Long-Term Series of Custom-Bone Hydroxyapatite Cranioplasty: Outcomes and Survival at 15 Years

Introduction: Cranioplasty (CP) is a surgical procedure used to repair or reconstruct bone defects in the skull. As CP is not without risk, identifying the safest reconstruction technique is essential to achieve optimal functional recovery. While heterologous prostheses such as HA address issues related to storage and preservation of autograft and help prevent bone resorption, they are associated with a specific spectrum of risks, including infection, dislocation, and fracture. The aim of our article is to evaluate the safety and performance of HA cranioplasty through a retrospective study conducted at 2 centres with extended follow-up of up to 15 years. This study represents one of the most comprehensive and long-term analyses available and provides important insights into the efficacy of this material in clinical practice. Methods: Data were collected from patients who underwent CP between December 2001 and December 2008. The authors conducted a retrospective study of a case series of 101 adult and paediatric patients who received custom-made HA implants after craniotomy for various reasons. The primary endpoint was to evaluate prosthesis survival and explantation rates. Secondary endpoints included the incidence of adverse events and the rate of surgical revision. Results: Over a period of 7 years (from December 2001 to December 2018), a total of 101 patients who underwent CP with custom-made HA prostheses. Skull reconstruction with CP was performed immediately in 22 cases. All patients were initially evaluated 30 days after CP, with subsequent follow-ups at 6 months, 12 months, 24 months, and then at 3, 4, 5, 10, and 15 years. Major complications requiring explantation were observed in 9 patients: The reasons for explantation were as follows: 3 cases of infection, 2 cases of tumour recurrence, 2 cases of fracture, 1 case of cicatrial retraction, and 1 case of cerebral hemorrhage. Minor complications occurred in 10 cases and resolved without the need for explantation of the HA prosthesis. At the 15-year follow-up, radiographic and clinical evaluations of 41 patients confirmed optimal results, with complete and stable integration of the implant into the surrounding bone and no significant resorption or migration. Conclusions: This study provides a comprehensive long-term evaluation of custom HA CP, providing valuable insight into its efficacy and safety over a 15-year follow-up period. Our findings support the viability of HA as a material for cranial reconstruction, demonstrating a high prosthesis survival rate with stable integration in the majority of patients.