Assessment of intraorbital hydroxyapatite implant exposure beyond 10 years of implantation.

Background: To analyze intraorbital Hydroxyapatite(HA) implant exposure occurring beyond ten years of implantation and suggest potential contributing factors.

Design: A retrospective cohort study based in the Shanghai Ninth People's Hospital.

Methods: One hundred and one Chinese patients with HA implant exposure were identified, from which 38 patients with implants exposure after ten years of insertion were selected and analyzed for demographic and medical records, clinical manifestations, surgery type, implant size, exposure area, follow-up duration, complications, details regarding prosthesis care, and treatment methods. All of the removed implants were sent for an HE pathologic examination.

Results: The 38 cases experienced exposure 10 to 19 years after implantation and presented to the clinic with increased secretions, proliferation of granulation tissue, visible suture exposure, and difficulty in wearing the external prosthesis. Other complications included implant forward position in 3 patients, eyelid retraction in 4 patients, and all the patients presented with post-enucleation socket syndrome. Reviewing the medical history, HA implant sizes ranged from 18 to 22 mm. Fourteen patients underwent implant repair surgery, of which 2 experienced recurrence, and ultimately, 26 implants were removed. Of the 26 removed implants, histologic examination showed that 17 exhibited chronic infection, and 12 had limited fibrovascular ingrowth. The questionnaires indicated that 26 patients did not renew the external prosthesis regularly.

Conclusion: This study identified late complications and potential risk factors for implant exposure beyond ten years of implantation, including chronic infection, non-absorbable sutures, and low and delayed vascularization.