Skull reconstruction after resection of bone tumors in a single surgical time by the association of the techniques of rapid prototyping and surgical navigation

Early experience with patient-specific low-cost 3D-printed polymethylmethacrylate cranioplasty implants in a lower-middle-income-country: Technical note and economic analysis

Background:

Polymethyl methacrylate (PMMA) cranioplasty, while widely prevalent, has limitations associated with freehand manual intraoperative molding. PMMA has been superseded by titanium or Polyetheretherketone implants, prefabricated commercially from preoperative CT scans, and boasting superior clinical and cosmetic outcomes. However, such services are extremely inaccessible and unaffordable in the lower-middle-income country (LMIC) settings. The study aims to describe, in detail, the process of making ultra-low-cost patient-specific PMMA cranioplasty implants with minimum resources using open-access software. We report the first such service from the public health-care system within Pakistan, a LMIC.

Methods:

Using open-source software, preoperative CT heads were used to prefabricate three-dimensional implants. Both implant and cranial defects were printed using polylactic acid (PLA) to assess the implant’s size and fit preoperatively. From the PLA implant, we fashioned a silicon mold that shapes the PMMA implant. Ten patients who underwent cranioplasty using our technique for various cranial defects with at least a 12-month follow-up were retrospectively reviewed. Clinical, cosmetic, and radiological outcomes were objectively assessed.

Results:

Etiology of injury was trauma (8), malignant MCA infarct (1), and arteriovenous fistula (1). We produced seven frontotemporal-parietal implants, one bifrontal, one frontal, and one frontoparietal. At 1 year, eight patients reported their cosmetic appearance comparable to before the defect. Radiological outcome was classified as “excellent” for eight patients. No postoperative complications were encountered, nor did any implant have to be removed. One patient’s implant involving the orbital ridge had an unsatisfactory cosmetic outcome and required revision surgery. The average cost per implant to the National Health Service was US$40.

Conclusion:

Prefabricated patient-specific PMMA cranioplasty implants are cost-effective. A single surgeon can fashion them in a limited resource setting and provide personalized medicine with excellent clinical/cosmetic-radiological results. Our method produces patient-specific cranioplasty implants in an otherwise unaffordable LMIC setting.

Feasibility of Customised Polymethyl Methacrylate Implants Fabricated Using 3D Printed Flexible Moulds for Correction of Facial Skeletal Deformities

INTRODUCTION

Use of patient specific Polymethyl methacrylate (PMMA) implants for the reconstruction of cranial defects has become a standard practice with excellent long-term results. However, for the reconstruction of midface and mandibular osseous defects other alloplastic materials are preferred but their use is limited due to high cost. This is a report of our experience with the use of low-cost patient specific PMMA implants fabricated using 3D printed moulds in the reconstruction of osseous defects involving different areas of the facial skeleton not limited to cranium.

METHODS

The 25 consecutive patients with craniofacial osseous defects who underwent reconstruction using customized PMMA implants were analyzed. All PMMA implants were fabricated intraoperatively with the use of 3D printed flexible moulds or templates.

RESULTS

A total of 34 implants were used in 25 consecutive patients. Out of 34 implants 25 were used for midface and mandibular osseous defects. Most common etiology was post-traumatic deformity (n = 19) followed by tumor (n = 3), craniofacial anomalies (n = 2) and post-craniotomy (n = 1). One patient out of 25 (n = 1) had postoperative implant exposure. The follow-up was ranged from 3 to 19 months with an average of 12 months. The aesthetic outcome was found to be good to excellent with mean visual analogue score of 4.08.

CONCLUSIONS

Polymethyl methacrylate implants fabricated intraoperatively using 3D printed moulds provide accurate and precise reconstruction at an exceptionally low cost. PMMA has an excellent moulding property with low infection rates. As shown in our study its application may be easily extended to all areas of the craniofacial skeleton.

