[Reconstruction of the cranial vault using CAD/CAM-fabricated glass bioceramic implants]

Cranial Reconstruction for Infiltrative Meningioma Using 68Ga-DOTATATE Positron Emission Tomography/Computed Tomography and Individual Patient Solutions CaseDesigner®: A Case Series

BACKGROUND AND OBJECTIVES

Meningioma with bone involvement presents challenges for complete resection and cranial reconstruction. 68Ga-dodecanetetreaacetic acid tyrosine-3-octreotide (DOTATATE) positron emission tomography (PET)/computed tomography (CT) has emerged as an excellent modality for localizing invasive meningiomas because of molecular interaction with somatostatin receptor-2. We present a novel technique to design 3-dimensional-printed artificial cranioplasty, using combined fine-slice CT, MRI, and 68Ga-DOTATATE PET/CT with Individual Patient Solutions (IPS) CaseDesigner® software. This study's objective was to generate proof-of-concept work for a novel artificial cranioplasty protocol that combines customized cranial implant software and DOTATATE PET/CT.

METHODS

Three patients with invasive bone meningiomas were retrospectively identified. For each patient, the proposed protocol combines CT, MRI, and 68Ga-DOTATATE PET/CT imaging to generate a 3-dimensional cranial reconstruction within the Karl Leibinger Surgical (KLS) Martin-IPS CaseDesigner® software. Subsequently, the virtual rendering is used to manufacture a customized polyetheretherketone (PEEK) implant, along with a guiding component, which ensures precise delineation of surgical borders before craniectomy. Finally, cranioplasty with the customized implant is performed using standard techniques.

RESULTS

The described preoperative cranioplasty design protocol was performed for each patient. Tumor invasion was visualized using 68Ga-DOTATATE PET/CT. Patient 1 presented with a recurrent right frontal meningioma with invasion into anterior skull base. In this case, IPS CaseDesigner® was used to create a mirror image PEEK implant for the left orbit and affected cranium. Patients 2 and 3 had intraosseous meningiomas invading the frontal bone; customized PEEK implants were tailored to the side of the planned craniectomy for both patients and were successfully placed without complication. Postoperatively, all patients remained neurologically intact and were discharged without complications. In all patients, the PEEK implants exhibited appropriate cranial continuity and integrity.

CONCLUSION

68Ga-DOTATATE PET/CT has high sensitivity and specificity for detecting meningiomas during preoperative planning, particularly when the tumor involves bone. IPS CaseDesigner® demonstrates excellent utility for planning and constructing customized cranioplasties tailored to each patient for skull reconstruction.

Customized alloplastic cranioplasty of large bone defects by 3D-printed prefabricated mold template after posttraumatic decompressive craniectomy: A technical note

Background

Manufacturing of customized three-dimensional (3D)-printed cranioplastic implant after decompressive craniectomy has been introduced to overcome the difficulties of intraoperative implant molding. The authors present and discuss the technique, which consists of the prefabrication of silicone implant mold using additive manufacturing, also known as 3D printing, and polymethyl methacrylate (PMMA) implant casting.

Methods

To reconstruct a large bone defect sustained after decompressive craniectomy due to traumatic brain injury (TBI), a 3D-printed prefabricated mold template was used to create a customized PMMA implant for cranial vault repair in five consecutive patients.

Results

A superb restoration of the symmetrical contours and curvature of the cranium was achieved in all patients. The outcome was clinically and cosmetically favorable in all of them.

Conclusion

Customized alloplastic cranioplasty using 3D-printed prefabricated mold for casting PMMA implant is easy to perform technique for the restoration of cranial vault after a decompressive craniectomy following moderate-to-severe TBI. It is a valuable and modern technique to advance manufacturing of personalized prefabricated cranioplastic implants used for the reconstruction of large skull defects having complex geometry. It is a safe and cost-effective procedure having an excellent cosmetic outcome, which may considerably decrease expenses and time needed for cranial reconstructive surgery.

[Modern aspects of reconstructive surgery of skull defects]

The aim of this study is to systematize the modern methods used for reconstruction of extensive and complex skull defects. Special attention is paid to computer technologies, including 3D imaging and CAD/CAM. Laser-based stereolithography is thoroughly reviewed among other additive technologies. We present our view of the problem associated with proper timing of cranioplasty and choice of materials for it. Complications of skull defect reconstruction are also discussed.

Evolution of cranioplasty techniques in neurosurgery: historical review, pediatric considerations, and current trends

Cranial bone repair is one of the oldest neurosurgical practices. Reconstructing the natural contours of the skull has challenged the ingenuity of surgeons from antiquity to the present day. Given the continuous improvement of neurosurgical and emergency care over the past century, more patients survive such head injuries, thus necessitating more than ever before a simple, safe, and durable means of correcting skull defects. In response, numerous techniques and materials have been devised as the art of cranioplasty has progressed. Although the goals of cranioplasty remain the same, the evolution of techniques and diversity of materials used serves as testimony to the complexity of this task. This paper highlights the evolution of these materials and techniques, with a particular focus on the implications for managing pediatric calvarial repair and emerging trends within the field.

