Complications and cosmetic outcomes of materials used in cranioplasty following decompressive craniectomy-a systematic review, pairwise meta-analysis, and network meta-analysis

Complication rates after autologous cranioplasty following decompressive craniectomy

OBJECTIVE

The reimplantation of autologous bone grafts after decompressive craniectomy (DC) is still up for debate. The objective of this study was to analyze the surgical revision rate for autologous cranioplasties in our center, aiming to identify predictors for procedure-related-complications.

METHODS

A retrospective single-center study was conducted for adult patients who underwent autologous cranioplasty after DC. The primary endpoint was the complication rate in terms of surgical revision and removal of the bone graft: infection, new onset seizures, dislocation, haemorrhage, osteolysis, wound dehiscence and cerebrospinal fluid (CSF) fistula. Demographic data, medical records, surgical reports and imaging studies were analysed and risk factors for complications were evaluated.

RESULTS

169 consecutive patients were included. The median interval between DC and cranioplasty was 84 days. Mean age was 51 ± 12.4 years. 26 patients (15.3%) had revision surgery for following reasons. n = 9 implant dislocations (5.3%), n = 7 osteolysis (3.6%), n = 6 infections (3.6%), n = 5 had re-bleedings (3%), n = 5 wound dehiscences (3%), and n = 2 CSF fistulas (1.2%). 18 patients developed new seizures (10.7%). Bi- and multivariate analysis revealed three independent risk factors, simultaneous ventriculo-peritoneal (VP) shunting increased the risk for material dislocation (p < 0.001); large bone grafts (> 193.5 cm2) increased the risk for osteolysis (p = 0.001) and bifrontal cranioplasties were associated with higher risk for infections (p = 0.04).

CONCLUSION

The complication rates in our study were comparable to previously reported data for autologous or artificial cranioplasties. As osteolysis was correlated to larger bone grafts, a synthetic alternative should be considered in selected cases.

Free bone flap reconstruction in retrosigmoid approach for microvascular decompression: a comparative cohort study

Titanium plates and screws are common material used for rigid bone flap fixation after retrosigmoid craniotomy such as microvascular decompression (MVD). We conducted this study to evaluate outcomes of the free bone flap cranioplasty without fixation in MVD and compared its postoperative complication rate with routine methods. We retrospectively reviewed all patients who underwent MVD at our institution from May 2017 to August 2022. Patients were divided into two groups according to whether the bone flap was fixed or not. Follow-ups periods spanned 6-28 months after the operation. Of 189 patients who underwent MVDs via retrosigmoid approach, 79 cases (42%) had their bone flaps replaced without titanium fixation after craniotomies (< 3 cm x 3 cm). Compared to fixed bone flap group, free bone flap group had shorter operative time (105.56 ± 15.87 min vs. 113.72 ± 17.80 min, P = 0.001), less in-patient costs (¥23059.66 ± 4488.54 vs. ¥27714.82 ± 2705.74, P < 0.001), and less proportion of postoperative headache and incisional pain (43.0% vs. 60.9%, P = 0.015). One case of incisional cerebrospinal fluid leak happened in free bone flap group while one case of incisional infection happened in fixed bone flap group. No statistical difference in bone flap displacement, duration of postoperative hospital stays or complication rate was found between the two groups. Nineteen patients in free bone flap group received long-term CT follow-up and all were proved to have good skull union. This study proves that free bone flap cranioplasty in MVD without titanium plate fixation can shorten the operation time and reduce hospitalization expenditure without increasing complication rates.

Cranial stair-step incision for minimizing postoperative complications in neuro-oncologic surgery: A propensity score-matched analysis

PURPOSE

Craniotomies for tumor resection can at times result in wound complications which can be devastating in the treatment of neuro-oncological patients. A cranial stair-step technique was recently introduced as an approach to mitigate these complications, especially in this patient population who often exhibit additional risk factors including steroids, chemoradiation, and VEGF inhibitor treatments. This study evaluates our cranial stair-step approach by comparing its postoperative complications using propensity score matching with those of a standard craniotomy wound closure.

