Recent trends, technical concepts and components of computer-assisted orthopedic surgery systems: A comprehensive review

Computer-assisted orthopedic surgery (CAOS) systems have become one of the most important and challenging types of system in clinical orthopedics, as they enable precise treatment of musculoskeletal diseases, employing modern clinical navigation systems and surgical tools. This paper brings a comprehensive review of recent trends and possibilities of CAOS systems. There are three types of the surgical planning systems, including: systems based on the volumetric images (computer tomography (CT), magnetic resonance imaging (MRI) or ultrasound images), further systems utilize either 2D or 3D fluoroscopic images, and the last one utilizes the kinetic information about the joints and morphological information about the target bones. This complex review is focused on three fundamental aspects of CAOS systems: their essential components, types of CAOS systems, and mechanical tools used in CAOS systems. In this review, we also outline the possibilities for using ultrasound computer-assisted orthopedic surgery (UCAOS) systems as an alternative to conventionally used CAOS systems.Web of Science1923art. no. 519

Desenvolvimento de protótipo para sensorização da interface de implantes ósseos

Over the last few years there has been an increase in the number of arthroplasties performed worldwide. With the growing number of young patients performing this surgery, new technologies are required to evaluate the bone-implant interface in order to avoid revision surgeries. The present work aims to develop a prototype for sensing the bone-implant interface for multifunctional instrumented/bioelectronic implants: the network-based cosurface capacitive system with ability to be extracorporeally controlled by clinicians. This prototype is composed by both hardware and software components. The hardware can also be seen as the data acquisition system and the software is the monitor and the control system. Considering that the societal scenario did not allow the manufacture of this new system prototype, the hardware was only designed for future implementation and validation. The software is a web application that allows the clinician to monitor and control the data acquisition system. For the development of the web application it was used Django, python, HTML5, CSS, and the storage and management of data were performed with MySQL. In order to assess its performance, different simulation tests were performed: (i) monitoring tests using random bone-implant interface states, in which capacitance data was generated from a polynomial function that characterizes the average capacitance change for different bone-implant bonding states; (ii) monitoring tests simulating an increasing bonding scenario. Through the web application it is possible to analyse the data collected from the data acquisition system in two dimensional plots or three dimensional plots. This software solution was also designed to allow downloading the data to an Excel file to give the user the possibility to perform different analyses related boneimplant interface state. The project for the data acquisition system is constituted by a Raspberry Pi, an I2C multiplexer, a capacitor-to-digital converter (EVAL AD-7746), and the sensing technology. The Raspberry Pi is responsible for the TCP-IP communication with the monitoring system and the I2C communication with the capacitor-to-digital converter through the I2C multiplexer. It is also responsible for saving data in the correct database. The capacitor-to-digital converter acquires the data from the sensing technology, which is based on three different printed circuit boards, containing twelve capacitors. Thus, it is intended to prove that with a sensing system comprising a network of cosurface capacitors it is possible to acquire bone-implant interface bonding during the daily life of patients, including region and magnitude debonding dataAo longo dos últimos anos tem-se verificado um aumento do número de artroplastias realizadas mundialmente. Com o crescente número de jovens a serem submetidos a esta cirurgia, torna-se necessário desenvolver novas tecnologias para a avaliação da interface osso-implante de modo a diminuir o número de cirurgias de revisão. O presente trabalho tem como objetivo o desenvolvimento de um protótipo para a sensorização da interface de implantes ósseos para incorporar implantes instrumentados, constituídos por uma rede de sistemas capacitivos e com a possibilidade de ser controlada extracoporealmente por médicos especializados. O protótipo é constituído por componentes de hardware e software. O hardware consiste no sistema de aquisição de dados e o software permite o controlo e monitorização do hardware. Considerando o estado social atual não foi possível produzir o protótipo deste novo sistema de monitorização, por esse motivo o hardware foi apenas projetado de forma a ser implementado e validado futuramente. O software é uma aplicação web que permite que o médico especialista monitorize o sistema de aquisição de dados. Para o desenvolvimento deste software foi utilizado Django, python, HTML5, CSS, e a gestão e armazenamento de dados foi feita através do MySQL. A validação das funcionalidades do software foi realizada através de dois testes diferentes: (i) testes de monitorização com base em estados aleaórios da interface osso-implante, onde os valores de capacidade foram obtidos com base numa polinomial que caracteriza a variação de capacidade para diferentes estados de ligação osso-implante; (ii) simulação de um teste de aproximação do osso à estrutura capacitiva. Através da aplicação web, é possível visualizar os resultados obtidos a partir de gráficos tridimensionais e bidimensionais. O website também permite o download de um ficheiro Excel com os dados adquiridos, para o utilizador realizar análises independentes relacionadas com o estado da interface osso-implante. O projeto do sistema de aquisição de dados é constituído por um Raspberry Pi, um multiplexer I2C, um conversor analógico-digital (EVAL-AD7746) e o sistema de sensorização. O Raspberry Pi estabelece uma comunicação TCP-IP com o sistema de monitorização e uma comunicação I2C com o conversor analógico-digital através de um multiplexer I2C. Este dispositivo guarda os dados recolhidos em bases de dados. O conversor analógico-digital recolhe os dados do sistema capacitivo de sensorização, que é constituído por três placas de circiuito impresso, onde cada uma contém um total de doze condensadores. Assim, pretende-se comprovar que com um sistema constituído por uma rede de condensadores é possível fazer uma aquisição de dados relativamente ao estado da interface osso-implante durante o dia-a-dia do pacienteMestrado em Engenharia Mecânic

