoperative orbital computed tomography (CT) scans (a and b). (a) Coronal and (b) sagittal views illustrate postsurgical alterations due to prior orbital reconstruction and a subsequent cystic lesion resulting in anterosuperior displacement of the left globe. Gross specimens of the explanted orbital implant and screws are shown (c) alongside the excised cyst (d). Follow-up orbital CT imaging (e and f): (e) Immediate postoperative appearance and (f) 6-month postoperative scan reveal resolution of the orbital wall deformity. The area marked with an asterisk (*) in the preoperative CT (a) shows an average Hounsfield unit (HU) value between 15 and 40. In contrast, the arrowhead (陕) on the 6-month postoperative CT (f) shows HU values ranging from 50 to 80

At 6 months postoperatively, BCVA remained 1.0 in both eyes. IOP was recorded as 12 mmHg in the right eye and 10 mmHg in the left eye. Both proptosis and hyperglobus had resolved. Follow-up orbital CT demonstrated favorable postoperative remodeling of the left orbital floor, with the resolution of the previously observed inferior wall bulging [Figure 3e and f]. The clinical characteristics, radiographic findings, and surgical outcomes of all three cases are summarized in Table 1.

Table 1.

Summary of clinical characteristics, radiographic findings, and surgical outcomes of patients with orbital implantation cysts

	Case 1	Case 2	Case 3
Sex/age	Male/23	Male/23	Male/32
Interval time since initial surgery (years)	14	11	9
Cyst location	Left inferior orbital wall	Left medial orbital wall	Left inferior orbital wall
Clinical features	Proptosis (right 12 mm, left 13 mm), left hypertropia (15 PD), left eye downgaze limitation, diplopia	Proptosis (right 21 mm, left 26 mm), Exotropia, (15 PD), left hypertropia (8 PD), diplopia	Left lower scleral show (3.5 mm), left hyperglobus (2–3 mm)
Prior implant type	Porous polyethylene (Medpor®)	Porous polyethylene (Medpor®)	Unknown
Preoperative CT findings (bony deformity)	Downward protrusion of the inferior orbital wall	Medial orbital wall bulging toward the medial side	Inferior wall bulging and globe anterosuperior displacement
Intraoperative findings/histopathology	Hematic cyst with viscous greenish material/chronic inflammation with fibrosis	Hematic cyst with milky fluid content/fibrotic tissue with hemorrhage and necrosis	Hematic cyst/organized chronic hemorrhage with fibrosis and calcification
Follow-up CT (bony realignment)	Gradual normalization of the left inferior wall contour. Complete normalization by 2 years	Progressive remodeling of the medial wall. Restoration of normal anatomical features by 2 years	Favorable remodeling of the left orbital floor. Resolution of bulging by 6 months

CT=Computed tomography

Discussion

Cystic complications following orbital floor fracture repair are an uncommon occurrence, with a reported prevalence of 0.4%,[8] although they are a recognized phenomenon that can develop with both porous and nonporous alloplastic implants. These cysts, commonly known as “chocolate cysts” because of their distinct dark brown content, have become increasingly acknowledged as a potential late complication that may arise years after the initial surgical procedure. Recent studies have described chocolate cyst formation occurring as late as 3–9 years after the placement of porous polyethylene implants for orbital fracture repair.[4] Most cysts identified in this context are pseudocysts that do not contain an epithelial lining. However, true cysts may develop due to the migration of conjunctival squamous epithelium along the surgical incision or the presence of sinus columnar respiratory epithelium through the orbital fracture site.[2]

Several mechanisms have been suggested to explain delayed hemorrhage around porous polyethylene implants, such as chronic erosion and irritation of the periosteum resulting from insufficient posterior fracture reduction, displacement of the implant, and rupture of capillaries within the fibrous capsule.[9] In addition, the nonporous barrier surface may promote capsule development, thereby creating a potential space for fluid accumulation.[4]

Chocolate cysts most often present with clinical features including proptosis, hyperglobus, eyelid retraction, restriction of ocular motility, diplopia, and visual disturbances.[3,4,8,9,10,11] In our cases, patients also exhibited proptosis, diplopia, and hyperglobus. On CT scans, these lesions typically appear as well-circumscribed homogeneous masses encasing the orbital implant.[4,8]