METHODS

A retrospective chart review was conducted on patients with intracranial neoplasms undergoing primary craniotomy at a single institution. Patients with prior craniotomies and less than three months of follow-up were excluded. Analyses were performed using R Studio.

RESULTS

383 patients were included in the study, 139 of whom underwent the stair-step technique while the rest underwent traditional craniotomy closures. The stair-step cohort was older, had higher ASA classes, and had a higher prevalence of coronary artery disease. The stair-step patients were administered fewer steroids before (40.29% vs. 56.56%, p < 0.01) and after surgery (87.05% vs. 94.26%, p = 0.02), fewer immunotherapy (12.95% vs. 20.90%, p = 0.05), but they received more radiation preoperatively (15.11% vs. 8.61%, p = 0.05). They also underwent fewer operations for recurrences and residuals (0.72% vs. 10.66%, p = 0.01). On propensity score matching, we found 111 matched pairs with no differences except follow-up duration (p < 0.01). The stair-step group had fewer soft tissue infections (0% vs. 3.60%, p = 0.04), fewer total wound complications (0% vs. 4.50%, p = 0.02), was operated on less for these complications (0% vs. 3.60%, p = 0.04), and had a shorter length of stay (6 vs. 9 days, p < 0.01). Notably, the average time to wound complication in our cohort was 44 days, well within our exclusion criteria and follow-up duration.

CONCLUSION

The cranial stair-step technique is safe and effective in reducing rates of wound complications and reoperation for neuro-oncologic patients requiring craniotomy.

Transcriptomic and cellular decoding of scaffolds-induced suture mesenchyme regeneration

Precise orchestration of cell fate determination underlies the success of scaffold-based skeletal regeneration. Despite extensive studies on mineralized parenchymal tissue rebuilding, regenerating and maintaining undifferentiated mesenchyme within calvarial bone remain very challenging with limited advances yet. Current knowledge has evidenced the indispensability of rebuilding suture mesenchymal stem cell niches to avoid severe brain or even systematic damage. But to date, the absence of promising therapeutic biomaterials/scaffolds remains. The reason lies in the shortage of fundamental knowledge and methodological evidence to understand the cellular fate regulations of scaffolds. To address these issues, in this study, we systematically investigated the cellular fate determinations and transcriptomic mechanisms by distinct types of commonly used calvarial scaffolds. Our data elucidated the natural processes without scaffold transplantation and demonstrated how different scaffolds altered in vivo cellular responses. A feasible scaffold, polylactic acid electrospinning membrane (PLA), was next identified to precisely control mesenchymal ingrowth and self-renewal to rebuild non-osteogenic suture-like tissue at the defect center, meanwhile supporting proper osteointegration with defect bony edges. Especially, transcriptome analysis and cellular mechanisms underlying the well-orchestrated cell fate determination of PLA were deciphered. This study for the first time cellularly decoded the fate regulations of scaffolds in suture-bony composite defect healing, offering clinicians potential choices for regenerating such complicated injuries.

Exploring complications following cranioplasty after decompressive hemicraniectomy: A retrospective bicenter assessment of autologous, PMMA and CAD implants

