Thoracic wall reconstruction using ultrasound images to model/bend the thoracic prosthesis for correction of pectus excavatum

Pectus excavatum is the most common congenital deformity of the anterior thoracic wall. The surgical correction of such deformity, using Nuss procedure, consists in the placement of a personalized convex prosthesis into sub-sternal position to correct the deformity. The aim of this work is the CT-scan substitution by ultrasound imaging for the pre-operative diagnosis and pre-modeling of the prosthesis, in order to avoid patient radiation exposure. To accomplish this, ultrasound images are acquired along an axial plane, followed by a rigid registration method to obtain the spatial transformation between subsequent images. These images are overlapped to reconstruct an axial plane equivalent to a CT-slice. A phantom was used to conduct preliminary experiments and the achieved results were compared with the corresponding CT-data, showing that the proposed methodology can be capable to create a valid approximation of the anterior thoracic wall, which can be used to model/bend the prosthesis

Automatic prebent customized prosthesis for pectus excavatum minimally invasive surgery correction

Pectus excavatum is the most common deformity of the thorax. A minimally invasive surgical correction is commonly carried out to remodel the anterior chest wall by using an intrathoracic convex prosthesis in the substernal position. The process of prosthesis modeling and bending still remains an area of improvement. The authors developed a new system, i3DExcavatum, which can automatically model and bend the bar preoperatively based on a thoracic CT scan. This article presents a comparison between automatic and manual bending. The i3DExcavatum was used to personalize prostheses for 41 patients who underwent pectus excavatum surgical correction between 2007 and 2012. Regarding the anatomical variations, the soft-tissue thicknesses external to the ribs show that both symmetric and asymmetric patients always have asymmetric variations, by comparing the patients’ sides. It highlighted that the prosthesis bar should be modeled according to each patient’s rib positions and dimensions. The average differences between the skin and costal line curvature lengths were 84 ± 4 mm and 96 ± 11 mm, for male and female patients, respectively. On the other hand, the i3DExcavatum ensured a smooth curvature of the surgical prosthesis and was capable of predicting and simulating a virtual shape and size of the bar for asymmetric and symmetric patients. In conclusion, the i3DExcavatum allows preoperative personalization according to the thoracic morphology of each patient. It reduces surgery time and minimizes the margin error introduced by the manually bent bar, which only uses a template that copies the chest wall curvature.

Automatic modeling of pectus excavatum corrective prosthesis using artificial neural networks

Pectus excavatum is the most common deformity of the thorax. Pre-operative diagnosis usually includes Computed Tomography (CT) to successfully employ a thoracic prosthesis for anterior chest wall remodeling. Aiming at the elimination of radiation exposure, this paper presents a novel methodology for the replacement of CT by a 3D laser scanner (radiation-free) for prosthesis modeling. The complete elimination of CT is based on an accurate determination of ribs position and prosthesis placement region through skin surface points. The developed solution resorts to a normalized and combined outcome of an artificial neural network (ANN) set. Each ANN model was trained with data vectors from 165 male patients and using soft tissue thicknesses (STT) comprising information from the skin and rib cage (automatically determined by image processing algorithms). Tests revealed that ribs position for prosthesis placement and modeling can be estimated with an average error of 5.0 ± 3.6 mm. One also showed that the ANN performance can be improved by introducing a manually determined initial STT value in the ANN normalization procedure (average error of 2.82 ± 0.76 mm). Such error range is well below current prosthesis manual modeling (approximately 11 mm), which can provide a valuable and radiation-free procedure for prosthesis personalization.

Automatic modeling of pectus excavatum corrective prosthesis using artificial neural networks

Pectus excavatum is the most common deformity of the thorax. Pre-operative diagnosis usually includes Computed Tomography (CT) to successfully employ a thoracic prosthesis for anterior chest wall remodeling. Aiming at the elimination of radiation exposure, this paper presents a novel methodology for the replacement of CT by a 3D laser scanner (radiation-free) for prosthesis modeling. The complete elimination of CT is based on an accurate determination of ribs position and prosthesis placement region through skin surface points. The developed solution resorts to a normalized and combined outcome of an artificial neural network (ANN) set. Each ANN model was trained with data vectors from 165 male patients and using soft tissue thicknesses (STT) comprising information from the skin and rib cage (automatically determined by image processing algorithms). Tests revealed that ribs position for prosthesis placement and modeling can be estimated with an average error of 5.0 ± 3.6 mm. One also showed that the ANN performance can be improved by introducing a manually determined initial STT value in the ANN normalization procedure (average error of 2.82 ± 0.76 mm). Such error range is well below current prosthesis manual modeling (approximately 11 mm), which can provide a valuable and radiation-free procedure for prosthesis personalization.

