Additive manufacturing: current concepts, future trends

3D printed bioabsorbable composite scaffolds of poly (lactic acid)-tricalcium phosphate-ceria with osteogenic property for bone regeneration

The fabrication of customized implants by additive manufacturing has allowed continued development of the personalized medicine field. Herein, a 3D-printed bioabsorbable poly (lactic acid) (PLA)- β-tricalcium phosphate (TCP) (10 wt %) composite has been modified with CeO2 nanoparticles (CeNPs) (1, 5 and 10 wt %) for bone repair. The filaments were prepared by melt extrusion and used to print porous scaffolds. The nanocomposite scaffolds possessed precise structure with fine print resolution, a homogenous distribution of TCP and CeNP components, and mechanical properties appropriate for bone tissue engineering applications. Cell proliferation assays using osteoblast cultures confirmed the cytocompatibility of the composites. In addition, the presence of CeNPs enhanced the proliferation and differentiation of mesenchymal stem cells; thereby, increasing alkaline phosphatase (ALP) activity, calcium deposition and bone-related gene expression. Results from this study have shown that the 3D printed PLA-TCP-10%CeO2 composite scaffold could be used as an alternative polymeric implant for bone tissue engineering applications: avoiding additional/revision surgeries and accelerating the regenerative process.

Continued Stabilization of a Cementless 3D-Printed Total Knee Arthroplasty: Five-Year Results of a Randomized Controlled Trial Using Radiostereometric Analysis

BACKGROUND

Three-dimensional (3D) printing of highly porous orthopaedic implants aims to promote better osseointegration, thus preventing aseptic loosening. However, short-term radiostereometric analysis (RSA) after total knee arthroplasty (TKA) has shown higher initial migration of cementless 3D-printed tibial components compared with their cemented counterparts. Therefore, critical evaluation of longer-term tibial component migration is needed. We investigated migration of a cementless 3D-printed and a cemented tibial component with otherwise similar TKA design during 5 years of follow-up, particularly the progression in migration beyond 2 years postoperatively.

METHODS

Seventy-two patients were randomized to a cementless 3D-printed Triathlon Tritanium (Stryker) cruciate-retaining (CR) TKA or a cemented Triathlon CR (Stryker) TKA implant. Implant migration was evaluated with RSA at baseline and postoperatively at 3 months and at 1, 2, and 5 years. The maximum total point motion (MTPM) of the tibial component was compared between the groups at 5 years, and progression in migration was assessed between 2 and 5 years. Individual implants were classified as continuously migrating if the MTPM was ≥0.1 mm/year beyond 2 years postoperatively. Clinical scores were evaluated, and a linear mixed-effects model was used to analyze repeated measurements.

RESULTS

At 5 years, the mean MTPM was 0.66 mm (95% confidence interval [CI], 0.56 to 0.78 mm) for the cementless group and 0.53 mm (95% CI, 0.43 to 0.64 mm) for the cemented group (p = 0.09). Between 2 and 5 years, there was no progression in mean MTPM for the cementless group (0.02 mm; 95% CI, -0.06 to 0.10 mm) versus 0.07 mm (95% CI, 0.00 to 0.14) for the cemented group. One implant was continuously migrating in the cementless group, and 4 were continuously migrating in the cemented group. The clinical scores were comparable between the groups across the entire time of follow-up.

CONCLUSIONS

No significant difference in mean migration was found at 5 years between the cementless and cemented TKA implants. Progression of tibial component migration was present beyond 2 years for the cemented implant, whereas the cementless implant remained stable after initial early migration.

LEVEL OF EVIDENCE

Therapeutic Level I . See Instructions for Authors for a complete description of levels of evidence.

The Role of 3D-Printed Patient-Specific Instrumentation in Total Knee Arthroplasty: A Literature Review

Total knee arthroplasty (TKA) is currently one of the most common orthopedic surgeries due to the ever-increasing average life expectancy. The constant need for effective and accurate techniques was contributed to the development of three-dimensional (3D) printing in that field, especially for patient-specific instrumentation (PSI) and custom-made implants fabrication. PSI may offer numerous benefits, such as resection accuracy, mechanical axis alignment, cost-effectiveness, and time economy. Nonetheless, the results of existing studies are controversial. For this purpose, a review article of the published articles was conducted to summarize the role of 3D-printed PSI in TKA.