Automated Implant Resizing for Single-Stage Cranioplasty

Patient-specific customized cranial implants (CCIs) are designed to fill the bony voids in the cranial and craniofacial skeleton. The current clinical approach during single-stage cranioplasty involves a surgeon modifying an oversized CCI to fit a patient's skull defect. The manual process, however, can be imprecise and time-consuming. This paper presents an automated surgical workflow with a robotic workstation for intraoperative CCI modification that provides higher resizing accuracy compared to the manual approach. We proposed a 2-scan method for intraoperative patient-to-CT registration using reattachable fiducial markers to address the registration issue caused by the clinical draping requirement. First, the draped defected skull was 3D scanned and registered to the CT space using our proposed 2-scan registration method. Next, our algorithm generates a robot cutting toolpath based on the 3D defect model. The robot then performs automatic 3D scanning to localize the implant and resizes the implant to match the cranial defect. We evaluated the implant resizing accuracy of the proposed paradigm against the resizing accuracy of the manual approach by an expert surgeon on two plastic skulls and two cadavers. The evaluation results showed that our system was able to decrease the bone gap distance by more than 60% and 30% on plastic skulls and cadavers respectively compared to the manual approach, indicating lower risk of post-surgical complication and better aesthetic restoration.

Using Cranial Sutures in a Single-Step Frame-Guided Resection and Reconstruction for Intraosseous Meningiomas: Technical Note

BACKGROUND

Single-stage surgical treatment of cranial intraosseous meningiomas includes complete tumor resection followed by aesthetic reconstruction. Tailored tumor resection with a computer-aided design/computer-aided manufacturing custom-made implant for the defect has been advocated in recent years to achieve a satisfactory cosmetic result with reduced operative time and fewer complications. However, several technical nuances related to the area of osseous removal may compromise cranioplasty.

METHODS

We present 2 cases of intraosseous meningiomas (sphenoid wing and retromastoid) to illustrate a step-by-step approach, from preoperative planning to single-step surgery.

RESULTS

For each case, a customized frame template delimiting bone removal was designed using cranial sutures as anatomical landmarks for precise placement of the cranioplasty template over the area of interest.

CONCLUSIONS

Custom templates based in cranial sutures may benefit single-step frame-guided resection and reconstruction of intraosseous tumors with compelling results.

Applications of 3D printing in breast cancer management

Three-dimensional (3D) printing is a method by which two-dimensional (2D) virtual data is converted to 3D objects by depositing various raw materials into successive layers. Even though the technology was invented almost 40 years ago, a rapid expansion in medical applications of 3D printing has only been observed in the last few years. 3D printing has been applied in almost every subspecialty of medicine for pre-surgical planning, production of patient-specific surgical devices, simulation, and training. While there are multiple review articles describing utilization of 3D printing in various disciplines, there is paucity of literature addressing applications of 3D printing in breast cancer management. Herein, we review the current applications of 3D printing in breast cancer management and discuss the potential impact on future practices.

Cranioplasty with three-dimensional customised mould for polymethylmethacrylate implant: a series of 16 consecutive patients with cost-effectiveness consideration

Background

Different methods of cranioplasty for the reconstruction of bony skull defects exist. In the absence of the autologous bone flap, a customised manufactured implant may be the optimal choice, but this implant has several limitations regarding its technical standardisation and better cost-effectiveness.

Methods

This study presents a series of 16 consecutive patients who had undergone cranioplasty with customised three-dimensional (3D) template moulds for polymethylmethacrylate (PMMA) implants manufactured after 3D modelling on a specific workstation. The virtual images were transformed into a two-piece physical model using a 3D printer for the biomaterials. PMMA implant was produced intraoperatively with the custom mould. Cosmetic results were analysed by comparing pre- and postoperative 3D computed tomography (CT) images and asking if the patient was satisfied with the result.

Results

The average total time for planning and production of customised mould was 10 days. The 16 patients were satisfied with the result, and CT images presented harmonious symmetry when comparing pre- and postoperative scans. Cases of postoperative infection, bleeding, or reoperation in this series were not observed.

Conclusion

Cranioplasty with high-technology customised 3D moulds for PMMA implants can allow for an aesthetic reconstruction with a fast and cost-effective manufacturing process and possibly with low complication rates.

