Clinical Internal Dosimetry and Biodistribution of 177 Lu-DOTA-Trastuzumab in HER2-Positive Metastatic and Locally Advanced Breast Carcinoma.

OBJECTIVE: The aim of this study was to assess the biodistribution and dosimetry of 177 Lu-DOTA-trastuzumab in patients with HER2-positive breast carcinoma using whole-body (WB) planar imaging at multiple time points. PATIENTS AND METHODS: This study was a prospective evaluation of HER2-positive metastatic/locally advanced breast carcinoma patients who underwent gamma camera imaging for dosimetry and biodistribution studies by using 177 Lu-DOTA-trastuzumab. The standard diagnostic dosimetry protocol was followed, which included cold trastuzumab injection followed by in-house produced 177 Lu-DOTA-trastuzumab. Serial WB planar images (anterior and posterior) were obtained on gamma camera after the infusion of 177 Lu-DOTA-trastuzumab at multiple time points. Whole-body and organ regions of interest were drawn, and the numbers of disintegrations were obtained. The mean absorbed doses for the liver, spleen, kidneys, heart, red marrow, and tumor were obtained from OLINDA EXM v2.1.1 and ORIGIN software. RESULTS: The study included a cohort of 21 female breast carcinoma patients. Tracer activity ( 177 Lu-DOTA-trastuzumab) was noted in the physiological organs such as the liver, spleen, kidneys, heart, as well as in the tumors. On visual analysis of 177 Lu-DOTA-trastuzumab biodistribution, the liver activity showed gradual clearance over time, and although spleen was comparatively faintly visualized than liver and similarly, kidneys were faintly visualized suggestive of the alternate route of tracer excretion. The maximum number of patients (n = 12) showed 2 components of clearance, namely, fast and slow. The average effective half-life of all the patients (including single and 2 components of clearance) was 106.25 ± 22.14 hours (84.11-128.39 hours). The mean absorbed dose for the liver, spleen, kidneys, heart, whole body, and red marrow was 1.0702 ± 0.731, 1.4114 ± 0.462, 1.4232 ± 0.364, 1.4719 ± 0.602, 0.2412 ± 0.0295, and 0.1485 ± 0.0213 mGy/MBq, respectively, by OLINDA EXM and 0.5741 ± 0.333, 0.8096 ± 0.224, 0.7943 ± 0.235, 1.8971 ± 0.713, and 0.09619 ± 0.0144 for liver, spleen, kidneys, heart and whole body respectively by ORIGIN. The absorbed radiation dose for tumor was 1.94E+2 by OLINDA EXM software and 1.78E+2 by ORIGIN software. In this study, during and after infusion of 177 Lu-DOTA-trastuzumab, no major adverse effects were noted in any patient except 1 patient who had grade 1 nausea and managed conservatively by antiemetic drug. CONCLUSIONS: The results of our study demonstrated expected and favorable biodistribution and dosimetry with 177 Lu-DOTA-trastuzumab in HER2-positive breast carcinoma patients. We noticed the mean absorbed dose to the normal organs within the limits of maximum tolerable dose, and also tumor dose was higher than the normal liver dose. Therefore, we conclude that 177 Lu-DOTA-trastuzumab radioimmunotherapy is feasible and a safe treatment option for treating HER2-positive breast carcinoma patients.

Mechanism of rectification and negative differential resistance in single-molecule junctions with asymmetric anchoring groups: a DFT study.