Liner type has no impact on bone mineral density changes around a 3D printed trabecular titanium acetabular component

BACKGROUND

Three-dimensional printing of implants allows the ability to produce implants and interfaces which theoretically better mimic "normal" bone behaviour, leading to a possible reduction in stress shielding thus maintaining bone mineral density (BMD). This issue was not investigated in vivo using bone scan and different bearings; therefore, we did a prospective study aiming to answer: 1) is there a loss of BMD around the 3D printed trabecular titanium cup, when compared to the native hip?; 2) does liner type influence the BMD changes around the acetabulum when a 3D printed trabecular titanium cup is used?

HYPOTHESIS

BMD changes around the acetabulum are not influenced by the liner type, and the cup will be associated with a reduction in BMD when compared to the native hip.

MATERIAL AND METHODS

This is a prospective observational study of patients receiving a primary total hip arthroplasty. A 3D printed trabecular titanium uncemented acetabular component was used in all cases. All patients received a ceramic femoral head, with either a ceramic or polyethylene acetabular liner. BMD measurements using DXA were performed at 6 weeks, 6, 12 and 24 months after surgery to evaluate remodeling changes. The 3 acetabular regions of interest (ROI) of DeLee and Charnley were used for serial comparisons of peri-acetabular BMD. The study was powered as a non-inferiority study with the principle variables compared using a two-step repeated analysis of variance.

RESULTS

A total of 48 consecutive patients were included in the study, with all patients completing their 2 year follow-up. There were no failures, revisions or complications within this cohort. We found no statistically significant difference in the BMD change scores between the operated and the native hip in any of the 3 ROI zones. We found no differences in BMD scores when comparing ceramic to polyethylene acetabular liners, head sizes and BMI.

DISCUSSION

This study shows a similar pattern of BMD behaviour around a 3D printed cup when compared to the contralateral native hip. We were unable to show a clinical or radiological difference between the bearing material, head size, or BMI when used with this type of acetabular component.

LEVEL OF EVIDENCE

III; prospective comparative study.

Modern cementless posterior stabilized mobile-bearing total knee arthroplasty shows comparable clinical and radiographical results to its cemented predecessor at 1-year follow-up

PURPOSE

The purpose of this study was to evaluate perioperative and short-term clinical and radiographical results of a modern PS mobile-bearing cementless TKA system.

METHODS

A retrospective review of a consecutive series of TKAs was performed by a single surgeon using a cementless or cemented TKA of the same design (Attune, DePuy Synthes, Massachusetts, USA). The 2011 Knee Society Score, Forgotten Joint Score-12, Hip-Knee-Ankle angle, and the presence of radiolucent lines (RLLs) were reviewed 1-year postoperatively with 1:1 matching performed for age, gender, body mass index, and preoperative UCLA score. Fisher's exact test or independent Student's t-test were used for statistical analyses.

RESULTS

Forty-five cementless and 45 cemented TKAs were reviewed after 1:1 matching. The mean operative time was 8.8 min shorter (P < .01), and the mean amount of drainage was 40.0 ml greater (P = .04) in the cementless cohort. At 1-year postoperatively, there were no significant differences in both cohorts in 2011 Knee Scores and Forgotten Joint Scores-12, with no patients requiring revision surgery (NS). The incidence of RLLs was significantly higher in cementless TKAs (51%) than that in cemented TKAs (22%, P < .01). However, the mean width of RLLs in the cementless TKAs (0.2 mm) was significantly smaller (P < .01) than that in the cemented TKAs (0.8 mm) at 1-year postoperatively with no progression.

CONCLUSION

A recently introduced cementless PS mobile-bearing TKA design demonstrated comparable postoperative and radiographical results to its cemented predecessor at 1-year follow-up.

LEVEL OF EVIDENCE

Retrospective cohort study, Level III.

[Update on 3D printing in the surgery of musculoskeletal tumors]

The importance of 3D printing applications in the surgery of musculoskeletal tumors has increased in recent years. Even prior to the era of 3D printing, computer-assisted techniques, such as navigation, have proved their utility. Due to the variable appearance of bone tumors, there is a need for individual solutions. The 3D printing can be used for the development of anatomical demonstration models, the construction of patient-specific instruments and custom-made implants. For these three applications, different regulatory hurdles exist. Especially for the resection of pelvic tumors, 3D printing technologies seem to provide advantages due to the complicated anatomy and the proximity to relevant neurovascular structures. With the introduction of titanium printing, construction of individualized implants that fit exactly into the defect became feasible.

