Development of a Co-Cr-Mo to Tantalum Transition using LENS for Orthopedic Applications

Biomedical implant material research using additive manufacturing is a popular field of study. Many potential material combinations exist which, if implemented properly, could have a significantly positive effect on implant life and functionality. One material combination of interest is attaching porous Ta bone ingrowth material to a CoCrMo corrosion and wear resistant bearing surface. An investigation of the ability of the LENS process to join Ta to CoCrMo was undertaken. Direct joining of CoCrMo to Ta was known to be problematic, and thus transitional layers of other biomedically-compatible materials were investigated. It was determined that a transitional layer of zirconium appeared to be the best transitional material for this application due to its excellent biocompatibility, followed by stainless steel, with a lesser biocompatibility but better adhesive properties.Mechanical Engineerin

Combined Nd:YAG and Er:YAG lasers for real-time closed-loop tissue-specific laser osteotomy

A novel real-time and non-destructive method for differentiating soft from hard tissue in laser osteotomy has been introduced and tested in a closed-loop fashion. Two laser beams were combined: a low energy frequency-doubled nanosecond Nd:YAG for detecting the type of tissue, and a high energy microsecond Er:YAG for ablating bone. The working principle is based on adjusting the energy of the Nd:YAG laser until it is low enough to create a microplasma in the hard tissue only (different energies are required to create plasma in different tissue types). Analyzing the light emitted from the generated microplasma enables real-time feedback to a shutter that prevents the Er:YAG laser from ablating the soft tissue

Robot Assisted Laser Osteotomy

In the scope of this thesis world\u27s first robot system was developed, which facilitates osteotomy using laser in arbitrary geometries with an overall accuracy below 0.5mm. Methods of computer and robot assisted surgery were reconsidered and composed to a workflow. Adequate calibration and registration methods are proposed. Further a methodology for transferring geometrically defined cutting trajectories into pulse sequences and optimized execution plans is developed

Optical fibers for endoscopic high-power Er:YAG laserosteotomy

ignificance: The highest absorption peaks of the main components of bone are in the mid-infrared region, making Er:YAG and CO2 lasers the most efficient lasers for cutting bone. Yet, studies of deep bone ablation in minimally invasive settings are very limited, as finding suitable materials for coupling high-power laser light with low attenuation beyond 2  μm is not trivial. Aim: The first aim of this study was to compare the performance of different optical fibers in terms of transmitting Er:YAG laser light with a 2.94-μm wavelength at high pulse energy close to 1 J. The second aim was to achieve deep bone ablation using the best-performing fiber, as determined by our experiments. Approach: In our study, various optical fibers with low attenuation (λ  =  2.94  μm) were used to couple the Er:YAG laser. The fibers were made of germanium oxide, sapphire, zirconium fluoride, and hollow-core silica, respectively. We compared the fibers in terms of transmission efficiency, resistance to high Er:YAG laser energy, and bending flexibility. The best-performing fiber was used to achieve deep bone ablation in a minimally invasive setting. To do this, we adapted the optimal settings for free-space deep bone ablation with an Er:YAG laser found in a previous study. Results: Three of the fibers endured energy per pulse as high as 820 mJ at a repetition rate of 10 Hz. The best-performing fiber, made of germanium oxide, provided higher transmission efficiency and greater bending flexibility than the other fibers. With an output energy of 370 mJ per pulse at 10 Hz repetition rate, we reached a cutting depth of 6.82  ±  0.99  mm in sheep bone. Histology image analysis was performed on the bone tissue adjacent to the laser ablation crater; the images did not show any structural damage. Conclusions: The findings suggest that our prototype could be used in future generations of endoscopic devices for minimally invasive laserosteotomy

The beginning of a new era in bone surgery Effectiveness and clinical application of a cold-ablation and robot-guided laser osteotome

