César Augusto Martins Pereira

Estudo biomecânico de resistência à tração de âncoras metálicas de sutura em diferentes ângulos de inserção

O objetivo deste trabalho e verificar se o ângulo de insercao das âncoras de sutura interfere na sua resistencia quando submetidas a uma forca de tracao constante. Foram realizados 20 ensaios com âncoras metalicas de sutura inseridas em 4 angulacoes diferentes (30°, 45°, 60°, 90°), em osso de cadaver humano (femur distal) e mais 20 ensaios em osso artificial (SawboneTM). Os testes foram realizados na Maquina Universal de Ensaios modelo Kratos, sendo as âncoras tracionadas a 90° em relacao ao seu plano de insercao na superficie ossea. Os valores encontrados no osso de cadaver humano nao foram estatisticamente significantes, ou seja, o ângulo de insercao nao influiu na resistencia a tracao. No osso artificial verificou-se que houve maior resistencia na insercao a 90o, com relevância estatistica em relacao aos demais ângulos testados.

Análise comparativa do controle postural de indivíduos com e sem lesão do ligamento cruzado anterior do joelho

Standing balance is the process which keeps the pressure center, vertical projection of the centre of gravity on ground inside the body weight-bearing. This study evaluates posture control in patients with unilateral lesion of anterior cruciate ligament of knee and in healthy individuals (control group), through parameters of pressure center. Nineteen healthy individuals (11 men, 8 women, age ranged from 18 to 30 years) and nineteen patients with unilateral lesion of anterior cruciate ligament of knee (18 men, 1 woman, age ranged from 15 to 33 years) were evaluated by FSCAN MAT® version 3848 (Tekscan® , Boston, MA, USA) sensors. Four different static tests with unilateral bearing were made, alternating the sides (dominant and non dominant) and keeping open or closed eyes. The parameters were calculated: total length path, antero-posterior amplitude, medio-lateral amplitude and maximum speed of pressure center. The results have pointed out that: the dominance of inferior limbs does not affect in a special way the balance of healthy individuals, the vision is an important factor in posture control and the unilateral lesion of anterior cruciate ligament of knee affects the balance in unilateral weight bearing, on both sides, however more evident on the side with the lesion.

Pedobarometric evaluation of the normal adult male foot.

Static and dynamic pedobarometric evaluations were performed on the feet of 100 normal adult white men aged from 20 to 49 years old (mean = 29.9±6.9), using version 3.848 of the F-SCAN system. All evaluations were performed using new pressure sensor insoles with standardized conditions. Maximum vertical forces and plantar peak pressure measurements were taken during 7.88 seconds each of walking in a straight line at subjects own pace and standing. Feet were separated based on their side and lower limb dominance. The means of three consecutive and three alternate tests provided quantitative data. Maximum static and vertical dynamic forces were found to be greater on the dominant side and were significantly correlated with body weight. There were significant differences between dominant and non-dominant sides in static plantar peak pressure evaluations at the forefoot and midfoot, and in the dynamic evaluations at the midfoot. There was a significant correlation between dynamic plantar peak pressures at the midfoot and body weight.

DiGeorge Syndrome: a not so rare disease

INTRODUCTION: The DiGeorge Syndrome was first described in 1968 as a primary immunodeficiency resulting from the abnormal development of the third and fourth pharyngeal pouches during embryonic life. It is characterized by hypocalcemia due to hypoparathyroidism, heart defects, and thymic hypoplasia or aplasia. Its incidence is 1:3000 live births and, despite its high frequency, little is known about its natural history and progression. ←This is probably due to diagnostic difficulties and the great variety of names used to describe it, such as velocardiofacial, Shprintzen, DiGeorge, and CATCH 22 Syndromes, as well as conotruncal facial anomaly. All represent the same genetic condition, chromosome 22q11.2 deletion, which might have several clinical expressions. OBJECTIVES: To describe clinical and laboratorial data and phenotypic characteristics of patients with DiGeorge Syndrome. METHODS: Patients underwent standard clinical and epidemiological protocol and tests to detect heart diseases, facial abnormalities, dimorphisms, neurological or behavioral disorders, recurrent infections and other comorbidities. RESULTS: Of 14 patients (8m – 18y11m), only one did not have 22q11.2 deletion detected. The main findings were: conotruncal malformation (n  =  12), facial abnormalities (n  =  11), hypocalcemia (n  =  5) and low lymphocyte count (n = 2). CONCLUSION: The authors pointed out the necessity of DGS suspicion in all patient presenting with heart defects, facial abnormalities (associated or not with hypocalcemia), and immunological disorders because although frequency of DGS is high, few patients with a confirmed diagnosis are followed up.

