Thank you so much. We're going to move on to an encore performance from Tommi Körnén once again on cranioplasty. Thank you. It's an honor to be able to present the results from two of my studies. The topic of my second speech tonight is, or are, the predictors of bone flap survival after primary autograft cranioplasty. To investigate this, we have recently launched a Finnish nationwide registry of cranioplasty, the Finnish National Cranial Implant Registry, or FinSIHR. The total population of Finland is about 5 million, and the population in the current study currently includes about half of that. The current cohort comprises data from three out of five tertiary-level university hospitals in Finland. The data includes the outcomes of all any material cranioplasties performed in those three hospital districts from between 2002 to 2015, with a total of 479 procedures. This is a retrospective study, but because we are doing it in Finland, there are some advantages to it. The Finnish patient databases are known to be very reliable, and in the Finnish healthcare model, all cranioplasties from these areas are performed in the three corresponding university hospitals. Additionally, all of the cranioplasty complications are also referred to one of the study hospitals. Therefore, we are able to follow almost all of the patients in the areas for the whole study process, and thus we lost 0% of our patients for follow-up in the present study. The study design is a multi-century retrospective study, and the current cohort I am presenting here consists of all of the primary autologous cranioplasty patients who have underwent a cranioplasty between 2002 to 2015, with the primary endpoint being bone flap removal and the secondary endpoint being bone flap resorption. As you can see, the cohort mostly consists of stroke and trauma patients. The mean age of the cranioplasty was 41.2 years, and the mean follow-up time was 3.7 years, ranging from two days to 11.9 years. We followed our patients until cranioplasty removal death on the 31st of December 2015, and as I noted, we lost no patients for follow-up, and about two-thirds of our cohort were male, and the rest, one-third, were females. The overall complication rate is high, almost 40%, and the bone flap removal rate is about half of that, which are 19.3%, and it quite nicely corresponds to the rate of bone flap resorption and deep infections, which are the causes of bone flap removal most often. 5.3% of our patients died during the follow-up period, but these deaths were not related to cranioplasty procedures itself. The primary endpoint being the bone flap removal, and we found two important predictors of bone flap removal. First is age under the median age of the cohort, or under 45 years. The incidence of bone flap removal in the patients aged less than 45 years was two-fold compared to the older part of the cohort, and perhaps more interestingly, smoking was found to be an independent predictor of bone flap removal. Also, the smokers' bone flap removal rate was 37.2%, and with non-smokers, it was 14.6%, so about 2.5-fold increase in the incidence there, and why is this? We found that smoking increases the incidence of surgical site infections, both deep and superficial surgical site infections, which were about three times as common in the smoking part of the cohort than the non-smoking part. We postulated that this could be due to decreased wound perfusion or tissue oxygenation due to smoking or microthrombi in the wound perfusion system. The secondary endpoint were the predictors of bone flap resorption. The most important predictor of bone flap resorption was an age of under 30 years. The incidence of bone flap resorption was 90.6% in the younger patients and 6.2% in the older patients. These are the negative results. Interestingly, freezer time or the time between craniectomy and cranioplasty had no effect on the outcome or bone flap resorption, even though the P-value here for bone flap resorption seems to be statistically significant, it was disproved in further logistic regression analysis. Additionally, primary diagnosis, intoxicant abuse or obesity had no statistically significant effect on outcome or bone flap resorption. Another interesting variable is diabetes, but there were 2.5 times more bone flap removals in the diabetic part of our cohort, but it only consisted of five patients, so it is obviously difficult to draw any clear conclusions from that. So, we would like to conclude that in terms with the study question, smoking and young age predict poor outcome after primary otologous cranioplasty, and this seems to happen through two different distinct pathways. Smoking increases the incidence of surgical site infections and subsequent bone flap removal, while a younger age at cranioplasty seems to increase the rate of bone flap resorption and then removal of the bone flap. And further, patients should be encouraged to quit smoking before cranioplasty, and perhaps even mandatory cessation of smoking should be brought to question with these patients, as this is to our knowledge the general direction that surgery as a whole is taken, and while orthopedic surgeons and plastic surgeons are currently requiring their patients to quit smoking before any major procedures due to increased rates of adverse outcomes. And additionally, younger patients should be followed more rigorously due to the increased incidence of bone flap resorption, but as I noted in the previous presentation, perhaps this follow-up should not be conducted with computed tomography, but instead with mechanical assessment of bone flap stability, as it is known that bone instability is a prognostic factor for poor ossification from the standpoint of clinical orthopedics. Thank you.

bone flap survival

primary autograft cranioplasty

predictors

smoking

wound perfusion