3D-printed Implant Research Articles

Initial Safety of Total Talus Replacement Used to Treat Talar Avascular Necrosis.

Total talus replacement (TTR) implants are designed to replace the diseased talar anatomy, reduce pain, maintain ankle range of motion, and restore ankle function after conservative treatments have failed. Currently TTR implants are produced by 3D printing a patient-specific implant designed from the patient's preoperative anatomy. TTR surgery using patient-specific implants is a relatively new technique that remains understudied in the literature. Therefore, the purpose of this investigation was to determine the early safety and potential benefit of the TTR implant in patients with talar avascular necrosis. This retrospective, multicenter, cohort study evaluates the safety and potential benefits of TTR using 3D-printed patient-specific implants across 4 US centers. The primary outcome was the occurrence of early adverse events after TTR surgery. Secondary outcomes including, pain, and physical function were assessed using the pain visual analog scale (VAS), and Patient-Reported Outcomes Measurement Information System (PROMIS) physical function (PF), respectively. The study team analyzed 15 patients with more than 1 year of follow-up. The mean duration of follow-up was 25.9 months (range: 18.3-41 months). Although 33.3% (5 of 15) of patients experienced adverse events, primarily occurring within the initial 6 months postoperatively, 93% (14 of 15) of patients reported implant survivorship. Of the 5 cases (33.3%) resulting in an adverse event, 3 (60.0%) were determined to be unrelated to the subject device, 2 (40.0%) were determined to be possibly procedure-related, and none (0%) were determined to be device-related. Although further studies are needed to compare TTR with the standard of care, the results of this study demonstrate the relative early safety of TTR surgery using a 3D-printed implant for the treatment of challenging talar pathologies. A larger and longer clinical study is required to see if the efficacy of this approach will be statistically and clinically meaningful.

Customized 3D-Printed Mesh, Membrane, Bone Substitute, and Dental Implant Applied to Guided Bone Regeneration in Oral Implantology: A Narrative Review.

Background: The new frontiers of computer-based surgery, technology, and material advances, have allowed for customized 3D printed manufacturing to become widespread in guided bone regeneration (GBR) in oral implantology. The shape, structural, mechanical, and biological manufacturing characteristics achieved through 3D printing technologies allow for the customization of implant-prosthetic rehabilitations and GBR procedures according to patient-specific needs, reducing complications and surgery time. Therefore, the present narrative review aims to elucidate the 3D-printing digital radiographic process, materials, indications, 3D printed manufacturing-controlled characteristics, histological findings, complications, patient-reported outcomes, and short- and long-term clinical considerations of customized 3D printed mesh, membranes, bone substitutes, and dental implants applied to GBR in oral implantology. Methods: An electronic search was performed through MEDLINE/PubMed, Scopus, BioMed Central, and Web of Science until 30 June 2024. Results: Three-dimensionally printed titanium meshes and bone substitutes registered successful outcomes in vertical/horizontal bone defect regeneration. Three-dimensionally printed polymeric membranes could link the advantages of conventional resorbable and non-resorbable membranes. Few data on customized 3D printed dental implants and abutments are available, but in vitro and animal studies have shown new promising designs that could improve their mechanical properties and tribocorrosion-associated complications. Conclusions: While 3D printing technology has demonstrated potential in GBR, additional human studies are needed to evaluate the short- and long-term follow-up of peri-implant bone levels and volumes following prosthetic functional loading.

Characterisation of 3D-printed acetabular hip implants.

Three-dimensional printing is a rapidly growing manufacturing method for orthopaedic implants and it is currently thriving in several other engineering industries. It enables the variation of implant design and the construction of complex structures which can be exploited in orthopaedics and other medical sectors. In this review, we develop the vocabulary to characterise 3D printing in orthopaedics from terms defined by industries employing 3D printing, and by fully examining a 3D-printed off-the-shelf acetabular cup (Fig. 1). This is a commonly used 3D-printed implant in orthopaedics, and it exhibits a range of prominent features brought about by 3D printing. The key features and defects of the porous and dense regions of the implant are clarified and discussed in depth to determine reliable definitions and a common understanding of characteristics of 3D printing between engineers and medical experts in orthopaedics. Despite the extensive list of terminology derived here, it is clear significant gaps exist in the knowledge of this field. Therefore, it is necessary for continued investigations of unused implants, but perhaps more significantly, examining those in vivo and retrieved to understand their long-term impact on patients and the effects of certain features (e.g. surface-adhered particles). Analyses of this kind will establish an understanding of 3D printing in orthopaedics and additionally it will help to update the regulatory approach to this new technology.

