An overview of 3D printed metal implants in orthopedic applications: Present and future perspectives

Systematic Review of joint preservation limb salvage in osteosarcoma around the knee

Introduction

Joint preservation limb salvage (JPLS) has benefited from advancements in tumor imaging and precision surgical technologies. However, discrepancies exist between the anticipated outcomes of surgical designs and actual clinical results. This study aims to provide a clearer understanding of JPLS.

Methods

A systematic search was conducted across the MEDLINE, Embase, and Cochrane Library databases from January 1, 2003, to December 31, 2023. The search utilized the following keywords: "osteosarcoma," "bone tumor," "limb salvage surgery," "surgery," "operation," and "knee." Inclusion criteria were: (1) publication of original studies in English; (2) clinical research pertaining to JPLS; and (3) studies offering detailed individual patient information.

Results

Ultimately, 25 articles encompassing 224 patients were included. The mean age at diagnosis was 16.8 years (range 2-59 years), with the peak incidence occurring between 9 and 18 years. Male patients predominated, with a male-to-female ratio of 1.46:1. Osteosarcomas were primarily located in the distal femur (170 cases) and proximal tibia (54 cases). Resection lengths were documented for 152 patients, averaging 167.6 mm (range 55-396 mm). Notably, reconstruction methods varied: 76 patients received allograft repair, 90 underwent inactivated tumor bone replantation, and 23 patients had autologous bone reconstruction. Additionally, 35 patients underwent prosthetic reconstruction, with 17 receiving traditionally manufactured customized prostheses and 18 utilizing 3D-printed prostheses. The average Musculoskeletal Tumor Society (MSTS) score for limb function was 26.7 points. Twelve patients experienced local tumor recurrence, 39 succumbed to tumor progression, and there were 96 non-oncological complications, predominantly fractures, infections, and bone nonunion.

Discussion

This review underscores the clinical efficacy of JPLS and examines tumor resection methods, reconstruction techniques, and associated complications.

Sintering 3D-Printed Hydroxyapatite-Wollastonite Lattices Improve Bioactivity and Mechanical Integrity for Bone Composite Scaffolds

The advancement of bone tissue engineering relies on the development of scaffolds that combine structural integrity with bioactivity. This study introduces a novel composite scaffold integrating three-dimensional (3D) printed hydroxyapatite (HA)-wollastonite (WOL) gyroid lattices with chitosan-gelatin cryogels, designed to fulfill these dual requirements. The HA-WOL lattices were fabricated using digital light processing (DLP) 3D-printing and subjected to optimized thermal treatment cycles demonstrating statistically superior compressive modulus and ultimate strength. This thermal process facilitated the phase transformation of HA-WOL to bioactive β-tricalcium phosphate (β-TCP) and silicocarnotite mixed phases, with MG63 (osteoblast-like) cell culture revealing significantly enhanced viability and biocompatibility. The chitosan-gelatin polymer network was successfully incorporated into the lattice, resulting in a composite scaffold with retained relative swelling capacity, improved mechanical stability, and superior bioactivity compared to cryogel-only constructs. Additional MG63 cell culture studies revealed that the composite scaffold supported cell viability and proliferation into the constructs, demonstrating its potential to conduct tissue regeneration across bone defects. This work highlights the synergistic effects of integrating bioactive ceramics with polymer-based cryogels, offering a promising solution to address bone regeneration in orthopaedic reconstruction. Future research will focus on in vivo validation and optimization of scaffold architecture to further enhance clinical relevance. This study paves the way for next-generation composite scaffolds capable of bridging the gap between mechanical integrity and biological performance in bone regeneration.

The Use of 3D Printing as an Educational Tool in Orthopaedics

Background

Three-dimensional (3D) printing has proven to be effective in orthopaedic surgery, improving both surgical planning and outcomes. Despite its increasing use in surgical programs, reviews evaluating its educational impact are sparse. Therefore, the aim of this review was to provide educators with evidence-based findings on 3D printing's potential in training junior surgeons, as well as discuss its benefits in enhancing patient communication.

Methods

A comprehensive search using PubMed and Web of Science databases was performed to identify articles related to orthopaedics, 3D printing, and education. After removing duplicates, 2,160 articles were screened, 152 underwent full-text review, and 50 met inclusion criteria. Articles discussed the impact of 3D-printed models on comprehension or surgical performance. Data on publication details, sample size, teaching focus, learning outcomes, costs, and conclusions were extracted. Learning effects in the control (didactic) and experimental (3DP) groups were compared.

Results

In fracture management training, studies demonstrated significantly improved fracture classification accuracy, surgical performance, and interobserver classification agreement with 3D models compared with didactic learning and traditional imaging modalities. These benefits were particularly evident in cases of complex fractures and junior trainees. In arthroscopy, 3D-printed simulators improved procedural accuracy and were more cost-effective than virtual reality simulators and cadaveric laboratory results. Three-dimensionally printed simulators were also assessed for skills related to spine surgery, in which trainees demonstrated clear learning curve improvements for pedicle screw placement and osteotomy techniques, as well as a better understanding of vital paraspinal structures. The application of 3D printing in patient education was equally promising, as it facilitated the process of informed consent, ultimately promoting shared decision making.

Conclusion

The use of 3D-printed models offers effective and customizable methods for developing essential surgical skills. Future research should focus on larger, more diverse study populations and should include long-term follow-up to better assess the impact of 3D printing on education and patient outcomes.

