Complications of cranioplasty using a bone flap sterilised by autoclaving following decompressive craniectomy

Three-dimensional personalized porous polyethylen cranioplasty in patients at increased risk of surgical site infection

BACKGROUND

Surgical site infection (SSI) is the most consistently reported complication of cranioplasty. No material showed a categorical superiority in the incidence of infection. Porous polyethylene (PE) is considered a low risk material regarding SSI. However, the literature data are very limited. Thus, our objective was to verify the assumed low incidence of SSI after PE cranioplasty in patients at high risk of SSI. The primary objective was the infection rate, while secondary objectives were implant exposure, revision and cosmetic results.

METHOD

Patients who underwent three-dimensional (3D) personalized PE cranioplasty in the period 2014-2023 were evaluated prospectively. Only patients with an increased risk of SSI, and a satisfactory clinical conditions were included in the study.

RESULTS

Thirty procedures were performed in 30 patients. Cranioplasty was performed 23 times after hemispheric decompressive craniectomy, five times after limited size craniotomy and two times after bifrontal decompressive craniectomy. Risk factors for the development of infection were 18 previous SSIs, 16 previous repeated revision surgeries, four intraoperatively opened frontal sinuses and two times radiotherapy. Neither infection nor implant exposure was detected in any patient. All patients were satisfied with the aesthetic result. In two cases, a revision was performed due to postoperative epidural hematoma.

CONCLUSIONS

Three-dimensional personalized PE cranioplasty is associated with an extremely low incidence of SSI even in high-risk patients. However, our conclusions can only be confirmed in larger studies.

Excessive Heat Generation by Power-Driven Craniotomy Tools: A Possible Cause of Autologous Bone Flap Resorption Observed in an Ex Vivo Simulation

BACKGROUND

Bone flap resorption is an issue after autologous cranioplasty. Critical temperatures above 50°C generated by power-driven craniotomy tools may lead to thermal osteonecrosis, a possible factor in resorption. This ex vivo study examined whether the tools produced excessive heat resulting in bone flap resorption.

METHODS

Using swine scapulae maintained at body temperature, burr holes, straight and curved cuts, and wire-pass holes were made with power-driven craniotomy tools. Drilling was at the conventional feed rate (FR) plus irrigation (FR-I+), at a high FR plus irrigation (hFR-I+), and at high FR without irrigation (hFR-I-). The temperature in each trial was recorded by an infrared thermographic camera.

RESULTS

With FR-I+, the maximum temperature at the burr holes, the cuts, and the wire-pass holes was 69.0°C, 56.7°C, and 46.2°C, respectively. With hFR-I+, these temperatures were 53.1°C, 52.1°C, and 46.0°C, with hFR-I- they were 56.0°C, 66.5°C, and 50.0°C; hFR-I- burr hole- and cutting procedures resulted in the highest incidence of bone temperatures above 50°C followed by FR-I+, and hFR-I+. At the site of wire-pass holes, only hFR-I- drilling produced this temperature.

CONCLUSIONS

Except during prolonged procedures in thick bones, most drilling with irrigation did not reach the critical temperature. Drilling without irrigation risked generating the critical temperature. Knowing those characteristics may be a help to perform craniotomy with less thermal bone damage.

The Reconstruction of Post-traumatic Cranial Bone Depression by Duplicating an Autogenous Bone Flap With a Prosthetic Polymethyl Methacrylate Cranial Stent

Cranioplasty is a common surgical procedure used to restore the shape of the calvaria. Autogenous bone flaps provide biological repair with the least morbidity to the donor location. One method for reusing bone autograft during cranioplasty involves low-temperature preservation followed by autoclaving. According to the literature, there was a good to modest improvement in the skull's symmetry, cosmesis, scars, and contour. It was determined that autoclaved frozen autogenous cerebral bone flaps are a safe and reliable method of cranioplasty. Despite its apparent simplicity, cranioplasty has been found to carry a relatively high complication rate, ranging from 12% to 50%, which starkly contrasts with the standard elective craniotomy, with a complication rate typically ranging from 24% to 60%. Complications associated with autogenous bone flap procedures are varied. The presented case report primarily focuses on the duplication of autogenous bone flaps by using clear polymethyl methacrylate.

Staged or simultaneous operations for ventriculoperitoneal shunt and cranioplasty: Evidence from a meta-analysis

OBJECTIVE

To date, there is no consensus on the surgery strategies of cranioplasty (CP) and ventriculoperitoneal shunt (VPS) placement. This meta-analysis aimed to investigate the safety of staged and simultaneous operation in patients with comorbid cranial defects with hydrocephalus to inform future surgery protocols.

