Predictors of Surgical Site Infection in Autologous Cranioplasty: A Retrospective Analysis of Subcutaneously Preserved Bone Flaps in Abdominal Pockets

BACKGROUND

Decompressive craniectomy (DC) is a surgical procedure performed to manage intracranial hypertension. Once performed, patients are obligated to undergo another surgical procedure known as cranioplasty to reconstruct the cranial defect. Cranioplasty still has one of the highest rates of infection. The factors contributing to the high rate of surgical site infection (SSI) after cranioplasty are not well established. This study aims to estimate the incidence of SSI and determine its possible risk factors for patients who underwent cranioplasty using bone flaps subcutaneously preserved in abdominal pockets.

METHODS

A retrospective cohort study was conducted to investigate the predictors of infection among patients who underwent cranioplasty from subcutaneously preserved bone flaps in abdominal pockets between January 2005 and December 2018 at a level l trauma center.

RESULTS

A total of 103 cases of cranioplasty from subcutaneously preserved bone flaps were included in the study. The mean age of the patients was 31.2 ± 14.8 years (range, 5-67 years). The median interval between DC and cranioplasty was 115 days. The most frequent indication for DC was traumatic brain injury (76.4%). The incidence of SSI was noted in 15.7% of patients. The most significant predictors of infection in patients requiring cranioplasty were blood glucose levels and skull defect size (P = 0.03 and P = 0.02, respectively).

CONCLUSIONS

Blood glucose levels and skull defect size were the only identifiable risk factors associated with SSI. Storing bone flaps in subcutaneous abdominal pockets is cost-efficient but carries considerable risk of infection.

Retrospective Chronologic Computed Tomography Analysis of Bone Flap Fusion and Resorption After Craniotomy and Autologous Cryopreserved Cranioplasty

BACKGROUND

In open brain surgery, fixation of the bone flap is the final procedure. The bone flaps then fuse naturally. The objective of this study was to investigate the chronological process of bone fusion after craniotomy and autologous cranioplasty.

METHODS

Retrospective data were collected from patients who underwent craniotomy or cranioplasty after August 2004 and had at least 1 computed tomography (CT) scan at 3 months postsurgery. The patients were divided into a craniotomy group and a cranioplasty group. Head CT scans were analyzed to evaluate bone fusion and resorption.

RESULTS

Records from 978 patients who underwent craniotomy or cranioplasty between September 2004 and November 2015 were reviewed; 369 patients were eligible for the final analysis (craniotomy, n = 276; cranioplasty, n = 93). The mean cryopreservation period for the bone flap in the cranioplasty group was 49.3 days. The mean patient age was 51.4 ± 18.1 years in the craniotomy group and 51.6 ± 17.1 years in the cranioplasty group. Head CT scans showed bone fusion rates of 76.6% in the craniotomy group and 53.3% in the cranioplasty group at 6 months postsurgery (P = 0.015) and 78.6% and 78.1%, respectively, at 1 year postsurgery (P = 0.951). There was also a significant difference in the bone flap resorption rate between the 2 groups.

CONCLUSIONS

Bone flap fusion rates after craniotomy and cranioplasty were significantly different before 12 months, but not significantly different thereafter. Bone resorption occurred more frequently in the cranioplasty group over time.

Review of Cranioplasty after Decompressive Craniectomy

Cranioplasty is an in evitable operation conducted after decompressive craniectomy (DC). The primary goals of cranioplasty after DC are to protect the brain, achieve a natural appearance and prevent sinking skin flap syndrome (or syndrome of the trephined). Furthermore, restoring patients' functional outcome and supplementing external defects helps patients improve their self-esteem. Although early cranioplasty is preferred in recent year, optimal timing for cranioplasty remains a controversial topic. Autologous bone flaps are the most ideal substitute for cranioplasty. Complications associated with cranioplasty are also variable, however, post-surgical infection is most common. Many new materials and techniques for cranioplasty are introduced. Cost-benefit analysis of these new materials and techniques can result in different outcomes from different healthcare systems.

Resorption of Autogenous Bone Graft in Cranioplasty: Resorption and Reintegration Failure

Objective

Re-implantation of autologous skull bone has been known to be difficult because of its propensity for resorption. Moreover, the structural characteristics of the area of the defect cannot tolerate physiologic loading, which is an important factor for graft healing. This paper describes our experiences and results with cranioplasty following decompressive craniectomy using autologous bone flaps.

Methods

In an institutional review, the authors identified 18 patients (11 male and 7 female) in whom autologous cranioplasty was performed after decompressive craniectomy from January 2008 to December 2011. We examined the age, reasons for craniectomy, size of the skull defect, presence of bony resorption, and postoperative complications.

Results

Postoperative bone resorption occurred in eight cases (44.4%). Among them, two experienced symptomatic breakdown of the autologous bone graft that required a second operation to reconstruct the skull contour using porous polyethylene implant (Medpor®). The incidence of bone resorption was more common in the pediatric group and in those with large cranial defects (>120 cm²). No significant correlation was found with sex, reasons for craniectomy, and cryopreservation period.

Conclusion

The use of autologous bone flap for reconstruction of a skull defect after decompressive craniectomy is a quick and cost-effective method. But, the resorption rate was greater in children and in patients with large skull defects. As a result, we suggest compressive force of the tightened scalp, young age, large skull defect, the gap between bone flap and bone edge and heat sterilization of autologous bone as risk factors for bone resorption.