In-vivo and ex-vivo evaluation of bio-inspired structures fabricated via PBF-LB for biomedical applications

Titanium-based lattice structures have gained significant attention in biomedical engineering due to their potential to mimic bone-like behavior and improve implant performance. This study evaluates the performance of bio-inspired Ti64 TPMS Gyroyd and Stochastic lattice structures fabricated via Powder Bed Fusion-Laser Beam (PBF-LB), focusing on their in-vivo and ex-vivo mechanical and biological responses for biomedical applications. Utilizing an SLM 280 HL printer, samples exhibited notable geometric accuracy essential for mechanical integrity. The study highlights significant mechanical properties and geometric precision improvements achieved through chemical etching. Mechanical characterization revealed that the as-built Gyroid lattice had the highest elastic modulus (3.64 GPa) and yield strength (200.65 MPa), which improved post-etching (3.62 GPa and 219.35 MPa, respectively). The Stochastic lattice demonstrated lower yield strength values post-etching (169.81 MPa). In-vivo analyses in horse models, both structures demonstrated excellent biocompatibility and osseointegration with no adverse inflammatory responses. Ex-vivo push-out tests showed that the chemically etched Gyroid structure achieved the highest resistance to push-out force (1645.407 N) and most significant displacement (2.754 mm), indicating superior energy absorption (4920.425 mJ). These findings underscore the critical influence of microstructural design and surface treatments on implant functionality, offering novel insights into improving biomedical implant performance through lattice architecture and post-processing.

Advancements in 3D printing technologies for personalized treatment of osteonecrosis of the femoral head

Three-dimensional (3D) printing technology has shown significant promise in the medical field, particularly in orthopedics, prosthetics, tissue engineering, and pharmaceutical preparations. This review focuses on the innovative application of 3D printing in addressing the challenges of osteonecrosis of the femoral head (ONFH). Unlike traditional hip replacement surgery, which is often suboptimal for younger patients, 3D printing offers precise localization of necrotic areas and the ability to create personalized implants. By integrating advanced biomaterials, this technology offers a promising strategy approach for early hip-preserving treatments. Additionally, 3D-printed bone tissue engineering scaffolds can mimic the natural bone environment, promoting bone regeneration and vascularization. In the future, the potential of 3D printing extends to combining with artificial intelligence for optimizing treatment plans, developing materials with enhanced bioactivity and compatibility, and translating these innovations from the laboratory to clinical practice. This review demonstrates how 3D printing technology uniquely addresses critical challenges in ONFH treatment, including insufficient vascularization, poor mechanical stability, and limited long-term success of conventional therapies. By introducing gradient porous scaffolds, bioactive material coatings, and AI-assisted design, this work outlines novel strategies to improve bone regeneration and personalized hip-preserving interventions. These advancements not only enhance treatment efficacy but also pave the way for translating laboratory findings into clinical applications.

Comprehensive review of 3D printing techniques emphasizing thermal characterization in biomedical prototyping

The rapid advancement of 3D printing technology has revolutionized biomedical engineering, enabling the creation of complex and personalized prototypes. Thermal properties play a crucial role in the performance and safety of these biomedical devices. Understanding their thermal behavior is essential for ensuring their effectiveness, reliability, and compatibility with the human body. This review article aims to provide a comprehensive overview of the thermal properties of 3D printed biomedical prototypes. It categorizes these prototypes based on thermal characteristics, examines the thermal attributes of various 3D printing materials, explores the thermal considerations for different biomedical devices, and identifies the challenges and future prospects in this dynamic field.

An insightful overview on osteogenic potential of nano hydroxyapatite for bone regeneration

The orthopaedic surgeries were greatly aided by bone grafting with the use of nanomaterials which provide new strategies for bone regeneration, despite the significant drawbacks of traditional treatments. Hydroxyapatite is one of the bioactive ceramics that has gained substantial research attention due to its biocompatibility, bioactivity and osteointegration ability for the manufacturing of nano bone grafts. The organized complex and porous structures of the human bone tissue is a nanocomposite which consists of both organic and inorganic matrix including hydroxyapatite naturally. Conventional hydroxyapatite was known to provide good adhesion and proliferation of host cells but very low mechanical strength. Hence biomaterial made of hydroxyapatite with various polymers and cross linking agents were used to enhance the mechanical strength of the material. Out of 293 articles obtained from the literature search, only 90 articles met the inclusion criteria about bone regeneration using nano hydroxyapatite materials. The present review addresses the potential capping agents with plant extracts for the synthesis of hydroxyapatite nanomaterials with multi-functional applications include drug delivery for targeting the desired therapeutic effect for bone regeneration with osteoprotective ability and tumour therapy.

Evolution of Metals and Alloys in Orthopedics with Their Relevance in Osteoporosis

Background

The evolution of metals and alloys in orthopedics has significantly improved the management of bone-related disorders, particularly osteoporosis, where decreased bone density and fragility complicate implant stability and healing. Traditional materials such as stainless steel and cobalt-chromium alloys provided strength and wear resistance but were associated with challenges like stress shielding and implant loosening.

Materials and Methods

To address these limitations, titanium alloys emerged as a superior alternative due to their biocompatibility, lightweight nature, and bone-like elasticity, making them suitable for osteoporotic patients. Recent advancements have led to the development of magnesium-based biodegradable implants and nitinol (shape-memory alloy), which enable minimally invasive procedures and provide dynamic support. Additionally, porous and bioactive coatings, such as hydroxyapatite (HA), have been introduced to enhance osseointegration and implant fixation in compromised bone.