CONTEXT: This study aims to investigate the electronic transport properties of tetracene molecule connected to gold (Au) electrodes with asymmetric anchoring groups. More specifically, we investigate the effect of asymmetric electrode coupling on the rectification ratio of tetracene-based molecular device. To introduce coupling asymmetry in these junctions, one end of the tetracene molecule is terminated with thiol (-SH) or isocyanide (-NC) while the other end with amine (-NH2) or nitro (-NO2) anchoring group. The results indicate that the electronic transport behavior is affected by the nature of molecule-electrode coupling, and the rectification ratio can be modulated by a proper choice of the anchoring groups. We reveal that the tetracene molecule when connected with isocyanide and amine combination exhibits remarkable rectifying performance (with a rectification ratio of 74) in contrast with other configurations. Furthermore, a prominent negative differential resistance (NDR) feature is observed when the molecule is connected with thiol as one of the anchors. Our present findings with excellent rectifying performance and negative differential resistance pave a new roadmap for designing multifunctional molecular devices. METHODS: By applying non-equilibrium Green's function (NEGF) formalism combined with density functional theory (DFT) Atomistic Tool Kit software package, the electronic transport properties of tetracene molecule connected to gold electrodes with asymmetric anchoring groups have been investigated. The calculations were performed using the Perdew-Burke-Ernzerhof (PBE) parameterization of DFT within generalized gradient approximation (GGA) exchange-correlation functional. To improve calculation precision and save computational efforts, the molecule and anchor groups were double-ζ (DZ) polarized, while single-ζ (SZ) polarized basis set was used for gold electrodes.

Tuning the transport properties of tetracene-based single-molecule junctions with chemical or structural variation of side and anchoring groups.

CONTEXT: This study aims to tune the transport properties of tetracene single-molecule junctions with the proper choice and placement of side and anchoring groups. For the operationalization of the molecule that was anchored with thiol or isocyanide groups, two different side groups, amine and nitro, in two different positions, were taken into consideration. For unperturbed tetracene molecule, a prominent negative differential resistance (NDR) feature at 1.8 V was observed with the isocyanide anchoring group while the thiol anchoring group exhibits a plateau region over a bias voltage of 2.2 to 3.2 V. At a bias voltage that is dependent on the chemical or structural change of side or anchoring groups, NDR feature of varying degree was seen in all configurations. Results show that the current flowing through the thiol-anchored molecule perturbed with the amine group at S' position is relatively larger than other configurations because of the smaller HOMO-LUMO gap and broader transmission peaks resulting in a peak to valley current ratio (PVCR) of 1.22. In addition, multiple NDR regions were realized in nitro-perturbed isocyanide-anchored molecule at S position. These results suggest their promising applications in switches, logic cells, and storage devices. METHODS: The modeling and simulation of side-group mediated anchored tetracene molecule through two electrodic systems were studied using density functional theory (DFT) combined with non-equilibrium Green's function (NEGF) in Virtual NanoLab-AtomistixToolkit (ATK). The electron transport properties were calculated using Perdew-Burke-Ernzerhof (PBE) generalized gradient approximation (GGA) exchange-correlation function. To optimize computing time, gold electrodes were single zeta polarized whereas the molecule, anchor groups, and side groups were double zeta polarized.

Rise of silicene and its applications in gas sensing.

Reviewing a subject is done to provide an insight into theoretical and conceptual background of the study. Looking back into the history of an emerging field and summarizing it in a few pages is a herculean task. Anyway, it was imperative to write a few words about the rise of silicene, its properties, and its applications as gas sensors. Currently, silicene is a growing field of interest. It is probably one of the most studied materials nowadays and scientists and researchers are studying it because of its intriguing electronic properties and potential applications in nanoelectronics. Various experimental and theoretical investigations are going on worldwide to explore the various aspects of this field. It is essential to review the literature based on investigations by various scientists in this field.

Defective GaAs nanoribbon-based biosensor for lung cancer biomarkers: a DFT study.

Density functional theory-based first-principles investigation is performed on pristine and mono vacancy induced GaAs nanoribbons to detect the presence of three volatile organic compounds (VOCs), aniline, isoprene and o-toluidine, which will aid in sensing lung cancer. The study has shown that pristine nanoribbon senses all three analytes. For the pristine structure, we observe decent adsorbing parameters and the bandgap widens after the adsorption of analytes. However, the introduction of the carrier traps induced by defect causes deep energy wells that vary the electrical properties as indicated in the bandgap analysis of GaAs, wherein adsorption of aniline and o-toluidine reduces the bandgap to 0 eV, making the structure highly conductive in nature. The adsorption energies of defect-induced nanoribbon are more as compared with the pristine counterpart. Nonetheless, the introduction of defects has improved the sensitivity further.