Evaluating the Mechanical Strength of Three Dimensionally (3D) Printed Implants in Septorhinoplasty through Finite Element Analysis (FEA).

Autologous nasoseptal cartilage grafts are used to correct nasal asymmetry and deviation in rhinoplasty, but patients who have undergone multiple surgeries may have limited autologous cartilage tissue available. 3D-printed L-strut implants may address these challenges in the future, but their mechanical strength is understudied. Silk fibroin-gelatin (SFG), polycaprolactone (PCL), and polylactide (PLA) are bio-inks known for their strength. We present Finite Element Analysis (FEA) models comparing the mechanical strength of 3D-printed SFG, PCL, and PLA implants with nasoseptal cartilage grafts when autologous or allografts are not available. FEA models compared the stress and deformation responses of 3D-printed solid and scaffold implant replacements to cartilage. To simulate a daily force from overlying soft tissue, a unidirectional load was applied at the "keystone" region given its structural role and compared with native cartilaginous properties. 3D-printed solid SFG, PCL, and PLA and scaffold PCL and PLA models demonstrated lower deformations compared to cartilage. Solid SFG balanced strength and flexibility. The maximum stress was below all materials' yield stresses suggesting their deformations are unlikely permanent under a daily load. Our FEA models suggest that 3D-printed L-strut implants carry promising mechanical strength. Solid SFG's results mimicked cartilage's mechanical behavior. Thus, scaffold SFG merits further geometric optimization for potential use for cartilage substitution. 3D-printed septal cartilage replacement implants can potentially enhance surgical management of patients who lack available donor cartilage in select settings. Computational simulations can evaluate 3D-printed implant strength and their potential to replace septal cartilage in septorhinoplasty.

An Investigative Study on the Oral Health Condition of Individuals Undergoing 3D-Printed Customized Dental Implantation.

The advent of three-dimensional (3D) printing technology has revolutionized the field of dentistry, enabling the precise fabrication of dental implants. By utilizing 3D printing, dentists can devise implant plans prior to surgery and accurately translate them into clinical procedures, thereby eliminating the need for multiple surgical procedures, reducing surgical discomfort, and enhancing surgical efficiency. Furthermore, the utilization of digital 3D-printed implant guides facilitates immediate restoration by precisely translating preoperative implant design plans, enabling the preparation of temporary restorations preoperatively. This comprehensive study aimed to assess the postoperative oral health status of patients receiving personalized 3D-printed implants and investigate the advantages and disadvantages between the 3D-printed implant and conventional protocol. Additionally, variance analysis was employed to delve into the correlation between periodontal status and overall oral health. Comparisons of continuous paired parameters were made by t-test. The results of our study indicate a commendable one-year survival rate of over 94% for 3D-printed implants. This finding was corroborated by periodontal examinations and follow-up surveys using the Oral Health Impact Profile-14 (OHIP-14) questionnaire, revealing excellent postoperative oral health status among patients. Notably, OHIP-14 scores were significantly higher in patients with suboptimal periodontal health, suggesting a strong link between periodontal health and overall oral well-being. Moreover, we found that the operating time (14.41 ± 4.64 min) was less statistically significant than for the control group (31.76 ± 6.83 min). In conclusion, personalized 3D-printed implant surgery has emerged as a reliable clinical option, offering a viable alternative to traditional implant methods. However, it is imperative to gather further evidence-based medical support through extended follow-up studies to validate its long-term efficacy and safety.

