Cryopreservation of Autologous Cranial Bone Flaps for Cranioplasty: A Large Sample Retrospective Study

Bone graft absorption complication following cranioplasty: A retrospective institutional study

The aim of the present retrospective study was to confer the factors that are related to bone graft absorption and affect the outcomes of patients following cranioplasty (CPL). The present retrospective study includes cases of patients that underwent CPL between February, 2013 and December, 2022. All participants had a follow-up period of 1 to 10 years from the day of discharge from the hospital. In total, 116 (62.3%) of the 186 patients that underwent decompressive craniectomy (DC) were enrolled in the present study for CPL. A total of 109 (93.9%) patients were included in group A, and 7 (6.0%) patients were included in group B. On the whole, the results of the present study suggest that a CPL after 2.5-7.7 months of DC increases the possibility of bone absorption.

Biomaterials for Regenerative Cranioplasty: Current State of Clinical Application and Future Challenges

Acquired cranial defects are a prevalent condition in neurosurgery and call for cranioplasty, where the missing or defective cranium is replaced by an implant. Nevertheless, the biomaterials in current clinical applications are hardly exempt from long-term safety and comfort concerns. An appealing solution is regenerative cranioplasty, where biomaterials with/without cells and bioactive molecules are applied to induce the regeneration of the cranium and ultimately repair the cranial defects. This review examines the current state of research, development, and translational application of regenerative cranioplasty biomaterials and discusses the efforts required in future research. The first section briefly introduced the regenerative capacity of the cranium, including the spontaneous bone regeneration bioactivities and the presence of pluripotent skeletal stem cells in the cranial suture. Then, three major types of biomaterials for regenerative cranioplasty, namely the calcium phosphate/titanium (CaP/Ti) composites, mineralised collagen, and 3D-printed polycaprolactone (PCL) composites, are reviewed for their composition, material properties, and findings from clinical trials. The third part discusses perspectives on future research and development of regenerative cranioplasty biomaterials, with a considerable portion based on issues identified in clinical trials. This review aims to facilitate the development of biomaterials that ultimately contribute to a safer and more effective healing of cranial defects.

Subcutaneous preservation versus cryopreservation of autologous bone grafts for cranioplasty: A systematic review and meta-analysis

BACKGROUND

Cranioplasty corrects cranial bone defects using various bone substitutes or autologous bone flaps created during a previous craniectomy surgery. These autologous bone flaps can be preserved through subcutaneous preservation (SP) or cryopreservation (CP).

AIM

We aim to compare outcomes and complications for both SP and CP techniques to enhance the current evidence about autologous bone flap preservation.

METHODS

Five electronic databases were searched to collect all relevant studies. Records were screened for eligibility. Data were extracted from the included studies independently. We categorized surgical site infection (SSI) as either due to Traumatic brain injury (TBI) or not to reveal potential variations in SSI incidence. The double-arm meta-analysis utilized risk ratios (RR) and mean differences (MD) with corresponding confidence intervals (CI) to pool categorical and continuous outcomes, respectively. Proportions with their respective 95% CIs were pooled for single-arm meta-analyses to determine outcomes related to SP technique.

RESULTS

Seventeen studies involving 1169 patients were analyzed. No significant difference in SSI rates was observed between SP and CP methods in patients with or without TBI. SP was linked to shorter hospital stays in two studies (194 patients). Single-arm analysis showed a 17% revision surgery rate across five studies (375 patients) and infection rates in 17 studies for SP. New bone formation occurred in 13.2% of patients, with 19.9% showing resorption.

CONCLUSION

SP and CP methods showed similar SSI rates post-craniectomy in TBI and non-TBI patients. SP was associated with reduced hospitalization time, low infection rates, and a moderate need for revision surgery.

Autologous Cranioplasty with Bone Flap Preserved in Conventional Freezers: An Adequate Option in Low Resource Settings

BACKGROUND

Autologous cranioplasty has been used for decades and is the gold standard treatment in patients who underwent decompressive craniectomy (DC). One of the most common methods to store the cranial bone flap is cryopreservation at very low temperatures (-70 to -80°). The only way to achieve these low temperatures is by using special freezers which are not always available in all medical facilities, especially in low-resource centers. This paper describes our experience with the storage of cranial bone flaps in freezers of conventional refrigerators.

METHODS

This retrospective study included patients treated with autologous cranioplasty, operated between 2015 and 2020. The cranial bone flap was stored at -18°C in the freezer of conventional refrigerators. Complications and outcomes were analyzed and compared with reports of patients in whom ultra-low temperature freezers were used for bone flap preservation.

RESULTS

Twenty-five patients were included. The average follow-up period was 33 months. Trauma was the most common cause of DC, followed by stroke. The mean age was 36.7. Aseptic bone flap resorption was observed in 4 cases (16%). No cases of infection were observed.

CONCLUSIONS

The use of freezers from conventional refrigerators may be an acceptable alternative for the preservation of the cranial bone flap in facilities where special freezers are not available. The rate of aseptic bone necrosis and infections observed in this paper was similar to the incidence of these complications reported in studies where ultra-low temperatures were used.

Bone Flap Resorption After Cranioplasty: Risk Factors and Proposal of the Flap Integrity Score

BACKGROUND

Bone flap resorption is a known complication of postdecompressive autologous cranioplasty. Although several potential etiopathogenetic factors have been investigated, their role is still under discussion. To further complicate things, resorption is not an all-or-nothing event, patients frequently presenting with different degrees of flap remodeling. Focus of this paper was to describe the elaboration of a score quantifying bone resorption according to a set of clinical and radiological criteria, hopefully allowing prompt identification of patients needing resurgery before the development of adverse events.

METHODS

In a 10-year period, 281 autologous cranioplasties were performed at our institution following decompressive craniectomy. Pertinent clinical and radiological information was registered. A set of 3 clinical and 3 radiological parameters was established to score the degree of resorption, identified under the acronym FIS (Flap Integrity Score). Three groups of patients emerged, respectively showing no (208), partial (32), and advanced (41) resorption.

RESULTS

An overall 14.6% incidence of advanced bone resorption was found in our series. Younger age, bone multifragmentation, higher postcranioplasty Glasgow Outcome Scale scores, <2 cm distance of medial craniectomy border from the midline, and cause leading to decompressive craniectomy were associated to a statistically significant higher risk of developing a relevant bone flap resorption. The first three variables were confirmed as risk factors in multivariate analysis. Flap Integrity Score well discriminated the 3 different groups.

