Annals of 3D printed medicine最新文献

Segmental defects affecting the continuity of the mandible have a profound impact on a patient's quality of life. Adequate reconstruction of such continuity defects is essential to restore aesthetics and function. While reconstruction using an autologous bone transplant supported by a stock reconstruction plate is the gold standard treatment, it has various drawbacks that can be attested to the plates’ off-the-shelf nature.

To mitigate these drawbacks, this study develops a patient-specific implant for the reconstruction of Brown class II defects with a high ramal osteotomy. The implant is intended to be additively manufactured in Ti6Al4V grade 23 ELI and features porous scaffold zones at the symphyseal and condylar sides which can induce bone ingrowth.

Finite element (FE) analyses were used to assess the implants’ performance in terms of failure, stability and stress shielding by simulating four clenching tasks. In addition, the implant was topologically optimized and re-evaluated.

The results showed that the implant experienced stress below its yield strength and fatigue limit. Relative micromotions between the implant and the bone indicated adequate stability to allow bone ingrowth to occur. Strains in the bone indicated limited stress shielding should occur between screw connections and around the osteotomy planes.

Finally, topological optimization reduced implant volume by 49% compared to the initial design, while FE analyses showed similar performance to the original design. The resulting implant is a promising first prototype that is numerically evaluated and can be optimized further in terms of fixation, surgical approach and dental restoration by in situ testing.

A novel 3D-printed glucose sensor is presented for cell culture application. Glucose sensing was performed using a fluorescence resonance energy transfer (FRET)-based assay principle based on ConA and dextran. Both molecules are encapsulated in alginate microspheres and embedded in the UV-curable, stable hydrogel polyvinyl alcohol (PVA). The rheology of the formulation was adapted to obtain good properties for an extrusion-based printing process. The printed sensor structures were tested for their ability to detect glucose in vitro. A proportional increase in fluorescence intensity was observed in a concentration range of 0 - 2 g/L glucose. Tests with HEK cell cultures also showed good cell compatibility and excellent adhesion properties on plasma-treated Petri dishes. The printed sensors were able to detect the glucose decay associated with the metabolic activities of the fast-growing HEK cells in the cell culture medium over ten days. The proof-of-principle study shows that metabolic processes in cell cultures can be monitored with the new printed sensor using a standard fluorescence wide-field microscope.

Background

Nasal bridles help prevent nasoenteric feeding tube dislodgement. If placed incorrectly, nasal bridles can cause injury, epistaxis, skin ulceration, or failure to prevent dislodgment. Training is frequently performed on patients, which can lead to discomfort or complications. To improve training prior to placing nasal bridles in patients, we utilized an anatomically accurate 3D printed simulator for nasal bridle placement training.

Methods

The model was modified from a nasopharyngeal swab simulator by BONE 3D, which was developed from imaging data through segmentation, computer-aided design, and 3D printing. Eighteen radiology residents and 3 medical students received a pre-test covering the anatomical knowledge and technique relevant to nasal bridle placement followed by a training session using the model. After training, participants provided feedback on the impact of training with the model on anatomical knowledge, hands-on skills, and confidence via a post-test using a 5-point Likert scale [from 1 (not beneficial/confident) to 5 (extremely beneficial/ confident)].

Results

Twenty participants completed both pre- and post-tests. The group performed significantly better on the post-test (4.8 ± 0.52) than the pre-test (2.6 ± 1.64), and the intervention demonstrated a large effect on knowledge (p < 0.0001; d = 1.82) and confidence level (p < 0.0001, d = 2.45) with mean magnitude of improvement of 2.3 out of 5 points. All respondents requested the 3D printed model be offered in formal training.

Conclusions

An anatomically accurate 3D printed model is a feasible and acceptable training aid with the potential to facilitate novice knowledge, proficiency, and confidence for nasal bridle placement.

The fibula free flap (FFF) surgery has long been used for complicated mandibular reconstruction. Virtual surgical planning (VSP) has been incorporated into the reconstruction planning by surgeons and has been found to reduce operating time and surgeon stress intraoperatively. When compared to traditional reconstruction, VSP enhances accuracy, surgical efficiency, and clinical outcomes. However, VSP on the other hand, need advanced technology such as software and 3D printing equipment, which are not always accessible in all centres. We describe our workflow on VSP reconstruction of the mandible with FFF by using open-source software.

Methods

Three patients underwent mandible reconstruction with FFF. VSP was used for all reconstruction planning.