Results

The integration of pharmacological strategies, such as bisphosphonates and sclerostin antibodies, with advanced implant surfaces has further enhanced bone regeneration. Emerging innovations, including 3D-printed personalized implants and smart alloys capable of adapting to physiological changes, show promise for improved long-term stability and faster recovery in osteoporotic patients.

Conclusion

The continuous development of orthopedic materials has paved the way for more effective treatments for osteoporosis, addressing key challenges such as implant stability, stress shielding, and bone regeneration. Innovations in bioactive coatings, biodegradable metals, and personalized implants represent the future of orthopedic care, offering improved outcomes for patients with compromised bone health. However, continuous research is essential to optimize these technologies for broader clinical applications.

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.

[Research progress of bioactive scaffolds in repair and regeneration of osteoporotic bone defects]

Objective

To summarize the research progress of bioactive scaffolds in the repair and regeneration of osteoporotic bone defects.

Methods

Recent literature on bioactive scaffolds for the repair of osteoporotic bone defects was reviewed to summarize various types of bioactive scaffolds and their associated repair methods.

Results

The application of bioactive scaffolds provides a new idea for the repair and regeneration of osteoporotic bone defects. For example, calcium phosphate ceramics scaffolds, hydrogel scaffolds, three-dimensional (3D)-printed biological scaffolds, metal scaffolds, as well as polymer material scaffolds and bone organoids, have all demonstrated good bone repair-promoting effects. However, in the pathological bone microenvironment of osteoporosis, the function of single-material scaffolds to promote bone regeneration is insufficient. Therefore, the design of bioactive scaffolds must consider multiple factors, including material biocompatibility, mechanical properties, bioactivity, bone conductivity, and osteogenic induction. Furthermore, physical and chemical surface modifications, along with advanced biotechnological approaches, can help to improve the osteogenic microenvironment and promote the differentiation of bone cells.

Conclusion

With advancements in technology, the synergistic application of 3D bioprinting, bone organoids technologies, and advanced biotechnologies holds promise for providing more efficient bioactive scaffolds for the repair and regeneration of osteoporotic bone defects.

Econometric analysis of consumers' preference heterogeneity for yoghurt and ice cream products in Tanzania: A latent class model and mixed logit model

In Tanzania, a growing upper and middle classes, particularly among urbanites, exhibit distinct preferences for higher-quality processed foods, including dairy products. This study examines variations in consumer preferences and their willingness to pay for yogurt and ice cream, which serve as stand-ins for processed milk products. The analysis is based on a discrete choice experiment involving 400 participants in Dar es Salaam. A random parameter logit model was utilized to account for preference heterogeneity, while latent class models (LCMs) were applied to uncover the underlying factors driving these differences in preferences. Our findings reveal three distinct consumer classes: processed milk sceptics (who prefer unprocessed dairy products), processed milk advocates (who prefer processed products), and neutral consumers (indifferent between processed and unprocessed milk). Preferences are influenced by product attributes, socioeconomic characteristics, and attitudes towards processed foods. The results indicate that Tanzanian consumers place the greatest value on sensory attributes, packaging, and the product's origin (local versus imported). This research offers fresh perspectives on the intricate preferences of dairy consumers in Tanzania, a topic that has been relatively underexplored. The findings suggest that producers and marketers must adapt to the dynamic market by balancing intrinsic and extrinsic factors against price. Understanding consumers' socioeconomic and product attributes is essential for increasing market share and effectively segmenting markets. These findings would be useful incorporated into strategic planning to enhance the competitiveness and sustainability of Tanzania's dairy industry.

Hybrid additive manufacturing for Zn-Mg casting for biomedical application

Zinc (Zn) and its alloys have been the focus of recent materials and manufacturing research for orthopaedic implants due to their favorable characteristics including desirable mechanical strength, biodegradability, and biocompatibility. In this research, a novel process involving additive manufacturing (AM) augmented casting was employed to fabricate zinc-magnesium (Zn-0.8 Mg) artifacts with surface lattices composed of triply periodic minimal surfaces (TPMS), specifically gyroid. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) analysis confirmed that Zn-Mg intermetallic phases formed at the grain boundary. Micro indentation testing resulted in hardness value ranging from 83.772 to 99.112 HV and an elastic modulus varying from 92.601 to 94.625 GPa. Results from in vitro cell culture experiments showed that cells robustly survived on both TPMS and solid scaffolds, confirming the suitability of the material and structure as biomedical implants. This work suggests that this novel hybrid manufacturing process may be a viable approach to fabricating next generation biodegradable orthopaedic implants.

Graphical Abstract

Exploring the frontiers of metal additive manufacturing in orthopaedic implant development

This paper provides a thorough analysis of recent advancements and emerging trends in the integration of metal additive manufacturing (AM) within orthopedic implant development. With an emphasis on the use of various metals and alloys, including titanium, cobalt-chromium, and nickel-titanium, the review looks at their characteristics and how they relate to the creation of various orthopedic implants, such as spinal implants, hip and knee replacements, and cranial-facial reconstructions. The study highlights how metal additive manufacturing (AM) can revolutionize the field by enabling customized implant designs that take patient anatomical variances into account. The review discusses the drawbacks of conventional manufacturing techniques and emphasizes the benefits of metal additive manufacturing (AM), such as increased design flexibility and decreased material waste. Important material selection factors, including mechanical qualities and biocompatibility, are covered in relation to metal additive manufacturing applications. The work ends with a summary of the issues facing metal AM today, such as surface finish and material certification, and suggestions for future developments, like the creation of advanced materials and the application of AI to design optimization.

