Management of infected hydroxyapatite cranioplasty: Is salvage feasible?

Introduction: The use of hydroxyapatite cranioplasties has grown progressively over the past few decades. The peculiar biological properties of this material make it particularly suitable for patients with decompressive craniectomy where bone reintegration is a primary objective. However, hydroxyapatite infection rates are similar to those of other reconstructive materials. Research question: We investigated if infected hydroxyapatite implants could be saved or not. Materials and methods: We present a consecutive series over a 10-year period of nine patients treated for hydroxyapatite cranioplasty infection. Clinical and radiological data from admission and follow-up, photo and video material documenting the different phases of infection assessment and treatment, and final outcomes were retrospectively reviewed in an attempt to identify the best options and possible pitfalls in a case-by-case decisionmaking process. Results: Five unilateral and four bifrontal implants became infected. Wound rupture with cranioplasty exposure was the most common presentation. At revision, all implants were ossified, requiring a new craniotomy to clean the purulent epidural collections. The cranioplasty was fully saved in one hemispheric and 2 bifrontal implants and partially saved in the remaining 2 bifrontal implants. A complete cranioplasty removal was needed in the other 4 cases, but immediate cranial reconstruction was possible in 2. Skin defects were covered by free flaps in 3 cases. Four patients underwent adjunctive hyperbaric therapy, which was effective in one case. Discussion and conclusion: In our experience, infected hydroxyapatite cranioplasty management is complex and requires a multidisciplinary approach. Salvage of a hydroxyapatite implant is possible under specific circumstances. 1. Introduction The use of hydroxyapatite (HA) cranioplasty has progressively gained acceptance in neurosurgical practice over the past few decades (Stefini et al. 2013; Fricia et al. 2019). The unique biological properties of this material (especially its microporous structure aiming at osteointegration and its self-repairing ability in case of breaks) make it suitable for cranial reconstruction after decompressive craniectomy (DC), particularly in young patients (Staffa et al. 2012; Iaccarino et al. 2015). However, though several solutions have been proposed to avoid dislocations/ mobilizations, HA cranioplasties are difficult to adequately anchor to the surrounding skull. They are also usually thicker than other implants but practically no longer adjustable once placed, as any intraoperative modification could cause micro-fractures in the still fragile prostheses