3D-printed Custom Research Articles

3D-printed custom ankle braces for people with Charcot-Marie-Tooth disease: A pilot study.

Charcot-Marie-Tooth disease (CMT) is a neurodegenerative condition resulting in footdrop, ankle instability and impaired balance and gait. This study aimed to determine (1) whether 3D-printed custom ankle braces improve function and balance in people with CMT and (2) whether this is an acceptable device for use in this population. A within-subject comparison pragmatic/pilot study was undertaken. Ten people with CMT (mean [SD] age 48 [14] years, 60% male) were fitted with 3D-printed ankle braces. Following a 4-week wear-in period, walking and balance tests and patient-reported outcomes were assessed in two experimental conditions: (i) usual shoes and (ii) usual shoes with 3D-printed custom ankle braces. Differences in outcome measures between experimental conditions were analysed using linear mixed models. Comfort, aesthetics and overall satisfaction of the brace were assessed via 100-mm visual analogue scale (VAS). Adverse events and tripping/falls associated with the brace during the wear-in period were also recorded by participants using daily diaries. A significant improvement was seen during single-leg balance with eyes open (p=0.026, Cohen's d=0.55) and a significant reduction in foot pain (p=0.045, Cohen's d=0.82), with use of the ankle brace. Mean (SD) 100mm VAS scores were 62.7mm (17.9) for overall comfort and 73.9mm (21.2) for overall satisfaction. Subjective data from the daily dairies showed that one participant found the brace too firm around the ankle due to loss of soft tissue mass and two participants found it challenging to don and doff the brace due to loss of hand dexterity. This pilot study suggests that a 3D-printed custom ankle brace may improve balance and reduce foot pain in people with CMT; however, larger-scale trials are needed to further explore the impact of this brace on function and balance. Further customisation of the brace may also be required to improve acceptability for some people.

The Mechanical and Clinical Properties of Customized Orthodontic Bracket Systems-A Comprehensive Review.

The rise of computer-aided design and computer-aided manufacturing (CAD/CAM) and 3D printing technologies in orthodontics has revolutionized the development of customized labial and lingual bracket systems with a variety of materials, which offer potential advantages over traditional orthodontic brackets. To highlight the current state of knowledge regarding the mechanical and clinical properties of CAD/CAM and 3D-printed custom bracket systems, we conducted a comprehensive search across the PubMed, Embase, Cochrane Library, Web of Science, and Scopus databases to identify relevant articles published before April 2024. Mechanical (including fracture toughness, hardness, modulus of elasticity, frictional resistance, slot accuracy, torque transmission, and shear bond strength) and clinical (including treatment efficiency and duration, cost, and comfort) properties were compared between traditional and customized orthodontic bracket systems in the current review. Our findings suggest that customized brackets have the potential to increase bracket slot precision, reduce treatment time, and offer cost-efficiency. However, it is worth noting that the advantages and disadvantages of customized bracket systems vary depending on the bracket material and the manufacturing methods, warranting comprehensively controlled investigations in the future.

A customizable digital holographic microscope

We propose a compact, portable, and low-cost holographic microscope designed for the characterization of micrometric particles suspended in a liquid. This system is built around a commercial optical microscope by substituting its illumination source (a light-emitting diode) with a collimated laser beam. Similarly, a quartz flow cell replaces the microscope glass slide using a 3D-printed custom mount. With the hardware presented in this paper, the holographic imaging of the electromagnetic fields emitted by the particles that intercept the laser beam achieves a resolution close to that of optical microscopes but with a greater depth of field. Several morphological and optical features can be extracted from the holograms, including particle projected section, aspect ratio, and extinction cross-section. Additionally, we introduce a remote system control that enables users to process the acquired holograms on a remote computational device. This work provides a comprehensive description of the methodology of image processing in holographic microscopy and a series of validation measurements conducted using calibrated particles. This technique is suitable for the characterization of airborne particles found in snow, firn, and ice; here we report experimental results obtained from Alpine ice cores.