Automatic prebent customized prosthesis for pectus excavatum minimally invasive surgery correction

Pectus excavatum is the most common deformity of the thorax. A minimally invasive surgical correction is commonly carried out to remodel the anterior chest wall by using an intrathoracic convex prosthesis in the substernal position. The process of prosthesis modeling and bending still remains an area of improvement. The authors developed a new system, i3DExcavatum, which can automatically model and bend the bar preoperatively based on a thoracic CT scan. This article presents a comparison between automatic and manual bending. The i3DExcavatum was used to personalize prostheses for 41 patients who underwent pectus excavatum surgical correction between 2007 and 2012. Regarding the anatomical variations, the soft-tissue thicknesses external to the ribs show that both symmetric and asymmetric patients always have asymmetric variations, by comparing the patients’ sides. It highlighted that the prosthesis bar should be modeled according to each patient’s rib positions and dimensions. The average differences between the skin and costal line curvature lengths were 84 ± 4 mm and 96 ± 11 mm, for male and female patients, respectively. On the other hand, the i3DExcavatum ensured a smooth curvature of the surgical prosthesis and was capable of predicting and simulating a virtual shape and size of the bar for asymmetric and symmetric patients. In conclusion, the i3DExcavatum allows preoperative personalization according to the thoracic morphology of each patient. It reduces surgery time and minimizes the margin error introduced by the manually bent bar, which only uses a template that copies the chest wall curvature.

Artificial neural networks for automatic modelling of the pectus excavatum corrective prosthesis

Pectus excavatum is the most common deformity of the thorax and usually comprises Computed Tomography (CT) examination for pre-operative diagnosis. Aiming at the elimination of the high amounts of CT radiation exposure, this work presents a new methodology for the replacement of CT by a laser scanner (radiation-free) in the treatment of pectus excavatum using personally modeled prosthesis. The complete elimination of CT involves the determination of ribs external outline, at the maximum sternum depression point for prosthesis placement, based on chest wall skin surface information, acquired by a laser scanner. The developed solution resorts to artificial neural networks trained with data vectors from 165 patients. Scaled Conjugate Gradient, Levenberg-Marquardt, Resilient Back propagation and One Step Secant gradient learning algorithms were used. The training procedure was performed using the soft tissue thicknesses, determined using image processing techniques that automatically segment the skin and rib cage. The developed solution was then used to determine the ribs outline in data from 20 patient scanners. Tests revealed that ribs position can be estimated with an average error of about 6.82±5.7 mm for the left and right side of the patient. Such an error range is well below current prosthesis manual modeling (11.7±4.01 mm) even without CT imagiology, indicating a considerable step forward towards CT replacement by a 3D scanner for prosthesis personalization.

Knee muscle strength, balance and functional independence in persons with stroke

Purpose: to investigate the relationship between knee muscle strength, balance and functional independence within the first month after stroke. Relevance: cerebral vascular disease is one of the main causes of morbidity, disability and mortality in developed countries. Problems with movement control are frequent after stroke. Lower limb weakness and impaired balance are common problems that are related with the risk of falls and are likely to interfere with the ability to perform daily life activities. Physiotherapy intervention usually starts early after stroke and addresses impairments related to movement and posture in order to improve motor recovery and restore function.

Consumo energético e eficiência da marcha com dois modelos de joelhos protésicos: estudo de caso