Main Applications and Recent Research Progresses of Additive Manufacturing in Dentistry

In recent ten years, with the fast development of digital and engineering manufacturing technology, additive manufacturing has already been more and more widely used in the field of dentistry, from the first personalized surgical guides to the latest personalized restoration crowns and root implants. In particular, the bioprinting of teeth and tissue is of great potential to realize organ regeneration and finally improve the life quality. In this review paper, we firstly presented the workflow of additive manufacturing technology. Then, we summarized the main applications and recent research progresses of additive manufacturing in dentistry. Lastly, we sketched out some challenges and future directions of additive manufacturing technology in dentistry.

Three-Dimensional (3D) Printing: Implications for Risk Assessment and Management in Occupational Settings

The widespread application of additive manufacturing (AM) technologies, commonly known as three-dimensional (3D) printing, in industrial and home-business sectors, and the expected increase in the number of workers and consumers that use these devices, have raised concerns regarding the possible health implications of 3D printing emissions. To inform the risk assessment and management processes, this review evaluates available data concerning exposure assessment in AM workplaces and possible effects of 3D printing emissions on humans identified through in vivo and in vitro models in order to inform risk assessment and management processes. Peer-reviewed literature was identified in Pubmed, Scopus, and ISI Web of Science databases. The literature demonstrated that a significant fraction of the particles released during 3D printing could be in the ultrafine size range. Depending upon the additive material composition, increased levels of metals and volatile organic compounds could be detected during AM operations, compared with background levels. AM phases, specific job tasks performed, and preventive measures adopted may all affect exposure levels. Regarding possible health effects, printer emissions were preliminary reported to affect the respiratory system of involved workers. The limited number of workplace studies, together with the great variety of AM techniques and additive materials employed, limit generalizability of exposure features. Therefore, greater scientific efforts should be focused at understanding sources, magnitudes, and possible health effects of exposures to develop suitable processes for occupational risk assessment and management of AM technologies.

Meniscal Salvage: Where We Are Today

The menisci are fibrocartilaginous semilunar structures in the knee that provide load support. Injury to the meniscus alters its load sharing and biomechanical profile. Knee arthroscopy with meniscus débridement is the most common orthopaedic surgical procedure done in the United States. The current goals of meniscal surgery are to preserve native meniscal tissue and maintain structural integrity. Meniscal preservation is critical to maintain the normal mechanics and homeostasis of the knee; however, it is not always feasible because of the structure's poor blood supply and often requires removal of irreparable tissue with meniscectomy. Efforts have increasingly focused on the promotion of meniscal healing and the replacement of damaged menisci with allografts, scaffolds, meniscal implants, or substitutes. The purpose of this article was to review current and future meniscal salvage treatments such as meniscus transplant, synthetic arthroplasty, and possible bioprinted meniscus to allow patients to maintain quality of life, limit pain, and delay osteoarthritis.

Monitoring of Particulate Matter Emissions from 3D Printing Activity in the Home Setting

Consumer-level 3D printers are becoming increasingly prevalent in home settings. However, research shows that printing with these desktop 3D printers can impact indoor air quality (IAQ). This study examined particulate matter (PM) emissions generated by 3D printers in an indoor domestic setting. Print filament type, brand, and color were investigated and shown to all have significant impacts on the PM emission profiles over time. For example, emission rates were observed to vary by up to 150-fold, depending on the brand of a specific filament being used. Various printer settings (e.g., fan speed, infill density, extruder temperature) were also investigated. This study identifies that high levels of PM are triggered by the filament heating process and that accessible, user-controlled print settings can be used to modulate the PM emission from the 3D printing process. Considering these findings, a low-cost home IAQ sensor was evaluated as a potential means to enable a home user to monitor PM emissions from their 3D printing activities. This sensing approach was demonstrated to detect the timepoint where the onset of PM emission from a 3D print occurs. Therefore, these low-cost sensors could serve to inform the user when PM levels in the home become elevated significantly on account of this activity and furthermore, can indicate the time at which PM levels return to baseline after the printing process and/or after adding ventilation. By deploying such sensors at home, domestic users of 3D printers can assess the impact of filament type, color, and brand that they utilize on PM emissions, as well as be informed of how their selected print settings can impact their PM exposure levels.

