ForumOutcomes of Cranioplasty with Synthetic Materials and Autologous Bone Grafts
Introduction
In modern neurosurgical practice, craniectomy is a common procedure that may be needed secondary to a traumatic skull bone fracture, tumor infiltration of the skull bone, a malignant middle cerebral artery infarction, or severe infection. The objective of cranioplasty—reconstruction of a skull bone defect—is to diminish the complications of a craniectomy. These complications include herniation of the cortex through the bone defect, subdural effusion, seizures, and syndrome of the trephined 13, 15. Other objectives are to restore the earlier contour of skull bone and to protect the underlying brain.
Cranioplasty is associated with a high complication rate with present surgical methods 23, 32. A postoperative complication rate of 10%–40% has been reported in large cranioplasty series 2, 6, 17, 35. Frozen autologous bone graft is traditionally used for primary reconstruction because it is readily available. However, more recent reports suggest that problems after cranioplasty with frozen bone may be more common than was thought previously 12, 18. Polymethyl methacrylate (PMMA) is used as bone cement (i.e., polymerized in situ from methyl methacrylate monomer and polymer powder mixture) and as a bulk polymer implant material. PMMA, when used in bulk polymer form, is considered a reliable and inexpensive implant material (14), which showed better long-term outcomes compared with frozen autograft (22). PMMA, when used as bone cement, causes local toxic reactions, and the material becomes encapsulated by fibrous tissues. Other commercially available materials include hydroxyapatite (HA); titanium; polyethylene (PE); polyetheretherketone (PEEK) (19); and glass fiber–reinforced composite (FRC), which is loaded with particulates of bioactive glass (BG).
Meta-analyses of available data are scarce 9, 28, 29. The optimal timing of cranioplasty and numerous associated risk factors predicting complications are unknown. In the present study, we investigated whether preexisting medical conditions are associated with complications after cranioplasty and compared the degree of complication with different surgical materials. A 10-year consecutive retrospective study was performed to analyze these after cranioplasty.
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Selection Criteria and Study Population
We reviewed electronic medical records from all patients who underwent a skull bone defect (>4 cm2) reconstruction during a 10-year period at our tertiary care institution, which has Neurosurgical and Head and Neck surgery departments that are responsible for craniofacial reconstructive surgery of people living in Southwest Finland, Satakunta, and Åland Islands areas (combined population of 725,000). A database was generated by querying procedures with the current procedural terminology codes
Description of Sample
Altogether 100 cranioplasties (84 individual patients) with sufficient complete data were included. Of these 100 cranioplasty procedures, there were 81 primary, 16 secondary, 2 tertiary, and 1 fourth reconstruction during the period 2002–2012. A cranioplasty was performed in 34 female patients (34.0%) and 66 male patients (66.0%) with an average age of 42.1 years (range, 3–79 years). The average body mass index was 26.5 (range, 17.3–40.8).
The average defect size was 105.2 cm2 (range, 4.0–420.0
Discussion
The main finding of this study was that after skull bone reconstruction with autogenous bone, the implanted bone flap needed to be removed in 40.0% of cases. Leading causes for complication and removal of the autograft were infection and resorption (25.0% and 15.0%, respectively). Survival analysis of autograft, HA, FRC, and other alloplast subgroups showed the best survival in HA and FRC groups; however, the difference compared with the autograft group was not statistically significant.
At our
Conclusions
Based on the results of the present study, synthetic cranioplasty materials show more promising outcomes compared with autograft. Even with large defect sizes, survival of FRC implants did not differ from survival of smaller defects with HA bone cement. A prospective study comparing autograft with synthetic materials is warranted to reach more in-depth conclusions.
Acknowledgment
Robert M. Badeau, Ph.D., of Aura Professional English Consulting, Ltd. (www.auraenglish.com), is acknowledged for the language content editing of the manuscript.
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Conflict of interest statement: This research was funded by the Emil Aaltonen Foundation and Turku University Hospital. The principal financing partners of the FRC implant research are Tekes (the Finnish Agency for Technology and Innovation), Academy of Finland, and European Commission (Grant No. NEWBONE NMP3-CT-006-026279-2). J.M.P., J.P.P., and V.V. have received financial support in the form of a congress fee and travel expenses from Skulle Implants Corporation. K.M.J.A. and P.K.V. are board members and shareholders of the start-up company Skulle Implants Corporation, which is aiming to commercialize FRC implants. T.K. does not have any conflicts of interest to declare.