METHODS

A meta-analysis of PubMed, Ovid, Web of Science, and Cochrane Library databases from the inception dates to February 8, 2023 adherent to PRISMA guidelines was conducted. The pooled analyses were conducted using RevMan 5.3 software. The outcomes included postoperative infection, reoperation, shunt obstruction, hematoma, and subdural effusion.

RESULTS

Of the 956 studies initially retrieved, 10 articles encompassing 515 patients were included. Among the total patients, 193 (37.48%) and 322 (62.52%), respectively, underwent simultaneous and staged surgeries. The finding of pooled analysis indicated that staged surgery was associated with lower rate of subdural effusion (14% in the simultaneous groups vs. 5.4% in the staged groups; OR = 2.39, 95% CI: 1.04-5.49, p = 0.04). However, there were no significant differences in overall infection (OR = 1.92, 95% CI: 0.74-4.97, p = 0.18), central nervous system infection (OR = 1.50, 95% CI: 0.68-3.31, p = 0.31), cranioplasty infection (OR = 1.58, 95% CI: 0.50-5.00, p = 0.44), shunt infection (OR = 1.30, 95% CI: 0.38-4.52, p = 0.67), reoperation (OR = 1.51, 95% CI: 0.38-6.00, p = 0.55), shunt obstruction (OR = 0.73, 95% CI: 0.25-2.16, p = 0.57), epidural hematoma (OR = 2.20, 95% CI: 0.62-7.86, p = 0.22), subdural hematoma (OR = 1.20, 95% CI: 0.10-14.19, p = 0.88), and intracranial hematoma (OR = 1.31, 95% CI: 0.42-4.07, p = 0.64). Moreover, subgroup analysis failed to yield new insights.

CONCLUSIONS

Staged surgery is associated with a lower rate of postoperative subdural effusion. However, from the evidence of sensitivity analysis, this result is not stable. Therefore, our conclusion should be viewed with caution, and neurosurgeons in practice should make individualized decisions based on each patient's condition and cerebrospinal fluid tap test.

Optimization and manufacture of polyetheretherketone patient specific cranial implants by material extrusion - A clinical perspective

Polyetheretherketone (PEEK) is a high performing thermoplastic that has established itself as a 'gold-standard' material for cranial reconstruction. Traditionally, milled PEEK patient specific cranial implants (PSCIs) exhibit uniform levels of smoothness (excusing suture/drainage holes) to the touch (<1 μm) and homogenous coloration throughout. They also demonstrate predictable and repeatable levels of mechanical performance, as they are machined from isotropic material blocks. The combination of such factors inspires confidence from the surgeon and in turn, approval for implantation. However, manufacturing lead-times and affiliated costs to fabricate a PSCI are high. To simplify their production and reduce expenditure, hospitals are exploring the production of in-house PEEK PSCIs by material extrusion-based additive manufacturing. From a geometrical and morphological perspective, such implants have been produced with good-to-satisfactory clinical results. However, lack of clinical adoption persists. To determine the reasoning behind this, it was necessary to assess the benefits and limitations of current printed PEEK PSCIs in order to establish the status quo. Afterwards, a review on individual PEEK printing variables was performed in order to identify a combination of parameters that could enhance the aesthetics and performance of the PSCIs to that of milled implants/cranial bone. The findings from this review could be used as a baseline to help standardize the production of PEEK PSCIs by material extrusion in the hospital.

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.

Cryopreservation of autologous bone flaps following decompressive craniectomy: A new method reduced positive cultures without increase in post-cranioplasty infection rate

Introduction

Cranioplasty (CP) after decompressive craniectomy (DC) is a common neurosurgical procedure. Implementation of European Union (EU) directives recommending bacterial cultures before cryopreservation, lead to increased number of autologous bone flaps being discarded due to positive cultures. A new method for handling bone flaps prior to cryopreservation, including the use of pulsed lavage, was developed.

Research question

The aim was to evaluate the effect of a new method on proportion of positive bacterial cultures and surgical site infection (SSI) following CP surgery.

Material and methods

Sixty-one bone flaps from 53 consecutive DC surgery patients were retrospectively included and the study period was divided into before and after method implementation. Patient demographics, laboratory and culture results, type of CP and occurrence of SSI were analyzed.

Results

Twenty-six and 18 bone flaps were available for analysis during the first and second period, respectively. The proportion of positive bacterial cultures was higher in the first period compared to the second (n ​= ​9(35%) vs 0(0%); p ​= ​0.001), and thus the use of custom made implants was considerably higher in the first study period (p ​= ​0.001). There was no difference in the frequency of post-cranioplasty SSI between the first and second study period (n ​= ​3 (11.5%) vs 1 (4.8%), p ​= ​0.408).