A New Additive-Manufactured Cementless Highly Porous Titanium Acetabular Cup for Primary Total Hip Arthroplasty-Early Two-Year Follow Up

INTRODUCTION

Additive-manufacturing technologies are increasingly being used, not only to create acetabular components with porous coating architecture very similar to the complex trabecular structure of cancellous bone, but also for producing the entire implant in a single step. The aim of this study is to assess two-year clinical and radiological outcomes of a new additive-manufactured cup in primary total hip arthroplasty (THA).

MATERIALS AND METHODS

We reviewed 266 primary THAs (254 patients) performed in our institution between December 2016 and December 2018 using a new highly porous titanium acetabulum shell fabricated via additive manufacturing. Clinical and functional outcomes were measured using SF/VR-12 and HOOS JR to determine patient satisfaction with surgery. Radiographs were assessed to determine the presence of migration, radiolucency, and loosening. Patients records were reviewed to assess cup survivorship in terms of all-cause revisions and revision for aseptic cup loosening.

RESULTS

At a minimum of two-year follow up (range: 2-3.45 years), the patient cohort demonstrated significant improvement in postoperative functional scores (hip disability and osteoarthritis outcome score for joint replacement [HOOS JR.] and clinical scores (12-item short-form health survey [SF/VR-12]) (p<0.001). One cup developed progressive radiolucent lines at the prosthesis-bone interface consistent with loosening and was revised. The overall acetabular component two-year survivorship free of all-cause failure was 97.4% (95% confidence interval [CI]: 95.5-99.4%). When aseptic loosening of the acetabular component was used as the failure endpoint, the two-years survivorship rate was 99.6% (95% CI: 98.9-100%).

CONCLUSION

Highly porous titanium cementless acetabular cups produced via additive-manufacturing showed promising early clinical and radiological results in primary THA with low rates of aseptic loosening. Further follow-up studies are needed to assess the long-term survivorship and outcomes of this new acetabular component.

Synergic Sustainability Implications of Additive Manufacturing in Automotive Spare Parts: A Case Analysis

Triple bottom line (3BL) approaches to sustainable supply chain management (SSCM) often involve trade-offs between their three dimensions (economic, environmental, and social), thus curtailing its application and leading to goal unalignment among stakeholders. Under some circumstances, however, synergic approaches (typically involving disruptive innovations) might allow simultaneous improvement in one or more dimensions without compromising the others. This paper analyzes one such case: the potential of properly designed additive manufacturing approaches in the automotive spare parts industry to simultaneously boost profits and reduce environmental impact. It is based on the systematic analysis of the real spare parts business of a mid-size automotive brand in Spain. Its results suggest that such synergic, self-reinforcing opportunities do indeed exist, and might even be further developed by strategically integrating sustainability constituents such as circularity.

Migration of a novel 3D-printed cementless versus a cemented total knee arthroplasty: two-year results of a randomized controlled trial using radiostereometric analysis

Aims

Although bone cement is the primary mode of fixation in total knee arthroplasty (TKA), cementless fixation is gaining interest as it has the potential of achieving lasting biological fixation. By 3D printing an implant, highly porous structures can be manufactured, promoting osseointegration into the implant to prevent aseptic loosening. This study compares the migration of cementless, 3D-printed TKA to cemented TKA of a similar design up to two years of follow-up using radiostereometric analysis (RSA) known for its ability to predict aseptic loosening.

Methods

A total of 72 patients were randomized to either cementless 3D-printed or a cemented cruciate retaining TKA. RSA and clinical scores were evaluated at baseline and postoperatively at three, 12, and 24 months. A mixed model was used to analyze the repeated measurements.

Results

The mean maximum total point motion (MTPM) at three, 12, and 24 months was 0.33 mm (95% confidence interval (CI) 0.25 to 0.42), 0.42 mm (95% CI 0.33 to 0.51), and 0.47 mm (95% CI 0.38 to 0.57) respectively in the cemented group, versus 0.52 mm (95% CI 0.43 to 0.63), 0.62 mm (95% CI 0.52 to 0.73), and 0.64 mm (95% CI 0.53 to 0.75) in the cementless group (p = 0.003). However, using three months as baseline, no difference in mean migration between groups was found (p = 0.497). Three implants in the cemented group showed a > 0.2 mm increase in MTPM between one and two years of follow-up. In the cementless group, one implant was revised due to pain and progressive migration, and one patient had a liner-exchange due to a deep infection.