Introdução – Os componentes protésicos têm um papel fundamental na eficiência energética da marcha dos indivíduos amputados. Esta é uma área de conhecimento ainda em desenvolvimento, onde a investigação desempenha um papel central. Objectivos – Comparar e analisar o efeito de dois joelhos protésicos, 3R34, monocêntrico modular, de fricção constante, com auxiliar de extensão incorporado (A) e 3R92, monocêntrico modular, com travão de fricção e controlo pneumático da fase de balanço (B) no consumo energético e eficiência da marcha. Metodologia – Um indivíduo do sexo masculino de 27 anos, com amputação transfemural longa, foi sujeito a um protocolo submáximo de avaliação da resposta ao exercício em passadeira rolante (H/P/Cosmos(R) Mercury), através de um sistema de análise de gases breath‑by‑breath (Cosmed Quark PFT Ergo). Foi efetuado o mesmo protocolo com intervalo de dois dias, primeiro utilizando o joelho A e depois o B. As variáveis analisadas foram o consumo de O2 (VO2), o equivalente metabólico (MET) e a eficiência energética da marcha (Quociente de VO2 esperado de um individuo saudável e o VO2 do individuo em estudo). O esforço percecionado foi medido com a escala RPE de Borg. Resultados – O consumo energético com o joelho A (24,2 ml O2/kg/min; 6,9 MET) foi inferior ao obtido com o joelho B (28,68 ml O2/kg/min; 8,2 MET). A eficiência energética da marcha foi mais elevada para o joelho A (43%) do que para o joelho B (39%). Conclusão – A utilização do joelho A na prótese do indivíduo em estudo resulta numa marcha de menor consumo energético e maior eficiência. No entanto, este valor poderá estar influenciado pelo curto período de adaptação ao joelho B, sendo necessários mais estudos para confirmar os resultados do estudo e a influência deste fator. ABSTRACT - Background – Prosthetic components have a crucial role in the energy efficiency of amputee’s gait. This is an area of knowledge still in development, where research plays a central role. Objective – The purpose of this case study is to compare the impact in energy consumption of two prosthetic knees, titanium single‑axis constant friction knee joint with internal extension assist, 3R34 (A) and a single‑axis pneumatic swing phase control, 3R92 (B). Methodology – The participant was a transtibial amputee, male, with 27 years old, with no other clinical or functional impairments. To measure the energy expenditure a submaximal treadmill (H/P/Cosmos(R) Mercury) exercise stress test combined with a breath‑by‑breath analysis system (Cosmed Quark PFT Ergo) was used. The same test was applied to both knees, separated by two days. The analyzed variables were O2 consumption (VO2), metabolic equivalent (MET) and gait efficiency (VO2 ratio expected from a healthy individual and the studied individual). A rate of perceived exertion (Borg’s Scale) was used. Results – The results were favorable to knee A (24.2 ml O2/kg/min; 6.9 MET, 43% efficiency) compared with knee B (28.68 ml O2/kg/min; 8.2 MET, 39% efficiency). Conclusion – In this case, a less energy consumption gait corresponds to the prosthesis with knee A. These values may be influenced by the short adaptation period with knee B, so it’s necessary to perform more studies to confirm the previous results and to understand the truly impact of correct adaptation factor to the best prosthetics components for different patients.

Knee angular displacement analysis in amateur ballet dancers: a pilot study

Ballet gestures are highly non-anatomical and physiological, leading to compensatory behaviors. The knee joint is most affected by this behavior, leading to an increase risk of injury. Our purpose is to describe the knee angular displacement in amateur dancers, during a demi-plié exercise, with emphasis on valgus mechanisms frequency. Methods: 192 demi-pliés collected in six amateur female dancers (mean age = 15.33 ± 1.37 years), were analyzed regarding sagittal and frontal plane angular displacement, with an electrogoniometer connected to a signal acquisition unit at 1000 Hz. Results: all subjects presented valgus peaks along the trials, despite the global varus tendency of the knee frontal plane behavior. A significant positive correlation between the frequency of valgus and practice time was noted. Discussion: A variable angular frontal displacement was observed, with some trials comprehending a high incidence of valgus peaks along the ascending or descending phase of the demi-plié exercise. Conclusion: the frontal knee angle behavior is variable. It may present fast peaks of valgus or an initial trend of varus/valgus that is different from the global varus trend. The analysis of the activity should be considered in the training. The practice time may be related to the observed behavior.