Discussion and conclusion

The new method for handling bone flaps resulted in a lower frequency of positive bacterial cultures, without increased frequency of post-cranioplasty SSI, thus demonstrating it is safe to use, allows compliance with the EU-directives, and may reduce unnecessary discarding of bone flaps.

•

New method of bone flap handling and preservation reduced positive bacterial cultures from 35% to 0%.

•

The new method used pulsed lavage of bone flap with saline solution and subsequent swab culture.

•

There was no increase in post-cranioplasty surgical site infection following introduction of the new method.

Two-center validation of the Oulu resorption score for bone flap resorption after autologous cranioplasty

OBJECTIVE

Autologous bone has been the gold standard of cranioplasty materials for decades. Unique to autologous cranioplasty, bone flap resorption is a poorly understood and unclearly defined complication. Even further, it has been unclear, whether the resorption process eventually stabilizes over time. Thus, the sufficient follow-up period after autologous cranioplasty is unknown. The Oulu Resorption Score (ORS) is a straight-forward classification system for the radiological interpretation of bone flap resorption. The aims of the present study were to evaluate the reliability of the ORS using intra-class correlation coefficient (ICC) and to assess the temporal progression of the resorption process.

METHODS

We identified 108 consecutive autologous cranioplasty patients treated between 2005 and 2018 in two tertiary referral centers. All 365 head CT scans the patients had undergone were evaluated using the ORS in a blinded, independent two-center setting. Intra- and inter-observer reliabilities were calculated. The ORS was applied to study the temporal progression of the resorption process.

RESULTS

The intra-observer reliability of the ORS was excellent (ICC 0.94, 95%CI 0.93-0.95). Inter-observer reliability was good-to-excellent (ICCs 0.87 and 0.89, 95%CIs 0.84-0.89 and 0.87-0.91, respectively). In scatterplot smoothing analyses, the progression of bone flap resorption appeared to stabilize 12-24 months after cranioplasty.

CONCLUSIONS

ORS is the only validated radiological tool for the standardized analysis of bone flap resorption after autologous cranioplasty. Evaluated using the ORS, the resorption process seemed to stabilize during the first two postoperative years after cranioplasty, suggesting that the sufficient follow-up time after autologous cranioplasty is two years.

Split-Thickness Decompression in the Management of Intracranial Pressure

Surgical management of elevated intracranial pressures due to stroke or traumatic brain injury has classically been through decompressive craniectomy (DC). There is significant morbidity associated with DC including subdural hygromas, syndrome of the trephined, and the need for subsequent cranioplasty. Alternative techniques including the hinged and floating craniotomy have shown promise though can still suffer from complications associated with an unsecured bone flap. We report a case in which a patient who presented with an acute subdural hematoma and associated midline shift that was successfully treated with decompression via thinning and re-securing of the bone flap in a “split-thickness decompression.”

Complications Following Decompressive Craniectomy

BACKGROUND

 Decompressive craniectomy (DC) has become the definitive surgical procedure to manage a medically intractable rise in intracranial pressure. DC is a life-saving procedure resulting in lower mortality but also higher rates of severe disability. Although technically straightforward, DC is accompanied by many complications. It has been reported that complications are associated with worse outcome. We reviewed a series of patients who underwent DC at our department to establish the incidence and types of complications.

METHODS

 We retrospectively evaluated the incidence of complications after DC performed in 135 patients during the time period from January 2013 to December 2018. Postoperative complications were evaluated using clinical status and CT during 6 months of follow-up. In addition, the impact of potential risk factors on the incidence of complications and the impact of complications on outcome were assessed.

RESULTS

 DC was performed in 135 patients, 93 of these for trauma, 22 for subarachnoid hemorrhage, 13 for malignant middle cerebral artery infarction, and 7 for intracerebral hemorrhage. Primary DC was performed in 120 patients and secondary DC in 15 patients. At least 1 complication occurred in each of 100 patients (74%), of which 22 patients (22%) were treated surgically. The following complications were found: edema or hematoma of the temporal muscle (34 times), extracerebral hematoma (33 times), extra-axial fluid collection (31 times), hemorrhagic progression of contusions (19 times), hydrocephalus (12 times), intraoperative malignant brain edema (10 times), temporal muscle atrophy (7 times), significant intraoperative blood loss (6 times), epileptic seizures (5 times), and skin necrosis (4 times). Trauma (p = 0.0006), coagulopathy (p = 0.0099), and primary DC (p = 0.0252) were identified as risk factors for complications. There was no significant impact of complications on outcome.