CONCLUSIONS

Autologous bone repositioning is still a valuable, low-cost, cosmetically and functionally satisfactory procedure. Nonetheless, although resorption affects a minor percentage of patients, its early identification and treatment can improve long-term results.

Infection-related failure of autologous versus allogenic cranioplasty after decompressive hemicraniectomy - A systematic review and meta-analysis

Introduction

Cranioplasty is required after decompressive craniectomy (DC) to restore brain protection and cosmetic appearance, as well as to optimize rehabilitation potential from underlying disease. Although the procedure is straightforward, complications either caused by bone flap resorption (BFR) or graft infection (GI), contribute to relevant comorbidity and increasing health care cost. Synthetic calvarial implants (allogenic cranioplasty) are not susceptible to resorption and cumulative failure rates (BFR and GI) tend therefore to be lower in comparison with autologous bone. The aim of this review and meta-analysis is to pool existing evidence of infection-related cranioplasty failure in autologous versus allogenic cranioplasty, when bone resorption is removed from the equation.

Materials and methods

A systematic literature search in PubMed, EMBASE, and ISI Web of Science medical databases was performed on three time points (2018, 2020 and 2022). All clinical studies published between January 2010 and December 2022, in which autologous and allogenic cranioplasty was performed after DC, were considered for inclusion. Studies including non-DC cranioplasty and cranioplasty in children were excluded. The cranioplasty failure rate based on GI in both autologous and allogenic groups was noted. Data were extracted by means of standardized tables and all included studies were subjected to a risk of bias (RoB) assessment using the Newcastle-Ottawa assessment tool.

Results

A total of 411 articles were identified and screened. After duplicate removal, 106 full-texts were analyzed. Eventually, 14 studies fulfilled the defined inclusion criteria including one randomized controlled trial, one prospective and 12 retrospective cohort studies. All but one study were rated as of poor quality based on the RoB analysis, mainly due to lacking disclosure why which material (autologous vs. allogenic) was chosen and how GI was defined. The infection-related cranioplasty failure rate was 6.9% (125/1808) for autologous and 8.3% (63/761) for allogenic implants resulting in an OR 0.81, 95% CI 0.58 to 1.13 (Z ​= ​1.24; p ​= ​0.22).

Conclusion

In respect to infection-related cranioplasty failure, autologous cranioplasty after decompressive craniectomy does not underperform compared to synthetic implants. This result must be interpreted in light of limitations of existing studies. Risk of graft infection does not seem a valid argument to prefer one implant material over the other. Offering an economically superior, biocompatible and perfect fitting cranioplasty implant, autologous cranioplasty can still have a role as the first option in patients with low risk of developing osteolysis or for whom BFR might not be of major concern.

Trial registration

This systematic review was registered in the international prospective register of systematic reviews. PROSPERO: CRD42018081720.

Predictors of Clinical Outcomes in Autologous Cranioplasty

BACKGROUND

Cranioplasty is a common neurosurgical procedure and autologous grafts are preferred due to their aesthetic and biocompatibility benefits. Multiple risk factors are implicated as predictors for neurologic outcome. This study focuses on risk factors that may be associated with complications and analyzes the predictors of neurologic outcomes after autologous cranioplasty.

METHODS

This is a retrospective observational study conducted at a tertiary care center between 2015 and 2021. Adults with autologous cranioplasty (n = 132) were recruited from procedure logs and the hospital electronic health record. Clinicodemographic parameters, risk factors, and complications were recorded. Neurologic outcomes were measured using the dichotomized Glasgow Outcome Scale (GOS). Primary outcome measure was pre- and post-cranioplasty GOS at the last follow up. Secondary outcome measures were the predicting factors that contributed to enhanced neurologic outcome post-cranioplasty.

RESULTS

Mean age was 41.4 (standard deviation ± 13.5) years with male predominance (12.2:1). Complications developed in 12.9% (n = 17), with infections in 3.8% (n = 5) and hydrocephalus in 2.3% (n = 3). In bivariate analysis, pre-cranioplasty GOS good grades 4 and 5 (P < 0.001), trauma as an indication for decompressive craniectomy (DC) (P < 0.001), and early cranioplasty ≤12 weeks (P = 0.023) were statistically significant predictors for post-cranioplasty neurologic recovery at follow-up. In a multiple logistic regression model, adjusted odds ratio for pre-cranioplasty GOS was 28.77 (95% confidence interval [CI] 7.21-114.74, P < 0.001), for trauma as indication for DC was 5.15 (95% CI 1.65-16.05, P = 0.003), and for early cranioplasty ≤12 weeks was 3.04 (95% CI 1.12-8.27 P = 0.029).

CONCLUSIONS

Autologous cranioplasty contributes to a quantifiable neurologic outcome. Pre-cranioplasty neurologic status, cranioplasty done for traumatic DC and early cranioplasty may have potential for enhanced neurologic recovery. Further clinical studies with better evidence may expound upon these findings.

Ten-Year Institutional Experience to Predict Risk of Calvarial Bone Flap Loss Using Long-Term Outcome Data

BACKGROUND

Calvarial bone flap (CBF) loss is a common complication following craniotomy and subsequent skull reconstruction can be challenging. Defining predictors of CBF failure not only improves patient outcomes but reduces the need for complex reconstruction often requiring plastic surgery consultation. As CBF failure can occur many years following craniotomy, this study aimed to determine risk factors of CBF loss using long-term follow-up.

MATERIALS AND METHODS

This retrospective study included patients who underwent craniotomy with CBF reinsertion between 2003 and 2013 at a tertiary academic institution. Patients were included if demographics, comorbidities, and long-term outcomes were available. Multivariable logistic regression modeled the odds of CBF failure, defined as permanent removal for bone flap-related issues. The median follow-up was 6.9 years (interquartile range: 1.8-10.8 y).

RESULTS

There were 222 patients who met inclusion criteria and underwent craniotomy with CBF reinsertion, primarily for tumor resection or intracranial pressure relief. CBF failure occurred in 76 (34.2%) patients. Up to 4 CBF reinsertions were performed in both failure and nonfailure groups. The risks of CBF loss increased with each additional CBF elevation by 17-fold (P<0.001), male sex by 3-fold (P=0.005), and tumor etiology by 3-fold (P=0.033) (C-index=0.942).

CONCLUSIONS

Each CBF reinsertion dramatically increases the risk of CBF loss. This finding may optimize patient selection and surgical planning. Early multidisciplinary discussions between plastic surgeons and neurosurgeons may avoid multiple CBF elevations and prevent the adverse sequela of high-risk calvarial reconstruction efforts.