Surgical Planning and 3D-Printed Mesh Implant for Effective Bone Gap Management: A Case Report

Introduction: Critical-size bone defects in distal tibial open wounds pose a formidable challenge, requiring interventions that can address osseous reconstruction with less number of surgeries. Current treatment modalities may fall short in achieving optimal outcomes, with respect to early weight bearing due to the inability of the graft to sustain weight, graft-related infections, non-union in large defects, donor site morbidity, and non-availability of bone grafts due to earlier harvest. This case report explores the potential application of a 3D-printed mesh implant to this complex clinical scenario. Case Report: A 38-year-old male, post-road traffic accident, presented with an inability to walk due to fractures of the medial malleolus and distal tibia-fibula with a grade 3b open wound. Initial treatment was done with an external fixator and fibula plating, with the fixator removed after 5 months. The fracture showed atrophic non-union and a 2.5 cm limb shortening at the end of 5 months. Preferring thick flap incisions, the patient operated with a 3D-printed titanium mesh implant with a plate construct. Post-surgery, we followed a non-weight-bearing regime for 1.5 months, progressing to full weight-bearing by 3 months. At 1.5 years, CT scans confirmed good bone integration and ambulation restoration. Conclusion: The use of 3D-printed mesh implants may be a viable option for managing critical-size bone defects in distal tibial open wounds. Porotic nature of mesh implant facilitates bone ingrowth in large gaps. Keywords: 3D-printing, mesh implant, non-union.

Nanoscaled Titanium Oxide Layer Provokes Quick Osseointegration on 3D-Printed Dental Implants: A Domino Effect Induced by Hydrophilic Surface.

Three-dimensional printing is a revolutionary strategy to fabricate dental implants. Especially, 3D-printed dental implants modified with nanoscaled titanium oxide layer (H-SLM) have impressively shown quick osseointegration, but the accurate mechanism remains elusive. Herein, we unmask a domino effect that the hydrophilic surface of the H-SLM facilitates blood wetting, enhances the blood shear rate, promotes blood clotting, and changes clot features for quick osseointegration. Combining computational fluid dynamic simulation and biological verification, we find a blood shear rate during blood wetting of the hydrophilic H-SLM 1.2-fold higher than that of the raw 3D-printed implant, which activates blood clot formation. Blood clots formed on the hydrophilic H-SLM demonstrate anti-inflammatory and pro-osteogenesis effects, leading to a 1.5-fold higher bone-to-implant contact and a 1.8-fold higher mechanical anchorage at the early stage of osseointegration. This mechanism deepens current knowledge between osseointegration speed and implant surface characteristics, which is instructive in surface nanoscaled modification of multiple 3D-printed intrabony implants.

Finite Element Analysis of Patient-Specific 3D-Printed Cranial Implant Manufactured with PMMA and PEEK: A Mechanical Comparative Study.

This article reports on a patient who required a cranial protection system. Using additive manufacturing techniques and surgical planning with the help of bio-models, a patient-specific bone implant solution was proposed that allows aesthetic restoration of the affected area and provides an adequate level of protection. In addition, through a comparative analysis with finite elements, the mechanical response to external actions of the medical device, printed with two materials: polymethylmethacrylate (PMMA) and polyether-ether-ketone (PEEK), is simulated. The tested materials have recognized biocompatibility properties, but their costs on the market differ significantly. The results obtained demonstrate the similarities in the responses of both materials. It offers the possibility that low-income people can access these devices, guaranteeing adequate biomechanical safety, considering that PMMA is a much cheaper material than PEEK.

Comparison of Fit and Stability Between 3D-Printed and Milled Implant Abutments with Titanium-6Al-4V and Co-Cr Metal Alloys.

To compare the fit of 3D-printed titanium (Ti) and cobalt-chromium (Co-Cr) abutments with implants to computer numerical control (CNC)-milled, ready-made abutment-implant assemblies. Their clinical applicability was also evaluated by measuring removal torque values (RTVs) and percentage torque loss of abutment screws. A total of 138 abutments were included in the study: 92 abutments were fabricated with Ti and Co-Cr alloys using computer-assisted design (CAD) through selective laser melting, and 46 ready-made abutments were prepared. The fit of interfaces between 90 abutments from the three groups (30 ready-made, 30 3D-printed Ti, and 30 3D-printed Co-Cr abutments) and implant assemblies was demonstrated by scanning electron microscopy (SEM) and confocal scanning laser microscopy (CSLM). After 30-Ncm torque tightening of Ti abutment screws twice within 10 minutes, the RTVs and percentage torque loss of screws of 48 abutments (16 ready-made, 16 3D-printed Ti, and 16 3D-printed Co-Cr) were evaluated after 10 minutes of thermocycling and cyclic loading. The fits of 3D-printed Co-Cr abutments were not statistically different from those of ready-made abutments (P = .383), while the fit of 3D-printed Ti abutments was inadequate (P < .001). The RTVs of 3D-printed abutments after cyclic loading were significantly decreased compared with those of CNC-milled abutments (P < .001). The fit of interfaces between 3D-printed Co-Cr abutments and implants was adequate. The RTVs of 3D-printed Co-Cr abutments were not significantly different from those of CNC-milled abutments after 10 minutes of 30-Ncm torque tightening and thermocycling.