Influence of laser light on bioimplants used in otorhinolaryngology

In otorhinolaryngology, dermatology and reconstructive surgery biomaterials as implants and a variety of lasers are used. Laser light applied near to an implant could have the risk to damage these materials. Therefore, their resistance exposed to laser light is of interest. A diode laser emitting at 940 nm and a CO2 laser were used to investigate its effects to the biomaterials Bioverit®, Medpor® and Palacos®, and in addition, an excised implant containing Medpor® and nasal turbinate tissue, excised and fixed in formalin. The macro- and microscopic changes of the material, temperature development during laser energy application in dependency to distance of fibre and material, time of exposure and applied power were investigated. Interaction of diode laser light with Bioverit® (0 mm distance, 360 s, 10 W, 3,600 J) resulted in minimal microscopic effects in direct contact of with the fibre. Using Medpor® (1 mm, 10s, 10 W, 100 J) resulted in melting and perforation. In the case of Palacos® (0.6 mm, 10s, 10 W, 100 J), melting occurred creating a flat excavation. The effect to Medpor® in nasal turbinate (1-2 mm, 10s, 10 W, 100 J) showed tissue denaturation and carbonisation and creation of a hole. The interaction of the CO2 laser with Bioverit® (3 cm, 0.5, 1 and 5 s, 2, 10 or 20 W) induced melting and discolouring resulting finally in a perforating hole. Depending on the material, first damage starts 10 s after an impact of 100 J (threshold value). So interaction between laser energy and biomaterials occurs. This should be carefully considered during clinical laser treatments especially nearby implants.

Prefabricated patient-matched cranial implants for reconstruction of large skull defects

Cranial defects can be caused by injury, infection, or tumor invasion. Large defects should be reconstructed to protect the brain and normalize the cerebral hemodynamics. The conventional method is to cover the defect with bone cement. Custom-made implants designed for the individual patient are now available. We report our experience with one such product in patients with large cranial defects (>7.6 cm in diameter). A CT scan with 2 mm slices and a three-dimensional reconstruction were obtained from the patient. This information was dispatched to the company and used as a template to form the implant. The cranial implant was received within four weeks. From 2005 to 2010, custom-made cranial implants were used in 13 patients with large cranial defects. In 10 of the 13 patients, secondary deep infection was the cause of the cranial defect. All the implants fitted well or very well to the defect. No infections were seen after implantation; however, one patient was reoperated on for an epidural hematoma. A custom-made cranial implant is considerably more expensive than an implant made of bone cement, but ensures that the defect is optimally covered. The use of custom-made implants is straightforward and timesaving, and they provide an excellent medical and cosmetic result.

Autologous bone flap versus hydroxyapatite prosthesis in first intention in secondary cranioplasty after decompressive craniectomy: a French medico-economical study

BACKGROUND AND PURPOSE

Decompressive craniectomy is the most common justification for cranioplasty. A medico-economial study based on the effective cost of the hydroxyapatite prosthesis, the percentage of autologous bone graft's loss due to bacterial contamination and the healthcare reimbursment, will allow us to define the best strategy in term of Healthcare economy management for the cranioplasties. A comparison was made between the two groups of patients, autologous bone flap versus custom-made prosthesis in first intention, based on the clinical experience of our department of neurosurgery.

RESULTS

No differences was shown between the two groups of patients, in terms of lenght of in-hospital stay and population's characteristics or medical codification. The mean cost of a cranioplasty using the autologous bone graft in first intention was €4045, while the use of hydroxyapatite prosthesis led to a cost of €8000 per cranioplasty.

CONCLUSION

In term of Healthcare expenses, autologous bone flap should be used in first intention for cranioplasties, unless the flap is contaminated or in specific indications, when the 3D custom-made hydroxyapatite prosthesis should be privilegied.

Customized cranioplasty implants using three-dimensional printers and polymethyl-methacrylate casting

Objective

The prefabrication of customized cranioplastic implants has been introduced to overcome the difficulties of intra-operative implant molding. The authors present a new technique, which consists of the prefabrication of implant molds using three-dimensional (3D) printers and polymethyl-methacrylate (PMMA) casting.

Methods

A total of 16 patients with large skull defects (>100 cm²) underwent cranioplasty between November 2009 and April 2011. For unilateral cranial defects, 3D images of the skull were obtained from preoperative axial 1-mm spiral computed tomography (CT) scans. The image of the implant was generated by a digital subtraction mirror-imaging process using the normal side of the cranium as a model. For bilateral cranial defects, precraniectomy routine spiral CT scan data were merged with postcraniectomy 3D CT images following a smoothing process. Prefabrication of the mold was performed by the 3D printer. Intraoperatively, the PMMA implant was created with the prefabricated mold, and fit into the cranial defect.

Results

The median operation time was 184.36±26.07 minutes. Postoperative CT scans showed excellent restoration of the symmetrical contours and curvature of the cranium in all cases. The median follow-up period was 23 months (range, 14-28 months). Postoperative infection was developed in one case (6.2%) who had an open wound defect previously.

Conclusion

Customized cranioplasty PMMA implants using 3D printer may be a useful technique for the reconstruction of various cranial defects.