Surgical Management of Neurotrauma: When to Intervene

Neurotrauma, often defined as abrupt damage to the brain or spinal cord, is a substantial cause of mortality and morbidity that is widely recognized. As such, establishing an effective course of action is crucial to the enhancement of neurotrauma guidelines and patient outcomes in healthcare worldwide. Following the onset of neurotraumatic injuries, time is perhaps the most critical facet in diminishing mortality and morbidity rates. Thus, procuring the airway should be of utmost priority in a patient to allow for optimal ventilation, with a shift in focus resorting to surgical interventions after the patient reaches a suitable care facility. In particular, ventriculoperitoneal shunt (VPS) procedures have long been utilized to treat traumatic brain and spinal cord injuries to direct additional cerebrospinal fluid (CSF) from the lateral ventricles through a ventricular catheter attached to a valve that is further connected to a distal catheter. Decompressive cranio omie (DCs), cranioplasties, and intracranial pressure measurements (ICP) are also frequently performed in combination with VPS to manage intracranial hypertension and cerebral edema. Although the current surgical methods utilized in the treatment of neurotrauma prove to be highly efficacious in the prevention of adverse outcomes, emergent therapies are growing in popularity. Of interest, the Three Pillars Expansive Craniotomy, cisternostomy, and external lumbar drainages are cutting-edge procedures with promising results that can potentially usher change in the neurosurgical industry but require additional examination.

Cryopreservation of Animals and Cryonics: Current Technical Progress, Difficulties and Possible Research Directions

The basis of cryonics or medical cryopreservation is to safely store a legally dead subject until a time in the future when technology and medicine will permit reanimation after eliminating the disease or cause of death. Death has been debunked as an event occurring after cardiac arrest to a process where interjecting its progression can allow for reversal when feasible. Cryonics technology artificially halts further damages and injury by restoring respiration and blood circulation, and rapidly reducing temperature. The body can then be preserved at this extremely low temperature until the need for reanimation. Presently, the area has attracted numerous scientific contributions and advancement but the practice is still flooded with challenges. This paper presents the current progression in cryonics research. We also discuss obstacles to success in the field, and identify the possible solutions and future research directions.

A systematic review and meta-analysis of factors involved in bone flap resorption after decompressive craniectomy

Decompressive craniectomy (DC) is effective in controlling increasing intracranial pressure determined by a wide range of conditions, mainly traumatic brain injury (TBI) and stroke, and the subsequent cranioplasty (CP) displays potential therapeutic benefit in terms of overall neurological function. While autologous bone flap (ABF) harvested at the time of DC is the ideal material for skull defect reconstruction, it carries several risks. Aseptic bone flap resorption (BFR) is one of the most common complications, often leading to surgical failure. The aim of our study was to systematically review the literature and carry out a meta-analysis of possible factors involved in BFR in patients undergoing ABF cranioplasty after DC. A systematic review and meta-analysis was performed in accordance with the PRISMA guidelines. Different medical databases (PubMed, Embase, and Scopus) were screened for eligible scientific reports until April 30th 2021. The following data were collected for meta-analysis to assess their role in BFR: sex, age, the interval time between DC and CP, the presence of systemic factors, the etiology determining the DC, CP surgical time, CP features, VP shunt placement, CP infection. Studies including pediatric patients or with less than 50 patients were excluded. Fifteen studies were included. There was a statistically significant increased incidence of BFR in patients with CPF > 2 compared to patients with CPF ≤ 2 (54.50% and 22.76% respectively, p = 0.010). TBI was a significantly more frequent etiology in the BFR group compared to patients without BFR (61.95% and 47.58% respectively, p < 0.001). Finally, patients with BFR were significantly younger than patients without BFR (39.12 ± 15.36 years and 47.31 ± 14.78 years, respectively, p < 0.001). The funnel plots were largely symmetrical for all the studied factors. Bone flap fragmentation, TBI etiology, and young age significantly increase the risk of bone resorption. Further studies are needed to strengthen our results and to clarify if, in those cases, a synthetic implant for primary CP should be recommended.

Evidence of linear bone flap resorption in patients undergoing autologous cranioplasty following decompressive craniectomy: A 3D Slicer segmented analysis of serial CT images

OBJECTIVES

Autologous cranioplasty (CP) following decompressive craniectomy (DC) carries risk of bone flap resorption (BFR). The current literature offers limited information regarding the natural progression of BFR, and the rate at which it occurs. We aim to characterize the progression of BFR over time and elucidate risk factors for accelerated BFR.

METHODS

A retrospective analysis was conducted on patients who underwent DC and autologous CP. Serial computed tomography (CT) images were used to quantify degree of BFR over time. Risk factors included age, diabetes, smoking status, flap fragmentation, defect size, and DC-CP time interval. Chi-square analyses and Student's t-tests were performed to examine differences between patients who experienced BFR and those who did not.

RESULTS

Overall, 82% of patients demonstrated evidence of clinically relevant resorption on CT. On average, the bone flap decreased in volume by 36.7% within the first year, with a linear loss in volume after multiple years of follow-up. Individuals who developed greater BFR were significantly younger (43 ± 17 vs. 56 ± 12, p=0.022), had a lower incidence of diabetes (5.9% vs. 43%, p=0.037), and had more bone flap fragments (1.4 ± 0.67 vs. 1.00 ± 0, p <0.001) than those who did not.

CONCLUSION

Resorption following CP with cryopreserved bone appears to progress in a fairly linear and continuous fashion over time. Using serial CT images, we found a resorption rate of 82% at our institution. We identified several possible risk factors for resorption, including flap fragmentation, younger age, and absence of diabetes.

A Narrative Review of Cell-Based Approaches for Cranial Bone Regeneration

Current cranial repair techniques combine the use of autologous bone grafts and biomaterials. In addition to their association with harvesting morbidity, autografts are often limited by insufficient quantity of bone stock. Biomaterials lead to better outcomes, but their effectiveness is often compromised by the unpredictable lack of integration and structural failure. Bone tissue engineering offers the promising alternative of generating constructs composed of instructive biomaterials including cells or cell-secreted products, which could enhance the outcome of reconstructive treatments. This review focuses on cell-based approaches with potential to regenerate calvarial bone defects, including human studies and preclinical research. Further, we discuss strategies to deliver extracellular matrix, conditioned media and extracellular vesicles derived from cell cultures. Recent advances in 3D printing and bioprinting techniques that appear to be promising for cranial reconstruction are also discussed. Finally, we review cell-based gene therapy approaches, covering both unregulated and regulated gene switches that can create spatiotemporal patterns of transgenic therapeutic molecules. In summary, this review provides an overview of the current developments in cell-based strategies with potential to enhance the surgical armamentarium for regenerating cranial vault defects.

