【摘要】 目的：分析羟基磷灰石（hydroxyapatite,HA）义眼台眶内植入术后结膜脓性肉芽肿形成的原因。
方法：回顾性分析我院眶内植入HA义眼台250例（钻孔及栓钉置入68例），随诊18mo～10a，脓性肉芽肿形成后首先药物保守治疗，无效后采用手术治疗。结果：植入HA义眼台250例中发生脓性肉芽肿10例，其中9例在钻孔及栓钉置入术4～7a后发生，1例发生时羟基磷灰石义眼台未钻孔。9例保守治疗效果均欠佳，行HA义眼台取出术，1例拒绝眼台取出而继续保守治疗。 结论：脓性肉芽肿是严重的义眼台植入术后并发症，发生原因可能与义眼台植入后血管化不足，义眼台暴露与继发感染，异体材料包被，义眼台钻孔及栓钉置入等因素有关，而与栓钉的材料无关。脓性肉芽肿的发生意味着义眼台可能发生了感染，最终需行义眼台取出术。
【关键词】 HA义眼台；脓性肉芽肿；治疗
INTRODUCTION
Porous hydroxyapatite (HA) has been used as an orbital implant for socket reconstruction after enucleation and evisceration, the HA implant appeared to provide superior cosmesis and motility. However, with the increasing use, many reports such as implant exposure, infection, extrusion and pyogenic conjunctival granuloma were noted by oculoplastic surgeons. Among them, pyogenic conjunctival granuloma was the most serious and infrequent complication. We reports our experience to deal with 10 pyogenic conjunctival granulomas after orbital HA implants for volume replacement in our hospital from September 1995 to July 2006.
MATERIALS
We reports 250 cases with orbital HA implants in our hospital from September 1995 to July 2006,including 162 males, 88 females, 56 cases need banked sclera implant, 68 cases with drilling and peg insertion. The cases were followed up from 18 months to 10 years. Pyogenic granuloma developed in 9 cases after drilling and peg insertion and 1 case without pegged implant.
METHODS
Four cases with pyogenic granuloma were used autogenous sclera as patch graft after evisceration, the other 6 cases with banked sclera after enucleation. 4 cases with pyogenic granuloma were directly used orbital HA implant for volume replacement after enucleation and evisceration, 6 cases with secondary implant. The diameter of HA is 1820mm.
THE THERAPY OF PYOGENIC CONJUNCTIVAL GRANULOMA
After pyogenic granulomas were detected, conventional bacterial culture and secretion smear examination were necessary in early period. Broadspectrum antibiotics covering grampositive, gramnegative, and anaerobic organisms were required for 2 weeks or until the condition improved significantly. Corresponding antibiotics were used according to bacterial culture results. Combined antibiotics and glucocorticoid were used if necessary. Although the medicine therapy usually alleviated symptoms and put off the process temporarily, the pyogenic conjunctival granuloma would not be cured. Medicine therapy for 1 month without obvious improvement seemed to be ineffective, and the simple excision of the granulomas was not treated successfully in patients with pyogenic conjunctival granuloma.Explantation of the implant was performed finally. 9 cases showed implant exposure after removing pyogenic granuloma. Partial vascularization and infection were observed by histological examination. Grampositive anaerobic coccobacteria was the main pathogenic bacteria.
PROGNOSIS
The incidence of pyogenic conjunctival granuloma was 4.0% in our hospital, 9 HA implants were removed and the medicine therapy was proved to be ineffective finally.
Partial vascularization,implant exposure，banked sclera implant, drilling and pegging of HA implant were risk factors that affect the development of pyogenic conjunctival granuloma. The pyogenic granuloma denotes the infection of HA implant, Grampositive anaerobic coccobacteria is the main pathogenic bacteria. Removing implant is the effective method for curing pyogenic conjunctival granuloma.
DISCUSSION
Porous HA has been used as an orbital implant for socket reconstruction after enucleation and evisceration since 1985. The material developed and has become popular.
With the increasing use of the HA, many reports such as implant exposures, infection and extrusion of the HA were noted by oculoplastic surgeons. Pyogenic granuloma is the serious implant complication seldomly seen in cases. The reasons leading to pyogenic conjunctival granuloma were not clear, so it was difficult to deal with the disease. We consider that pyogenic granuloma might require complete removal of the implant. According to our cases and referring to the relevant literature, we think the following factors were risk factors of the pyogenic granuloma.
Vascularization or Fibrovascular Tissue Ingrowths of HA Angiogenesis The benefits of using this HA implant is its extensive porous system permitting fibrovascular tissue ingrowth[1]. The porous microstructure of HA implant communicate with the periimplant bed and allowed extensive ingrowth and permeation by fibrovascular connective tissue. The HA implant must be sufficiently vascularized before being drilled which decrease the risk of implant extrusion and infection.
Most HA implants are vascularized within 6 months of implantation. Vascularization can be assessed objectively by means of a technetium 99m bone scan or nuclear magnetic resonance imaging (MRI).
If the ingrowing of host fibrovascular tissue was compromised, inadequate vascularisation may be developed. Partial vascularization of the HA implant may result in ischemia, implant extrusion and infection. Inadequate vascularization of the implant may be the foundation of the development of pyogenic conjunctival granuloma. Partial vascularisation may be the main cause of medicine treatment fail. By MRI and gross anatomy, we checked 9 HA implants extracted from pyogenic granuloma cases, all HA implants were partial vascularization. Coating material, surgical style and the lower HA transformation efficiency were risk factors of partial vascularization of HA. The HA implant must be sufficiently vascularized before being drilled and pegged. Pegging and drilling of HA implant may destroy fibrovascular integration, which would increase risk of pyogenic granuloma.
Exposure and Infection of HA Increased Risk of the Pyogenic Granuloma Many reports of implant exposures were noted, the need to deal with this complication has become apparent to oculoplastic surgeons [2]. Exposure defects were detected after the pyogenic granuloma excision, and the exposed area were not covered by the surface epithelium in all patients of pyogenic granuloma. In chronic exposure, the porous spaces of HA may harbour infectious pathogens and cause infection or abscess of orbital implants. Owji et al[3] reported 5 unusual cases of exposed hydroxyapatite orbital implants that presented as pyogenic granulomas. Exposure defects were detected in all patients at the time of lesion excision. They recommended that ophthalmologists must be aware of the possibility of conjunctival dehiscence with hydroxyapatiteimplant exposure beneath the lesion. Patients with conjunctiva dehiscence postoperatively should be closely observed for infection because organisms may gain access through this portal of entry. Patients with chronic medical diseases or long term steroid use may have a predisposition to infection after implant exposure[4].
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