The Effect of 3D-Printed Custom Insoles on Plantar Pressure for Obese Individual

ABSTRACT Introduction There are many types of insoles made for obese individuals. However, there is a need for studies on insoles produced with 3D printers using flexible materials and comparing and examining the effect of these on plantar pressure. Materials and Methods An obese individual with a body mass index (BMI) > 35 recommended by physicians to use insoles was included in this study. The individual’s foot was scanned using a 3D scanner, and insoles were designed using CAD software. The insoles were produced with TPU-75A flexible filament on a 3D printer at different fill rates (5%, 10%, and 15%). The effects of the insoles on underfoot pressures were clinically compared. Results Custom insoles with different filling ratios were made for an obese individual using flexible filament in 3D printers. The most appropriate insole print filling ratio for minimum foot pain experienced by the obese patient during their daily activities has been determined. The results reveal that 3D-printed insoles distribute the plantar pressure more effectively with significantly reduced pressure in certain foot locations (i.e., heel, under the first metatarsal) as compared with the existing insoles. Conclusions Manufactured by additive manufacturing, these insoles are produced using a fully digitized scanning process that creates virtually no material wastage. The thermoplastic polyurethane was preferred due to its favorable properties. By changing the pressure structure and internal filling system, it allows producing personalized insoles in the desired contact areas of hard and soft. Clinical Relevance This study provides evidence that insoles produced in 3D printers with flexible materials are as effective as insoles produced with traditional methods in reducing plantar pressure. Therefore, it is an alternative to traditional methods due to less labor.

The 3D-Printed Custom Elbow Prosthesis for Salvage Treatment of Complex Intra-Articular Distal Humerus Fracture Malunion

Intra-articular fractures of the distal humerus are complex injuries that often require surgery with the goal of restoring elbow range-of-motion and function. Open reduction and internal fixation has been the preferred surgical modality; however, restoration of the medial and/or lateral columns can be complicated in fractures involving a major loss of the articular surface and bony structure. Over the past decade, 3-dimensional (3D) printing has made significant advances in the field of orthopedic surgery, specifically in guiding surgeon preoperative planning. Recently, the incorporation of 3D-printing has proven to provide a safe and reliable construct for the restoration of anatomy in complex trauma cases. We present a 47-year-old woman who sustained a complex, intra-articular distal humerus fracture with associated shearing of the capitellum that went onto malunion. Patient was treated with a patient-specific 3D-printed custom elbow prosthesis with excellent outcomes. Our goal was to shed light on the use of 3D-printing technology as a viable salvage option in treating complex, intra-articular distal humeral fractures associated with lateral condylar damage that subsequently went onto malunion.

Advanced Pelvic Girdle Reconstruction with three dimensional-printed Custom Hemipelvic Endoprostheses following Pelvic Tumour Resection

PurposeResection of pelvic bone tumours and subsequent pelvic girdle reconstruction pose formidable challenges due to the intricate anatomy, weight-bearing demands, and significant defects. 3D-printed implants have improved pelvic girdle reconstruction by enabling precise resections with customized guides, offering tailored solutions for diverse bone defect morphology, and integrating porous surface structures to promote osseointegration. Our study aims to evaluate the long-term efficacy and feasibility of 3D-printed hemipelvic reconstruction following resection of malignant pelvic tumours.MethodsA retrospective review was conducted on 96 patients with primary pelvic malignancies who underwent pelvic girdle reconstruction using 3D-printed custom hemipelvic endoprostheses between January 2017 and May 2022. Follow-up duration was median 48.1 ± 17.9 months (range, 6 to 76 months). Demographic data, imaging examinations, surgical outcomes, and oncological evaluations were extracted and analyzed. The primary endpoints included oncological outcomes and functional status assessed by the Musculoskeletal Tumor Society (MSTS-93) score. Secondary endpoints comprised surgical duration, intraoperative bleeding, pain control and complications.ResultsIn 96 patients, 70 patients (72.9%) remained disease-free, 15 (15.6%) had local recurrence, and 11 (11.4%) succumbed to metastatic disease. Postoperatively, function improved with MSTS-93 score increasing from 12.2 ± 2.0 to 23.8 ± 3.8. The mean operating time was 275.1 ± 94.0 min, and the mean intraoperative blood loss was 1896.9 ± 801.1 ml. Pain was well-managed, resulting in substantial improvements in VAS score (5.3 ± 1.8 to 1.4 ± 1.1). Complications occurred in 13 patients (13.5%), including poor wound healing (6.3%), deep prosthesis infection (4.2%), hip dislocation (2.1%), screw fracture (1.0%), and interface loosening (1.0%). Additionally, all patients achieved precise implantation of customized prosthetics according to preoperative plans. T-SMART revealed excellent integration at the prosthesis-bone interface for all patients.ConclusionThe use of a 3D-printed custom hemipelvic endoprosthesis, characterized by anatomically designed contours and a porous biomimetic surface structure, offers a potential option for pelvic girdle reconstruction following internal hemipelvectomy in primary pelvic tumor treatment. Initial results demonstrate stable fixation and satisfactory mid-term functional and radiographic outcomes.