[Features of modeling a polymer implant for closing a defect after decompressive craniotomy]

BACKGROUND

Individual polymer implants are widespread for bone reconstruction after decompressive craniectomy. Despite the availability of customized titanium products, various specialists and hospitals prefer polymer implants.

OBJECTIVE

To compare the methods of modeling and manufacturing the polymethylmethacrylate implants and identify the features affecting the quality of reconstruction.

MATERIAL AND METHODS

We analyzed 14 patients with extensive skull defects after installation of polymethyl methacrylate implants. Software used for modeling of individual implants by different specialists was compared.

RESULTS

Satisfactory reconstruction result was obtained in all cases. There were no infectious complications. The authors outlined certain important aspects for modeling of individual polymer products: local use of anatomical thickness of the implant, leaving safe spaces, prevention of temporal retraction, template-based resection before reconstruction.

CONCLUSION

To date, skull defect closure with polymeric materials remains relevant, and even has certain advantages over customized titanium products.

Subgaleal drains may be associated with decreased infection following autologous cranioplasty: a retrospective analysis

BACKGROUND

Autologous bone is often the first choice in cranioplasty following a decompressive craniectomy. However, infection is a common complication, with reported rates up to 25%. While the incidence and management of infection are well documented, the risk factors associated with infection remain less clear. The current study aims to identify predictors of infection risk following autologous cranioplasty.

METHODS

A retrospective analysis was conducted on patients who underwent decompressive craniectomy and cranioplasty using cryopreserved autologous bone flaps between 2010 and 2020. Patient demographics and factors related to both surgeries and infection rates were recorded from patient records. Logistic regressions were conducted to determine which factors were implicated in the development of infection.

RESULTS

In our cohort, 126 patients underwent autologous cranioplasty. A total of 10 patients (7.9%) developed an infection following reconstruction, with half resulting in implant failure. We did not identify any significant risk factors for infection. Regression analysis identified placement of subgaleal drain following cranioplasty as a protective factor against the development of infection (OR: 0.16, p = 0.007). On average, drains remained in for 3 days, with no difference between the length of drains for those with infection vs. those without (p = 0.757).

CONCLUSIONS

The current study demonstrates an infection rate of 7.9% in patients who receive an autologous cranioplasty following decompressive craniectomy, which is consistent with previous data. Half (4%) of patients who experienced an infection ultimately required removal of the implant. While it is common practice for neurosurgeons to use drains to prevent hematomas and fluid collections, we found that subgaleal drain placement following cranioplasty was associated with decreased infection, thus demonstrating another benefit of a commonly used tool.

Predictive Value of Swab Cultures for Cryopreserved Flaps During Delayed Cranioplasties

OBJECTIVE

To assess the predictive value of swab cultures of cryopreserved skull flaps during cranioplasties for surgical site infections (SSIs).

METHODS

A retrospective review was conducted of consecutive patients who underwent delayed cranioplasties with cryopreserved autografts between 2009 and 2017. The results of cultures obtained from swabs and infected surgical sites were assessed. The accuracy, sensitivity, and specificity of swab cultures for SSIs were evaluated.

RESULTS

The study included 422 patients categorized into two groups, swab and nonswab, depending on whether swab cultures were implemented during cranioplasties. The overall infection rate was 7.58%. No difference was seen in infection rates between groups. There were 18 false-positive and no true-positive swab culture results. All bacteria between swab cultures and SSI cultures were discordant. Meanwhile, there were 19 false-negative swab cultures. The results showed high specificity but low sensitivity for swab cultures to predict SSI occurrence and the pathogens.

CONCLUSIONS

Owing to low accuracy and sensitivity, swab cultures of cryopreserved autografts should not be routinely performed during delayed cranioplasties.

Comparison of subcutaneous pocket with cryopreservation method for storing autologous bone flaps in developing surgical wound infection after Cranioplasty: A randomized clinical trial

BACKGROUND

Following a decompressive craniectomy (DC), the harvested bone flap is stored for future cranioplasty. There are two different methods proposed for bone banking, namely subcutaneous pocketing (SP) in the abdominal wall and cryopreservation (CP) in a refrigerator. This study was designed to evaluate the risk of developing infection in each study group.

METHODS

In this randomized clinical trial design, a total of 143 patients underwent a primary decompressive craniectomy. Thereafter, they were randomly allocated into two groups, as SP and CP, and they were then scheduled for a future cranioplasty. Next, 108 patients underwent cranioplasty using an autologous bone flap and then followed-up for 18 months. Some variables, including demographic data, indications for primary DC, rate of post-operative clinical infection, bacterial culture results, the interval between craniectomy and cranioplasty, post-operative hospitalization duration, new morbidities, mortality rate, bone flap resorption rate, and several possible associated risk factors, were also recorded. The obtained data were analyzed by an expert bio-statistician using proper bio-statistical methods. A P value < 0.05 was considered as statistically significant.

RESULTS

Four patients in the cryopreservation group (n = 50) indicated post-operative bone flap infection (8%), which was statistically significant (P = 0.041). Accordingly, all of them were resulted as positive for Methicillin-Resistant-Staphylococcus aureus (MRSA). Using the subcutaneous pocket method, no post-operative infection was observed after cranioplasty. The overall postoperative infection rate was estimated as 4%. The mean of age in the post-operative infection group's participants was 50.25 years old, and in the non-infected, it was 34.93 years old, which was also significant (P = 0.048). Bone flap resorption (BFR) rate was found to be higher by the use of CP method in comparison to SP technique (p = 0.0001). Of note, no other risk factor was found attributable to a higher BFR rate (p-values > 0.05).

CONCLUSIONS

Older age and cryopreservation method at higher storage temperature (-18C˚) may be associated with infection's development after performing cranioplasty. BFR is more prevalent in the use of CP method rather than SP preservation technique.

Decision-Making in Adult Cranial Vault Reconstruction

LEARNING OBJECTIVES

After studying this article, the participant should be able to: 1. Define and classify different types of cranial defects 2. Compare both autologous and alloplastic options for reconstruction 3. Develop an optimal approach for cranial vault reconstruction in various clinical scenarios.