Results

The mean operative time was min 765 minutes (range: 615 – 960 minutes), the mean ischemic time was 260 minutes (range: 120 – 355 minutes) and the mean length of stay was 10.7 days (range: 10 – 12 days). There were no flap failures. There were no major complications.

Conclusion

VSP is a very viable method that saves time and cost, making surgery more efficient.

Three dimensional (3D) bioprinting is a rapidly developing and emerging field in medicine and engineering. It allows for the production of three-dimensional structures that mimic body tissue function, which can be used in drug delivery and medical research such as cancer studies. In addition, bioprinting can provide patients with specific, controlled microstructures that mimic their natural geometries, increasing the rate of take-up with tissue implants and ongoing success. Towards that, a comprehensive review on the development of biomaterials, osseous tissues, bone and the vascular tissue bioprinting was conducted. These provide an insight into the latest research trends, difficulties, and understanding of the technologies used. Before implementation to replicate a human organ, there are variety of limitations to overcome together with the questions of ethics. Though bioprinting is still in its infancy period, it can play a vital role in tissue engineering in near future.

3D printing and its application in both medicine and increasingly in areas of forensic science exists today, however, evidence of its use and application in forensic medicine has been relatively understudied. There is currently no standard method of post mortem reconstruction techniques, especially in situations requiring replacement of skull fragments after trauma or structural repair of these regions after brain retrievals. Current methods can be time consuming and have been observed to lack structure and stability during movement of the deceased following autopsy. The present study investigated the use of 3D printed clips to reconstruct the cranial vault following brain removal. The aim of this new technique is to improve the efficiency of the reconstruction method and stability of the calvarium during reconstruction and post mortem transportation. The 3D printed clips are light weight, can be attached easily and efficiently and produce no observable external evidence of their presence on the patient.

Introduction

In orthognathic surgery, surgical splints made of polymethymethacrylate or its variants are used to position the jaws before osteofixation, and occasionally left in-situ for a short duration to guide the occlusion postoperatively. However, allergic reactions can be caused by unreacted dental resin (monomers). Computer aided design/Computer Aided Manufacturing (CADCAM) surgical splints are now more commonly used than the conventionally “handmade” splints. It is unclear if these splints contain uncured residual monomers in any detectable quantity.

Materials and methods

CADCAM surgical splints were made from 2 commonly used resins and compared with splints made manually with autopolymerising resin. The splints were immersed in saline at 37°C for 2 weeks to simulate use in the mouth, and the contents were analysed for uncured resin leaching with High Power Liquid Chromatography (HPLC) at different time intervals.

Results

Uncured resin content was higher in the conventionally made splint (15,246µg/L on Day 1, 13,539 µg/L on Day 7, and 6,203µg/L on Day 14). One of the CADCAM resins had undetectable monomer quantities, while the other CADCAM resin demonstrated significantly less free monomer compared to the autopolymerising resin (382 µg/L on Day 1, 179 µg/L on Day 7 and 65.2 µg/L on Day 14).

Conclusion

CADCAM surgical splints have much lower free monomer content compared to the conventionally made splint, and are safe for clinical use.

Dental rehabilitation is a major challenge for patients with severe jaw atrophy since the latter hinders the use of conventional dental implants. Virtual planning and CAD/CAM technologies have contributed to developing customized subperiosteal implants (IPS Implants® Pre-prosthetic, KLS Martin), which can be a safe and predictable treatment alternative in these cases. We present maxillary dental rehabilitation using custom subperiosteal implants in a 29-year-old patient with bilateral complete cleft lip and palate along with severe hard and soft tissue atrophy in the premaxilla following primary surgery. Customized subperiosteal implants are an alternative treatment option in cases where conventional dental implants are not possible or where bone augmentation procedures have failed or are not feasible. We therefore propose the use of these implants in patients with cleft lip and palate with complex bone defects.

Distal radius malunions are common complications in patients with distal radius fractures. There are several possible therapies; correction must be perfect in all three spatial planes. Planning and three-dimensional (3D) printing aid the surgeon in performing a customized, personalized dorsal-opening osteotomy to correct a distal radius malunion. We report the case of such a patient; surgery was assisted by 3D-printing of guides for correction of the distal radius malunion. The drilling and cutting guides allowed us to perform a standardized intervention, reducing the need for intraoperative fluoroscopy and eliminating all steps that usually require subjective decisions.