A Systematic Review of the Contribution of Additive Manufacturing toward Orthopedic Applications

Human bone holds an inherent capacity for repairing itself from trauma and damage, but concerning the severity of the defect, the choice of implant placement is a must. Additive manufacturing has become an elite option due to its various specifications such as patient-specific custom development of implants and its easy fabrication rather than the conventional methods used over the years. Additive manufacturing allows customization of the pore size, porosity, various mechanical properties, and complex structure design and formulation. Selective laser melting, powder bed fusion, electron beam melting, and fused deposition modeling are the various AM methods used extensively for implant fabrication. Metals, polymers, biocrystals, composites, and bio-HEA materials are used for implant fabrication for various applications. A wide variety of polymer implants are fabricated using additive manufacturing for nonload-bearing applications, and β-tricalcium phosphate, hydroxyapatite, bioactive glass, etc. are mainly used as ceramic materials in additive manufacturing due to the biological properties that could be imparted by the latter. For decades metals have played a major role in implant fabrication, and additive manufacturing of metals provides an easy approach to implant fabrication with augmented qualities. Various challenges and setbacks faced in the fabrication need postprocessing such as sintering, coating, surface polishing, etc. The emergence of bio-HEA materials, printing of shape memory implants, and five-dimensional printing are the trends of the era in additive manufacturing.

Knee Arthroscopy in the Era of Precision Medicine: A Comprehensive Review of Tailored Approaches and Emerging Technologies

Knee arthroscopy, a minimally invasive procedure, has transformed the treatment of knee pathologies by enabling direct visualization and management with minimal tissue disruption. Recent advances in precision medicine have introduced a new dimension to this field, allowing for highly individualized surgical approaches considering each patient's unique genetic, environmental, and biomechanical characteristics. This review explores the integration of precision medicine into knee arthroscopy, focusing on tailored approaches and emerging technologies. Key innovations such as robotic-assisted surgery, advanced imaging, and patient-specific instrumentation have enhanced surgical accuracy and patient outcomes, reduced recovery times, and minimized postoperative complications. The review also examines the role of biomarkers in guiding personalized treatment strategies, including ligament reconstructions, meniscal repairs, and cartilage restoration, which are now being refined to cater to the specific needs of individual patients. While the benefits of these innovations are clear, there are challenges to widespread adoption, including cost, resource allocation, and the need for further research to validate the efficacy of precision-driven approaches in knee arthroscopy. Moreover, the ethical considerations surrounding personalized medicine, such as patient privacy and genetic data usage, must also be addressed. Despite these barriers, the future of knee arthroscopy in the era of precision medicine holds great promise, with ongoing developments in artificial intelligence, genomics, and biomarker discovery poised to further refine patient-centered care. This comprehensive review provides valuable insights into how precision medicine reshapes knee arthroscopy, offering a glimpse into the future of more targeted and effective orthopedic interventions. By embracing these advancements, surgeons and healthcare providers can ensure optimal outcomes for patients undergoing knee arthroscopy.

Toward Fully Automated Personalized Orthopedic Treatments: Innovations and Interdisciplinary Gaps

Personalized orthopedic devices are increasingly favored for their potential to enhance long-term treatment success. Despite significant advancements across various disciplines, the seamless integration and full automation of personalized orthopedic treatments remain elusive. This paper identifies key interdisciplinary gaps in integrating and automating advanced technologies for personalized orthopedic treatment. It begins by outlining the standard clinical practices in orthopedic treatments and the extent of personalization achievable. The paper then explores recent innovations in artificial intelligence, biomaterials, genomic and proteomic analyses, lab-on-a-chip, medical imaging, image-based biomechanical finite element modeling, biomimicry, 3D printing and bioprinting, and implantable sensors, emphasizing their contributions to personalized treatments. Tentative strategies or solutions are proposed to address the interdisciplinary gaps by utilizing innovative technologies. The key findings highlight the need for the non-invasive quantitative assessment of bone quality, patient-specific biocompatibility, and device designs that address individual biological and mechanical conditions. This comprehensive review underscores the transformative potential of these technologies and the importance of multidisciplinary collaboration to integrate and automate them into a cohesive, intelligent system for personalized orthopedic treatments.

From imaging to personalized 3D printed molds in cranioplasty

Cranioplasty is the surgical repair of a bone defect in the skull resulting from a previous operation or injury, which involves lifting the scalp and restoring the contour of the skull with a graft made from material that is reconstructed from scans of the patient's own skull. The paper introduces a 3D printing technology in creating molds, which are filled with polymethyl methacrylate (PMMA) to reconstruct the missing bone part of the skull. The procedure included several steps to create a 3D model in an STL format, conversion into a G-code which is further used to produce the mold itself using a 3D printer. The paper presents our initial experience with 5 patients who undergone cranioplasty utilizing 3D printed molds. Making a patient-specific model is a very complex process and consists of several steps. The creation of a patient-specific 3D model loading of DICOM images obtained by CT scanning, followed by thresholding-based segmentation and generation of a precise 3D model of part of the patient's skull. Next step is creating the G-code models for 3D printing, after which the actual models are printed using Fused Deposition Modeling printer and PLA material. All surgeries showed good match of the missing bone part and part created using 3D printed mold, without additional steps in refinement. In such a way, 3D printing technology helps in creating personalized and visually appealing bone replacements, at a low cost of the final product.