Orientation of Transverse Acetabular Ligament With Reference to Anterior Pelvic Plane.

BACKGROUND: Transverse acetabular ligament (TAL) is a 3-dimensional structure which cannot be defined by a single plane. Therefore, we aimed at describing the orientation of different parts of TAL with respect to anterior pelvic plane (APP) and correlate it with gender, body mass index (BMI), and Lewinnek's safe zone. METHODS: A total of 109 consecutive patients undergoing imageless navigated THA were prospectively studied. Computer navigation was used as the measurement tool. APP was registered for navigation. After excision of osteophytes, a trial component matching the size of unreamed acetabular cavity was aligned with acetabular rim, outer and inner margins, and middle of TAL to record cup orientation with computer tracker. RESULTS: Ninety-nine patients (41 males and 58 females, mean BMI of 28.8kg/m2) were studied after applying exclusion criteria. Mean acetabular inclination was 55.15°, 53.00°, 47.70°, and 42.60° respectively, for acetabular rim, outer, middle, and inner margins of the TAL. Corresponding mean acetabular anteversion was 6.63°, 7.41°, 11.23° and 14.90°respectively. Overall, 17.17%, 28.28%, 47.47% and 71.71% of cup orientation corresponding to acetabular rim, outer, middle, and inner margin of TAL respectively, were within Lewinnek's safe zone. No association was established between BMI and acetabular orientation. Males had overall lesser anteversion than females. CONCLUSION: We describe orientation of outer, middle, and inner margins of TAL, as reference planes for TAL, in relation to APP. The anteversion differs significantly with gender. A knowledge about these will assist surgeon in component placement during THA, with inner margin of TAL providing the best chance of orientation out of the studied landmarks.

Regulation of cid and lrg expression by CodY in Streptococcus mutans.

The ability of Streptococcus mutans to persist in a variety of adverse environments and to emerge as a numerically dominant member of stable oral biofilm communities are essential elements for its cariogenicity. The S. mutans Cid/Lrg system has been studied as a key player in the integration of complex environmental signals into regulatory networks that modulate virulence and cell homeostasis. Cid/Lrg has also been shown to be closely associated with metabolic pathways of this organism, due to distinct patterns of cid and lrg expression in response to growth phase and glucose/oxygen levels. In this study, a comparison of cid and lrg promoter regions with conserved CodY (a regulator which responds to starvation stress)-binding motifs revealed the presence of a potential CodY-binding site, which is arranged similarly in both cid and lrg promoters. Electrophoretic mobility shift assays (EMSAs) and promoter reporter assays demonstrated that expression of the cid and lrg operons is directly mediated by the global transcriptional regulator CodY. DNase I footprinting analyses confirmed the predicted binding sequences for CodY in both the cid and the lrg promoter regions. Overexpression of CodY had no obvious effect on lrgAB expression, but deficiency of CodY still affected lrgAB expression in a lytST-overexpressing strain, suggesting that CodY is required for the full regulation of lrgAB by LytST. We also demonstrated that both CodY and CcpA are involved in regulating pyruvate flux and utilization. Collectively, these data show that CodY directly regulates cid and lrg expression, and together with CcpA (previously shown to directly regulate cid and lrg promoters) contributes to coordinating pyruvate uptake and utilization in response to both the external environment and the cellular metabolic status.

Analysis of uric acid adsorption on armchair silicene nanoribbons: a DFT study.

Density functional theory based first-principles investigation study is done on armchair silicene nanoribbons (ASiNRs) for adsorption of uric acid molecule. Pristine and defect-induced variants of ASiNR are considered, and the electronic and transport properties are calculated with the adsorption. The pristine ASiNR with zero band gap is engineered with defect to create a band gap, and a significant change in the band structure of defective ASiNR after the adsorption is observed. The adsorption energy of the defective complex is calculated as - 9.21 eV which is more compared to that of the pristine counterpart, whose adsorption energy comes out to be 7.76 eV. The study shows that introduction of defect reduced the sensitivity of ASiNR toward uric acid molecule.