Evaluation of Implant Impression Accuracy Using Different Trays and Techniques with a 3D Superimposition Method.

To evaluate the dimensional accuracy of implant impressions obtained using five different tray types and two techniques. A partially dentate maxillary Kennedy Class II model was created as a reference model through 3D printing. Then, implant analogs 4.3 mm in diameter were placed at the first premolar, first molar, and second molar sites. Five types of trays were used to create impressions: (1) metal stock trays, (2) plastic stock trays, (3) custom trays fabricated using liquid crystal display (LCD), (4) custom trays fabricated using fused deposition modeling (FDM), and (5) custom trays fabricated using urethane dimethacrylate (UDMA) resin. Open and closed tray techniques were also compared. In total, 150 impressions were obtained. The reference model and impressions were scanned using a laboratory scanner. Additionally, the positional and angular deviations of implants with different tray types and techniques were evaluated using the superimposition method. There was no statistically significant difference (P > .05) between the impression accuracy with the different tray types and impression techniques. The angular deviations with plastic and UDMA trays were greater than those with metal, FDM, and LCD trays. Angular deviation at the second molar was greater when using closed plastic trays compared to open plastic trays. The highest and lowest positional deviations were observed at the first molar implant with an open plastic tray impression (mean ± SD of 62.46 ± 28.54 mm) and a closed LCD tray impression (36.59 ± 29.93 mm). The greatest angular deviation was observed with an open FDM tray impression at the first premolar implant (0.067 ± 0.024 degree), and the lowest angular deviation was observed with a closed metal stock tray impression at the second molar implant (0.039 ± 0.025 degree). Statistical differences were detected using the Mann-Whitney U test for paired groups and the Kruskal-Wallis test for groups with more than three comparisons (P > .05). Plastic and metal stock trays or conventional and 3D-printed custom trays can be used to obtain implant impressions for maxillary partially edentulous arches with similar dimensional accuracy. The five tray types and two techniques may be safely used to obtain impressions of partially edentulous maxillary arches with three implants.

3D-printed custom tray for maxillofacial implant assisted partial denture.

This technique presents a new fabrication workflow for a three-dimensional (3D) printed custom tray, which duplicates the morphology of the treatment denture for maxillofacial prostheses using an intraoral scanner, computer-aideddesign (CAD) software, and a 3D printer. A 70-year-old man underwent reconstruction of segmental mandibulectomy for mandibular osteoblastoma, followed by implant placement and secondary surgery. During the surgical treatment, a treatment denture was fabricated to restore oral function and determine the morphology of the definitive denture. To create the definitive denture with the same morphology as the treatment denture a custom tray was fabricated with the denture morphology after chairside adjustments. The oral cavity was scanned using an intraoral scanner, and the data acquired were imported into general-purpose CAD software, adjusted, and imported into a 3D printer to produce the custom tray. This was fitted into the patient's mouth without any issues, and closed tray impressions were made with impression caps for the locator attachments on the implant body. The morphology of the treatment denture was replicated in the definitive denture by making a silicon impression of the cameo surface at the fabrication of the cast after impression making. In this technique, the morphology of the treatment denture was transferred accurately to the definitive implant partial denture by leveraging existing digital technology. This method represents a practical approach for partial denture fabrication, including maxillofacial defects with complex denture configurations.

Quantitative analysis of 3D-printed custom ossicular prostheses motion using laser Doppler vibrometry.

