Long-term follow-up of cryopreservation with glycerol of autologous bone flaps for cranioplasty after decompressive craniectomy

Background Autologous bone flaps adequately preserved can be used successfully for repair of cranial bone defects with biological and economic advantages. However, the effect or advantages of cryopreservation of autologous bone flaps using cryoprotectant solutions have not been investigated. The aim of this study was to investigate the utility of autologous bone flaps frozen with glycerol in cranioplasty after decompressive craniectomy. Methods We evaluated postoperative complications and clinical and aesthetic results in 40 consecutive patients who underwent delayed cranioplasty using autologous bone flaps frozen with glycerol following decompressive craniectomy between 2001 and 2010. Bone flaps removed at the time of external decompression were dipped in 20 % glycerol solution with a sterilized plastic vessel and stored at −84 °C in an ultra-low temperature freezer. The bone flaps were thawed in the vessel at room temperature for 12 h. The bone flaps were taken out of melting glycerol, replaced in their original positions, and fixed with silk sutures or titanium plates. Follow-up periods ranged from 35 to 3745 days (median, 558 days). Results Mild resorption of the bone flap occurred in one case. However, there were no cases with local infection and no cases requiring reoperation for complications during the follow-up period. Conclusions Cryopreservation with glycerol is a simple and safe method for preservation of autologous bone grafts. The clinical and aesthetic results of delayed cranioplasty using autologous bone flaps frozen with glycerol solution were satisfactory.