First principles investigation on armchair zinc oxide nanoribbons as uric acid sensors.

A study is done to check the sensing functionality of armchair zinc oxide (ZnO) nanoribbon towards uric acid. The main focus of the research is to observe the change in the electronic properties (adsorption energy, bandstructure and density of states) and transport properties (current-voltage characteristics) of nanoribbon on adsorption of uric acid. In this work, two armchair ZnO nanoribbons of width, N = 4 and 6 atoms are used, and additional variations are created in the nanoribbon by introducing defect and doping agent. Manganese is used as a dopant. The work reveals that chemisorption occurs only in the case of doping for both widths of nanoribbons, and there is an enormous increase in the conductivity of defective armchair ZnO nanoribbon with width, N = 6 as compared to others on adsorption of uric acid. All calculations are carried out using density functional theory (DFT) and non-equilibrium Green's function (NEGF). Graphical abstract.

Characterization of LrgAB as a stationary phase-specific pyruvate uptake system in Streptococcus mutans.

BACKGROUND: Our recent '-omics' comparisons of Streptococcus mutans wild-type and lrgAB-mutant revealed that this organism undergoes dynamic cellular changes in the face of multiple exogenous stresses, consequently affecting its comprehensive virulence traits. In this current study, we further demonstrate that LrgAB functions as a S. mutans pyruvate uptake system. RESULTS: S. mutans excretes pyruvate during growth as an overflow metabolite, and appears to uptake this excreted pyruvate via LrgAB once the primary carbon source is exhausted. This utilization of excreted pyruvate was tightly regulated by glucose levels and stationary growth phase lrgAB induction. The degree of lrgAB induction was reduced by high extracellular levels of pyruvate, suggesting that lrgAB induction is subject to negative feedback regulation, likely through the LytST TCS, which is required for expression of lrgAB. Stationary phase lrgAB induction was efficiently inhibited by low concentrations of 3FP, a toxic pyruvate analogue, without affecting cell growth, suggesting that accumulated pyruvate is sensed either directly or indirectly by LytS, subsequently triggering lrgAB expression. S. mutans growth was inhibited by high concentrations of 3FP, implying that pyruvate uptake is necessary for S. mutans exponential phase growth and occurs in a Lrg-independent manner. Finally, we found that stationary phase lrgAB induction is modulated by hydrogen peroxide (H2O2) and by co-cultivation with H2O2-producing S. gordonii. CONCLUSIONS: Pyruvate may provide S. mutans with an alternative carbon source under limited growth conditions, as well as serving as a buffer against exogenous oxidative stress. Given the hypothesized role of LrgAB in cell death and lysis, these data also provide an important basis for how these processes are functionally and mechanically connected to key metabolic pathways such as pyruvate metabolism.

Computer assisted orthopaedic surgery: Past, present and future.

Computer technology is ubiquitous and relied upon in virtually all professional activities including neurosurgery, which is why it is surprising that it is not the case for orthopaedic surgery with fewer than 5% of surgeons using available computer technology in their procedures. In this review, we explore the evolution and background of Computer Assisted Orthopaedic Surgery (CAOS), delving into the basic principles behind the technology and the changes in the discussion on the subject throughout the years and the impact these discussions had on the field. We found evidence that industry had an important role in driving the discussion at least in knee arthroplasty-a leading field of CAOS-with the ratio between patents and publications increased from approximately 1:10 in 2004 to almost 1:3 in 2014. The adoption of CAOS is largely restrained by economics and ergonomics with sceptics challenging the accuracy and precision of navigation during the early years of CAOS moving to patient functional improvements and long term survivorship. Nevertheless, the future of CAOS remains positive with the prospect of new technologies such as improvements in image-guided surgery, enhanced navigation systems, robotics and artificial intelligence.