Gold-Enhanced Brachytherapy by a Nanoparticle-Releasing Hydrogel and 3D-Printed Subcutaneous Radioactive Implant Approach.

Brachytherapy (BT) is a widely used clinical procedure for localized cervical cancer treatment. In addition, gold nanoparticles (AuNPs) have been demonstrated as powerful radiosensitizers in BT procedures. Prior to irradiation by a BT device, their delivery to tumors can enhance the radiation effect by generating low-energy photons and electrons, leading to reactive oxygen species (ROS) production, lethal to cells. No efficient delivery system has been proposed until now for AuNP topical delivery to localized cervical cancer in the context of BT. This article reports an original approach developed to accelerate the preclinical studies of AuNP-enhanced BT procedures. First, an AuNP-containing hydrogel (Pluronic F127, alginate) is developed and tested in mice for degradation, AuNP release, and biocompatibility. Then, custom-made 3D-printed radioactive BT inserts covered with a AuNP-containing hydrogel cushion are designed and administered by surgery in mice (HeLa xenografts), which allows for measuring AuNP penetration in tumors (≈100µm), co-registered with the presence of ROS produced through the interactions of radiation and AuNPs. Biocompatible AuNPs-releasing hydrogels could be usedin the treatment of cervical cancer prior to BT, with impact on the total amount of radiation needed per BT treatment, which will result in benefits to the preservation of healthy tissues surrounding cancer.

A 3D-Printed Graphene BioFuse Implant for Postsurgical Adjuvant Therapy of Cancer: Proof of Concept in 2D- and 3D-Spheroid Tumor Models.

Three-dimensional printing is an emerging technology that is finding its niche applications in diverse fields owing to its flexibility concerning personalization and design. Surgery followed by adjuvant therapy is the standard treatment plan in most cancers from stage I to stage III. Most of the available adjuvant therapies, like chemotherapy, radiation therapy, immunotherapy, hormonal therapy, etc., are associated with severe side effects that considerably reduce the quality of life of patients. In addition, there is always the chance of tumor recurrence or metastasis development followed by surgery. This investigation reports the development of a 3D-printed, biodegradable, laser-responsive implant with a chemo-combined thermal ablating potential for adjuvant therapy of cancer. The 3D-printable ink was developed using poly(l-lactide) and hydroxypropyl methylcellulose as the base polymer, doxorubicin as the chemotherapeutic agent, and reduced graphene oxide as the photothermal ablating agent. The personalized implant released the drug pH-dependently (p value < 0.0001) for an extended period (93.55 ± 1.80% → 28 days). The 3D-printed implant exhibited acceptable biophysical properties (tensile strength: 3.85 ± 0.15 MPa; modulus: 92.37 ± 11.50 MPa; thickness: 110 μm) with laser-responsive hyperthermia (ΔT: 37 ± 0.9 °C → 48.5 ± 1.07 °C; 5 min; 1.5 W/cm2) and inherent biodegradable property (SEM analysis). The 3D-printed implant was evaluated for its therapeutic potential in 2D- and 3D-spheroid tumor models (MDA-MB 231 and SCC 084 2D cells) employing MTT cytotoxicity assay, apoptosis assay, cell cycle analysis, and gene expression analysis. The biomolecular aspects and biomechanics of the 3D-printed BioFuse implant were also evaluated by determining the effect of treatment on the expression levels of HSP1A, Hsp70, BAX, and PTEN. It is advocated that the knowledge developed in this project will significantly assist and advance the science aiming to develop a clinically translatable postsurgical adjuvant therapy for cancer.