CONCLUSIONS

 The incidence of complications following DC is high. However, we did not confirm a significant impact of complications on outcome. We emphasize that some phenomena are so frequent that they can be considered a consequence of primary injury or natural sequelae of the DC rather than its direct complication.

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.

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.

ACE-inhibitors: a preventive measure for bone flap resorption after autologous cranioplasty?

OBJECTIVE

Decompressive craniectomy (DC) is an established treatment for refractory intracranial hypertension. It is usually followed by autologous cranioplasty (AC), the reinsertion of a patient's explanted bone flap. A frequent long-term complication of AC is bone flap resorption (BFR), which results in disfigurement as well as loss of the protective covering of the brain. This study investigates risk factors for BFR after AC, including medical conditions and antihypertensive drug therapies, with a focus on angiotensin-converting enzyme inhibitors (ACEIs), which have been associated with a beneficial effect on bone healing and bone preservation in orthopedic, osteoporosis, and endocrinology research.

METHODS

In this single-center, retrospective study 183 consecutive cases were evaluated for bone flap resorption after AC. Information on patient demographics, medical conditions, antihypertensive therapy, and BFR-defined as an indication for revision surgery established by a neurosurgeon based on clinical or radiographic assessments-was collected. A Kaplan-Meier analysis of time from AC to diagnosis of BFR was performed, and factors associated with BFR were investigated using the log-rank test and Cox regression.

RESULTS

A total of 158 patients were considered eligible for inclusion in the data analysis. The median follow-up time for this group was 2.2 years (95% CI 1.9-2.5 years). BFR occurred in 47 patients (29.7%), with a median time to event of 3.7 years (95% CI 3.3-4.1 years). An ACEI prescription was recorded in 57 cases (36.1%). Univariate Kaplan-Meier analysis and the log-rank test revealed that ACEI therapy (2-year event free probability [EFP] 83.8% ± 6.1% standard error vs 63.9% ± 5.6%, p = 0.02) and ventriculoperitoneal (VP) shunt treatment (2-year EFP 86.9% ± 7.1% vs 66% ± 5.0%, p = 0.024) were associated with a lower probability of BFR. Multiple Cox regression analysis showed ACEI therapy (HR 0.29, p = 0.012), VP shunt treatment (HR 0.278, p = 0.009), and male sex (HR 0.500, p = 0.040) to be associated with a lower risk for BFR, whereas bone fragmentation (HR 1.92, p = 0.031) was associated with a higher risk for BFR.

CONCLUSIONS

Hypertensive patients treated with ACEIs demonstrate a lower rate of BFR than patients treated with other hypertensive medications and nonhypertensive patients. Our results are in line with previous reports on the positive influence of ACEIs on bone healing and preservation. Further analysis of the association between ACEI treatment and BFR development is needed and will be evaluated in a multicenter prospective trial.

Is Three-Dimensional Virtual Planning in Cranial Reconstruction for Advanced Cutaneous Squamous Cell Carcinoma of the Skull a Feasible Option?

BACKGROUND

Cutaneous squamous cell carcinoma (cSCC) is a common type of malignant skin disorder. An uncommon feature is local bony invasion, as can rarely be seen in lesions on the scalp. The optimal treatment strategy in these rare cases is still under debate.

OBJECTIVE

The aim of this case report is to present a 1-stage three-dimensional planned surgical resection and reconstruction of a cSCC with bony invasion into the scalp and to discuss the alternative options and potential pitfalls.

MATERIALS AND METHODS

A patient diagnosed with rT4N0M0 cSCC of the scalp underwent a cranial resection and reconstruction in 1 stage. With the use of computer-assisted design and computer-assisted manufacturing a patient-specific implant (PSI) of poly (ether ether ketone) was manufactured. After the PSI was inserted, it was covered with a latissimus dorsi muscle and a split-thickness skin graft.

RESULTS

Intraoperatively the resection template generated an accurate resection and accurate and fast placement of the PSI. The reconstruction had a clinical satisfactory esthetic result, but was hampered by the development of a small wound dehiscence was observed over the postoperative course.

CONCLUSION

Three-dimensional planned resection and reconstruction for composite defects of the skull after resection of a cSCC of the scalp with bony invasion may lead to an accurate and predictable resection and accurate and fast placement of the PSI. However, patient specific characteristics should be considered to assess potential risks and benefits before opting for this one-stage treatment strategy.