Advancements in Custom 3D-Printed Titanium Interbody Spinal Fusion Cages and Their Relevance in Personalized Spine Care

3D-printing technology has revolutionized spinal implant manufacturing, particularly in developing personalized and custom-fit titanium interbody fusion cages. These cages are pivotal in supporting inter-vertebral stability, promoting bone growth, and restoring spinal alignment. This article reviews the latest advancements in 3D-printed titanium interbody fusion cages, emphasizing their relevance in modern personalized surgical spine care protocols applied to common clinical scenarios. Furthermore, the authors review the various printing and post-printing processing technologies and discuss how engineering and design are deployed to tailor each type of implant to its patient-specific clinical application, highlighting how anatomical and biomechanical considerations impact their development and manufacturing processes to achieve optimum osteoinductive and osteoconductive properties. The article further examines the benefits of 3D printing, such as customizable geometry and porosity, that enhance osteointegration and mechanical compatibility, offering a leap forward in patient-specific solutions. The comparative analysis provided by the authors underscores the unique challenges and solutions in designing cervical, and lumbar spine implants, including load-bearing requirements and bioactivity with surrounding bony tissue to promote cell attachment. Additionally, the authors discuss the clinical outcomes associated with these implants, including the implications of improvements in surgical precision on patient outcomes. Lastly, they address strategies to overcome implementation challenges in healthcare facilities, which often resist new technology acquisitions due to perceived cost overruns and preconceived notions that hinder potential savings by providing customized surgical implants with the potential for lower complication and revision rates. This comprehensive review aims to provide insights into how modern 3D-printed titanium interbody fusion cages are made, explain quality standards, and how they may impact personalized surgical spine care.

Biomechanical analysis of patient specific cone vs conventional stem in revision total knee arthroplasty

BACKGROUND

In revision total knee arthroplasty, addressing significant bone loss often involves the use of cemented or press-fit stems to ensure implant stability and long-term fixation. A possible alternative to stem was recently introduced utilizing custom-made porous metaphyseal cones, designed to reconstruct the missing tibial and femoral geometries. Early clinical and radiological assessments have shown promising results. The objective of this research was to biomechanically evaluate the performances of these custom-made cones.

METHODS

The biomechanical study was conducted using a validated finite element model. The bone geometries of a patient (selected for their history of four knee revisions due to infection and periprosthetic fractures, followed by a successful treatment with custom-made 3D-printed metaphyseal cones) were employed for the study. On these bone models, different revision scenarios were simulated and examined biomechanically: (A) custom-made cementless metaphyseal cones; (B) cemented stems; (C) press-fit stems; (D) distal femoral reconstruction with press-fit stem. All the models were analyzed at 0 °and 90 °of flexion, under physiological load conditions simulating daily activities; stress distribution, average Von-Mises stresses and risk of fracture were then analyzed and compared among configurations.

RESULTS

The use of custom-made 3D-printed cones exhibited the most favorable stress distribution in both femoral and tibial bones. Tibial bone stress was evenly distributed in custom-made cone configurations, while stress concentration was observed in distal regions for the other scenarios. Additionally, custom-made cones displayed overall homogeneity and lower stress levels, potentially contributing to limit pain. Symmetrical stress distribution was observed between the lateral and medial proximal tibia in custom-made cone models, whereas other scenarios exhibited uneven stress, particularly in the anterior tibial bone.

CONCLUSIONS

The biomechanical analysis of porous custom-made metaphyseal cones in re-revision arthroplasties is in agreement with the positive clinical and radiological outcomes. These findings provide valuable insights into the potential benefits of using custom-made cones, which offer more uniform stress distribution and may contribute to improve patient outcomes in revision TKA procedures. Further studies in this direction are warranted to validate these biomechanical findings.

Comparative outcomes of uncemented and cemented stem revision in managing periprosthetic femoral fractures: a retrospective cohort study

INTRODUCTION

Periprosthetic femoral fractures (PFFs) following hip arthroplasty, especially Vancouver B2 and B3 fractures, present a challenge due to the association with a loose femoral stem, necessitating either open reduction and internal fixation or stem revision. This study aims to compare outcomes between uncemented and cemented stem revisions in managing Vancouver B2 and B3 fractures, considering factors such as hip-related complications, reoperations, and clinical outcome.

METHODS

A retrospective cohort study was conducted at Danderyd Hospital, Sweden, from 2008 to 2022, encompassing operatively treated Vancouver B2 and B3 fractures. Patients were categorized into uncemented and cemented stem revision groups, with data collected on complications, revision surgeries, fracture healing times, and clinical outcomes.

RESULTS

A total of 241 patients were identified. Significant differences were observed between the two groups in patient demographics, with the cemented group comprising older patients and more females. Follow up ranged from 1 to 15 years. Average follow up time was 3.9 years for the cemented group and 5.5 years for the uncemented group. The cemented stems demonstrated lower rates of dislocation (8.9% versus 22.5%, P = 0.004) and stem loosening (0.6% versus 9.3%, P = 0.004) than the uncemented method. Moreover, the cemented group exhibited shorter fracture healing times (11.4 weeks versus 16.7 weeks, P = 0.034). There was no difference in clinical outcome between groups. Mortality was higher in the cemented group.