<b><br>Introduction:</b> In chronic otitis media, the reconstruction of the middle ear's sound conducting system involves repairing the tympanic membrane and filling the space between ossicular chain remnants. The final shape of the prosthesis is usually determined intraoperatively. However, the ossicular chain may be preoperatively measured using computed tomography (CT) scans, and an individualized prosthesis can be designed. Custom 3D printing seems to be an attractive solution for optimal adjustment.</br> <b><br>Aim:</b> Our study aimed to assess the 3D-printed custom prosthesis movability and compare it to the original ossicular chain.</br> <b><br>Material and methods:</b> Five fresh-frozen temporal bone specimens were used. Using Cone-Beam CT scans, the incus model was designed individually and 3D-printed. The ossicular chain was reconstructed inside the cadaveric temporal bone. Acoustic stimuli were applied to the external ear canal one frequency at a time. The laser Doppler vibrometer (LDV) measured the intact and 3D-printed prosthesis reconstructed ossicular chain vibrations.</br> <b><br>Results:</b> At all stimulation frequencies, there was no significant difference in velocity values between the intact and reconstructed ossicular chain at the intensity of 80 dB SPL. The obtained values of the velocity gain were: -7.9 (SD-19) dB, -6.8 (SD8.12) dB, -10,9 (SD-5.3) dB, -7.4 (SD-8.16) dB for 500 Hz, 1000 Hz, 2000 Hz, 4000 Hz, respectively. The vibration threshold shift values ranged between -0.57 dB at 500 Hz and 3.81 dB at 2000 Hz.</br> <b><br>Conclusions:</b> This study analyzed the movability of individualized 3D-printed custom ossicular prostheses using LDV. Compared to the intact ossicular chain, the reconstructed ossicular chain movability was characterized by statistically insignificant reduced movability at all tested frequencies. Because the prosthesis's new design conception as custom 3D individualized printing allows for patient-specific ossiculoplasty, it represents a promising new direction for ossicular chain reconstruction. It seems to be an attractive solution for prosthesis optimal adjustment and, hopefully, better hearing results.</br&gt.

The application of custom 3D-printed prostheses with ultra-short stems in the reconstruction of bone defects: a single center analysis

Objective: Considering the advantages and widespread presence of 3D-printing technology in surgical treatments, 3D-printed porous structure prostheses have been applied in a wide range of the treatments of bone tumor. In this research, we aimed to assess the application values of the 3D-printed custom prostheses with ultra-short stems for restoring bone defects and maintaining arthrosis in malignant bone tumors of lower extremities in children.Methods: Seven cases of pediatric patients were included in this study. In all cases, the prostheses were porous titanium alloy with ultra-short stems. MSTS 93 (Musculoskeletal Tumor Society) scores were recorded for the functional recovery of the limbs. VAS (Visual analogue scale) scores were utilized to assess the degree of painfulness for the patients. X-ray and MRI (magnetic resonance imaging) were applied to evaluate the bone integration, prostheses aseptic loosening, prostheses fracture, wound healing, and tumor recurrence during follow-up.Results: During follow-up, none of the patients developed any postoperative complications, including prostheses aseptic loosening, prostheses fracture, or tumor recurrence. Radiological examinations during the follow-up showed that prostheses implanted into the residual bone were stably fitted and bone defects were effectively reconstructed. The MSTS 93 scores were 24.9 ± 2.9 (20–28). VAS scores were decreased to 5.8 ± 1.2 (4.0–7.0). No statistically significant differences in leg length discrepancy were observed at the time of the last follow-up.Conclusion: 3D-printing technology can be effectively applied throughout the entire surgical treatment procedures of malignant bone tumors, offering stable foundations for the initial stability of 3D-printed prostheses with ultra-short stems through preoperative design, intraoperative precision operation, and personalized prosthesis matching. With meticulous postoperative follow-up, close monitoring of postoperative complications was ensured. These favorable outcomes indicate that the utilization of 3D-printed custom prostheses with ultra-short stems is a viable alternative for reconstructing bone defects. However, further investigation is warranted to determine the long-term effectiveness of the 3D-printing technique.

Custom 3D-Printed External Cranial Orthotic for Prevention and Treatment of Syndrome of the Trephined.

Syndrome of the Trephined (SoT) is a frequently misunderstood and underdiagnosed outcome of decompressive craniectomy, especially in cases of trauma. The pressure gradient between atmospheric pressure and the sub-atmospheric intracranial pressure results in a sinking of the scalp overlying the craniectomy site. This gradually compresses the underlying brain parenchyma. This parenchymal compression can disrupt normal autoregulation and subsequent metabolism, yielding symptoms ranging from headaches, dizziness, altered behavior to changes in sensation, and difficulty with ambulation, coordination, and activities of daily living. We present a case of SoT treated with a 3D-printed custom polycarbonate external cranial orthotic that allowed us to re-establish this pressure gradient by returning the cranium to a closed system. The patient demonstrated subjective improvement in quality of life and his symptoms. This was consistent with the re-expanded brain parenchyma on CT imaging.