Cranioplasty Using Autoclaved Autologous Skull Bone Flaps Preserved at Ambient Temperature

Context

Decompressive craniectomy followed by cranioplasty (CP) uses autologous craniectomy flaps or synthetic materials like titanium. Sterilization and preservation methods for the autologous bone flaps continue to be the surgeon's choice.

Aim

This study aimed to assess the short-term as well as long-term clinical outcomes of CP using autoclaved autologous bone grafts.

Settings and Design

This retrospective observational study was performed on patients admitted in a tertiary care teaching neurosurgery department.

Patients and Methods

Seventy-two patients who underwent CP with autoclaved autologous skull flaps preserved under ambient conditions with strict aseptic precautions were included in the study.

Statistical Analysis Used

Frequencies and percentages of the various characteristics before and after the surgery were tabulated. Continuous variables were summarized as means and standard deviations.

Results

The primary CP had a satisfactory clinical outcome in 62 cases (86.11%). Osteomyelitis was observed in four patients (5.56%) nearly 2 months after the surgery. Radiologically significant bone resorption was noted in a single patient (1.39%) after 1 year. Five patients (6.94%) developed bone fragmentation or fracture, and the mean time taken for this was about 36 months. In all these ten cases, secondary CP was successfully done using a prefabricated, patient-specific titanium mesh.

Conclusions

The efficacy and safety of the studied craniectomy flaps used for cranial reconstruction showed a good patient outcome. Further retrospective studies with larger cohorts and prospective case-control studies are essential so as to issue standard guidelines for sterilization and preservation of autologous bone flaps.

Risk factors for surgical site infection after craniotomy: a prospective cohort study

Background

Although surgical site infection after craniotomy (SSI-CRAN) is a serious complication, risk factors for its development have not been well defined. We aim to identify the risk factors for developing SSI-CRAN in a large prospective cohort of adult patients undergoing craniotomy.

Methods

A series of consecutive patients who underwent craniotomy at a university hospital from January 2013 to December 2015 were prospectively assessed. Demographic, epidemiological, surgical, clinical and microbiological data were collected. Patients were followed up in an active post-discharge surveillance programm e for up to one year after surgery. Multivariate analysis was carried out to identify independent risk factors for SSI-CRAN.

Results

Among the 595 patients who underwent craniotomy, 91 (15.3%) episodes of SSI-CRAN were recorded, 67 (73.6%) of which were organ/space. Baseline demographic characteristics were similar among patients who developed SSI-CRAN and those who did not. The most frequent causative Gram-positive organisms were Cutibacterium acnes (23.1%) and Staphylococcus epidermidis (23.1%), whereas Enterobacter cloacae (12.1%) was the most commonly isolated Gram-negative agent. In the univariate analysis the factors associated with SSI-CRAN were ASA score > 2 (48.4% vs. 35.5% in SSI-CRAN and no SSI-CRAN respectively, p = 0.025), extrinsic tumour (28.6% vs. 19.2%, p = 0.05), and re-intervention (4.4% vs. 1.4%, p = < 0.001). In the multivariate analysis, ASA score > 2 (AOR: 2.26, 95% CI: 1.32-3.87; p = .003) and re-intervention (OR: 8.93, 95% CI: 5.33-14.96; p < 0.001) were the only factors independently associated with SSI-CRAN.

Conclusion

The risk factors and causative agents of SSI-CRAN identified in this study should be considered in the design of preventive strategies aimed to reduce the incidence of this serious complication.

Predictors of primary autograft cranioplasty survival and resorption after craniectomy

OBJECTIVE

Craniectomy is a common neurosurgical procedure that reduces intracranial pressure, but survival necessitates cranioplasty at a later stage, after recovery from the primary insult. Complications such as infection and resorption of the autologous bone flap are common. The risk factors for complications and subsequent bone flap removal are unclear. The aim of this multicenter, retrospective study was to evaluate the factors affecting the outcome of primary autologous cranioplasty, with special emphasis on bone flap resorption.

METHODS

The authors identified all patients who underwent primary autologous cranioplasty at 3 tertiary-level university hospitals between 2002 and 2015. Patients underwent follow-up until bone flap removal, death, or December 31, 2015.

RESULTS

The cohort comprised 207 patients with a mean follow-up period of 3.7 years (SD 2.7 years). The overall complication rate was 39.6% (82/207), the bone flap removal rate was 19.3% (40/207), and 11 patients (5.3%) died during the follow-up period. Smoking (OR 3.23, 95% CI 1.50-6.95; p = 0.003) and age younger than 45 years (OR 2.29, 95% CI 1.07-4.89; p = 0.032) were found to independently predict subsequent autograft removal, while age younger than 30 years was found to independently predict clinically relevant bone flap resorption (OR 4.59, 95% CI 1.15-18.34; p = 0.03). The interval between craniectomy and cranioplasty was not found to predict either bone flap removal or resorption.