Cranioplasty (CP) after decompressive hemicraniectomy (DHC) is a common neurosurgical procedure with a high complication rate. The best material for the repair of large cranial defects is unclear. The aim of this study was to evaluate different implant materials regarding surgery related complications after CP. Type of materials include the autologous bone flap (ABF), polymethylmethacrylate (PMMA), calcium phosphate reinforced with titanium mesh (CaP-Ti), polyetheretherketone (PEEK) and hydroxyapatite (HA). A retrospective, descriptive, observational bicenter study was performed, medical data of all patients who underwent CP after DHC between January 1st, 2016 and December 31st, 2022 were analyzed. Follow-up was until December 31st, 2023. 139 consecutive patients with a median age of 54 years who received either PMMA (56/139; 40.3%), PEEK (35/139; 25.2%), CaP-Ti (21/139; 15.1%), ABF (25/139; 18.0%) or HA (2/139; 1.4%) cranial implant after DHC were included in the study. Median time from DHC to CP was 117 days and median follow-up period was 43 months. Surgical site infection was the most frequent surgery-related complication (13.7%; 19/139). PEEK implants were mostly affected (28.6%; 10/35), followed by ABF (20%; 5/25), CaP-Ti implants (9.5%; 2/21) and PMMA implants (1.7%, 1/56). Explantation was necessary for 9 PEEK implants (25.7%; 9/35), 6 ABFs (24.0%; 6/25), 3 CaP-Ti implants (14.3%; 3/21) and 4 PMMA implants (7.1%; 4/56). Besides infection, a postoperative hematoma was the most common cause. Median surgical time was 106 min, neither longer surgical time nor use of anticoagulation were significantly related to higher infection rates (p = 0.547; p = 0.152 respectively). Ventriculoperitoneal shunt implantation prior to CP was noted in 33.8% (47/139) and not significantly associated with surgical related complications. Perioperative lumbar drainage, due to bulging brain, inserted in 38 patients (27.3%; 38/139) before surgery was protective when it comes to explantation of the implant (p = 0.035). Based on our results, CP is still related to a relatively high number of infections and further complications. Implant material seems to have a high effect on postoperative infections, since surgical time, anticoagulation therapy and hydrocephalus did not show a statistically significant effect on postoperative complications in this study. PEEK implants and ABFs seem to possess higher risk of postoperative infection. More biocompatible implants such as CaP-Ti might be beneficial. Further, prospective studies are necessary to answer this question.

Comparison of Perioperative and Long-term Outcomes Following PEEK and Autologous Cranioplasty: A Single Institution Experience and Review of the Literature

OBJECTIVE

Three-dimensionally (3D) printed polyether-ether-ketone (PEEK) implants are a relatively novel option for cranioplasty that have recently gained popularity. However, there is ongoing debate with respect to material efficacy and safety compared to autologous bone grafts. The purpose of this study was to offer our institution's experience and add to the growing body of literature.

METHODS

A single-institution retrospective analysis of patients undergoing cranioplasties between 2016 and 2021. Patients were divided into PEEK and autologous cranioplasty cohorts. Parameters of interest included patient demographics as well as perioperative (<3 months postoperative) and long-term outcomes (>3 months postoperative). A P value < 0.05 was considered statistically significant.

RESULTS

A total of 31 patients met inclusion criteria (PEEK: 15, Autologous: 16). Mean age of total cohort was 48.9 years (range 19-82 years). Modified Frailty Index (mFI) revealed greater rate of comorbidities among the Autologous group (P = 0.073), which was accounted for in statistical analyses. Multiple logistic regression model revealed significantly higher rate of surgical site infection in the Autologous cohort (31.3% vs. 0%, P = 0.011). Minor complications were similar between groups, while the Autologous group experienced significantly more major postoperative complications (50%) versus PEEK (13.3%) (P = 0.0291). Otherwise perioperative and long term complication profiles were similar between groups. Additionally, generalized linear model demonstrated both cohorts had similar mean hospital length of stay (LoS) (Autologous: 16.1 vs. PEEK: 10.7 days).

CONCLUSIONS

PEEK cranioplasty implants may offer more favorable perioperative complication profiles with similar long-term complication rates and hospital LoS compared to autologous bone implants. Future studies are warranted to confirm our findings in larger series, and further examine the utility of PEEK in cranioplasty.

Explanted Skull Flaps after Decompressive Hemicraniectomy Demonstrate Relevant Bone Avitality-Is Their Reimplantation Worth the Risk?

BACKGROUND

Reimplantations of autologous skull flaps after decompressive hemicraniectomies (DHs) are associated with high rates of postoperative bone flap resorption (BFR). We histologically assessed the cell viability of explanted bone flaps in certain periods of time after DH, in order to conclude whether precursors of BRF may be developed during their storage.

METHODS

Skull bone flaps explanted during a DH between 2019 and 2020 were stored in a freezer at either -23 °C or -80 °C. After their thawing process, the skulls were collected. Parameters of bone metabolism, namely PTH1 and OPG, were analyzed via immunohistochemistry. H&E stain was used to assess the degree of avital bone tissue, whereas the repeated assays were performed after 6 months.