SUMMARY

Defects of the cranium result from various causes, including traumatic loss, neurosurgical intervention, skull tumors, and infection. Cranial vault reconstruction aims to restore both the structural integrity and surface morphology of the skull. To ensure a successful outcome, the choice of appropriate cranioplasty reconstruction will vary primarily based on the cause, location, and size of the defect. Other relevant factors that must be considered include adequacy of soft-tissue coverage, presence of infection, and previous or planned radiation therapy. This article presents an algorithm for the reconstruction of various cranial defects using both autologous and alloplastic techniques, with a comparison of their advantages and disadvantages.

Bone Flap Resorption in Pediatric Patients Following Autologous Cranioplasty

Following a decompressive craniectomy, the autologous bone flap is generally considered the reconstructive material of choice in pediatric patients. Replacement of the original bone flap takes advantage of its natural biocompatibility and the associated low risk of rejection, as well as the potential to reintegrate with the adjacent bone and subsequently grow with the patient. However, despite these advantages and unlike adult patients, the replaced calvarial bone is more likely to undergo delayed bone resorption in pediatric patients, ultimately requiring revision surgery. In this review, we describe the materials that are currently available for pediatric cranioplasty, the advantages and disadvantages of autologous calvarial replacement, the incidence and classification of bone resorption, and the clinical risk factors for bone flap resorption that have been identified to date.

Complications of cranioplasty following decompressive craniectomy for traumatic brain injury: systematic review and meta-analysis

BACKGROUND

Decompressive craniectomy (DC) is a common neurosurgical intervention for severe traumatic brain injury (TBI), as well as malignant stroke, malignancy and infection. DC necessitates subsequent cranioplasty. There are significant demographic differences between TBI and non-TBI patients undergoing cranioplasty, which may influence their relative risk profiles for infection, aseptic bone flap resorption (aBFR) and re-operation.

OBJECTIVE

Perform a meta-analysis to determine the relative infection, aBFR and re-operation risk profiles of TBI patients as compared to other indications for DC.

METHODS

A systematic review and meta-analysis was performed in accordance with the PRISMA guidelines. PubMed, MEDLINE, EMBASE and Google Scholar were searched until 26/11/2020. Studies detailing rates of infection, re-operation and/or aBFR in specific materials and the post-TBI population were included, while studies in paediatrics or craniosynostosis repair were excluded.

RESULTS

Twenty-six studies were included. There was no difference in relative risk of infection between TBI and non-TBI cohorts (RR 0.81, 95% CI 0.57-1.17), with insignificant heterogeneity (I² = 33%). TBI was a risk factor for aBFR (RR 1.54, 95% CI 1.25-1.89), with no significant heterogeneity (I² = 13%). TBI was a risk factor for re-operation in the autologous sub-group (RR 1.49, 95% CI 1.05-2.11) but not in the alloplastic sub-group (RR = 0.86, 95% CI 0.34-2.18). Heterogeneity was insignificant (I² = 11%).

CONCLUSION

TBI is a risk factor for aBFR and re-operation following cranioplasty. Use of an alloplastic graft for primary cranioplasty in these patients may partially mitigate this increased risk.

Bony Union and Flap Resorption in Cranioplasty with Autologous Subcutaneous Pocket Preserved Bone Flap: Early Report on an Ambidirectional CT Scan-Based Study

Introduction Absence of sufficient number of prospective randomized controlled studies and comparatively small sample size and short follow-up period of most of the studies, available so far, have left ambiguity and lack of standardization of different aspects of cranioplasty.

Materials and Methods This is an early report of a computed tomography scan image-based ambidirectional study on cranioplasties performed with autologous subcutaneous pocket preserved bone flaps. Retrospective arm compared bony union and factors influencing it between cranioplasties and craniotomies. Patients with poor bony union and aseptic resorption were followed up in the prospective arm.

Results Retrospective arm of the study, followed up for five years (mean 32.2 months), comprised 42 patients as cases (Group 1) and 29 as controls (Group 2). Twenty-seven individuals (64.3%) in Group 1 had good bony union, as compared with 20 (68.9%) good unions in Group 2 out of the 29 patients. Four patients (9.5%) in Group 1 showed evidence of flap resorption, a finding absent in any patient in Group 2. Age, sex, smoking habits, superficial skin infection, and method of fixation did not appear to have any implication on bony union. Craniotomies done using Gigli saws fared better as compared with those done with pneumatic saw with lesser flap size–craniectomy size discrepancy, though it was not statistically significant. Fifteen patients have been included in the Prospective arm at the time of submission of this article.

Conclusion Ours is a study with a small sample size, unable to put its weight on any side, but can surely add some more data to help the Neurosurgeons in choosing the best for their patients.

Cranioplasty with Autologous Bone Flaps Cryopreserved with Dimethylsulphoxide: Does Tissue Processing Matter

OBJECTIVE

The aim of this article was to study the outcome of patients who underwent cranioplasty with cryopreserved autologous bone after decompressive craniectomy.

METHODS

Data from 74 patients were retrospectively analyzed. They were divided into groups according to the storage time and the age at cranioplasty. To assess the predictive potential for complication, factors were related to successive stages (preoperative, craniectomy, tissue processing, cranioplasty, and postoperative). Cooling and warming rates applied on bone flap were calculated. The ability to inhibit microbial growth was determined exposing bone fragments to a panel of microorganisms. The concentration of antibiotics eluted from the bone was also determined. A bone explant culture method was used to detect living cells in the thawed cranial bone.

RESULTS

Hydrocephalus was significantly more frequent in pediatric patients (26.7%) than in adults (5.1%). The overall rate of bone flap resorption was 21.6% (43.7% of which required reoperation). Surgical site infection after cranioplasty was detected in 6.8% of patients. There was no correlation between infection as a postoperative complication and previous microbiological-positive culture during processing. The cause of craniectomy did not influence the risk of bone flap contamination. Vancomycin was the only antibiotic detected in the supernatant where the bone was incubated. Outgrowth from bone explants was observed in 36.8% of thawed skulls. An early start of bone flap processing at the tissue bank had a positive effect on cell viability.

CONCLUSIONS

The outcome after autologous cranioplasty is a multifactorial process, which is modulated by patient-related, surgery-related, and bone-related factors.

Reconstruction using a frozen autograft for a skull and humeral lesion of synchronous multicentric osteosarcoma after undergoing successful neoadjuvant chemotherapy: a case report and review of the literature

Background

Synchronous multicentric osteosarcoma (SMOS) is a rare disease characterized by simultaneous multicentricity of intraosseous osteosarcoma without visceral involvement. SMOS, including a skull lesion, which occurs relatively rarely, and reconstruction using a frozen autograft after the excision of a lesion of SMOS has been infrequently reported previously.

