Annals of 3D printed medicine最新文献

Since the 1980s, 3D printing has considerably broadened its field of application. Although only recently developed, there are now several techniques that allow the custom design of 3D objects. Plastic surgery, with its wide range of surgical indications, also benefits from the various 3D printing techniques. It brings a precious help to the surgeon, whether it is within the framework of pre-operative planning, of the custom design of cutting tools in maxillofacial surgery, or within a pedagogical framework with the learning of surgical techniques to students or for the provision of more precise information to patients. This work first recalls the different modalities of three-dimensional printing, then describes the main uses of 3D printing in plastic surgery.

Aims

Twin blocks are appliances used for Class II skeletal discrepancies, where the lower jaw is positioned more posteriorly compared to the upper. The conventional method of fabrication of this appliance is tedious and labour-intensive; hence this study intends to explore the feasibility of a digital workflow to three-dimensionally (3D) print them.

Methods

Three sets of twin blocks, identical except for amount of offset (0.0 mm, 0.1 mm and 0.2 mm), were designed and 3D printed for 5 anonymized scans of patients with Class II skeletal discrepancies. The intaglio surfaces of the 0.0 mm offset twin blocks were scanned and superimposed onto their original computer-aided-design files. The resultant colour maps, root mean square (RMS) deviations, and percentage in-tolerance values at thresholds of 0.1 mm and 0.2 mm were assessed. The fit and retention of all twin blocks were assessed on their 3D printed models via a fit and retention score (FRS).

Results

The median RMS deviation was 0.10 mm; percentage in-tolerance values at thresholds of 0.1 mm and 0.2 mm were 79.90%, and 94.51%. Printing deviations occurred most often at labial and incisal edges anteriorly, and buccal and occlusal surfaces posteriorly. There was no significant difference between the total FRS for the three groups (p = 0.076). However, the frequency of satisfactory scores for upper fit (p = 0.049), lower fit (p = 0.018), upper retention (p = 0.038) and lower retention (p = 0.015) differed significantly between the three groups.

Conclusion

This study demonstrated the viability of a digital workflow to 3D print twin blocks. Print accuracy was satisfactory, with 0.1 mm offset providing the best fit and retention.

During imaging follow-up, the residual dissection after a type A repair dissection could progress and may require repair of the aortic arch and the distal aorta. Our approach for repairing the evolving dissection includes open aortic arch replacement involving all 3 supra-aortic branches in combination with the frozen elephant trunk (FET) technique (n = 14). Distal arch repair combines a vascular and endovascular treatment to treat aortic arch disease (n = 13). A 3D printed aorta model has been used preoperatively and intraoperatively to improve surgical results. Hereby we report our aortic arch surgical experience and results in the treatment for this challenging pathology.

Lactobacilli, play a beneficial role in the female reproductive tract (FRT), regulating pH via lactic acid metabolism to help maintain a healthy environment. Bacterial vaginosis (BV) is characterized by a dysregulated flora in which anaerobes such as Gardnerella vaginalis (Gardnerella) create a less acidic environment. Current treatment focuses on antibiotic administration, including metronidazole, clindamycin, or tinidazole; however, lack of patient compliance as wel as antibiotic resistance may contribute to 50% recurrence within a year. Recently, locally administered probiotic such as Lactobacillus crispatus (L. crispatus) have been evaluated as a prophylactic against recurrence. To mitigate the lack of patient compliance, sustained probiotic delivery has been proposed via 3D-bioprinted delivery vehicles. Successful delivery depends on a variety of vehicle fabrication parameters influencing timing and rate of probiotic recovery; detailed evaluation of these parameters would benefit from computational modeling complementary to experimental evaluation. This study implements a novel simulation platform to evaluate sustained delivery of probiotics from 3D-bioprinted scaffolds, taking into consideration bacterial lactic acid production and associated pH changes. The results show that the timing and rate of probiotic recovery can be realistically simulated based on fabrication parameters that affect scaffold degradation and probiotic survival. Longer term, the proposed approach could help personalize localized probiotic delivery to the FRT to advance women's health.

Adolescent idiopathic scoliosis (AIS) is a noticeable spinal deformity in both adult and adolescent population. In majority of the cases, the gold standard of treatment is surgical intervention. Technological advancements in medical imaging and 3D printing have revolutionised the surgical planning and intraoperative decision making for surgeons in spinal surgery. However, its applicability for planning complex spinal surgeries is poorly documented with human subjects. The objective of this study is to evaluate the accuracy of 3D printed models for complex spinal deformities based on Cobb angles between 40° to 95°.This is a retrospective cohort study where, five CT scans of the patients with AIS were segmented and 3D printed for evaluating the accuracy. Consideration was given to the Inter-patient and acquisition apparatus variability of the CT-scan dataset to understand the effect on trueness and accuracy of the developed CAD models. The developed anatomical models were re-scanned for analysing quantitative surface deviation to assess the accuracy of 3D printed spinal models. Results show that the average of the root mean square error (RMSE) between the 3DP models and virtual models developed using CT scan of mean surface deviations for the five 3d printed models was found to be 0.5±0.07 mm. Based on the RMSE, it can be concluded that 3D printing based workflow is accurate enough to be used for presurgical planning for complex adolescent spinal deformities. Image acquisition and post processing parameters, type of 3D printing technology plays key role in acquiring required accuracy for surgical applications.

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.