Assessing the Impact of Resin Type, Post-Processing Technique, and Arch Location on the Trueness and Precision of 3D-Printed Full-Arch Implant Surgical Guides

Objective: The purpose of this study was to assess the impact of photopolymer resin type, arch location, and post-processing techniques on the trueness and precision of three-dimensionally printed (3DP) full-arch surgical implant guides. Methods: Stereolithography reference images of an upper and lower surgical guide with six drill holes from a full-mouth rehabilitation clinical case were used. The files were imported into the Asiga MAX UV slicing software (Asiga Composer) where build orientation, print resolution, and support structures were added. A digital light processing 3D printer (MAX UV, Asiga Max) was used for printing the samples. The samples assessed were printed using two different, manufacturer-validated resins, DentaGuide (n = 35) and DentaClear (n = 20). The samples were subdivided and measured based on the post-processing technique used: handwashing (n = 20), sonication (n = 25), a mix of handwashing and sonication (n = 10), and post-curing using 385 nm UVA light with nitrogen (n = 50) or without nitrogen (n = 5). The diameter of each drill hole per guide was measured using a coordinate measuring machine (Absolute Arm 7-Axis, Hexagon) and compared with the reference STL to calculate each sample’s trueness (median error) and precision (interquartile range). The Mann–Whitney and Kruskal–Wallis tests were used for statistical analyses. Results: All samples demonstrated a dimensional error of &lt;70 µm. No significant differences (p &gt; 0.05) were observed between upper and lower arches and between post-processing techniques using nitrogen, irrespective of the use of hand- or ultrasonic washing. In contrast, DentaClear resin was significantly (p &lt; 0.001) more accurate with a trueness of 26 µm and precision of 12 to 34 µm versus the DentaGuide at −31 µm and −54 to −17 µm, respectively. The samples post-cured without nitrogen were significantly (p &lt; 0.05) the least accurate of all surgical guides, with a trueness of −42 µm and precision of −68 to −39 µm. Conclusion: The resin type and nitrogen post-processing are parameters that can significantly impact the accuracy of surgical guides. The tolerance of 3DP surgical guides needs to account for the dimensional changes occurring during the manufacturing process to minimise implant positioning errors.

Fabrication of 3D-Printed Implant for Two-Stage Ear Reconstruction Surgery and Its Clinical Application.

Ear reconstruction is one of the most difficult areas in the field of reconstructive surgery. Due to limitations of the current practice, a novel method of auricular reconstruction is needed. Major advancements in three-dimensional (3D) printing technique have rendered the process of ear reconstruction more favorable. Herein, we present our experience in designing and clinically using 3D implants in both 1st and 2nd stage ear reconstruction surgery. After obtaining 3D CT data from each patient, a 3D geometric ear model was created using mirroring and segmentation processes. The 3D-printed implant design resembles but does not exactly match the normal ear shape, and can be inserted in harmony with the currently used surgical technique. The 2nd stage implant was designed to minimize dead space and support the posterior ear helix. The 3D implants were finally fabricated with a 3D printing system and used in ear reconstruction surgery in our institute. The 3D implants were manufactured for application to the currently used two-stage technique while maintaining the shape of the patient's normal ear. The implants were successfully used for ear reconstruction surgery in microtia patients. A few months later, the 2nd stage implant was used in the 2nd stage operation. The authors were able to design, fabricate, and apply patient-specific 3D-printed ear implants for 1st and 2nd stage ear reconstruction surgeries. This design, combined with 3D bioprinting technique, may be a future alternative for ear reconstruction.

Custom 3D-Printed Implants for Acetabular Reconstruction: Intermediate-Term Functional and Radiographic Results.

We reviewed a database of consecutive patients who had undergone acetabular reconstruction with the use of a custom 3D-printed implant with a dual-mobility bearing for the treatment of Paprosky type-3B defects between 2016 and 2019. Functional and radiological outcomes were assessed. A total of 26 patients (17 women and 9 men) with a minimum follow-up of 36 months (median, 53 months; range, 36 to 77 months) were identified. The median age at surgery was 69 years (range, 49 to 90 years), and 4 patients had pelvic discontinuity. The cumulative implant survivorship was 100%. The median Oxford Hip Score improved significantly from 8 (range, 2 to 21) preoperatively to 32 (range, 14 to 47) postoperatively (p = 0.0001). One patient had a transient sciatic nerve palsy, 1 hip dislocated 6 months postoperatively and was managed nonoperatively, and 1 infection recurred. No patient had a fracture. Radiographic evaluation showed bone ingrowth at the bone-implant interface in 24 patients (92%) at ≥12 months of follow-up and showed no evidence of implant loosening or migration at the latest follow-up (3 to 6 years). Excellent functional improvement, implant survivorship, and osseointegration were recorded in the patient cohort. Accurate preoperative planning and the adoption of custom 3D-printed implants showed promising results in complex revision hip surgery. Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Outcomes of mandibular reconstruction using three-dimensional custom-made porous titanium prostheses