Improving prosthetic selection and predicting BMD from biometric measurements in patients receiving total hip arthroplasty

There are two surgical approaches to performing total hip arthroplasty (THA): a cemented or uncemented type of prosthesis. The choice is usually based on the experience of the orthopaedic surgeon and on parameters such as the age and gender of the patient. Using machine learning (ML) techniques on quantitative biomechanical and bone quality data extracted from computed tomography, electromyography and gait analysis, the aim of this paper was, firstly, to help clinicians use patient-specific biomarkers from diagnostic exams in the prosthetic decision-making process. The second aim was to evaluate patient long-term outcomes by predicting the bone mineral density (BMD) of the proximal and distal parts of the femur using advanced image processing analysis techniques and ML. The ML analyses were performed on diagnostic patient data extracted from a national database of 51 THA patients using the Knime analytics platform. The classification analysis achieved 93% accuracy in choosing the type of prosthesis; the regression analysis on the BMD data showed a coefficient of determination of about 0.6. The start and stop of the electromyographic signals were identified as the best predictors. This study shows a patient-specific approach could be helpful in the decision-making process and provide clinicians with information regarding the follow up of patients

Desempenho de sistema de monitorização capacitivo em implante ósseo instrumentado

Musculoskeletal disorders are becoming an ever-growing societal burden and, as a result, millions of bone replacements surgeries are performed per year worldwide. Although total joint replacements are recognized among the most successful surgeries of the last century, implant failure rates exceeding 10% are still reported. These numbers highlight the necessity of technologies to provide an accurate monitoring of the bone-implant interface state. This work aims to identify the performance of an instrumented implant to monitor implant stability using a planar capacitive technology. A 5x10x0.8 mm printed circuit with two 5x2 mm electrodes was fabricated to be integrated in an implantable device, with the objective of assessing the effect of a fully implantation into a biological specimen. The implant was fabricated with a conic geometry, to achieve a press-fit fixation, with 55 mm of length and a minimum/maximum diameters of 12 and 15 mm, respectively. After implantation, the system was put under compression and decompression cycles, so the bone-implant interface could be altered. In the compression cycle, the observed capacitance values decreased, indicating the sensor was moving away from the bone; and contrarily, in the decompression cycle, the capacitance increased with the progressive unloading. Values were obtained in intervals of [2.2090; 3.0764] pF for the compression and [1.9806; 3.1841] pF for the decompression. The mean percentage of capacitance change for the compression cycle was 3.67% and 5.06% for the decompression, indicating a greater change rate in the decompression cycle. Additional tests were carried where the implant and the sensor were rotated 90 and 180º, to show the influence of different interfaces in the measured capacitance. The latter tests allowed to support the results obtained without rotation, as different sensor positions provided different behaviors of the capacitance