A 3D-printed patient-specific modular implants for pelvic reconstruction of bone tumors involving the sacroiliac joint.

Background: Current reconstruction methods of the pelvic ring after extensive resection of tumors involving the sacroiliac joint have a high incidence of failure. We aimed to study the effect of 3D-printed patient-specific implant reconstruction to show that this method is stable and has a low risk of failure. Methods: Between February 2017 and November 2021, six patients with bone tumors involving the sacroiliac joint (Enneking I + IV) who received 3D-printed patient-specific implants for pelvic reconstructive surgery were retrospectively analyzed. Two female and four male patients with a mean age of 41.83years (range 25-65years) were included. Two were osteosarcomas, two chondrosarcomas, one malignant fibrous histiocytoma, and one giant cell tumor of bone. For each patient, preoperative osteotomy guides were designed to ensure accurate tumor resection and individualized prostheses were designed to ensure a perfect fit of the bone defect. General, oncologic, and functional outcomes, implant status, and complications were retrospectively analyzed. The Visual Analog Scale (VAS) was used to assess pain and the Musculoskeletal Tumor Society (MSTS) score was used to assess hip function. Osseointegration was assessed by CT. Results: According to the preoperative design, complete resection of the entire tumor and reconstruction with a custom 3D-printed sacroiliac joint implant was completed without perioperative severe complications or deaths. Relatively satisfactory surgical margins were achieved. The mean operative time and intraoperative blood loss were 495min (420-600min) and 2533.33mL (range, 1,200-3,500mL), respectively. The mean follow-up was 49.83months (range, 18-75months). At the last follow-up, all four patients were disease-free, and the two patients who developed lung metastases were alive with tumors. All patients could walk unassisted. The mean VAS was 1.33 (range, 0-2). The mean MSTS score was 25.33 (range, 24-27). CT showed complete osseointegration of the implant to the ilium and sacrum. Conclusion: The 3D-printed custom prosthesis can effectively reconstruct pelvic stability after total sacroiliac joint resection with satisfactory clinical results.

Rheological formulation of room temperature vulcanizing silicone elastomer ink for extrusion-based 3D printing at room temperature

Silicone elastomer is a versatile material that is widely used in various industries due to its exceptional properties such as resistance to extreme temperatures, thermal conductivity, and bioinert. However, conventional fabrication methods of silicone are limited by molding which has design restrictions and makes it unsuitable for highly customized applications. This study presents a novel room temperature vulcanizing (RTV) silicone formulation that enables three-dimensional printing using an extrusion-based method. The study identifies that rheological measurements such as static yield stress are critical in determining the success of 3D silicone printing. Chemical additives, including nano-silica and plasticizers, have a significant impact on the static yield stress of the silicone ink, enabling the printing of complex structures. By adding 7 wt% of nano-silica and 10 wt% of plasticizers, a static yield stress of 400 Pa was achieved, which allowed the printing of complex 3D structures, including supportless macro-porous scaffolds. The newly formulated silicone ink demonstrated printability and the ability to achieve complex structures, reducing fabrication time, improving scalability, and allowing flexibility in the scaffold's design and specifications. This novel approach opens up new possibilities for the development of highly customized and cost-effective silicone-based 3D printing ink for the fabrication of complex silicone articles and macro-porous scaffolds. The potential applications of this approach include tissue engineering and biomedical devices.

The Role of 3D Printing in Treatment Planning of Spine and Sacral Tumors.

Three-dimensional (3D) printing technology has proven to have many advantages in spine and sacrum surgery. 3D printing allows the manufacturing of life-size patient-specific anatomic and pathologic models to improve preoperative understanding of patient anatomy and pathology. Additionally, virtual surgical planning using medical computer-aided design software has enabled surgeons to create patient-specific surgical plans and simulate procedures in a virtual environment. This has resulted in reduced operative times, decreased complications, and improved patient outcomes. Combined with new surgical techniques, 3D-printed custom medical devices and instruments using titanium and biocompatible resins and polyamides have allowed innovative reconstructions.