CONCLUSIONS

This retrospective study indicates that cemented stem revision for Vancouver B2-3 fractures is correlated with lower dislocation and stem loosening rates, necessitating fewer reoperations and shorter fracture healing times compared with the uncemented approach. The cemented group had a notably higher mortality rate, urging caution in its clinical interpretation.

LEVEL OF EVIDENCE III

Evolution of Titanium Interbody Cages and Current Uses of 3D Printed Titanium in Spine Fusion Surgery

PURPOSE OF REVIEW

To summarize the history of titanium implants in spine fusion surgery and its evolution over time.

RECENT FINDINGS

Titanium interbody cages used in spine fusion surgery have evolved from solid metal blocks to porous structures with varying shapes and sizes in order to provide stability while minimizing adverse side effects. Advancements in technology, especially 3D printing, have allowed for the creation of highly customizable spinal implants to fit patient specific needs. Recent evidence suggests that customizing shape and density of the implants may improve patient outcomes compared to current industry standards. Future work is warranted to determine the practical feasibility and long-term clinical outcomes of patients using 3D printed spine fusion implants. Outcomes in spine fusion surgery have improved greatly due to technological advancements. 3D printed spinal implants, in particular, may improve outcomes in patients undergoing spine fusion surgery when compared to current industry standards. Long term follow up and direct comparison between implant characteristics is required for the adoption of 3D printed implants as the standard of care.

Surgical Management of Cystic Pelvic Hydatid Bone Disease Using Additively Manufactured Customized Implants for Salvage Reconstruction: A Report of Two Cases

The diagnosis and treatment of pelvic bone hydatidosis (BH) present substantial challenges for orthopedic surgeons, requiring collaboration with parasitologists, radiologists, pathologists, and engineers. Surgical treatment selection depends on factors such as the extent of bone loss, soft tissue management, previously applied therapies, and local colonization status. This report details the advanced management of two young patients diagnosed late with severe cystic pelvic BH, an atypical presentation due to their geographic origin and age. Following extensive diagnostic assessments, including serology and 3D imaging, the patients underwent a two-step surgical intervention. The initial surgery involved extensive debridement and the placement of a poly-methyl-methacrylate spacer, followed by a second procedure utilizing a custom-made, tri-flanged implant for definitive pelvic reconstruction. The custom implant, designed via an electron beam melting process, successfully restored hip functionality and anatomy, as evidenced by improvements in functional scores and post-operative imaging. Short-term monitoring confirmed the integration of the implant and the absence of infection recurrence, demonstrating the approach's effectiveness. These cases highlight the potential of using additive manufacturing (AM) to create patient-specific implants for managing complex hip cases and emphasize the necessity for early detection and a multidisciplinary approach in treatment planning.

Transformative applications of additive manufacturing in biomedical engineering: bioprinting to surgical innovations

This paper delves into the diverse applications and transformative impact of additive manufacturing (AM) in biomedical engineering. A detailed analysis of various AM technologies showcases their distinct capabilities and specific applications within the medical field. Special emphasis is placed on bioprinting of organs and tissues, a revolutionary area where AM has the potential to revolutionize organ transplantation and regenerative medicine by fabricating functional tissues and organs. The review further explores the customization of implants and prosthetics, demonstrating how tailored medical devices enhance patient comfort and performance. Additionally, the utility of AM in surgical planning is examined, highlighting how printed models contribute to increased surgical precision, reduced operating times, and minimized complications. The discussion extends to the 3D printing of surgical instruments, showcasing how these bespoke tools can improve surgical outcomes. Moreover, the integration of AM in drug delivery systems, including the development of innovative drug-loaded implants, underscores its potential to enhance therapeutic efficacy and reduce side effects. It also addresses personalized prosthetic implants, regulatory frameworks, biocompatibility concerns, and the future potential of AM in global health and sustainable practices.

Revolutionizing bone tumor management: cutting-edge breakthroughs in limb-saving treatments

Limb salvage surgery has revolutionized the approach to bone tumors in orthopedic oncology, steering away from historical amputations toward preserving limb function and enhancing patient quality of life. This transformative shift underscores the delicate balance between tumor eradication and optimal postoperative function. Primary and metastatic bone tumors present challenges in early detection, differentiation between benign and malignant tumors, preservation of function, and the risk of local recurrence. Conventional methods, including surgery, radiation therapy, chemotherapy, and targeted therapies, have evolved with a heightened focus on personalized medicine. A groundbreaking development in limb salvage surgery is the advent of 3D-printed patient-specific implants, which significantly enhance anatomical precision, stability, and fixation. These implants reduce soft tissue disruption and the associated risks, fostering improved osseointegration and correction of deformities for a more natural and functional postoperative outcome. Biological and molecular research has reshaped the understanding of bone tumors, guiding surgical interventions with advancements such as genomic profiling, targeted intraoperative imaging, precision targeting of molecular pathways, and immunotherapy tailored to individual tumor characteristics. In the realm of imaging technologies, MRI, CT scans, and intraoperative navigation systems have redefined preoperative planning, minimizing collateral damage and optimizing outcomes through accurate resections. Postoperative rehabilitation plays a crucial role in restoring function and improving the quality of life. Emphasizing early mobilization, effective pain management, and a multidisciplinary approach, rehabilitation addresses the physical, psychological, and social aspects of recovery. Looking ahead, future developments may encompass advanced biomaterials, smart implants, AI algorithms, robotics, and regenerative medicine. Challenges lie in standardization, cost-effectiveness, accessibility, long-term outcome assessment, mental health support, and fostering global collaboration. As research progresses, limb salvage surgery emerges not just as a preservation tool but as a transformative approach, restoring functionality, resilience, and hope in the recovery journey. This review summarizes the recent advances in limb salvage therapy for bone tumors over the past decade.

