Indications and Limitations of Carbonated Calcium Phosphate Cement for Secondary Contouring Cranioplasty: A Long-Term Institutional Experience

The authors describe our long-term institutional experience utilizing carbonated calcium phosphate (CCP) cement for secondary cranioplasty refinements with the goals to(1)define an ideal patient population,(2)categorize failures to optimize patient selection, and(3)determine factors affecting success.The authors conducted a retrospective cohort study of patients undergoing secondary cranioplasty for forehead reshaping utilizing CCP between June 2007 and August 2018. Exclusion criteria included < 3-month follow-up. The primary outcome was aesthetic forehead correction determined by Whitaker classification, while secondary outcomes included complications and reoperations. In total, 107 patients met inclusion with a median age of 15.5years. The majority of bony deficits were limited to the frontal region (90.7%), required onlay application (87.7%) of large (96.0cm²) partial thickness (85.7%) cranial defects, in a clean setting (99.0%), and ASA grade II (69.7%). Median Whitaker classification decreased from 2.3 [IQR: 2, 2.3] preoperatively to 1.0 [1.0, 1.3] postoperatively (P<0.01). There was no difference in Whitaker classification between early and late postoperative timepoints (P<0.17). The complication rate was 13.2%, with the majority related to infection (5/14). Factors associated with complications included frontal sinus proximity (OR 3.6, P<0.04) and the use of interposition titanium mesh for full-thickness reconstruction (OR 6.4, P<0.02). CCP remains an effective alloplastic bone substitute with a complication rate of 13.2% in patients undergoing secondary, onlay cranioplasty. Early postoperative Whitaker classification may predict long-term aesthetic results. Complications may arise years following implantation, warranting long-term follow-up.