What Are the MSTS Scores and Complications Associated With the Use of Three-dimensional Printed, Custom-made Prostheses in Patients Who Had Resection of Tumors of the Hand and Foot?

There are a few good options for restoring bone defects in the hand and foot. 3D-printed implants have been used in the pelvis and elsewhere, but to our knowledge, they have not been evaluated in the hand and foot. The functional outcome, complications, and longevity of 3D-printed prostheses in small bones are not well known. (1) What are the functional outcomes of patients with hand or foot tumors who were treated with tumor resection and reconstruction with a 3D-printed custom prosthesis? (2) What complications are associated with using these prostheses? (3) What is the 5-year Kaplan-Meier cumulative incidence of implant breakage and reoperation? Between January 2017 and October 2020, we treated 276 patients who had tumors of the hands or feet. Of those, we considered as potentially eligible patients who might have extensive loss in their joint that could not be fixed with a bone graft, cement, or any prostheses available on the market. Based on this, 93 patients were eligible; a further 77 were excluded because they received nonoperative treatment such as chemoradiation, resection without reconstruction, reconstruction using other materials, or ray amputation; another three were lost before the minimum study follow-up of 2 years and two had incomplete datasets, leaving 11 for analysis in this retrospective study. There were seven women and four men. The median age was 29 years (range 11 to 71 years). There were five hand tumors and six tumors of the feet. Tumor types were giant cell tumor of bone (five), chondroblastoma (two), osteosarcoma (two), neuroendocrine tumor (one), and squamous cell carcinoma (one). Margin status after resection was ≥ 1 mm. All patients were followed for a minimum of 24 months. The median follow-up time was 47 months (range 25 to 67 months). Clinical data; function according to the Musculoskeletal Tumor Society, DASH, and American Orthopedic Foot and Ankle Society scores; complications; and survivorship of implants were recorded during follow-up in the clinic, or patients with complete charts and recorded data were interviewed on the telephone by our research associates, orthopaedic oncology fellows, or the surgeons who performed the surgery. The cumulative incidence of implant breakage and reoperation was assessed using a Kaplan-Meier analysis. The median Musculoskeletal Tumor Society score was 28 of 30 (range 21 to 30). Seven of 11 patients experienced postoperative complications, primarily including hyperextension deformity and joint stiffness (three patients), joint subluxation (two), aseptic loosening (one), broken stem (one), and broken plate (one), but no infection or local recurrence occurred. Subluxations of the metacarpophalangeal and proximal interphalangeal joints in two patients' hands were caused by the design of the prosthesis without a joint or stem. These prostheses were revised to a second-generation prosthesis with joint and stem, leading to improved dexterity. The cumulative incidence of implant breakage and reoperation in the Kaplan-Meier analysis was 35% (95% CI 6% to 69%) and 29% (95% CI 3% to 66%) at 5 years, respectively. These preliminary findings suggest that 3D implants may be an option for reconstruction after resections that leave large bone and joint defects in the hand and foot. Although the functional results generally appeared to be good to excellent, complications and reoperations were frequent; thus, we believe this approach could be considered when patients have few or no alternatives other than amputation. Future studies will need to compare this approach to bone grafting or bone cementation. Level IV, therapeutic study.

A novel three dimensional-printed biomechanically evaluated patient-specific sacral implant in spinopelvic reconstruction after total en bloc sacrectomy.

