Long-term Outcome after Reimplantation of Autologous Bone Flaps in a Consecutive Series of 100 Patients

Objective: Reimplantation of cryoconserved autologous bone flaps is still a standard procedure after decompressive craniotomies. Aseptic necrosis and resorption is among the most frequent complications of this procedure. Consensus about the definition of the relevant extent and indication for surgical revision are still missing. To identify the incidence of bone flap resorption in our hospital and the required duration of follow-up for these patients we performed a retrospective analysis.

Methods: Between February 2009 and March 2012 there were 100 cryoconserved autologous bone flaps reimplanted at the Department of Neurosurgery at Inselspital Berne. All patients received a first follow-up at 6 weeks and a second one more than 12 months postoperatively. A clinical and CT-based score was developed for judgment of relevance and decision making for surgical revision.

Results: Mean follow-up period was 17 months postoperatively (range: 12 to 47 months). 48% of the patients showed no signs of bone flap resorption, 21% showed minor resoption with no need of surgical revision and 31% showed major resorption (in 4% the bone flap was instable or collapsed).

Discussion: Aseptic necrosis and resorption of reimplanted autologous bone flaps occurred more frequent in our series of patients than in most reports in the literature. Most cases were identified between 6 and 12 months postoperatively. To clinically observe these patients for at least 12 months or even routinely perform a CT scan after this period should be considered. Furthermore, favoring patient specific implants instead of autologous bone flaps seems a sensible option.