Computer-assisted navigation in orbitofacial surgery

The purpose of this systematic review is to investigate the most common indications, treatment, and outcomes of computer-assisted surgery (CAS) in ophthalmological practice. CAS has evolved over the years from a neurosurgical tool to maxillofacial as well as an instrument to orbitofacial surgeries. A detailed and organized scrutiny in relevant electronic databases, journals, and bibliographies of the cited articles was carried out. Clinical studies with a minimum of two study cases were included. Navigation surgery, posttraumatic orbital reconstruction, computer-assisted orbital surgery, image-guided orbital decompression, and optic canal decompression (OCD) were the areas of interest. The search generated 42 articles describing the use of navigation in facial surgery: 22 on orbital reconstructions, 5 related to lacrimal sac surgery, 4 on orbital decompression, 2 articles each on intraorbital foreign body and intraorbital tumors, 2 on faciomaxillary surgeries, 3 on cranial surgery, and 2 articles on navigation-guided OCD in traumatic optic neuropathy. In general, CAS is reported to be a useful tool for surgical planning, execution, evaluation, and research. The largest numbers of studies and patients were related to trauma. Treatment of complex orbital fractures was greatly improved by the use of CAS compared with empirically treated control groups. CAS seems to add a favourable potential to the surgical armamentarium. Planning details of the surgical approach in a three-dimensional virtual environment and execution with real-time guidance can help in considerable enhancement of precision. Financial investments and steep learning curve are the main hindrances to its popularity.

Radiological Society of North America (RSNA) 3D printing Special Interest Group (SIG): guidelines for medical 3D printing and appropriateness for clinical scenarios

Medical three-dimensional (3D) printing has expanded dramatically over the past three decades with growth in both facility adoption and the variety of medical applications. Consideration for each step required to create accurate 3D printed models from medical imaging data impacts patient care and management. In this paper, a writing group representing the Radiological Society of North America Special Interest Group on 3D Printing (SIG) provides recommendations that have been vetted and voted on by the SIG active membership. This body of work includes appropriate clinical use of anatomic models 3D printed for diagnostic use in the care of patients with specific medical conditions. The recommendations provide guidance for approaches and tools in medical 3D printing, from image acquisition, segmentation of the desired anatomy intended for 3D printing, creation of a 3D-printable model, and post-processing of 3D printed anatomic models for patient care.

Cranioplasty with a low-cost customized polymethylmethacrylate implant using a desktop 3D printer

OBJECTIVE

Cranioplasty implants should be widely available, low in cost, and customized or easy to mold during surgery. Although autologous bone remains the first choice for repair, it cannot always be used due to infection, fragmentation, bone resorption, or other causes, which led to use of synthetic alternatives. The most frequently used allogenic material for cranial reconstructions with long-term results is polymethylmethacrylate (PMMA). Three-dimensional printing technology has allowed the production of increasingly popular customized, prefabricated implants. The authors describe their method and experience with a customized PMMA prosthesis using a precise and reliable low-cost implant that can be customized at any institution with open-source or low-cost software and desktop 3D printers.

METHODS

A review of 22 consecutive patients undergoing CT-based, low-cost, customized PMMA cranioplasty over a 1-year period at a university teaching hospital was performed. Preoperative data included patient sex and age; CT modeling parameters, including the surface area of the implant (defect); reason for craniectomy; date(s) of injury and/or resections; the complexity of the defect; and associated comorbidities. Postoperative data included morbiditiy and complications, such as implant exposure, infection, hematoma, seroma, implant failure, and seizures; the cost of the implant; and cosmetic outcome.

RESULTS

Indications for the primary craniectomy were traumatic brain injury (16, 73%), tumor resection (3, 14%), infection (1, 4%), and vascular (2, 9%). The median interval between previous surgery and PMMA cranioplasty was 12 months. The operation time ranged from 90 to 150 minutes (mean 126 minutes). The average cranial defect measured 65.16 cm2 (range 29.31-131.06 cm2). During the recovery period, there was no sign of infection, implant rejection, or wound dehiscence, and none of the implants had to be removed over a follow-up ranging from 1 to 6 months. The aesthetic appearance of all patients was significantly improved, and the implant fit was excellent.

CONCLUSIONS

The use of a customized PMMA was associated with excellent patient, family, and surgeon satisfaction at follow-up at a fraction of the cost associated with commercially available implants. This technique could be an attractive option to all patients undergoing cranioplasty.