Evaluation of Cranioplasty Using Native Bone Autograft Versus Synthetic Bone Allograft

Elevated intracranial pressure (ICP) is a common neurosurgical emergency that may arise from several conditions, which cause an intracranial mass effect. In the case of conservatively refractory ICP elevation, one viable treatment option is ICP-lowering surgery, i.e., decompressive craniectomy (DC) in which a large portion of the skull bone is removed and the dura mater opened, creating more room for the brain tissue to expand and thus reducing the ICP. In many centers, the bone flap removed in DC is customarily kept deep frozen at -70°C until reimplantation during cranioplasty (CP). The cranium is repaired during CP by returning the previously removed autologous bone flap or by placing an artificial implant in the defect area. A successful CP will restore the contour of the cranium, protect the brain, and ensure a natural ICP, and some patients also show neurological improvement post-CP1-4. Thus, CP has a great potential for improving the patient's quality of life. Although widely regarded as a routine operation, CP often involves serious complications, such as postoperative hemorrhages, surgical site infection (SSI), and, most importantly, resorption of the autologous bone flap5-8.

Bone flap resorption (BFR) implies weakening and loosening of the autologous bone flap after reimplantation and is regarded as a late CP complication involving nonunion of the bone flap with the surrounding bone margins and cavity formation in the flap itself, which eventually necessitates removal of the bone flap and a new CP using a synthetic implant. These additional operations increase costs and necessitate further hospital stays, while rendering the patient vulnerable to additional complications. The reported prevalence of BFR with autologous CPs has varied significantly, from 1.4% to 32.0%, with infection rates ranging from 4.6% to 16.4%9-12.

CP is a common procedure for cranial reconstruction in the setting of trauma, stroke, skull neoplasm, osteomyelitis, or after procedures that are approached via craniectomy such as microvascular decompression or acoustic neuroma.

Recently there have been two major areas of interest presenting in the literature. First, there have been at least 6 manuscripts published on retrospective data comparing autologous bone versus synthetic prosthetic for CP13-18. Each has shown benefit for synthetic prosthetics. However, the community is resistant to implement a treatment pattern where synthetic bone is a "first line" choice for CP. Therefore, a prospective randomized controlled trial is needed to understand with high confidence the option that is most beneficial for patients.

Prior research performed as part of the FDA approval process has shown the ASPCI's to be a safe and effective means of performing cranial reconstruction, the anticipated risks do not differ from the risks faced by a patient undergoing either option as they are both currently considered standards of care.