Case presentation

We report an 18-year-old girl with SMOS, with lesions located in the left distal femur, right proximal humerus, and left occipital bone. Her major complaint was pain and swelling around the left knee joint. Asymptomatic lesions of the humerus and skull bone were detected on a systemic bone scan. No visceral organ metastasis was observed. A biopsy of the distal femoral lesion revealed osteosarcoma. Based on the histological findings, multiple bone lesions, and absence of visceral lesion, the clinical diagnosis of SMOS was made. After five courses of neoadjuvant chemotherapy with a regimen of doxorubicin and cisplatin, reconstruction using a tumor prosthesis following wide excision of the left distal femur was performed, and total necrosis was histologically observed in the retracted specimen. Following three cycles of adjuvant chemotherapy, tumor excision and reconstruction with a frozen autograft treated with liquid nitrogen was conducted for both lesions of the humerus and skull, rather than tumor prosthesis or synthetics, in order to retain a normal shoulder function, and to obtain a good cosmetic and functional outcome after treatment of the skull lesion. Further adjuvant chemotherapy could not be administered after the completion of the surgical treatment for all lesions because the adverse events due to chemotherapy were observed. At over 5 years after the diagnosis, she remains clinically disease-free.

Conclusions

An early correct diagnosis, the proper management of chemotherapy, and surgical treatment for all lesions are essential for achieving a good clinical outcome, even in SMOS including a skull lesion. By performing reconstruction using a frozen autograft for a proximal humeral lesion and a skull lesion after confirming the good histological efficacy of neoadjuvant chemotherapy for the primary lesion, the excellent function of the shoulder joint and a good cosmetic outcome at the site of the skull lesion was acquired without complications or recurrence.

The storage of skull bone flaps for autologous cranioplasty: literature review

The use of autologous bone flap for cranioplasty after decompressive craniectomy is a widely used strategy that allows alleviating health expenses. When the patient has recovered from the primary insult, the cranioplasty restores protection and cosmesis, recovering fluid dynamics and improving neurological status. During this time, the bone flap must be stored, but there is a lack of standardization of tissue banking practices for this aim. In this work, we have reviewed the literature on tissue processing and storage practices. Most of the published articles are focused from a strictly clinical and surgical point of view, paying less attention to issues related to tissue manipulation. When bone resorption is avoided and the risk of infection is controlled, the autograft represents the most efficient choice, with the lowest risk of complication. Otherwise, depending on the degree of involvement, the patient may have to undergo new surgery, assuming further risks and higher healthcare costs. Therefore, tissue banks must implement protocols to provide products with the highest possible clinical effectiveness, without compromising safety. With a centralised management of tissue banking practices there may be a more uniform approach, thus facilitating the standardization of procedures and guidelines.

3D-Printer-Assisted Patient-Specific Polymethyl Methacrylate Cranioplasty: A Case Series of 16 Consecutive Patients

BACKGROUND

To develop a novel 3D-printer-assisted method to fabricate patient-specific implants for cranioplasty and to demonstrate its feasibility and its use in 16 consecutive cases.

METHODS

We report on 16 consecutive patients who have undergone cranioplasty surgery for an extensive skull defect after decompressive surgery and in which the bone flap was not available. We present the workflow for the implant production using a 3D-printer-assisted molding technique. Preoperative, intraoperative, and postoperative data were analyzed/evaluated.

RESULTS

Eleven out of our 16 patients (68.7%) presented with extensive hemispheric bone defects. Indication for initial craniotomy were traumatic brain injury (4; 25%), acute subdural hematoma (4; 25%), ischemic stroke (3; 18.8%), tumor (3; 18.8%), and ruptured aneurysm (2; 12.5%). Median (range) operation time was 121 (89-206) minutes. Median (range) intraoperative blood loss was 300 (100-3300) mL. The mean (range) follow-up period is 6 (0-21) months. Complications occurred in 7 out of our 16 patients (43.8%), in 6 (37.5%) of which a reoperation was required to evacuate an extra-axial hematoma (3; 50%), for shunting of an epidural fluid collection (1; 16.7%), or for skin flap necrosis (1; 16.7%). One patient (16.7%) developed a chronic asymptomatic subdural fluid collection that was stable over the follow-up period.

CONCLUSIONS

Our workflow to intraoperatively produce patient-specific implants in a timely manner to cover cranial defects proved to be feasible. The results are cosmetically appealing, and postoperative CT scans show well-fitting implants. As implantable printable substrates are already available, we aim to advance and certify 3D-printed patient-specific implants in the near future.

In situ bone regeneration of large cranial defects using synthetic ceramic implants with a tailored composition and design

Large cranial reconstructions are increasingly performed worldwide and still represent a substantial clinical challenge. The gold standard, autologous bone, has limited availability and high donor-site morbidity. Current alloplastic materials are associated with high complication and failure rates. This study shows the capacity of a customized, purely synthetic, 3D-manufactured bioceramic implant to regenerate and restore large cranial defects with mature, well-vascularized bone, with a morphology, ultrastructure, and composition similar to those of native skull bone. This approach triggers the regenerative potential of host tissue by tailoring the implant composition and design. The regeneration of large defects using purely synthetic material without adjunct cell therapy or growth factors represents a major advancement for rehabilitating patients in need of large cranial reconstructions.

The repair of large cranial defects with bone is a major clinical challenge that necessitates novel materials and engineering solutions. Three-dimensionally (3D) printed bioceramic (BioCer) implants consisting of additively manufactured titanium frames enveloped with CaP BioCer or titanium control implants with similar designs were implanted in the ovine skull and at s.c. sites and retrieved after 12 and 3 mo, respectively. Samples were collected for morphological, ultrastructural, and compositional analyses using histology, electron microscopy, and Raman spectroscopy. Here, we show that BioCer implants provide osteoinductive and microarchitectural cues that promote in situ bone regeneration at locations distant from existing host bone, whereas bone regeneration with inert titanium implants was confined to ingrowth from the defect boundaries. The BioCer implant promoted bone regeneration at nonosseous sites, and bone bonding to the implant was demonstrated at the ultrastructural level. BioCer transformed to carbonated apatite in vivo, and the regenerated bone displayed a molecular composition indistinguishable from that of native bone. Proof-of-principle that this approach may represent a shift from mere reconstruction to in situ regeneration was provided by a retrieved human specimen, showing that the BioCer was transformed into well-vascularized osteonal bone, with a morphology, ultrastructure, and composition similar to those of native human skull bone.