BackgroundOur aim was to report the long-term outcomes of mandibular reconstruction using CAD-CAM-designed 3D-printed porous titanium implants in patients not amenable to a free vascularized fibula flap reconstruction. MethodsThe implants were designed with ProPlan CMF® 2.2 software and manufactured with a Selective Laser Melting (SLM) “layer-by-layer” 3D-printing of pure porous titanium powder beds. Primary endpoints were implant exposure and implant removal calculated using Gray's tests. Secondary endpoints were predictive factors of implant exposure and implant removal, and rates of dental rehabilitation. ResultsThirty-six patients were operated between 2015 and 2017 and were included in this study. Reconstruction using a porous titanium 3D-printed implant was proposed due to medical contraindication for a fibula free flap (n = 13), due to the failure of a previous fibula free flap reconstruction (n = 7), or due to refusal of a fibula free flap reconstruction by the patient (n = 16). The medical indications for mandibular reconstruction were a primary tumor requiring mandibulectomy in nine patients, mandibular osteoradionecrosis requiring mandibulectomy in nineteen patients, and secondary reconstruction in eight patients. The 2-year rates of implant exposure and implant removal were 69.4% and 52.8%. Reconstruction of the symphysis was a high-risk exposure variable (OR 30; p = 0.0003). Only one patient underwent a successful dental rehabilitation. ConclusionThe use of a porous titanium 3D- implant for mandibular reconstruction in head and neck cancer patients resulted in high rates of implant exposure and of implant removal, notably when symphysis involvement.

Comparative Analysis of the Stress–Strain State of a Lightweight 3D-Printed Shoulder Implant

Comparative Analysis of the Stress–Strain State of a Lightweight 3D-Printed Shoulder Implant

Development and evaluation of hydroxytite-based anti-microbial surface coatings on polydopamine-treated porous 3D-printed Ti6Al4V alloys for overall biofunctionality

The current investigation aims to develop hydroxyapatite-based biofunctional composite coatings on polydopamine-treated porous 3D-printed Ti6Al4V alloy implant specimens for orthopedic uses. The porous 3D-printed implants based on Ashby Gibson’s mathematical model for cellular materials are fabricated at a 65% level of porosity, so as to attain the mechanical strength of human bones. Further, the addition of strontium and silver in hydroxyapatite for improved biocompatibility of the 3D-printed implant to enhance its biofunctionality and its validation is performed. The resulting coated substrates are subjected to a series of morphological, elemental, phase, mechanical, and biological tests. When subjected to the uniaxial compression, the values for modulus of elasticity and yield strength of 3D-printed substrates are compared to the targeted value of elastic modulus and yield strength for the human bones (10–30 GPa and 148–240 MPa, respectively). The effect of polydopamine-treated 3D-printed Ti6Al4V substrates on the coating compositions of calcium and phosphorus has been compared to the untreated samples. The coating thickness and adhesion strength have been calculated and compared for different coating groups. All the samples, except untreated pure hydroxyapatite samples, displayed antimicrobial activity for both the gram-positive and gram-negative bacteria in the zone inhibition test. Hence, the current experiment provides a novel option to fabricate porous Ti6Al4V scaffolds, with a low-temperature surface coating to attain improved biofunctionality for orthopedic applications.

Outcomes of Surgical Reconstruction Using Custom 3D-Printed Porous Titanium Implants for Critical-Sized Bone Defects of the Foot and Ankle.