Most industrial laser applications utilize computer and robot assistance, for guidance, safety, repeatability, and precision. For industrial applications, the increase in throughput and the processing speed are in the foreground. Nevertheless, these tools cannot just be transferred into clinical and surgical use because the focus in surgical interventions is on the exact implementation of a unique plan. The patient, as an inaccurately defined workpiece, with its individual anatomy and pathology, ultimately needs a single lot planning. Nowadays, medical laser systems are hand driven. The possibility of working precision, as used in industry lasers, is not exhausted. Therefore, medical laser beams have to be coupled to robot guidance. But due to the over-size of commercially available tools, efficient and ergonomic work in an operating room is impossible. Integration of the systems such as the laser source, and the robot arm are needed. Another key issue for the accuracy of the robotic arm is the inclusion of a tracking system. All these issues were encountered developing CARLO®: a Cold-Ablation and Robot-guided Laser Osteotome. This PhD thesis is divided in three parts: - an in-vivo study in sheep, - an in-vitro / wetlab study on human cadavers, and - a theoretical-experimental study to evaluate biomechanical changes in different osteotomy pattern. To test the applicability of the system in an operation theatre similar environment, an in-vivo animal trial was performed. Additionally, we wanted to demonstrate that bone healing after laser osteotomy is not impaired compared to the standard tool the piezo-osteotome. In terms of new mineralized bone formation, histological and micro-CT analysis showed clearly a higher tendency towards the acceleration of the healing process in the laser group. Additionally, no signs of bone necrosis were seen. In addition to the pure functioning of the device, the applicability in the clinic is important for technology to prevail. Therefore, dummy tests for the ergonomics and cadaver tests for the simulation of "real" operations in the cranio-maxillofacial field were performed. Wetlab tests were conducted on human cadavers where different macro-retentive osteotomy patterns were performed. It could be demonstrated that our prototype shows advantages over the current state of the art cutting tools, e.g. reduced bone loss, precise and real-time navigated execution of predefined geometries of freely selected osteotomy patterns. This advantage can be implemented in another indication of our prototype in the cranio-maxillofacial field: in craniosynostosis surgery. We performed a study using finite element analysis to simulate incomplete osteotomies on the inner side of the bone flap to facilitate the re-shaping (skull molding). This biomechanical analysis intended to create basic knowledge in terms of the best stress vs. force relation to obtain the largest projected bone surface. Moreover, a human multicenter study is ready to start for the clinical introduction of the cold-ablation and robot-guided laser osteotome and to gain more experience and information for future work

Robots and tools for remodeling bone

The field of robotic surgery has progressed from small teams of researchers repurposing industrial robots, to a competitive and highly innovative subsection of the medical device industry. Surgical robots allow surgeons to perform tasks with greater ease, accuracy, or safety, and fall under one of four levels of autonomy; active, semi-active, passive, and remote manipulator. The increased accuracy afforded by surgical robots has allowed for cementless hip arthroplasty, improved postoperative alignment following knee arthroplasty, and reduced duration of intraoperative fluoroscopy among other benefits. Cutting of bone has historically used tools such as hand saws and drills, with other elaborate cutting tools now used routinely to remodel bone. Improvements in cutting accuracy and additional options for safety and monitoring during surgery give robotic surgeries some advantages over conventional techniques. This article aims to provide an overview of current robots and tools with a common target tissue of bone, proposes a new process for defining the level of autonomy for a surgical robot, and examines future directions in robotic surgery

Biomimetic implant surfaces and their role in biological integration—a concise review

Background: The increased use of dental implants in oral rehabilitation has been followed by the development of new biomaterials as well as improvements in the performance of biomaterials already in use. This triggers the need for appropriate analytical approaches to assess the biological and, ultimately, clinical benefits of these approaches. Aims: To address the role of physical, chemical, mechanical, and biological characteristics in order to determine the critical parameters to improve biological responses and the long-term effectiveness of dental implant surfaces. Data sources and methods: Web of Science, MEDLINE and Lilacs databases were searched for the last 30 years in English, Spanish and Portuguese idioms. Results: Chemical composition, wettability, roughness, and topography of dental implant surfaces have all been linked to biological regulation in cell interactions, osseointegration, bone tissue and peri-implant mucosa preservation. Conclusion: Techniques involving subtractive and additive methods, especially those involving laser treatment or embedding of bioactive nanoparticles, have demonstrated promising results. However, the literature is heterogeneous regarding study design and methodology, which limits comparisons between studies and the definition of the critical determinants of optimal cell response.This research was supported by FCT project POCI-01-0145-FEDER-030498—Portugal, by FEDER funds through the COMPETE 2020—Programa Operacional Competitividade e Internacionalização (POCI) and ImpHib—Development of advanced Hybrid Implants—NORTE-01-0247-FEDER-034074. The role of the funders was limited to providing financial resources for the review