CONCLUSIONS

In this large, multicenter cohort of patients with autologous cranioplasty, smoking and younger age predicted complications leading to bone flap removal. Very young age predicted bone flap resorption. The authors recommend that physicians extensively inform their patients of the pronounced risks of smoking before cranioplasty.

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.

Epidural multi-slitted microporous non-absorbable patch in decompressive craniectomy to facilitate cranioplasty: a preliminary study

Developing a surgical plane between the temporalis muscle and the dura is the most technically challenging step when performing cranioplasty for post-decompressive craniectomy defects. The authors report a simple technique to demarcate this surgical plane by laying a multi-slitted, microporous polyesterurethane (MPU) patch during decompressive craniectomy. Specifically, they tried to avoid creating potential spaces around the patch, which is the inherent drawback of published anti-adhesive techniques. In 21 patients undergoing decompressive craniectomy, and in 11 of them subsequently undergoing cranioplasty, there was no wound related complications. During cranioplasty, no epidural fluid collection was found; the patch could be separated from the temporalis muscle and the dura with blunt dissection leaving the muscle intact. They conclude that their epidural MPU patch technique is a safe technique, and appears useful to facilitate cranioplasty by helping the surgeon in developing the surgical plane between the temporalis muscle and the dura during cranioplasty.

Autogenous Bone Reconstruction of Large Secondary Skull Defects

BACKGROUND

The authors sought to ascertain the upper limits of secondary skull defect size amenable to autogenous reconstructions and to examine outcomes of a surgical series. Published data for autogenous and alloplastic skull reconstructions were also examined to explore associations that might guide treatment.

METHODS

A retrospective review of autogenously reconstructed secondary skull defects was undertaken. A structured literature review was also performed to assess potential differences in reported outcomes between autogenous bone and synthetic alloplastic skull reconstructions. Weighted risks were calculated for statistical testing.

RESULTS

Ninety-six patients underwent autogenous skull reconstruction for an average defect size of 93 cm (range, 4 to 506 cm) at a mean age of 12.9 years. The mean operative time was 3.4 hours, 2 percent required allogeneic blood transfusions, and the average length of stay was less than 3 days. The mean length of follow-up was 28 months. There were no postoperative infections requiring surgery, but one patient underwent secondary grafting for partial bone resorption. An analysis of 34 studies revealed that complications, infections, and reoperations were more commonly reported with alloplastic than with autogenous reconstructions (relative risk, 1.57, 4.8, and 1.48, respectively).

CONCLUSIONS

Autogenous reconstructions are feasible, with minimal associated morbidity, for patients with skull defect sizes as large as 500 cm. A structured literature review suggests that autogenous bone reconstructions are associated with lower reported infection, complication, and reoperation rates compared with synthetic alloplasts. Based on these findings, surgeons might consider using autogenous reconstructions even for larger skull defects.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

Complications of skull reconstruction after decompressive craniectomy

INTRODUCTION

Decompressive craniectomy can be a life-saving procedure. Later reconstruction of the skull using the stored bone flap ("cranioplasty") is often associated with complications. These complications require new procedures and often result in the reconstruction of the skull using an expensive patient-specific cranial implant.

PATIENTS & METHODS

All adult patients who underwent cranioplasty after decompressive craniectomy in the last 10 years in our center were included (74 patients). Bone flap size, duration of the procedure, age, and other clinical parameters were included in our analysis.

RESULTS

29.7% of our patients who received in the first place an autologous cranioplasty developed a complication which necessitated removal of the bone flap and the implantation of a custom-made implant. Descriptive statistics demonstrate a significantly higher amount of complications in younger patients (20-40 years, p = 0.027). We also saw a trend toward lower complications when bone flaps were stored according to a biobank protocol (p = 0.075).

CONCLUSIONS

Cranioplasty using the stored bone flap after decompressive craniectomy is associated with a high percentage of complications. Selecting patients at risk could possibly indicate cases where an immediate custom-made implant technique would be required.

Comparison of Complications Following Cranioplasty Using a Sterilized Autologous Bone Flap or Polymethyl Methacrylate

Objective

The aims of current study are to compare complications following cranioplasty (CP) using either sterilized autologous bone or polymethyl methacrylate (PMMA), and to identify the risk factors for two of the most common complications: bone flap resorption (BFR) and surgical site infection (SSI).