Conclusion

The cementless TKA migrated more than the cemented TKA in the first two-year period. This difference was mainly due to a higher initial migration of the cementless TKA in the first three postoperative months after which stabilization was observed in all but one malaligned and early revised TKA. Whether the biological fixation of the cementless implants will result in an increased long-term survivorship requires a longer follow-up. Cite this article: Bone Joint J 2020;102-B(8):1016–1024.

3D printed locking osteosynthesis screw threads have comparable strength to machined or hand-tapped screw threads

Additive manufacturing, aka three dimensional (3D) printing, is increasingly being used for personalized orthopedic implants. Additively manufactured components normally undergo further processing, in particular 3D printed locking osteosynthesis plates require post-printing screw thread creation. The aim of this study was to compare 3D printed threads with machined and hand-tapped threads for a locking plate application. Pushout tests were performed on 115 additively manufactured specimens with tapered screw holes; additive manufacture was performed at 0°, 20°, 45°, or 90° build orientations. The screw holes were either machined, hand-tapped or 3D printed. The 3D printed screw holes were left as printed, or run through with a tap lubricated with water or with thread cutting oil. Printed threads run through using oil, with a build orientation of 90°, had comparable pushout force (median: 6377 N 95% confidence interval [CI]: 5616-7739 N) to machined (median: 6757 N; 95% CI: 6682-7303 N) and hand-tapped (median: 7805 N; 95% CI: 7154-7850 N) threads. As printed threads and those run through using water had significantly lower pushout forces. This study shows for the first time that 3D printed screw threads for a locking osteosynthesis plate application have comparable strength to traditionally produced screw threads.

Characterization of dimensional, morphological and morphometric features of retrieved 3D-printed acetabular cups for hip arthroplasty

Background

Three-dimensional (3D) printing of porous titanium implants is increasing in orthopaedics, promising enhanced bony fixation whilst maintaining design similarities with conventionally manufactured components. Our study is one of the first to non-destructively characterize 3D-printed implants, using conventionally manufactured components as a reference.

Methods

We analysed 16 acetabular cups retrieved from patients, divided into two groups: ‘3D-printed’ (n = 6) and ‘conventional’ (n = 10). Coordinate-measuring machine (CMM), electron microscopy (SEM) and microcomputed tomography (micro-CT) were used to investigate the roundness of the internal cup surface, the morphology of the backside surface and the morphometric features of the porous structures of the cups, respectively. The amount of bony attachment was also evaluated.

Results

CMM analysis showed a median roundness of 19.45 and 14.52 μm for 3D-printed and conventional cups, respectively (p = 0.1114). SEM images revealed partially molten particles on the struts of 3D-printed implants; these are a by-product of the manufacturing technique, unlike the beads shown by conventional cups. As expected, porosity, pore size, strut thickness and thickness of the porous structure were significantly higher for 3D-printed components (p = 0.0002), with median values of 72.3%, 915 μm, 498 μm and 1.287 mm (p = 0.0002). The median values of bony attachment were 84.9% and 69.3% for 3D-printed and conventional cups, respectively (p = 0.2635).

Conclusion

3D-printed implants are designed to be significantly more porous than some conventional components, as shown in this study, whilst still exhibiting the same shape and size. We found differences in the surface morphologies of the groups, related to the different manufacturing methods; a key finding was the presence of partially molten particles on the 3D-printed cups.

Evidence of structural cavities in 3D printed acetabular cups for total hip arthroplasty