Treatment generally involves drainage, implant removal, and partial excision of the fibrous wall.[2,3,8,9,10] En bloc cyst removal may help prevent recurrence.[2] However, complete excision of the capsule is often not feasible due to firm attachment to orbital tissues.[12] Chemical ablation of the remaining capsule using absolute alcohol or trichloroacetic acid 20% can be considered.[13,14] In keeping with these findings, intraoperative observations in our cases identified cyst-like lesions with pseudocapsules, and maximal efforts were made to resect potential epithelial linings.

Cases of bony deformation secondary to intraorbital cysts have been documented in prior research. Suller et al.[4] reported evidence of bone remodeling and orbital floor expansion resulting from the mass effect caused by cysts that developed after orbital fracture repair surgery. In addition, bone deformation associated with cyst formation has been observed in cases without previous surgical intervention, as reported by other studies. Fisher et al.[13] found that large arachnoid cysts can deform orbital bone due to mass effect, which may manifest clinically as significant exophthalmos. In the series by Ahmed and Eltanamly[15] examining 17 cases of epidermoid cysts, bone deformities – such as bony excavation and sclerotic margins – were identified in four patients. Persistent bone changes were observed in these patients after surgical cyst removal, with continued symptoms of enophthalmos and diplopia. These findings indicate that orbital cysts can exert enough pressure to induce lasting alterations of orbital bone structure, which may result in ongoing functional deficits despite appropriate intervention.

However, to the best of our knowledge, bony restoration with normalization of anatomical structure following resection of an intraorbital mass has not been previously documented. In our cases, the orbital bony contour gradually returned to normal after excision of the cystic lesion and removal of the preexisting implant, followed by the placement of a new implant.

Numerous previous studies have demonstrated spontaneous bony realignment in orbital fracture repairs involving implant insertion. Park et al.[6] and Jung et al.[7] observed bony realignment after orbital blowout fracture repair with implant insertion in their studies. They noted that the majority of bony depressions showed significant improvement postoperatively, with irregular bony contours gradually becoming smoother over time as fibrosis bridged the gap between the repositioned orbital bone and periosteum. In addition, these authors reported that the implant facilitates bony remodeling through enhanced mucosal repair and periosteal recovery at the implant interface. Several studies have indicated that younger patients exhibit more favorable bony realignment following orbital wall fractures.[5,6,7] All of our cases involved relatively young individuals who experienced satisfactory realignment of both the inferior and medial orbital walls.

Based on our case report of hematic cyst complications after orbital fracture repair, we propose that bone structures distorted by cysts may undergo analogous bony repositioning after cyst removal and implantation of a new prosthesis. This observation supports the idea that the implant acts as a scaffold for tissue regeneration, diminishing orbital pressure on the previously deformed bony anatomy and facilitating gradual restoration of normal orbital bone even in cases complicated by postoperative cyst development. Nevertheless, when selecting a new implant for this purpose, potential long-term adverse effects must be carefully considered.

The presented cases illustrated effective restoration of bony contours through the placement of a new absorbable orbital implant following cyst excision. Previous studies indicate that correction of enophthalmos cannot be reliably achieved without the incorporation of the new implant. The absorbable implant supplied adequate support for orbital tissues and served as an ideal framework for osseous remodeling. Nevertheless, extended patient follow-up is required to monitor potential cyst recurrence and to assess for the long-term implant-related complications.

Declaration of patient consent

This study was performed in accordance with and conforming to the Declaration of Helsinki. The authors certify that they have obtained all appropriate patient consent forms. In the form, the patients have given their consents for their images and other clinical information to be reported in the journal. The patients understand that their name and initials will not be published, and due efforts will be made to conceal identity, but anonymity cannot be guaranteed.

Data availability statement

The data supporting the findings of this study can be obtained from the corresponding author upon reasonable request.

Conflicts of interest

The authors declare that there are no conflicts of interests in this paper.

Funding Statement

Nil.