Robotic-Assisted 3D Bio-printing for Repairing Bone and Cartilage Defects through a Minimally Invasive Approach.

There is an unmet need for new techniques and methods of healing critical size tissue defects, by further reduction of invasiveness in implant, cell and tissue-based surgery. This paper presents the development of a new regenerative medicine that combines 3D bio-printing and robotic-assisted minimally invasive surgery techniques to meet this need. We investigated the feasibility of Remote Centre of Motion (RCM) and viscous material extrusion 3D printing. A hypothetical, intra-articular, regenerative medicine-based treatment technique for focal cartilage defects of the knee was used as a potential example of the application of 3D printing in vivo. The results of this study suggest, that RCM mechanism is feasible with viscous material extrusion 3D printing processes, without a major trade-off in imprint quality. The achieved printing accuracy at an average dimensional error of 0.06 ± 0.14 mm in this new modality of 3D printing is comparable to those described in literature for other types of bio-printing. Robotic assisted 3D bio-printing demonstrated here is a viable option for focal cartilage defect restoration.

Biodistribution and Dosimetry of Indigenously Produced 131I-Rituximab in B-Cell Lymphoma: Pilot Study Estimating Patient-Specific Dose Comparing 2 Different Dosimetric Methods.

Cost containment through indigenous production of radioimmunotherapy agents for non-Hodgkin lymphoma (NHL) would be a pivotal step toward wider clinical availability, especially in developing countries. We examined the biodistribution and dosimetry of indigenously developed and radiolabeled 131I-rituximab, using the monoclonal antibody of chimeric origin, in patients with B-cell lymphoma for potential use in radioimmunotherapy. Methods: This prospective study included 13 patients with B-cell NHL who underwent low-dose diagnostic scanning for dosimetric and biodistribution studies. Soon after rituximab infusion, a diagnostic dose of radioiodinated rituximab was administered. Serial planar whole-body γ-camera images were taken soon afterward and on days 1, 2, 4, and 6. A source of 131I with known activity was used as a reference standard for dosimetry calculations. Results: The patient-specific administered dose that would give a whole-body absorbed radiation dose of 75 cGy, calculated by the MIRD schema, ranged from 3,095.42 to 6,330.33 MBq (83.66-171.09 mCi), with a mean of 3,986.01 ± 863.95 MBq (107.73 ± 23.35 mCi) and a median of 3,697.41 MBq (99.93 mCi). The mean residence time was 69.54 h. Within the first 48 h at least 50% of the injected activity was cleared, and by 144 h at least 80% was cleared. The patient-specific administered dose that would give a whole-body absorbed radiation dose of 75 cGy, calculated by mean residence time and activity-hours, ranged from 2,654.75 to 6,210.45 MBq (71.75-167.85 mCi), with a mean of 3,576.42 ± 927.59 MBq (96.66 ± 25.07 mCi) and a median of 3,421.02 MBq (92.46 mCi). With respect to organ-specific dosimetry, the mean absorbed doses to organs (apart from blood pool [3.77 Gy] and spleen [4.02 Gy]) were 0.97 Gy to the lungs, 0.69 Gy to the liver, and 0.7 Gy to the kidneys. Conclusion: The indigenous product had kinetics similar to commercial radiopharmaceuticals, with the advantage of a lower human antimouse antibody response because of the pharmaceutical's being a chimeric antibody rather than a murine antibody. Hence, clinical administration was safe. In none of the organs did dose-limiting radiation exposure occur at the proposed therapeutic dose.

Density-functional study of hydrogen cyanide adsorption on silicene nanoribbons.