Recent Advances in Biomimetics for the Development of Bio-Inspired Prosthetic Limbs

Recent advancements in biomimetics have spurred significant innovations in prosthetic limb development by leveraging the intricate designs and mechanisms found in nature. Biomimetics, also known as "nature-inspired engineering", involves studying and emulating biological systems to address complex human challenges. This comprehensive review provides insights into the latest trends in biomimetic prosthetics, focusing on leveraging knowledge from natural biomechanics, sensory feedback mechanisms, and control systems to closely mimic biological appendages. Highlighted breakthroughs include the integration of cutting-edge materials and manufacturing techniques such as 3D printing, facilitating seamless anatomical integration of prosthetic limbs. Additionally, the incorporation of neural interfaces and sensory feedback systems enhances control and movement, while technologies like 3D scanning enable personalized customization, optimizing comfort and functionality for individual users. Ongoing research efforts in biomimetics hold promise for further advancements, offering enhanced mobility and integration for individuals with limb loss or impairment. This review illuminates the dynamic landscape of biomimetic prosthetic technology, emphasizing its transformative potential in rehabilitation and assistive technologies. It envisions a future where prosthetic solutions seamlessly integrate with the human body, augmenting both mobility and quality of life.

Powder Bed Fusion 3D Printing in Precision Manufacturing for Biomedical Applications: A Comprehensive Review

Precision manufacturing requirements are the key to ensuring the quality and reliability of biomedical implants. The powder bed fusion (PBF) technique offers a promising solution, enabling the creation of complex, patient-specific implants with a high degree of precision. This technology is revolutionizing the biomedical industry, paving the way for a new era of personalized medicine. This review explores and details powder bed fusion 3D printing and its application in the biomedical field. It begins with an introduction to the powder bed fusion 3D-printing technology and its various classifications. Later, it analyzes the numerous fields in which powder bed fusion 3D printing has been successfully deployed where precision components are required, including the fabrication of personalized implants and scaffolds for tissue engineering. This review also discusses the potential advantages and limitations for using the powder bed fusion 3D-printing technology in terms of precision, customization, and cost effectiveness. In addition, it highlights the current challenges and prospects of the powder bed fusion 3D-printing technology. This work offers valuable insights for researchers engaged in the field, aiming to contribute to the advancement of the powder bed fusion 3D-printing technology in the context of precision manufacturing for biomedical applications.

Performance of textured dual mobility total hip prosthesis with a concave dimple during Muslim prayer movements

The single mobility bearing as a previous bearing design of total hip prosthesis has severe mobility constraints that can result in dislocation during Muslim (people who follow the Islam as religion) prayer movements, specifically shalat that requires intense movement. There are five intense movements (i.e., bowing, prostration, sitting, transition from standing to prostration, and final sitting) during Muslim prayer that may generate an impingement problem for patients with total hip prosthesis. In this work, textured dual mobility total hip prosthesis with two textured cases (i.e., textured femoral head and textured inner liner) are presented and their performances are numerically evaluated against untextured surface model during Muslim prayer movement. The concave dimple design is chosen for surface texturing, while for simulating femoral head materials, SS 316L and CoCrMo is choosen. To represent the real condition, three-dimensional computational fluid dynamics (CFD) coupled with two-way fluid-structure interaction (FSI) methods are employed to analyze elastohydrodynamic lubrication problem with non-Newtonian synovial fluid model. The main aim of the present study is to investigate the tribological performance on dual mobility total hip prosthesis with applied textured surface with concave dimple in femoral head and inner liner surface under Muslim prayer movements. It is found that applying surface texturing has a beneficial effect on the lubrication performance for some intense movements. The textured femoral head model performs better than textured inner liner model and untextured model (both femoral head and inner liner). The numerical results also indicate superior performance of CoCrMo femoral head compared to SS 316L femoral head. These findings can be used as a reference for biomedical engineers and orthopedic surgeons in designing and choosing suitable total hip prosthesis for Muslims makes they can carry out Muslim prayer movements like humans in general who have normal hip joints.

Pushing boundaries in 3D printing: Economic pressure filament extruder for producing polymeric and polymer-ceramic filaments for 3D printers

3D printing technology can deliver tailored, bioactive, and biodegradable bone implants. However, producing the new, experimental material for a 3D printer could be the first and one of the most challenging steps of the whole bone implant 3D printing process. Production of polymeric and polymer-ceramic filaments involves using costly filament extruders and significantly consuming expensive medical-grade materials. Commercial extruders frequently require a large amount of raw material for experimental purposes, even for small quantities of filament. In our publication, we propose a simple system for pressure filament extruding, which allows obtaining up to 1-meter-long filament suitable for fused filament fabrication-type 3D printers, requiring only 30 g of material to begin work. Our device is based on stainless steel pipes used as a container for material, a basic electric heating system with a proportional-integral-derivative controller, and a pressurised air source with an air pressure regulator. We tested our device on various mixes of polylactide and polycaprolactone with β-tricalcium phosphate and demonstrated the possibility of screening production and testing of new materials for 3D-printed bone implants.