Development and evaluation of a head-controlled human-computer interface with mouse-like functions for physically disabled users

OBJECTIVES The objectives of this study were to develop a pointing device controlled by head movement that had the same functions as a conventional mouse and to evaluate the performance of the proposed device when operated by quadriplegic users. METHODS Ten individuals with cervical spinal cord injury participated in functional evaluations of the developed pointing device. The device consisted of a video camera, computer software, and a target attached to the front part of a cap, which was placed on the user’s head. The software captured images of the target coming from the video camera and processed them with the aim of determining the displacement from the center of the target and correlating this with the movement of the computer cursor. Evaluation of the interaction between each user and the proposed device was carried out using 24 multidirectional tests with two degrees of difficulty. RESULTS According to the parameters of mean throughput and movement time, no statistically significant differences were observed between the repetitions of the tests for either of the studied levels of difficulty. CONCLUSIONS The developed pointing device adequately emulates the movement functions of the computer cursor. It is easy to use and can be learned quickly when operated by quadriplegic individuals.

An in vitro biomechanical comparison of anterior cruciate ligament reconstruction: single bundle versus anatomical double bundle techniques

INTRODUCTION Anterior cruciate ligament ruptures are frequent, especially in sports. Surgical reconstruction with autologous grafts is widely employed in the international literature. Controversies remain with respect to technique variations as continuous research for improvement takes place. One of these variations is the anatomical double bundle technique, which is performed instead of the conventional single bundle technique. More recently, there has been a tendency towards positioning the two bundles through double bone tunnels in the femur and tibia (anatomical reconstruction). OBJECTIVES To compare, through biomechanical tests, the practice of anatomical double bundle anterior cruciate ligament reconstruction with a patellar graft to conventional single bundle reconstruction with the same amount of patellar graft in a paired experimental cadaver study. METHODS Nine pairs of male cadaver knees ranging in age from 44 to 63 years were randomized into two groups: group A (single bundle) and group B (anatomical reconstruction). Each knee was biomechanically tested under three conditions: intact anterior cruciate ligament, reconstructed anterior cruciate ligament, and injured anterior cruciate ligament. Maximum anterior dislocation, rigidity, and passive internal tibia rotation were recorded with knees submitted to a 100 N horizontal anterior dislocation force applied to the tibia with the knees at 30, 60 and 90 degrees of flexion. RESULTS There were no differences between the two techniques for any of the measurements by ANOVA tests. CONCLUSION The technique of anatomical double bundle reconstruction of the anterior cruciate ligament with bone-patellar tendon-bone graft has a similar biomechanical behavior with regard to anterior tibial dislocation, rigidity, and passive internal tibial rotation.

Método de ensaio biomecânico para análise da isometricidade na reconstrução do ligamento patelofemoral medial

OBJETIVO: Apresentar um dispositivo biomecânico para o estudo da reconstrucao do ligamento patelofemoral medial (LPFM) e sua isometricidade. METODOS: Foi desenvolvido um sistema biomecânico acessivel, que permite a aplicacao de forcas fisiologicas e nao fisiologicas no joelho, atraves de um braco mecânico e aplicacao de pesos e contrapesos, possibilitando a execucao de diferentes estudos, alem de ter um sistema de medidas bastante preciso de afericao de distâncias entre diferentes estruturas para analise dos experimentos. Este artigo descreve a montagem deste sistema, alem de sugerir algumas aplicacoes praticas. Foram estudados seis joelhos de cadaveres. Os joelhos foram preparados em uma maquina de ensaios desenvolvida no Laboratorio de Biomecânica do IOT HC FMUSP, que permitiu a avaliacao dinâmica do comportamento patelar, quantificando a sua lateralizacao entre 0 e 120 graus. A diferenca entre as distâncias encontradas, com e sem carga, aplicada na patela foram agrupadas segundo o ângulo de fixacao do enxerto (0°, 30°, 60° e 90°) e situacao do joelho (integro, reconstruido e lesado). RESULTADOS: Houve uma tendencia em ocorrer menor desvio lateral em ângulos de fixacao acima de 30 graus de flexao, principalmente entre os ângulos entre 45° e 60° graus de flexao, apos a reconstrucao. Para os demais ângulos nao houve significância estatistica. CONCLUSAO: O metodo desenvolvido e uma ferramenta util para os estudos da articulacao patelofemoral, alem de ter um sistema de medidas bastante preciso de afericao de distâncias entre diferentes estruturas e permitir a sua utilizacao em instituicoes com menos recursos disponiveis.