Adsorption of toxic hydrogen cyanide gas (HCN) on armchair silicene nanoribbons (ASiNRs) is investigated by the first principles method using density functional theory (DFT) to compute geometric, electronic, and transport properties. Two variants of ASiNRs are considered: pristine ASiNR (P-ASiNR) and defective ASiNR (D-ASiNR), which is created by introducing a vacancy in P-ASiNR by removal of a Si atom. Total energy optimizations are used to find the most stable structures. The calculated results reveal that although HCN is physisorbed in both variants, sensitivity in the case of D-ASiNR is sufficiently enhanced owing to more adsorption energy and charge transfer between the ASiNR-gas complex. Also, the inspection of current-voltage characteristics demonstrates that the introduction of defect has considerably increased the conductivity of ASiNR. Hence, D-ASiNR may be used as a promising sensor for HCN gas. Graphical abstract Transmission eigenstates of (a) Pristine ASiNR (b) Defective ASiNR after HCN adsorption.

On the development of a new flexible drill for orthopedic surgery and the forces experienced on drilling bovine bone.

This article presents the construction of a flexible drill which is designed to cut a curved canal in the bone or remove bone materials, to improve the outcome of orthopedic surgery and to facilitate minimally invasive. This article reports the design of the flexible drill and uses it in an experimental rig to evaluate the drilling force generated when cutting bovine bone. The experiments facilitate the measurement of action forces between the mill bits when moving the tip toward or across a bone sample in various configurations caused by bending the flexible drill sheath to enable cutting of a curved path of variable radius in the bone. The reaction force represents the force trying to deflect the mill bit tip away from the bone sample surface and must be resisted in order to continue cutting without deflection or buckling of the tip during the drilling of curved pathways. The experiment shows the flexible drill can cut bones in both configurations and experienced a maximal force of 3.4N in the vertical configuration and 0.54N in lateral configuration. The experimental results show that the flexible drill designed is able to produce sufficient force at variable bending angles to perform the required tasks for bone cutting.

Adsorption and dissociation of sulfur-based toxic gas molecules on silicene nanoribbons: a quest for high-performance gas sensors and catalysts.

The adsorption behavior of sulfur-based toxic gases (H2S and SO2) on armchair silicene nanoribbons (ASiNRs) was investigated using first-principles density functional theory (DFT). Being a zero band gap material, application of bulk silicene is limited in nanoelectronics, despite its high carrier mobility. By restricting its dimensions into one dimension, construction of nanoribbons, and by introduction of a defect, its band gap can be tuned. Pristine armchair silicene nanoribbons (P-ASiNRs) have a very low sensitivity to gas molecules. Therefore, a defect was introduced by removal of one Si atom, leading to increased sensitivity. To deeply understand the impact of the aforementioned gases on silicene nanoribbons, electronic band structures, density of states, charge transfers, adsorption energies, electron densities, current-voltage characteristics and most stable adsorption configurations were calculated. H2S is dissociated completely into HS and H species when adsorbed onto defective armchair silicene nanoribbons (D-ASiNRs). Thus, D-ASiNR is a likely catalyst for dissociation of the H2S gas molecule. Conversely, upon SO2 adsorption, P-ASiNR acts as a suitable sensor, whereas D-ASiNR provides enhanced sensitivity compared with P-ASiNR. On the basis of these results, D-ASiNR can be expected to be a disposable sensor for SO2 detection as well as a catalyst for H2S reduction. Graphical abstract Comparison of I-V characteristics of pristine and defective armchair silicene nanoribbons with H2S and SO2 adsorbed on them.

Investigating the influence of electrode Miller indices alteration on electronic transport in thiophene-based molecular junctions.

Electrical charge transport through thiophene-dithiol-based molecular wires attached to gold electrodes with three different types of crystallographic orientations (<1,1,1>, <1,1,0 > and <1,0,1 >) was investigated. Electron transport in the systems under consideration was evaluated systematically by analyzing current values, transmission spectrum, projected device density of states and zero bias orbital analysis utilizing density functional theory in conjunction with non-equilibrium Green's function. Investigations proved that tuning of conductance in nano-molecular junctions is possible through different electrode orientations. As the HOMO-LUMO gap in the <1,1,0 > oriented thiophene dithiol junction is drastically less than that of the other configurations under consideration, the <1,1,0 > configuration exhibited superior constructive conductance in comparison to other junction orientations. This provided us with ideas for designing pioneering hetero-cyclic nano-scale electronics devices. Also, <1,1,0 > has been found to show negative differential conductance behavior above +2.6 V and below -2.6 V, and hence has potential applications in oscillating and switching circuits.