change. Further development is still needed related to the experimental setup, more specifically the in vitro specimens fixation and the environment control of the experiment room. In addition, energy harvesting to create self powering systems to avoid exernal links or finite-life alternatives are also a necessity for future instrumented implants. This work further demonstrated the potential of capacitive technologies to monitor the bone-implant fixation. Therefore, it also contributed towards the design of a new era of high-sophisticated implantable medical devices.Distúrbios musculares estão a tornar-se um fardo cada vez maior para a sociedade atual, e, como resultado, milhões de artroplastias são realizadas anualmente por todo o mundo. Apesar da artroplastia estar reconhecida entre os procedimentos mais bem sucedidos do último século, ainda se observa uma taxa de falha em implantes de cerca de 10%. Estes números realçam a necessidade das tecnologias conseguirem fornecer um diagnóstico preciso da interface osso-implante, podendo reduzir significativamente a necessidade de cirurgias de revisão. Este trabalho tem como objetivo avaliar o desempenho de um implante instrumentado para monitorizar a estabilidade em implantes, utilizando uma tecnologia capacitiva planar. De forma a verificar o efeito de uma inserção completa em espécimes biológicos, um circuito impresso de dimensões 5x10x0.8 mm com dois elétrodos de 5x2 mm foi fabricado com o objetivo de ser integrado dentro de um implante. O implante foi projetado com uma geometria cónica, de forma a obter uma fixação press-fit, com diâmetros mínimo/máximo de 12 e 15 mm, respetivamente, e um comprimento de 55 mm. Depois de implantado, o sistema foi posto sobre ciclos de compressão e de descompressão de forma a alterar a interface osso-implante. Nos ciclos de compressão, os valores observados da capacidade decresceram, indicando que o sensor se estava a afastar do osso; contrariamente, nos ciclos de descompressão, a capacidade tendia a aumentar com o descarregamento. Os valores foram obtidos no intervalo de [2.2090; 3.0764] pF para os ciclos de compressão e de [1.9806; 3.1841] pF para a descompressão. A percentagem média de variação da capacidade para os ciclos de compressão foi de 3.67% e de 5.06% para os de descompressão, indicando uma maior taxa de variação nos ciclos de descompressão. Adicionalmente, foram realizados testes em que o implante e o sensor foram rodados 90 e 180 de forma a verificar o efeito de interfaces diferentes na capacidade medida. Estes últimos testes permitiram também corroborar a validade dos testes de compressão e descompressão, visto que orientações diferentes do sensor deveriam dar tendências diferentes nas curvas de capacidade. No entanto ainda é necessário um desenvolvimento adicional relativamente ao setup experimental, mais concretamente na fixação dos espécimes biológicos durante os ensaios in vitro, assim como no controlo das condições ambiente do laboratório. Adicionalmente, o desenvolvimento de sistemas de energy harvesting são uma necessidade para o futuro dos implantes instrumentados de forma a ter um sistema auto-sustentável, evitando ligações com o exterior ou soluções de vida limitada. Este trabalho permitiu comprovar o potencial de tecnologias capacitivas para a monitorização do estado da interface osso-implante. Assim, também contribuiu para o desenvolvimento de uma nova era de dispositivos médicos implantáveis altamente sofisticados.Mestrado em Engenharia Mecânic