The use of three-dimensional (3D) printing to manufacture off-the-shelf titanium acetabular cups for hip arthroplasty has increased; however, the impact of this manufacturing technology is yet not fully understood. Although several studies have described the presence of structural cavities in 3D printed parts, there has been no analysis of full postproduction acetabular components. The aim of this study was to investigate the effect of 3D printing on the material structure of acetabular implants, first comparing different designs of 3D printed cups, second comparing 3D printed with conventionally manufactured cups. Two of the 3D printed cups were produced using electron beam melting (EBM), one using laser rapid manufacturing (LRM). The investigation was performed using X-ray microcomputed tomography, imaging both the entire cups and samples sectioned from different regions of each cup. All 3D printed cups showed evidence of structural cavities; these were uniformly distributed in the volume of the samples and exhibited a prevalent spherical shape. The LRM-manufactured cup had significantly higher cavity density (p = .0286), with a median of 21 cavities/mm³ compared to 3.5 cavities/mm³ for EBM cups. However, the cavity size was similar, with a median of 20 μm (p = .7385). The conventional cups showed a complete absence of distinguishable cavities. The presence of cavities is a known limitation of the 3D printing technology; however, it is noteworthy that we found them in orthopedic implants used in patients. Although this may impact their mechanical properties, to date, 3D printed cups have not been reported to encounter such failures.

Comparative analysis of current 3D printed acetabular titanium implants

BACKGROUND

The design freedom allowed by three-dimensional (3D) printing enables the production of acetabular off-the-shelf cups with complex porous structures. The only studies on these designs are limited to clinical outcomes. Our aim was to analyse and compare the designs of different 3D printed cups from multiple manufacturers (Delta TT, Trident II Tritanium and Mpact 3D Metal).

METHODS

We analysed the outer surface of the cups using scanning electron microscopy (SEM) and assessed clinically relevant morphometric features of the lattice structures using micro-computed tomography (micro-CT). Dimensions related to the cup wall (solid, lattice and overall thickness) were also measured. Roundness and roughness of the internal cup surface were analysed with coordinate measuring machine (CMM) and optical profilometry.

RESULTS

SEM showed partially molten titanium beads on all cups, significantly smaller on Trident II (27 μm vs ~ 70 μm, p < 0.0001). We found a spread of pore sizes, with median values of 0.521, 0.841 and 1.004 mm for Trident II, Delta TT and Mpact, respectively. Trident II was also significantly less porous (63%, p < 0.0001) than the others (Delta TT 72.3%, Mpact 76.4%), and showed the thinnest lattice region of the cup wall (1.038 mm, p < 0.0001), while Mpact exhibited the thicker solid region (4.880 mm, p < 0.0044). Similar roundness and roughness of the internal cup surfaces were found.

CONCLUSION

This was the first study to compare the designs of different 3D printed cups. A variability in the morphology of the outer surface of the cups and lattice structures was found. The existence of titanium beads on 3D printed parts is a known by-product of the manufacturing process; however, their prevalence on acetabular cups used in patients is an interesting finding, since these beads may potentially be released in the body.

Surgical applications of three-dimensional printing in the pelvis and acetabulum: from models and tools to implants

There are numerous orthopaedic applications of three-dimensional (3D) printing for the pelvis and acetabulum. The authors reviewed recently published articles and summarized their experience. 3D printed anatomical models are particularly useful in pelvic and acetabular fracture surgery for planning, implant templating and for anatomical assessment of pathologies such as CAM-type femoroacetabular impingement and rare deformities. Custom-made metal 3D printed patient-specific implants and instruments are increasingly being studied for pelvic oncologic resection and reconstruction of resected defects as well as for revision hip arthroplasties with favourable results. This article also discusses cost-effectiveness considerations when preparing pelvic 3D printed models from a hospital 3D printing centre.

3D Printed Acetabular Cups for Total Hip Arthroplasty: A Review Article

Three-dimensional (3D) printed titanium orthopaedic implants have recently revolutionized the treatment of massive bone defects in the pelvis, and we are on the verge of a change from conventional to 3D printed manufacture for the mass production of millions of off-the-shelf (non-personalized) implants. The process of 3D printing has many adjustable variables, which taken together with the possible variation in designs that can be printed, has created even more possible variables in the final product that must be understood if we are to predict the performance and safety of 3D printed implants. We critically reviewed the clinical use of 3D printing in orthopaedics, focusing on cementless acetabular components used in total hip arthroplasty. We defined the clinical and engineering rationale of 3D printed acetabular cups, summarized the key variables involved in the manufacturing process that influence the properties of the final parts, together with the main limitations of this technology, and created a classification according to end-use application to help explain the controversial and topical issues. Whilst early clinical outcomes related to 3D printed cups have been promising, in-depth robust investigations are needed, partly because regulatory approval systems have not fully adapted to the change in technology. Analysis of both pristine and retrieved cups, together with long-term clinical outcomes, will help the transition to 3D printing to be managed safely.