Bone Flap Resorption Associated with Indolent Propionibacterium acnes Infection After Cranioplasty: Case Report with Pathological Analysis

BACKGROUND

Autologous bone resorption is a frequent complication of cranioplasty, often necessitating reoperation. The etiology of this phenomenon is unknown, although it has recently been associated with indolent Propionibacterium acnes infection.

CASE DESCRIPTION

A 59-year-old man initially presented with a traumatic acute subdural hematoma treated with emergent decompressive hemicraniectomy and hematoma evacuation. His bone flap was cryopreserved. He underwent cranioplasty with autologous bone 3 months later. Over the subsequent 14 months, serial imaging demonstrated progressive bone flap resorption, ultimately requiring repeat cranioplasty with a custom allograft. Although there was no evidence of infection at the time of repeat cranioplasty, routine culture swabs were taken and grew P. acnes after the patient had been discharged home. Pathologic analysis of the fragments of the original bone flap that were removed demonstrated osteonecrosis with marrow fibrosis but no evidence of inflammation or infection. He was treated with 6 weeks of intravenous antibiotics and had no evidence of infection at 8-month follow-up.

CONCLUSIONS

Indolent P. acnes infection can precipitate autologous bone flap resorption. While the mechanism of this is unknown, pathologic analysis of a partially resorbed bone flap in the setting of an indolent P. acnes infection found no evidence of an infectious process or inflammation within the bone. Further studies are needed to elucidate the mechanism of action of P. acnes in bone flap resorption.

Injectable Magnesium-Zinc Alloy Containing Hydrogel Complex for Bone Regeneration

Gelatin methacryloyl (GelMA) has been widely used in bone engineering. It can also be filled into the calvarial defects with irregular shape. However, lack of osteoinductive capacity limits its potential as a candidate repair material for calvarial defects. In this study, we developed an injectable magnesium-zinc alloy containing hydrogel complex (Mg-IHC), in which the alloy was fabricated in an atomization process and had small sphere, regular shape, and good fluidity. Mg-IHC can be injected and plastically shaped. After cross-linking, it contents the elastic modulus similar to GelMA, and has inner holes suitable for nutrient transportation. Furthermore, Mg-IHC showed promising biocompatibility according to our evaluations of its cell adhesion, growth status, and proliferating activity. The results of alkaline phosphatase (ALP) activity, ALP staining, alizarin red staining, and real-time polymerase chain reaction (PCR) further indicated that Mg-IHC could significantly promote the osteogenic differentiation of MC3T3-E1 cells and upregulate the genetic expression of collagen I (COL-I), osteocalcin (OCN), and runt-related transcription factor 2 (RUNX2). Finally, after applied to a mouse model of critical-sized calvarial defect, Mg-IHC remarkably enhanced bone formation at the defect site. All of these results suggest that Mg-IHC can promote bone regeneration and can be potentially considered as a candidate for calvarial defect repairing.

Cranioplasty With Autogenous Frozen and Autoclaved Bone: Management and Treatment Outcomes

Cranioplasty is a widely employed procedure for restoration of calvarial form and shape. The use of autogenous bone flap offers biological reconstruction with minimal donor site morbidity. One of the options to re-use bone autograft is low temperature preservation followed by autoclaving during cranioplasty. A retrospective evaluation of 12 patients with a mean age of 32.58 ± 10.04 years who underwent frozen autogenous autoclaved bone cranioplasty was done. Cranial bone flaps were removed during the initial craniectomy and stored at 4°C for 20 minutes followed by preservation at -40°C in the deep freezer of the blood bank. Cranioplasty subsequently was performed at a mean time period of 172.17 ± 26.20 days by thawing the bone at room temperature followed by autoclaving at 121°C under 15 psi for 40 minutes. Data regarding patients' characteristics and complications were recorded. Clinical outcomes based on skull shape and symmetry, cosmesis and scars were analyzed by a panel of 4 raters, including 3 doctors and 1 patient. Radiological outcomes were analyzed based on remaining bone thickness and bone gap widening. The present study revealed functionally, structurally, and cosmetically satisfying results. All the cases had satisfactory healing and no incidence of bone graft infection. The skull shape and symmetry, cosmesis and scars revealed excellent to moderate improvement in three-fourth of the patients. Radiological outcomes revealed none of the patients had severe resorption requiring surgical revision with excellent to good implant alignment in 92% of cases. It was concluded that frozen autogenous cranial bone flaps sterilized by autoclaving is safe and effective material for cranioplasty.

Vitrification and storage of oral mucosa epithelial cell sheets

Shipping time and shipping delays might affect the quality of the stem cells based engineered "organs." In our laboratory, we have developed a limbal stem cell deficient (LSCD) rabbit model. To reverse the LSCD, we cultured oral mucosal epithelial cells for 2-3 weeks and engineered cultured autologous oral mucosa epithelial cell sheets (CAOMECS), which were grafted on the LSCD cornea. The purpose of this study was to vitrify CAOMECS and to store it until the CAOMECS can be grafted onto patients. CAOMECS were vitrified in LN₂ for up to 204 days. We tested two different methods of vitrification with different solutions; however, CAOMECS were only viable when they were not stored in a vitrification solution; results were only reported from this CAOMECS. On the basis of hematoxylin and eosin staining, we showed that the CAOMECS morphology was well preserved after long-term storage in LN₂ . Most of the preservation solutions maintained the CAOMECS phenotype (Ki67, proliferating cell nuclear antigen (PCNA), Beta-Catenin, ZO-1, E-Cadherin, CK3, CK4, CK13). The exception was the solution composed with ethylene glycol and Dimethyl sulfoxide (DMSO): this resulted in loss of DeltaN-p63 expression. DeltaN-p63 is an important marker for cell proliferation. The expression of proteins involved in cell-cell connection and the differentiation markers were maintained. Apoptosis was not detected in the thawed CAOMECS. We demonstrated that CAOMECS can be stored long-term in LN₂ without affecting their morphology and phenotype.

Bone resorption in autologous cryopreserved cranioplasty: quantitative evaluation, semiquantitative score and clinical significance

BACKGROUND

Changes after reimplantation of the autologous bone have been largely described. However, the rate and the extent of resorption in cranial grafts have not been clearly defined. Aim of our study is to evaluate the bone flap resorption (BFR) after cryopreservation.