Análise comparativa da resistência de fêmures de cães após a confecção de janelas ósseas circular e quadrada

With the purpose of evaluating the weakness caused by holes in the cortical bone, the authors performed circular holes in the diaphysis cortical bone of eight femurs from dog carcasses, and square holes in the diaphysis cortical bone of the contralateral femurs, the diagonals being similar to the diameters. The specimens were submitted to torsion stress test in a mechanical test machine to determine maximum torque and rigidity to torsion. Maximum mean torque for the femurs with circular holes was 13.65 ± 5.12 Nm and mean rigidity was 1.18 ± 0.45 Nm/degree, while the femurs with square holes showed maximum mean torque of 13.39 ± 5.23 Nm and mean rigidity of 1.05 ± 0.41 Nm/degree. The resistance to torsion stress in femurs with circular or square holes was very similar and the statistical analysis did not show a significant difference (p = 0.05).

Measurement of the flexing force of the fingers by a dynamic splint with a dynamometer

PURPOSE AND METHODS In order to determine forces acting upon an articular joint during hand rehabilitation, a dynamic splint was built and connected to a dynamometer (capable of measuring forces in the range 0 - 600 gf). Through trigonometric calculation, the authors measured the flexing force in the proximal interphalangeal joint of the middle finger at 30 degrees, 45 degrees, 60 degrees, and 90 degrees of flexion. Measurements were obtained in a population of 40 voluntary adults, 20 females and 20 males, This flexing force was correlated with age, sex, and anthropometric measures. RESULTS Force in the flexing tendon is maximal at the start of flexion, and decreases as the angle of joint flexion increases. A relationship was observed between finger length and the magnitude of the force exerted on the tendon: the longer the finger, the greater the force exherted upon the tendon. Force is greater at all the measured angles, (except 30 degrees) in males and in individuals of higher stature, and bigger arm span. CONCLUSIONS The flexing force can be effectively measured at all flexing angles, that it correlates with a number of different anthropometric parameters, and that such data are likely to open the way for future studies.

Evaluation of the isometry of different points of the patella and femur for medial patellofemoral ligament reconstruction

BACKGROUND The location of patellar and femoral fixation of the graft in medial patellofemoral ligament reconstructions has been widely discussed. This study aimed to assess the distances between different patellar and femoral fixation points to identify the least anisometric pairs of points. METHODS Ten cadaver knees were attached to an apparatus that simulated an active range of motion of 120°, with three metallic markers fixed onto the medial side of the patella, and seven markings onto the medial epicondyle. The examined points included the proximal patella pole (1), the patellar center (3), the midpoint between points 1 and 3 (2), a point directly on the epicondyle (6), points 5mm anterior (5) and posterior (7) to the epicondyle, points 5mm anterior to point 5 (4) and 5mm posterior to point 7 (8), and points 5mm proximal (9) and distal (10) to the epicondyle. The distances between patella and femur points were measured by a photogrammetry system at 15° intervals. FINDINGS The pair of points that exhibited the lowest average variability in distance, and hence was the most isometric, was the patella center combined with the anterior to the medial femoral epicondyle. The pairs of points that exhibited the highest average variability in distance, and hence were the least isometric, were the ones located distal or posterior to the medial femoral epicondyle, with less influence by the patellar location. INTERPRETATION Surgeons should avoid positioning the graft distally or posterior to the epicondyle due to the increase in anisometry.