Design and integration of an instrumented knee prosthesis

Total knee arthroplasty is nowadays one of the most important orthopedic surgery. It consists of a procedure in which parts of the knee are replaced by a prosthesis. The largest indication for total knee arthroplasty is osteoarthritis, a knee disease that can cause the cartilage of the femur and tibia to wear away, so that the bones rub together with use. The major risk factors for osteoarthritis are aging and obesity. Both the life expectancy and the obesity rate are increasing in the developed countries, thus the number of estimated total knee arthroplasties is growing over the years. Although over one million of prosthetic joints are implanted every year in the developed countries, none of them contains sensors to help the orthopedic surgeons in improving the precision of the replacement surgery. The goal of this study is to design an electronic system to be embedded inside a total knee prosthesis, in order to measure the force applied to it and its kinematics. Providing the orthopedic surgeons with quantitative data on the biomechanics of the prosthetic knee can help them in improving the implant precision and, as a consequence, could reduce the risk of an early revision surgery. In the frame of this thesis, we worked with the F.I.R.S.T. prosthesis by Symbios Orthopedie SA, that was instrumented with sensors and electronics to measure, process and transmit force and kinematics data to an external reader. The constraints in the design have been established by the medical doctors and the prosthesis manufacturer and the technical solutions adopted are presented. In order to simplify a future approval for human tests, we decided to keep the shape of the knee artificial joint. To achieve that, we put all the sensors and the electronics inside the middle part of the prosthesis, constituted of a polyethylene insert located between the metallic parts of the artificial joint and whose function is to reduce the rubbing. An original encapsulation was designed to guarantee the bio-compatibility of the instrumented prosthesis and to avoid a potentially dangerous contact between the electronics and the human body. This should be ensured even in case of extreme wearing of the polyethylene insert, that can occur some years after the prosthesis implant and is one of the main indications for a revision surgery. The sensors were tested by using mechanical simulators of the knee joint and validated by means of reference sensors. Different demonstrators have been designed, from the first, with only the sensors located inside the prosthesis and all the electronics fabricated in a large-scale outside of it, to the last miniaturized versions, that can be entirely embedded inside the prosthesis. Moreover, an autonomous sensor for balancing the ligaments tension during the knee replacement surgery was designed, fabricated and tested. Such a device could be an important help for the medical doctors during the surgery to improve the precision of the implant and, being not-implantable, could easily obtain an approval for human clinical trials

Studies on Spinal Fusion from Computational Modelling to ‘Smart’ Implants

Low back pain, the worldwide leading cause of disability, is commonly treated with lumbar interbody fusion surgery to address degeneration, instability, deformity, and trauma of the spine. Following fusion surgery, nearly 20% experience complications requiring reoperation while 1 in 3 do not experience a meaningful improvement in pain. Implant subsidence and pseudarthrosis in particular present a multifaceted challenge in the management of a patient’s painful symptoms. Given the diversity of fusion approaches, materials, and instrumentation, further inputs are required across the treatment spectrum to prevent and manage complications. This thesis comprises biomechanical studies on lumbar spinal fusion that provide new insights into spinal fusion surgery from preoperative planning to postoperative monitoring. A computational model, using the finite element method, is developed to quantify the biomechanical impact of temporal ossification on the spine, examining how the fusion mass stiffness affects loads on the implant and subsequent subsidence risk, while bony growth into the endplates affects load-distribution among the surrounding spinal structures. The computational modelling approach is extended to provide biomechanical inputs to surgical decisions regarding posterior fixation. Where a patient is not clinically pre-disposed to subsidence or pseudarthrosis, the results suggest unilateral fixation is a more economical choice than bilateral fixation to stabilise the joint. While finite element modelling can inform pre-surgical planning, effective postoperative monitoring currently remains a clinical challenge. Periodic radiological follow-up to assess bony fusion is subjective and unreliable. This thesis describes the development of a ‘smart’ interbody cage capable of taking direct measurements from the implant for monitoring fusion progression and complication risk. Biomechanical testing of the ‘smart’ implant demonstrated its ability to distinguish between graft and endplate stiffness states. The device is prepared for wireless actualisation by investigating sensor optimisation and telemetry. The results show that near-field communication is a feasible approach for wireless power and data transfer in this setting, notwithstanding further architectural optimisation required, while a combination of strain and pressure sensors will be more mechanically and clinically informative. Further work in computational modelling of the spine and ‘smart’ implants will enable personalised healthcare for low back pain, and the results presented in this thesis are a step in this direction