Treating critically sized defects (CSDs) of bone remains a significant challenge in foot and ankle surgery. Custom 3D-printed implants are being offered to a small but growing subset of patients as a salvage procedure in lieu of traditional alternates such as structural allografts after the patient has failed prior procedures. The long-term outcomes of 3D-printed implants are still unknown and understudied because of the limited number of cases and short follow-up durations. The purpose of this study was to evaluate the outcomes of patients who received custom 3D-printed implants to treat CSDs of the foot and ankle in an attempt to aid surgeons in selecting appropriate surgical candidates. This was a retrospective study to assess surgical outcomes of patients who underwent implantation of a custom 3D-printed implant made with medical-grade titanium alloy powder (Ti-6Al-4V) to treat CSDs of the foot and ankle between June 1, 2014, and September 30, 2019. All patients had failed previous nonoperative or operative management before proceeding with treatment with a custom 3D-printed implant. Univariate and multivariate odds ratios (ORs) of a secondary surgery and implant removal were calculated for perioperative variables. There were 39 cases of patients who received a custom 3D-printed implant with at least 1 year of follow-up. The mean follow-up time was 27.0 (12-74) months. Thirteen of 39 cases (33.3%) required a secondary surgery and 10 of 39 (25.6%) required removal of the implant because of septic nonunion (6/10) or aseptic nonunion (4/10). The mean time to secondary surgery was 10 months (1-22). Multivariate logistic regression revealed that patients with neuropathy were more likely to require a secondary surgery with an OR of 5.76 (P = .03). This study demonstrated that 74% of patients who received a custom 3D-printed implant for CSDs did not require as subsequent surgery (minimum of 1-year follow-up). Neuropathy was significantly associated with the need for a secondary surgery. This is the largest series to date demonstrating the efficacy of 3D-printed custom titanium implants. As the number of cases using patient-specific 3D-printed titanium implant increases, larger cohorts of patients should be studied to identify other high-risk groups and possible interventions to improve surgical outcomes. Level IV, case series.

Biomechanical Analyses of Porous Designs of 3D-Printed Titanium Implant for Mandibular Segmental Osteotomy Defects.

Clinically, a reconstruction plate can be used for the facial repair of patients with mandibular segmental defects, but it cannot restore their chewing function. The main purpose of this research is to design a new three-dimensionally (3D) printed porous titanium mandibular implant with both facial restoration and oral chewing function reconstruction. Its biomechanical properties were examined using both finite element analysis (FEA) and in vitro experiments. Cone beam computed tomography images of the mandible of a patient with oral cancer were selected as a reference to create 3D computational models of the bone and of the 3D-printed porous implant. The pores of the porous implant were circles or hexagons of 1 or 2 mm in size. A nonporous implant was fabricated as a control model. For the FEA, two chewing modes, namely right unilateral molar clench and right group function, were set as loading conditions. Regarding the boundary condition, the displacement of both condyles was fixed in all directions. For the in vitro experiments, an occlusal force (100 N) was applied to the abutment of the 3D-printed mandibular implants with and without porous designs as the loading condition. The porous mandibular implants withstood higher stress and strain than the nonporous mandibular implant, but all stress values were lower than the yield strength of Ti-6Al-4V (800 MPa). The strain value of the bone surrounding the mandibular implant was affected not only by the shape and size of the pores but also by the chewing mode. According to Frost’s mechanostat theory of bone, higher bone strain under the porous implants might help maintain or improve bone quality and bone strength. The findings of this study serve as a biomechanical reference for the design of 3D-printed titanium mandibular implants and require confirmation through clinical investigations.

New way to obtain the poly(L-lactide-co-D,L-lactide) blend filled with nanohydroxyapatite as biomaterial for 3D-printed bone-reconstruction implants

A novel, bone-reconstruction dedicated polymeric-nanohydroxyapatite material has been prepared for 3D-printed implant. The composites of poly(L-lactide-co-D,L-lactide) (PLDLLA) and nanosized hydroxyapatite were prepared by a co-rotating twin-screw extrusion. Structural properties of the filler and polymeric blends were characterized by XRD (X-ray Powder Diffraction), SEM (Scanning Electron Microscopy), and EDS mapping (energy dispersive spectroscopy), FT-IR (Fourier-transformed infrared spectroscopy), and NMR (Nuclear Magnetic Resonance) technics. Molar masses of the composites at various preparation steps were also investigated. The structural studies and thermogravimetric analysis proved a successful preparation of the nanohydroxyapatite and its nanocomposites. Mechanical results in conjunction with density values, reported as close to human bone, evidenced usability of this novel material for internal bone fixation implant. Contact angle analysis showed favored growth of tissue on the biocomposite containing 10 wt% of the filler. The PLDLLA-based composite can be an excellent candidate for bone reconstruction implants due to their superior mechanical properties, bioactivity, and complete resorbability.