RESULTS

A total of 17 stored skull flaps (8 at -23 °C; 9 at -80 °C) were analyzed. The duration of cryopreservation varied between 2 and 17 months. A relevant degree of bone avitality was observed in all skull flaps, which significantly increased at the repeated evaluation after 6 months (p < 0.001). Preservation at -23 °C (p = 0.006) as well as longer storage times (p < 0.001) were identified as prognostic factors for higher rates of bone avitality in a linear mixed regression model.

CONCLUSIONS

Our novel finding shows a clear benefit from storage at -80° C, which should be carefully considered for the future management and storage of explanted skull flaps. Our analysis also further revealed a significant degree of bone avitality, a potential precursor of BFR, in skull flaps stored for several weeks. To this end, we should reconsider whether the reimplantation of autologous skull flaps instead of synthetic skull flaps is still justified.

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.

Bespoke Implants for Cranial Reconstructions: Preoperative to Postoperative Surgery Management System

Traumatic brain injury is a leading cause of death and disability worldwide, with nearly 90% of the deaths coming from low- and middle-income countries. Severe cases of brain injury often require a craniectomy, succeeded by cranioplasty surgery to restore the integrity of the skull for both cerebral protection and cosmetic purposes. The current paper proposes a study on developing and implementing an integrative surgery management system for cranial reconstructions using bespoke implants as an accessible and cost-effective solution. Bespoke cranial implants were designed for three patients and subsequent cranioplasties were performed. Overall dimensional accuracy was evaluated on all three axes and surface roughness was measured with a minimum value of 2.209 μm for Ra on the convex and concave surfaces of the 3D-printed prototype implants. Improvements in patient compliance and quality of life were reported in postoperative evaluations of all patients involved in the study. No complications were registered from both short-term and long-term monitoring. Material and processing costs were lower compared to a metal 3D-printed implants through the usage of readily available tools and materials, such as standardized and regulated bone cement materials, for the manufacturing of the final bespoke cranial implants. Intraoperative times were reduced through the pre-planning management stages, leading to a better implant fit and overall patient satisfaction.

The efficacy of platelet-rich plasma applicated in spinal fusion surgery: A meta-analysis

Objective

The purpose of this meta-analysis is to evaluate the effect of the application of platelet-rich plasma (PRP) in spinal fusion surgery on the fusion rate of the spine.

Methods

A comprehensive search of the PubMed, Embase, Cochrane Library, and Science Direct databases was conducted to identify randomized control trials (RCTs) or observational cohort studies that evaluated the efficacy and safety of PRP in spinal fusion. Data on final fusion rate, changes in the visual analog scale (VAS), estimated blood loss (EBL), and operative time was collected from the eligible studies for meta-analysis. Patients were divided into PRP and non-PRP groups according to whether PRP was used during the spinal fusion procedure.

Results

According to the selection criteria, 4 randomized controlled trials and 8 cohort studies with 833 patients and 918 levels were included. The outcomes indicated that PRP application is associated with a lower fusion rat (OR = 0.62, 95% CI: (0.43, 0.89), P = 0.009) at final follow-up (>24 months). Subgroup analysis showed a lower rate of spinal fusion in the PRP group compared to the non-PRP group (OR = 0.35, 95% CI: (0.21, 0.58), P < 0.001) when spinal fusion was assessed using only anterior-posterior radiographs. When the bone graft material was a combination of autologous bone + artificial bone, the spinal fusion rate was lower in the PRP group than in the non-PRP group (OR = 0.34, 95% CI: (0.16, 0.71), P = 0.004). The PRP and non-PRP groups showed no significant differences in VAS changes at the 24th postoperative month (WMD = 0.36, 95% CI: (−0.37, 1.09), P = 0.33); Application of PRP does not reduce the estimated blood loss (WMD = −86.03, 95% CI: (−188.23, 16.17), P = 0.10). In terms of operation time, using PRP does not prolong operation time (WMD = −3.74, 95% CI: (−20.53, 13.04), P = 0.66).

Conclusion

Compared with bone graft fusion alone, PRP cannot increase the rate of spinal fusion. Inappropriate methods of spinal fusion assessment or mixing PRP with artificial/allograft bone may have been responsible for the lower rate of spinal fusion in the PRP group.

Systematic Review Registration

doi: 10.37766/inplasy2022.5.0055