Development of Biocompatible 3D-Printed Artificial Blood Vessels through Multidimensional Approaches

Within the human body, the intricate network of blood vessels plays a pivotal role in transporting nutrients and oxygen and maintaining homeostasis. Bioprinting is an innovative technology with the potential to revolutionize this field by constructing complex multicellular structures. This technique offers the advantage of depositing individual cells, growth factors, and biochemical signals, thereby facilitating the growth of functional blood vessels. Despite the challenges in fabricating vascularized constructs, bioprinting has emerged as an advance in organ engineering. The continuous evolution of bioprinting technology and biomaterial knowledge provides an avenue to overcome the hurdles associated with vascularized tissue fabrication. This article provides an overview of the biofabrication process used to create vascular and vascularized constructs. It delves into the various techniques used in vascular engineering, including extrusion-, droplet-, and laser-based bioprinting methods. Integrating these techniques offers the prospect of crafting artificial blood vessels with remarkable precision and functionality. Therefore, the potential impact of bioprinting in vascular engineering is significant. With technological advances, it holds promise in revolutionizing organ transplantation, tissue engineering, and regenerative medicine. By mimicking the natural complexity of blood vessels, bioprinting brings us one step closer to engineering organs with functional vasculature, ushering in a new era of medical advancement.

Characterising Hydroxyapatite Deposited from Solution onto Novel Substrates: Growth Mechanism and Physical Properties

Whilst titanium, stainless steel, and cobalt-chrome alloys are the most common materials for use in orthopaedic implant devices, there are significant advantages in moving to alternative non-metallic substrates. Substrates such as polymers may have advantageous mechanical biological properties whilst other substrates may bring unique capability. A key challenge in the use of non-metal products is producing substrates which can be modified to allow the formation of well-adhered hydroxyapatite films which promote osteointegration and have other beneficial properties. In this work, we aim to develop methodology for the growth of hydroxyapatite films on surfaces other than bulk metallic parts using a wet chemical coating process, and we provide a detailed characterisation of the coatings. In this study, hydroxyapatite is grown from saturated solutions onto thin titanium films and silicon substrates and compared to results from titanium alloy substrates. The coating process efficacy is shown to be dependent on substrate roughness, hydrophilicity, and activation. The mechanism of the hydroxyapatite growth is investigated in terms of initial attachment and morphological development using SEM and XPS analysis. XPS analysis reveals the exact chemical state of the hydroxyapatite compositional elements of Ca, P, and O. The characterisation of grown hydroxyapatite layers by XRD reveals that the hydroxyapatite forms from amorphous phases, displaying preferential crystal growth along the [002] direction, with TEM imagery confirming polycrystalline pockets amid an amorphous matrix. SEM-EDX and FTIR confirmed the presence of hydroxyapatite phases through elemental atomic weight percentages and bond assignment. All data are collated and reviewed for the different substrates. The results demonstrate that once hydroxyapatite seeds, it crystallises in the same manner as bulk titanium whether that be on a titanium or silicon substrate. These data suggest that a range of substrates may be coated using this facile hydroxyapatite deposition technique, just broadening the choice of substrate for a particular function.

3D printing metal implants in orthopedic surgery: Methods, applications and future prospects

Background

Currently, metal implants are widely used in orthopedic surgeries, including fracture fixation, spinal fusion, joint replacement, and bone tumor defect repair. However, conventional implants are difficult to be customized according to the recipient's skeletal anatomy and defect characteristics, leading to difficulties in meeting the individual needs of patients. Additive manufacturing (AM) or three-dimensional (3D) printing technology, an advanced digital fabrication technique capable of producing components with complex and precise structures, offers opportunities for personalization.

Methods

We systematically reviewed the literature on 3D printing orthopedic metal implants over the past 10 years. Relevant animal, cellular, and clinical studies were searched in PubMed and Web of Science. In this paper, we introduce the 3D printing method and the characteristics of biometals and summarize the properties of 3D printing metal implants and their clinical applications in orthopedic surgery. On this basis, we discuss potential possibilities for further generalization and improvement.

Results

3D printing technology has facilitated the use of metal implants in different orthopedic procedures. By combining medical images from techniques such as CT and MRI, 3D printing technology allows the precise fabrication of complex metal implants based on the anatomy of the injured tissue. Such patient-specific implants not only reduce excessive mechanical strength and eliminate stress-shielding effects, but also improve biocompatibility and functionality, increase cell and nutrient permeability, and promote angiogenesis and bone growth. In addition, 3D printing technology has the advantages of low cost, fast manufacturing cycles, and high reproducibility, which can shorten patients' surgery and hospitalization time. Many clinical trials have been conducted using customized implants. However, the use of modeling software, the operation of printing equipment, the high demand for metal implant materials, and the lack of guidance from relevant laws and regulations have limited its further application.

Conclusions

There are advantages of 3D printing metal implants in orthopedic applications such as personalization, promotion of osseointegration, short production cycle, and high material utilization. With the continuous learning of modeling software by surgeons, the improvement of 3D printing technology, the development of metal materials that better meet clinical needs, and the improvement of laws and regulations, 3D printing metal implants can be applied to more orthopedic surgeries.

The translational potential of this paper

Precision, intelligence, and personalization are the future direction of orthopedics. It is reasonable to believe that 3D printing technology will be more deeply integrated with artificial intelligence, 4D printing, and big data to play a greater role in orthopedic metal implants and eventually become an important part of the digital economy. We aim to summarize the latest developments in 3D printing metal implants for engineers and surgeons to design implants that more closely mimic the morphology and function of native bone.