A Robotic Flexible Drill and Its Navigation System for Total Hip Arthroplasty.

This paper presents a robotic flexible drill and its navigation system for total hip arthroplasty (THA). The new robotic system provides an unprecedented and unique capability to perform curved femoral milling under the guidance of a multimodality navigation system. The robotic system consists of three components. Firstly, a flexible drill manipulator comprises multiple rigid segments that act as a sheath to a flexible shaft with a drill/burr attached to the end. The second part of the robotic system is a hybrid tracking system that consists of an optical tracking system and a position tracking system. Optical tracking units are used to track the surgical objects and tools outside the drilling area, while a rotary encoder placed at each joint of the sheath is synchronized to provide the position information for the flexible manipulator with its virtual object. Finally, the flexible drill is integrated into a computer-aided navigation system. The navigation system provides real time guidance to a surgeon during the procedure. The flexible drill system is then able to implement THA by bone milling. The final section of this paper is an evaluation of the flexible and steerable drill and its navigation system for femoral bone milling in sawbones.

A multi-modality tracking, navigation and calibration for a flexible robotic drill system for total hip arthroplasty.

BACKGROUND: This paper presents a novel multi-modality tracking and navigation system that provides a unique capability to guild a flexible drill tip inside the bone with accurate curved tunnelling. METHODS: As the flexible drill tip cannot be tracked optically inside the bone, this research focuses on developing a hybrid tracking and navigation system for tracking a flexible drill tip by using both optical and kinematic tracking. The tracking information is used to guide the THA (total hip arthroplasty) procedure, providing a real-time virtual model of the flexible drill. RESULTS: The flexible and steerable drill tip system is then tested on total hip arthroplasty followed by evaluation of the positioning and orientation of femoral stem placement by femoral milling. CONCLUSIONS: Based on this study, we conclude that the tracking and navigation system is able to guide the flexible drill to mill inside femoral canal.

Computer assisted navigation in total knee and hip arthroplasty.

INTRODUCTION: Computer assisted surgery was pioneered in early 1990s. The first computer assisted surgery (CAS) total knee replacement with an imageless system was carried out in 1997. In the past 25 years, CAS has progressed from experimental in vitro studies to established in vivo surgical procedures. METHODS: A comprehensive body of evidence establishing the advantages of computer assisted surgery in knee and hip arthroplasty is available. Established benefits have been demonstrated including its role as an excellent research tool. Its advantages include dynamic pre-operative and per-operative assessment, increased accuracy in correction of deformities, kinematics and mechanical axis, a better alignment of components, better survival rates of prostheses and a better functional outcome. Adoption of computer navigation in the hip arthroplasty is still at an early stage compared to knee arthroplasty, though the results are well documented. Evidence suggests improved accuracy in acetabular orientation, positioning, hip offset and leg length correction. RESULTS: Among the orthopaedic surgeons, navigated knee arthroplasty is gaining popularity though slowly. The uptake rates vary from country to country. The Australian joint registry data shows increased navigated knee arthroplasty from 2.4% in 2003 to 28.6% in 2015 and decreased revision rates with navigated knee arthroplasty in comparison with traditional instrumented knee arthroplasty in patient cohort under the age of 55 years. CONCLUSION: Any new technology has a learning curve and with practice the navigation assisted knee and hip arthroplasty becomes easy. We have actively followed the evidence of CAS in orthopaedics and have successfully adopted it in our routine practice over the last decades. Despite the cautious inertia of orthopaedic surgeons to embrace CAS more readily; we are certain that computer technology has a pivotal role in lower limb arthroplasty. It will evolve to become a standard practice in the future in various forms like navigation or robotics.