Background: Reconstruction after a total sacrectomy is a challenge due to the special anatomical and biomechanical factors. Conventional techniques of spinal-pelvic reconstruction do not reconstruct satisfactorily. We describe a novel three-dimensional-printed patient-specific sacral implant in spinopelvic reconstruction after total en bloc sacrectomy. Methods: We performed a retrospective cohort study including 12 patients with primary malignant sacral tumors, including 5 men and 7 women with a mean age of 58.25years (range 20-66years), undergoing total en bloc sacrectomy with 3D printed implant reconstruction from 2016 to 2021. There were 7 cases of chordoma, 3 cases of osteosarcoma, 1 case of chondrosarcoma and 1 case of undifferentiated pleomorphic sarcoma. We use CAD technology to determine surgical resection boundaries, design cutting guides, and individualized prostheses, and perform surgical simulations before surgery. The implant design was biomechanically evaluated by finite element analysis. Operative data, oncological and functional outcomes, complications, and implant osseointegration status of 12 consecutive patients were reviewed. Results: The implants were implanted successfully in 12 cases without death or severe complications during the perioperative period. Resection margins were wide in 11 patients and marginal in one patient. The average blood loss was 3875mL (range, 2000-5,000mL). The average surgical time was 520min (range, 380-735min). The mean follow-up was 38.5months. Nine patients were alive with no evidence of disease, two patients died due to pulmonary metastases, and one patient survived with disease due to local recurrence. Overall survival was 83.33% at 24months. The Mean VAS was 1.5 (range, 0-2). The mean MSTS score was 21 (range, 17-24). Wound complications occurred in 2 cases. A deep infection occurred in one patient and the implant was removed. No implant mechanical failure was identified. Satisfactory osseointegration was found in all patients, with a mean fusion time of 5months (range 3-6months). Conclusion: The 3D-printed custom sacral prosthesis has been effective in reconstructing spinal-pelvic stability after total en bloc sacrectomy with satisfactory clinical outcomes, excellent osseointegration, and excellent durability.

3D-printed custom ossicular prosthesis - methodology of design and LDV measurements in a cadaver study.

In tympanoplasty, surgical reconstruction of the tympanic membrane and ossicular chain is well-established; however, its hearing results still require improvement. Custom 3D printing of individualized ossicular prostheses seems to be an attractive solution for optimal prosthesis adjustment and better hearing results. The aim was to design a custom ossicular prosthesis using a 3D printing method based on Cone-beam Computed Tomography (CBCT) scans and assess the acoustic conduction properties of such prosthesis. A cadaver fresh frozen temporal bone was used. Based on CBCT images, a new incus prosthesis was designed and 3D printed. Next, canal wall-up tympanoplasty was performed. The intact ossicular chain and reconstructed 3D-printed prosthesis chain movements/vibrations were measured with Laser Doppler Vibrometer (LDV) system and analyzed in detail. The CBCT scans provided enough information about the anatomical structures. For frequencies 500 and 1000 Hz and 80 dB SPL sound intensity, collected velocities were higher for the intact ossicular chain than the 3D-printed ossicular prosthesis. The intensity thresholds for movement at 500 and 1000 Hz were lower in the intact ossicular chain than in the 3D-printed ossicular prosthesis. At 2000 Hz, there was the same intensity threshold value in the two measured circumstances. It is possible to design a custom individually fitted ossicular prosthesis using a 3D printing method based on CBCT scans. The acoustic conduction properties of such 3D-printed prosthesis showed differences in movability pattern between the intact and reconstructed ossicular chain. More data are needed to analyze the acoustic properties of such designed prostheses in detail. The results of our experiment showed the 3D-printed prosthesis presents the potential to be an interesting option for conductive hearing loss treatment caused by chronic otitis media and the ossicular chain defects.

Minimally invasive plate osteosynthesis of femoral fractures with 3D-printed bone models and custom surgical guides: A cadaveric study in dogs.

Assess the accuracy and efficiency of reduction provided by application of plates precontoured to 3-dimensional (3D)-printed femoral bone models using a custom fracture reduction system (FRS) or intramedullary pin (IMP) to facilitate femoral minimally invasive plate osteosynthesis (MIPO) in dogs. Experimental cadaveric study. Seven dog cadavers. Virtual 3D femoral models were created using computed tomographic images. Simulated, virtual mid-diaphyseal femoral fractures were created and reduced. Reduced femoral models were 3D-printed and a plate was contoured. Custom drill guides for plate screw placement were designed and 3D-printed for the FRS. Mid-diaphyseal simulated comminuted fractures were created in cadavers, and fractures were aligned using FRS or IMP and stabilized with the precontoured plates. Number of fluoroscopic images acquired per procedure and surgical duration were recorded. Computed tomographic scans were repeated to assess femoral length and alignment. Compared to the preoperative virtual plan, median change in femoral length and frontal, sagittal, and axial alignment was less than 3 mm, 2°, 3°, and 3° postoperatively, respectively, in both reduction groups. There was no difference in length or alignment between reduction groups (P > .05). During FRS, fewer fluoroscopic images were taken (P=.001), however, surgical duration was longer than IMP procedures (P=.011). Femoral alignment was accurate when using plates precontoured to 3D printed models, regardless of reduction method. Accurate plate contouring using anatomically accurate models may improve fracture reduction accuracy during MIPO applications. Custom surgical guides may reduce fluoroscopy use associated with MIPO.