METHODS

We retrospectively reviewed 27 patients, aged 18 years or older, subjected to cranioplasty (CP) adopting autologous cryopreserved flap. The BFR was derived from the percentage of decrease in flap volume (BFR%), comparing the first post-operative computed tomography (CT) and the last one available (performed at least 1 year after surgery). We also proposed a semiquantitative scoring system, based on CT, to define a clinically workable BFR classification.

RESULTS

After a mean ± SE follow-up of 32.5 ± 2.4 months, the bone flap volume decreased significantly (p < 0.0001). The mean BFR% was 31.7 ± 3.8% and correlated with CT-score (p < 0.001). Three BFR classes were described: mild (14.8% of cases) consisting in minimal bone remodelling, CT-score ≤ 6, mean BFR% = 3.5 ± 0.7%; moderate (51.9% of cases) corresponding to satisfactory cerebral protection, CT-score < 13, mean BFR% = 25.6 ± 2.2%; severe (33.3% of cases) consisting in loss of cerebral protection, CT-score ≥ 13, mean BFR% = 54.2 ± 3.9%. Females had higher BFR% than males (p = 0.022). BFR classes and new reconstructive surgery were not related (p = 0.58).

CONCLUSIONS

BFR was moderate or severe in 85.2% of re-implanted cryopreserved flaps. The proposed CT-score is an easy and reproducible tool to define resorption extent.

Factors related to failure of autologous cranial reconstructions after decompressive craniectomy

PURPOSE

Cranioplasty is customary after decompressive craniectomy. Many different materials have been developed and used for this procedure. The ideal material does not yet exist, while complication rates in cranioplasties remain high. This study aimed to determine factors related to autologous bone flap failure.

MATERIALS AND METHODS

In this two-center retrospective cohort study, 276 patients underwent autologous bone cranioplasty after initial decompressive craniectomy between 2004 and 2014. Medical records were reviewed regarding patient characteristics and factors potentially related to bone flap failure. Data were analyzed using univariable and multivariable regression analysis.

RESULTS

Independent factors related to overall bone flap failure were: duration of hospitalization after decompressive craniectomy [OR: 1.012 (95%CI: 1.003-1.022); p = 0.012], time interval between decompressive craniectomy and cranioplasty [OR: 1.018 (95%CI: 1.004-1.032); p = 0.013], and follow-up duration [OR: 1.034 (95%CI: 1.020-1.047); p < 0.001]. In patients with bone flap infection, neoplasm as initial diagnosis occurred significantly more often (29.2% vs. 7.8%; RD 21.3%; 95%CI 8.4 -38.3%; NNH 5; 95%CI 3 -12) and duration of hospitalization after decompressive craniectomy tended to be longer (means 54 vs. 28 days, MD 26.2 days, 95%CI -8.6 to 60.9 days). Patients with bone flap resorption were significantly younger (35 vs. 43 years, MD 7.7 years, 95%CI 0.8-14.6 years) and their cranial defect size tended to be wider than in patients without bone flap resorption (mean circumference 39 vs. 37 cm; MD 2.4 cm, 95% CI -0.43-5.2 cm) and follow-up duration was significantly longer (44 vs. 14 months, MD 29 months, 95%CI 17-42 months).

CONCLUSION

A neoplasm as initial diagnosis, longer hospitalization after decompressive craniectomy, larger time interval between decompressive craniectomy and cranioplasty, and longer follow-up duration are associated with a higher risk of failure of autologous bone flaps for cranioplasty. Patients with these risk factors may be better served with an early recovery program after decompressive surgery or an alloplastic material for cranioplasty.

Pediatric Cranioplasty

Historically, the approach to pediatric cranioplasty has been largely extrapolated from the treatment of adults. More recently, however, the intricacies of pediatric cranial reconstruction have become better understood, and the surgical management has been refined contemporaneously. Each patient's cranial defect bears a unique set of challenges and, as such, the choice of cranioplasty technique must be tailored accordingly.

Defining "early" cranioplasty to achieve lower complication rates of bone flap failure: resorption and infection

BACKGROUND

Although cranioplasty (CP) is a frequently performed and simple procedure, complications are common, particularly bone flap resorption and infection. The timing of surgery is as an important contributory factor, but the optimal timing has not been clearly determined.

OBJECTIVE

We retrospectively investigated bone flap resorption and surgical site infection after CP to determine the optimal timing of surgery for reduction of complications.

METHODS

The study enrolled 126 patients who underwent decompressive craniectomy (DC) and subsequent CP. Patients with bone flap resorption or surgical site infection were analyzed as the "complication" group. Receiver operating characteristic curve analysis was performed and the Youden index was used to dichotomize "early CP" and "late CP" groups. Univariate and multivariate survival analyses were performed.

RESULTS

The complication group included 42 patients. The Youden index was used to identify a cutoff value for the DC-CP interval of > 44 days, and this was used to define early (< 45 days) and late (≥ 45 days) CP. Late CP was a significant risk factor in univariate and multivariate Cox regression analyses.

CONCLUSION

This study showed that early CP before 45 days after DC is associated with a lower rate of bone flap resorption and surgical site infection than late CP.

Patient-Specific Titanium-Reinforced Calcium Phosphate Implant for the Repair and Healing of Complex Cranial Defects

BACKGROUND

The reconstruction of complex cranial defects is challenging and is associated with a high complication rate. The development of a patient-specific, titanium-reinforced, calcium phosphate-based (CaP-Ti) implant with bone regenerative properties has previously been described in 2 case studies with the hypothesis that the implant may improve clinical outcome.

OBJECTIVE

To identify whether the introduction of CaP-Ti implant has the potential to improve clinical outcome.

METHODS

A retrospective review of all patients having undergone CaP-Ti cranioplasty was conducted. Comprehensive clinical data were collected from the hospital computer database and patient records. Bone formation and osseointegration were analyzed in a single retrieval specimen.

RESULTS

Fifty patients, with 52 cranial defects, met the inclusion criteria. The patient cohort displayed a previous failure rate of 64% (32/50) with autologous bone, alloplastic materials, or both. At a median follow-up time of 25 months, the explantation rate due to either early postoperative infection or persistent wound dehiscence was 1.9% (1/53) or 3.8% (2/53), respectively. Surgical intervention with local wound revision was required in 2 patients without the need of implant removal. One patient had a brain tumor recurrence, and the implant was explanted 31 months after implantation. Histologic examination showed that the entire implant was partly yet evenly transformed into vascularized compact bone.

CONCLUSION

In the present study the CaP-Ti implant appears to have improved the clinical outcomes in a cohort of patients with a high rate of previous cranioplasty failures. The bone regenerative effect may in particular have an impact on the long-term success rate of the implant.