Methods

Between January 2004 and December 2013, 127 patients underwent CP and were followed at least 12 months. Variables, including sex, age, initial diagnosis, time interval between decompressive craniectomy (DC) and CP, operation time, size of bone flap, and presence of ventriculo-peritoneal shunt, were analyzed to identify the risk factors for BFR and SSI.

Results

A total of 97 (76.4%) patients underwent CP using PMMA (Group I) and 30 (23.6%) underwent CP using autologous bone (Group II). SSI occurred in 8 (8.2%) patients in Group I, and in 2 (6.7%) in Group II; there was no statistically significant difference between the groups (p=1.00). No statistically significant risk factors for SSI were found in either group. In Group I, there was no reported case of BFR. In Group II patients, BFR developed in 18 (60.0%) patients at the time of CP (Type 1 BFR), and at 12-month follow up (Type 2 BFR) in 4 (13.3%) patients. No statistically significant risk factors for BFR were found in Group II.

Conclusion

CP using sterilized autologous bone result in a significant rate of BFR. PMMA, however, is a safe alloplastic material for CP, as it has low complication rate.

Patient-specific polymethylmethacrylate prostheses for secondary reconstruction of large calvarial defects: A retrospective feasibility study of a new intraoperative moulding device for cranioplasty

PURPOSE

The aim of this study was to review a new template-based technique for intraoperative patient-specific cranioplasty manufacturing (PSCM) with polymethylmethacrylate (PMMA) to cover large calvarial defects.

MATERIAL AND METHODS

A polypropylene foil thermoformed on a three-dimensional reprint of the calvarial defect was used as an intraoperative moulding device for PMMA between August 2012 and December 2015. Surgical and radiological data were retrospectively reviewed, and a patient questionnaire was used to assess functional and cosmetic outcome (numeric rating scale, Odom's criteria).

RESULTS

Seventeen patients (mean age 42.2 ± 14.5 years) received PSCM. Operating time averaged 130 ± 34 min, and the approximate blood loss was 293 ± 185 ml. Volumetric analysis revealed a lower implant volume compared to index bone (mean 66.5 vs. 72 cm³, p = 0.513), the mean difference in thickness being the lowest in the posterior parietal and pterional (0.4-0.7 mm) and the highest in the anterior-superior frontal area (1.8 mm). Cosmetic satisfaction averaged 9 ± 1.5, with 70.6% of patients judging the overall result as excellent or good and 29.4% as satisfactory. Mean follow-up was 19.5 ± 13.3 months, with an overall complication rate of 17.6%, including 11.8% surgical site infections (SSIs) and one implant removal.

CONCLUSIONS

Intraoperative PSCM using PMMA moulded on a thermoformed polypropylene foil leads to satisfactory outcomes. It is a safe technique with complication rates comparable but not superior to those of other alloplastic techniques, but the device has considerable production costs.

Complications After In Vivo and Ex Vivo Autologous Bone Flap Storage for Cranioplasty: A Comparative Analysis of the Literature

INTRODUCTION

The most common bone flap storage strategies after decompressive hemicraniectomy for malignant intracranial hypertension include freezer cryopreservation (CP) and subcutaneous abdominal implantation (AP). Numerous series have reported on patient outcomes after cranioplasty in terms of infection, cosmesis, and resorption. This meta-analysis compares published outcomes of bone flap CP and subcutaneous storage with respect to efficacy and complication risk in patients undergoing cranioplasty after hemicraniectomy.

METHODS

A systematic review was performed using PubMed-searchable studies that included bone flap storage methods and outcome data for cranioplasties performed between 1975 and 2015.

RESULTS

A total of 48 studies including 5346 patients were identified that met the inclusion criteria. Of these patients, 4096 underwent cranioplasty with an autologous flap. Mean bone flap storage times for CP and AP flaps were 69.9 and 69.7 days. Mean follow-up time for CP and AP flaps was 16.9 and 16.5 months. No statistically significant differences were found when comparing CP with subcutaneous storage of bone flaps with respect to percentage of patients developing infection (7.3% vs. 7.1%), percentage of patients needing revision surgery (15.9% vs. 7.6%), and percentage of patients experiencing resorption (9.7% vs. 7.7%).

CONCLUSIONS

This is the largest and most robust review comparing published outcomes of CP and subcutaneous storage of bone flaps in patients who have undergone decompressive hemicraniectomy. This review found no statistically significant differences in clinical outcomes (infection, resorption, reoperation) when comparing storage methods for bone flap preservation. This study suggests that both strategies may be used safely and successfully.

