Cranioplasty with hydroxyapatite or acrylic is associated with a reduced risk of all-cause and infection-associated explantation

Abstract

Objective: Cranioplasty remains an essential procedure following craniectomy but is associated with high morbidity. We investigated factors associated with outcomes following first alloplastic cranioplasty. Methods: A single-centre, retrospective cohort study of patients undergoing first alloplastic cranioplasty at a tertiary neuroscience centre (01 March 2010–01 September 2021). Patient demographics and craniectomy/cranioplasty details were extracted. Primary outcome was all-cause explantation. Secondary outcomes were explantation secondary to infection, surgical morbidity and mortality. Multivariable analysis was performed using Cox proportional hazards regression or binary logistic regression. Results: Included were 287 patients with a mean age of 42.9 years [SD = 15.4] at time of cranioplasty. The most common indication for craniectomy was traumatic brain injury (32.1%, n = 92). Cranioplasty materials included titanium plate (23.3%, n = 67), hydroxyapatite (22.3%, n = 64), acrylic (20.6%, n = 59), titanium mesh (19.2%, n = 55), hand-moulded PMMA cement (9.1%, n = 26) and PEEK (5.6%, n = 16). Median follow-up time after cranioplasty was 86.5 months (IQR 44.6–111.3). All-cause explantation was 12.2% (n = 35). Eighty-three patients (28.9%) had surgical morbidity. In multivariable analysis, the risk of all-cause explantation and explantation due to infection was reduced with the use of both hydroxyapatite (HR 0.22 [95% CI 0.07–0.71], p =.011, HR 0.22 [95% CI 0.05–0.93], p =.040) and acrylic (HR 0.20 [95% CI 0.06–0.73], p =.015, HR 0.24 [95% CI 0.06–0.97], p =.045), respectively. In addition, risk of explantation due to infection was increased when time to cranioplasty was between three and six months (HR 6.38 [95% CI 1.35–30.19], p =.020). Mean age at cranioplasty (HR 1.47 [95% CI 1.03–2.11], p =.034), titanium mesh (HR 5.36 [95% CI 1.88–15.24], p =.002), and use of a drain (HR 3.37 [95% CI 1.51–7.51], p =.003) increased risk of mortality. Conclusions: Morbidity is high following cranioplasty, with over a tenth requiring explantation. Hydroxyapatite and acrylic were associated with reduced risk of all-cause explantation and explantation due to infection. Cranioplasty insertion at three to six months was associated with increased risk of explantation due to infection.