Estudo de caso de malformação congénita, com quantificação do êmbolo em 4 sistemas de suspensão para próteses endosqueléticas transtibiais com encaixe TSB

Introdução – O efeito de êmbolo é um dos principais problemas relacionados com a eficácia de uma prótese. Uma diminuição do mesmo pode levar a uma marcha mais natural através do aumento da propriocetividade. Objetivos – Verificar se existe diferença de valores do efeito de êmbolo entre vários sistemas de suspensão para próteses transtibiais com a utilização de Liners e testar a aplicação de testes de imagiologia na análise da melhor solução protésica para um determinado indivíduo. Metodologia – Foi obtida uma radiografia da prótese em carga na posição ortostática, mantendo o peso do indivíduo igualmente distribuído pelos dois pés. Seguidamente foi realizada outra radiografia no plano sagital com o joelho com 30° de flexão, com a prótese suspensa e um peso de 5kg aplicado na extremidade distal da mesma durante 30 seg. Através destes dois exames efetuaram-se as medições do êmbolo para cada tipo de sistema de suspensão. Resultados – Dos quatro sistemas estudados apenas três apresentam valores de êmbolo, visto que um dos sistemas não criou suspensão suficiente para suportar o peso colocado na extremidade distal da prótese. Através das medições realizadas nos exames imagiológicos dos três sistemas pudemos encontrar variações de efeito de êmbolo que vão dos 47,91mm aos 72,55mm. Conclusão – Através da realização do estudo imagiológico verificaram-se diferenças a nível do efeito de êmbolo nos vários sistemas de suspensão, provando que esta é uma ferramenta viável na avaliação do mesmo. Também através da análise dos resultados ficou notório que o sistema de suspensão Vacuum Assisted Suspention System (VASS) é o que apresenta menos êmbolo.

Validação do questionário 'Prosthesis Evaluation Questionnaire - PEQ'

Mestrado em Gestão e Avaliação de Tecnologias em Saúde

Human activity recognition for an intelligent knee orthosis

Dissertação para obtenção do Grau de Mestre em Engenharia Biomédica

Pseudo-Kaposi's Sarcoma Because of Suction-Socket Lower Limb Prosthesis

Pseudo-Kaposi sarcoma is a benign reactive vascular proliferation mainly involving the lower legs, which can be related to acquired chronic venous insufficiency or congenital arteriovenous malformations. In its most common presentation, acroangiodermatitis is seen in patients with chronic venous insufficiency of the lower limbs as an exaggeration of the stasis dermatitis. However, rare reports of acroangiodermatitis include descriptions in amputees (especially in those with poorly fitting suction-type devices), in patients undergoing hemodialysis (with lesions developing distally to arteriovenous shunts) and in patients with paralyzed legs. We report on a 28 year-old-male who presented pseudo-Kaposi's sarcoma in an amputation stump because of suction-socket lower limb prosthesis.

Isokinetic assessment of the flexor-extensor balance of the knee in athletes with total rupture of the anterior cruciate ligament

The purpose of this study was to assess the flexor-extensor group of muscles of the knee in young athletes diagnosed with a total rupture of the anterior cruciate ligament (ACL). Eighteen knees of 18 athletes (14 men and 4 women) with an average age of 21.6 years (range 16-32 years) were assessed with a Cybex 6000 model isokinetic apparatus. The average interval between occurrence of the injury and assessment was 10.2 months (range 2 - 48 months). There was an associated meniscal injury in eight of the knees. Athletes with any other kind of associated injury, limitation, or blockage of the movement of the joint, significant pain during the exam, or interval between injury and exam of less than two months were excluded from the study. The parameters studied were the peak torque-velocity and flexor-extensor relationships at the constant angular velocities of 60°/sec and 240°/sec. Previous warming-up was done by means of an ergometric bicycle and adaptation with 3 submaximal repetitions. The contra-lateral side, which presented no injury, was used as control. Peak torque (PT) at the constant velocity of 60°/sec was greater than that at 240°/sec for knees with and without injuries. However, there was no significant difference between the injured and uninjured sides at 60°/sec or at 240°/sec. The average value for the flexor-extensor relationship at 60°/sec on the injured was 60% (( 6), compared to 57% (( 10) on the contra-lateral side. At 240°/sec, the average value was 75% ((10) on the injured side, and 65% ((12) on the contra-lateral side. In conclusion, despite the complete rupture of the ACL of one knee, the average values for the flexor-extensor relationship were similar on the injured and uninjured sides at the velocity of 60°/sec. As the velocity increased, an increase in the values for the flexor-extensor relationship of the knee also occurred, indicating a tendency of the performance of the flexor muscle group to approach that of the extensor muscle group, and this tendency was more pronounced on the side of the injury.