Low Incidence of Bone Flap Resorption After Native Bone Cranioplasty in Adults

OBJECTIVE

Cranioplasty via use of the patient's autologous bone is performed often after craniectomy procedures. Bone resorption remains a matter of concern in patients with native bone cranioplasty. The objective of this study was to evaluate the rate of native bone resorption in adults and review associated factors that may increase the risk of resorption.

METHODS

This is a single-center retrospective cohort study that assessed consecutive patients who had cranioplasty via use of the patient's native bone flap. A total of 114 patients were identified. Electronic medical records were reviewed for demographic and operative data.

RESULTS

The mean age was 51.2 years. The main indications for initial craniectomy included subarachnoid hemorrhage (SAH) in 50.9%, intracerebral hemorrhage in 17.5%, ischemic stroke in 14.9%, and trauma in 13.2% of patients. Mean interval between craniectomy and cranioplasty was 6 months. Mean follow-up after cranioplasty was 25 months. Bone resorption occurred in 3 patients (2.7%): at 6 months in a 30-year-old woman who presented with SAH followed by decompressive craniectomy and cranioplasty 3.5 months later; at 19 months in a 67-year-old female patient who presented with intracerebral hemorrhage followed by decompressive craniectomy and cranioplasty 6 months later; and at 9 months in a 50-year-old man who presented with SAH followed by craniectomy for clip ligation and cranioplasty 3 months later. Two of these patients underwent replacement of the native flap with synthetic material.

CONCLUSIONS

The rate of autologous bone flap resorption in adult patients undergoing cranioplasty is low even after a mean interval for cranioplasty of 6 months.

The Autoclaving of Autologous Bone is a Risk Factor for Surgical Site Infection After Cranioplasty

BACKGROUND

This retrospective study was designed to evaluate the effectiveness of autoclaving for the prevention of surgical site infection (SSI) after cranioplasty.

METHODS

Patients who underwent cranioplasty with autologous bone were enrolled. SSI was defined as an infection requiring bone flap removal. Risk factors of SSI, as reported by other researchers, and microbiologic features of SSI were analyzed. All bone flaps were preserved in a deep freezer (-70°C). Autoclaving of the preserved autologous bone flap before cranioplasty was performed for 5 minutes at 135°C in the 26 patients.

RESULTS

Eighty patients were enrolled. The mean age was 53.3 years and the male/female ratio was 3:2. Causes of craniectomy included trauma (n = 37) and nontrauma (n = 43). The mean time interval between craniectomy and cranioplasty was 49.7 days. The SSI rate after cranioplasty with autologous bone was 17.5% (n = 14). In univariate analysis, the cranioplasty operation time (P = 0.09) and the use of autoclaved bone (P = 0.00) were supposed to be risk factors for SSI. The use of autoclaved autologous bone was found to be the only risk factor of SSI (P = 0.01; hazard ratio = 8.88) in binary logistic regression analysis. Non-methicillin-resistant Staphylococcus aureus (MRSA) causes were more frequent in the autoclaved group (MRSA, 30%; non-MRSA, 70%) compared with the nonautoclaved group (MRSA, 100%) (P = 0.07). A microscopic examination showed that autoclaving after long-term cryopreservation may result in a loss of bone viability.

CONCLUSIONS

Autoclaving of autologous bone causes SSI after cranioplasty and it seems to increase the risk of non-MRSA infection by normal skin flora.

Analysis of Factors Contributing to Infections After Cranioplasty: A Single-Institution Retrospective Chart Review

OBJECTIVE

Cranioplasty is one of the most common neurosurgical procedures, yet has one of the greatest rates of infection among cranial operations. Although studies have reported on cranioplasty complications, it is unclear what factors contribute to the high rate of infection. This study aims to determine which patient characteristics and operative factors lead to postcranioplasty infections.

METHODS

This was a retrospective chart review of 186 patients. Factors analyzed included sex, reason for cranioplasty, type of infection, medical comorbidities, and surgical factors.

RESULTS

The overall infection rate was 24%. Skin flora was the most common pathogen. Wound dehiscence and presence of a postoperative fluid collection were associated significantly with a greater rate of infection (P < 0.001), whereas the use of autologous bone flap and a state of immunosuppression trended toward statistical significance (P = 0.075 and P = 0.089, respectively). Male sex, history of previous infection, history of craniectomy for trauma, cranioplasty size, and time to cranioplasty were not found to be significant factors related to cranioplasty infection.

CONCLUSIONS

Although wound dehiscence and postoperative fluid collections were associated significantly with infection in this study, the number in each sample size was small, and further studies with a larger number of patients in each subgroup is necessary to validate our findings.