Ischial screw fixation can prevent cup migration in 3D-printed custom acetabular components for complex hip reconstruction

IntroductionCustom acetabular components have become an established method of treating massive acetabular bone defects in hip arthroplasty. Complication rates, however, remain high and migration of the cup is still reported. Ischial screw fixation (IF) has been demonstrated to improve mechanical stability for non-custom, revision arthroplasty cup fixation. We hypothesize that ischial fixation through the flange of a custom acetabular component aids in anti-rotational stability and prevention of cup migration.MethodsElectronic patient records were used to identify a consecutive series of 49 custom implants in 46 patients from 2016 to 2022 in a unit specializing in complex joint reconstruction. IF was defined as a minimum of one screw inserted into the ischium passing through a hole in a flange on the custom cup.The mean follow-up time was 30 months. IF was used in 36 cups. There was no IF in 13 cups. No difference was found between groups in age (68.9 vs. 66.3, P = 0.48), BMI (32.3 vs. 28.2, P = 0.11) or number of consecutively implanted cups (3.2 vs. 3.6, P = 0.43). Aseptic loosening with massive bone loss was the primary indication for revision. There existed no difference in Paprosky grade between the groups (P = 0.1). 14.2% of hips underwent revision and 22.4% had at least one dislocation event.ResultsNo ischial fixation was associated with a higher risk of cup migration (6/13 vs. 2/36, X2 = 11.5, P = 0.0007). Cup migration was associated with an increased risk for all cause revision (4/8 vs. 3/38, X2 = 9.96, P = 0.0016, but not with dislocation (3/8 vs. 8/41, X2 = 1.2, P = 0.26).ConclusionThe results suggest that failure to achieve adequate ischial fixation, with screws passing through the flange of the custom component into the ischium, increases the risk of cup migration, which, in turn, is a risk factor for revision.

Trueness and precision of artificial teeth in CAD-CAM milled complete dentures from custom disks with a milled recess

Statement of problemStudies on the movement of artificial teeth during the manufacturing of computer-aided design and computer-aided manufacturing (CAD-CAM) complete dentures using the custom disk method with milled recesses and on whether the movement is within a clinically acceptable range are lacking. PurposeThe purpose of this in vitro study was to assess the trueness and precision of the artificial teeth on custom disks the recesses of which were manufactured using a milling machine and to compare the results with the recesses manufactured using a 3-dimensional (3D) printer. Material and methodsFour types of artificial teeth (maxillary left central incisors [Max-L1], mandibular left central incisors [Man-L1], maxillary left first premolars [Max-L4], and maxillary left first molars [Max-L6]) were prepared. Milling data were created, and 3 of each type of tooth were attached to each disk made up of 3 concentric circles (large, medium, and small). Five each of the 3D-printed custom disks and custom disks with milled recesses were milled based on the milling data. Standard tessellation language data were obtained through cone beam computed tomography and superimposed by using a CAD software program. Mean absolute error (MAE) values were calculated to assess trueness and precision; MAE values of artificial teeth in custom disks with milled recesses and 3D-printed custom disks were statistically compared by using the 2-way analysis of variance test with 2 factors, 2 types of custom disks and 4 types of artificial teeth, and the Tukey post hoc comparison (α=.05). ResultsRegarding position trueness, the MAE value of Man-L1 on the milling custom disk was significantly lower than that of the 3D-printed custom disk (P<.001), whereas the MAE values of Max-L4 and Max-L6 on the milling custom disk were significantly higher than those on the 3D-printed custom disk (P<.001). No significant difference was found in the MAE value of the position trueness of Max-L1 between the milling and 3D-printed custom disks. Regarding position precision, the MAE values of Max-L1, Man-L1, and Max-L4 on the milling custom disk were significantly lower than those on the 3D-printed custom disks (P=.002, P<.001, P=.025, respectively). However, no significant difference was seen in the MAE value of position precision of Max-L6 between the milling and 3D-printed custom disks (P=.180) ConclusionsMovement of artificial teeth during the manufacture of dentures using the custom disk method and custom disks with milled recesses was within a clinically acceptable range.