Advanced Applications of Rapid Prototyping Technology in Modern Engineering

Rapid prototyping (RP) technology has been widely known and appreciated due to its flexible and customized manufacturing capabilities. The widely studied RP techniques include stereolithography apparatus (SLA), selective laser sintering (SLS), three-dimensional printing (3DP), fused deposition modeling (FDM), 3D plotting, solid ground curing (SGC), multiphase jet solidification (MJS), laminated object manufacturing (LOM). Different techniques are associated with different materials and/or processing principles and thus are devoted to specific applications. RP technology has no longer been only for prototype building rather has been extended for real industrial manufacturing solutions. Today, the RP technology has contributed to almost all engineering areas that include mechanical, materials, industrial, aerospace, electrical and most recently biomedical engineering. This book aims to present the advanced development of RP technologies in various engineering areas as the solutions to the real world engineering problems

The Future of the Operating Room: Surgical Preplanning and Navigation using High Accuracy Ultra-Wideband Positioning and Advanced Bone Measurement

This dissertation embodies the diversity and creativity of my research, of which much has been peer-reviewed, published in archival quality journals, and presented nationally and internationally. Portions of the work described herein have been published in the fields of image processing, forensic anthropology, physical anthropology, biomedical engineering, clinical orthopedics, and microwave engineering. The problem studied is primarily that of developing the tools and technologies for a next-generation surgical navigation system. The discussion focuses on the underlying technologies of a novel microwave positioning subsystem and a bone analysis subsystem. The methodologies behind each of these technologies are presented in the context of the overall system with the salient results helping to elucidate the difficult facets of the problem. The microwave positioning system is currently the highest accuracy wireless ultra-wideband positioning system that can be found in the literature. The challenges in producing a system with these capabilities are many, and the research and development in solving these problems should further the art of high accuracy pulse-based positioning

Sensor capacitivo para a monitorização da interface osso-implante

Mestrado em Engenharia MecânicaOs implantes ósseos usados atualmente não são capazes de substituir integralmente a articulação onde são aplicadas. A redistribuição da carga no osso origina o efeito stress-shielding, o que pode provocar perda de massa óssea e migração do implante. O desgaste das componentes integrais do implante também causa alterações na interface ossoimplante. Os pacientes com estas complicações, podem ser submetidos a operações de revisão, onde o risco de insucesso e infeções é elevado. Para prevenir tais casos, recentemente foi proposto o conceito de Implante Instrumentado para dotar esta tecnologia com: sistemas de atuação (sobre a interface osso-implante), monitorização da integração osso-implante, sistemas de comunicação implante-exterior e sistemas de geração autónoma de energia. No entanto, uma revisão da literatura mostrou que os sistemas de monitorização propostos não são viáveis para serem incorporados em implantes instrumentados. Este é um estudo preliminar que visa propor um sistema de monitorização capacitivo com configuração em co-superfície listrado integrado num circuito ressonante RLC. Foi desenvolvido um aparato experimental para o teste do sistema in vitro usando estruturas de osso porcino. Observaram-se variações de 0,2 fF da capacitância por cada μm de deslocamento relativo entre a estrutura óssea e o sistema de monitorização. Embora preliminar, este estudo apresenta resultados promissores para a monitorização de diferentes interfaces osso-implante usando em sistemas capacitivos em co-superfície.The prostheses currently used, are not able to fully replace the joint where they are applied. The redistribution of the load in the bone causes stressshielding, which origins loss of bone mass, and migration of the implant. Also, the wear of the integral components of the prosthesis causes changes between the interface of the bone and the implant. Patients with these complications can be submitted to review surgeries, where the risk of failure and infection is high. To prevent such cases, instrumented prosthesis have been recently proposed, to enhance this technology with: actuation systems (over the bone-implant interface), osseointegration monitoring, communication systems between implant-exterior and systems capable of generating energy autonomously. However, a review over these technologies showed that the proposed monitoring systems are not feasible to be incorporated into instrumented implants. This is a preliminary study which aims to advocate a monitoring capacitive system with a cosurface stripe pattern integrated in a RLC resonant circuit. An experimental apparatus was developed to test the system in vitro using a porcine bone. Variations of 0,2 fF in the capacitance were observed, for each ìm of relative movement between the bone and the monitoring system. Although preliminary, this study presents promising result for monitoring different bone-implant interfaces using a cosurface capacitive system