Cumulative Incidence and Risk Factors for Secondary Alloplastic Cranioplasty: A Time-to-Event Analysis

Area of Science:

• Neurosurgery
• Plastic Surgery
• Biomaterials

Background:

• Complications of autologous bone flap cranioplasty are documented, but long-term survival data and comorbidities for secondary reconstruction are scarce.
• Quantifying the need for secondary alloplastic cranioplasty is crucial for optimizing reconstructive strategies.

Purpose of the Study:

• To determine the incidence and predictors of secondary alloplastic cranioplasty following autologous bone flap reconstruction.
• To analyze long-term bone flap survival and associated risk factors.

Main Methods:

• Retrospective analysis of 367 patients undergoing delayed cranioplasty with banked, frozen autologous bone (2012-2025).
• Utilized Cox regression, spline analysis, and Kaplan-Meier survival analysis to assess risk factors.
• Identified indications for secondary cranioplasty, including bone flap resorption and infection.

Main Results:

• 13.6% of patients (n=50) required secondary cranioplasty, with resorption (52%) and infection (42%) as primary reasons.
• Risk factors for secondary cranioplasty due to resorption included traumatic injury (HR: 2.37), age <18 years (HR: 2.99), and defect size >95 cm² (HR: 2.54).
• Estimated 10-year cumulative incidence of secondary cranioplasty was 37%.

Conclusions:

• Autologous bone flap cranioplasty demonstrates considerable effectiveness but carries a significant risk of secondary reconstruction in specific patient groups.
• Patients with traumatic injuries, younger individuals, and those with larger cranial defects warrant careful consideration for alternative reconstructive options.
• Further research into alternative materials and techniques may be beneficial for high-risk patients.