Cryopreservation of autogeneous bone flap in cranial surgical practice: what is the future? A grade B and evidence...

Autogenous bone flap adequately preserved can be used successfully for repair of iatrogenic cranial bone defects because of its biological and economic advantages. The commonly used techniques of bone preservation are freezing at temperature ranging from -16 to -40 inverted exclamation mark C or subcutaneous pocketing.

We searched on NLM database querying as subject headings "cranioplasty and autologous bone" and found 7 papers meeting our criteria. For every series we considered the frequency of bone resorption and infection and performed statistical analysis by means of contingency tables carrying out for the chi2 test according to Pearson and considering to be statistically significant p(chi2) <0.05 values.

Compared series presented no statistically significant difference with regard to frequency of the complications (chi2=6.43 for critical value of 11.07 (k-1=5) (P>0.25) and chi2=5.48 for critical value of 7.81 (k-1=3) (P>0.10) respectively for infection and resorption.

Although we did not find any significative difference among the frequencies of the complications of the series, it is our opinion that freezing the bone flap is preferable to abdominal pocketing because it needs no double surgical abdominal time and the bone flap frozen is stronger to mechanical loading than fresh flap. Cryopreservation of autologous bone flap should be the standard technique of preservation for delayed cranioplasty but a multicentric prospective trial is advisable to obtain in short time statistically significant results focusing better on the rate of marginal resorption of the bone flap using new cryoprotectant solutions.