Hyperbaric oxygen therapy enhances graft healing and mechanical properties after anterior cruciate ligament reconstruction: An experimental study in rabbits.

Hyperbaric oxygen therapy (HBOT) has proven successful in wound healing. However, its potential effects on anterior cruciate ligament (ACL) injuries remain uncertain. This study aimed to investigate the impact of HBOT on graft healing following ACL reconstruction in rabbits. Male New Zealand rabbits underwent ACL reconstruction and were randomly divided into two groups: the HBOT group and the ambient air group. The HBOT group received 100% oxygen at 2.5 atmospheres absolute for 2 h daily for 5 consecutive days, starting from the first day after surgery. The ambient air group was maintained in normal room air throughout the entire period. After 12 weeks following the surgery, animals were euthanized, and their knees were harvested for analysis. The HBOT group demonstrated superior graft maturation and integration in comparison to the ambient air group, as evidenced by lower graft signal intensity on magnetic resonance imaging, decreased femoral and tibial tunnel size, and higher bone mineral density values on high-resolution peripheral quantitative computed tomography scans. Additionally, biomechanical testing indicated that the HBOT group had greater load to failure and stiffness values than the ambient air group. In conclusion, the adjuvant use of HBOT improved ACL graft maturation and integration, reduced tunnel widening, and enhanced the biomechanical properties of the graft. These results may provide important insights into the potential clinical application of HBOT as a therapeutic intervention to enhance graft healing after ACL reconstruction, paving the way for further research in this area.

Evaluation of ankle movements on a sudden inversion platform / Evaluación de los movimientos del tobillo en la plataforma de inversión súbita / Avaliação dos movimentos do tornozelo na plataforma de inversão súbita

ABSTRACT Introduction: Ankle sprains are frequent in sports activities and can lead to joint instability with clinical and performance consequences. Sudden ankle inversion platforms have been used to study the mechanism of ankle sprain. Objectives: To test a static platform that simulates the movement of ankle sprain (sudden inversion) in soccer players. Methods: A platform was developed to perform the sudden movement of an ankle sprain dissociated in three axes: inversion, plantar flexion, and medial rotation. A computer program was also created to read the angular velocity and the time to reach the maximum amplitude of the three axes of movement, synchronized with the platform movements. Thirty soccer players without ankle sprains were evaluated on the sudden inversion platform. Each athlete performed 10 randomly initiated tests, with five per leg. Results: There was no statistical difference in angular velocity or time to reach maximum range of motion of plantar flexion and medial rotation between the tests. During the tests, the angular velocity of the inversion increased. Conclusion: The sudden static platform evaluated the movements performed by the ankle during the sprain reliably in the 10 tests with no difference in the mechanical behavior. Level of evidence I; Therapeutic studies - Investigation of treatment outcomes.

RESUMEN Introducción: El esguince de tobillo es frecuente en las actividades deportivas y puede provocar inestabilidad articular con consecuencias clínicas y de desempeño. Se han utilizado plataformas de inversión súbita del tobillo para estudiar el mecanismo del esguince de tobillo. Objetivos: Probar una plataforma estática que simule el movimiento de esguince de tobillo (inversión súbita) en jugadores de fútbol. Métodos: La plataforma fue desarrollada para realizar el movimiento brusco del esguince de tobillo disociado en tres ejes: inversión, flexión plantar y rotación medial. También se creó un programa informático para leer la velocidad angular y el tiempo para alcanzar la máxima amplitud de los tres ejes de movimiento, sincronizados con los movimientos de la plataforma. Treinta futbolistas sin esguince de tobillo fueron evaluados en la plataforma súbita. Cada atleta realizó 10 pruebas, iniciadas al azar, cinco en cada pierna. Resultados: Entre las pruebas, no hubo diferencias estadísticas en las velocidades angulares y el tiempo para alcanzar la amplitud máxima de los movimientos de flexión plantar y rotación medial. Durante las pruebas, la velocidad angular de la inversión aumentó. Conclusión: La plataforma estática súbita, evaluada en 10 intentos, fue confiable para evaluar los movimientos realizados por el tobillo durante el esguince, y no hubo diferencias en el comportamiento mecánico. Nivel de Evidencia I; Estudios terapéuticos - Investigación de los resultados del tratamiento.

RESUMO Introdução: A entorse do tornozelo é frequente nas atividades esportivas, podendo levar à instabilidade articular com consequências clínicas e de desempenho. As plataformas de inversão súbita do tornozelo têm sido usadas para estudar o mecanismo de entorse do tornozelo. Objetivos: Testar uma plataforma estática que simule o movimento de entorse do tornozelo (inversão súbita) em jogadores de futebol. Métodos: A plataforma foi desenvolvida para realizar o movimento súbito da entorse de tornozelo dissociado em três eixos: inversão, flexão plantar e rotação medial. Também foi criado um programa de computador para leitura da velocidade angular e do tempo para atingir a amplitude máxima dos três eixos de movimento, sincronizados com os movimentos da plataforma. Trinta jogadores de futebol sem entorse de tornozelo foram avaliados na plataforma súbita. Cada atleta fez 10 testes, iniciados de forma aleatória, sendo cinco em cada perna. Resultados: Entre os testes, não houve diferença estatística das velocidades angulares e tempo para atingir a amplitude máxima do movimento de flexão plantar e rotação medial. Durante os testes, a velocidade angular da inversão aumentou. Conclusão: A plataforma estática súbita, avaliada em 10 tentativas, foi confiável para avaliar os movimentos executados pelo tornozelo durante a entorse, e não houve diferença de comportamento mecânico. Nível de evidência I; Estudos terapêuticos - Investigação dos resultados do tratamento.

A biomechanical comparison of matched four-strand and five-strand semitendinosus-gracilis grafts / Estudo biomecânico comparativo entre enxertos quádruplos e quíntuplos pareados de tendões dos músculos semitendíneo e grácil / Estudio biomecânico comparativo entre injertos de tendones semitendinoso e gracilis cuádruple e quíntuple

ABSTRACT Introduction: Recent studies have shown that the likelihood of semitendinosus-gracilis graft rupture is inversely correlated to its diameter. A graft can be prepared in a five-strand or four-strand fashion to increase its diameter. However, the biomechanical superiority of five-strand semitendinosus-gracilis grafts is still under debate. Objective: This study aimed to evaluate the biomechanical characteristics of matched four-strand and five-strand human semitendinosus-gracilis grafts. Methods: We evaluated semitendinosus-gracilis tendons harvested from ten fresh human male and female cadavers, aged 18-60 years. Four-strand or five-strand grafts were prepared with the tendons and fixed to wooden tunnels with interference screws. Each graft was submitted to axial traction at 20 mm/min until rupture; the tests were donor matched. Data were recorded in real time and included the analysis of the area, diameter, force, maximum deformation and stiffness of the grafts. Results: The diameter, area and tunnel size were significantly greater in the five-strand grafts than in the four-strand grafts. There were no significant differences in biomechanical properties. The area and diameter of the graft were positively correlated to stiffness, and inversely correlated to elasticity. There was no significant correlation between graft size and maximum force at failure, maximum deformation or maximum tension. Conclusion: Five-strand hamstring grafts have greater area, diameter and tunnel size than four-strand grafts. There were no significant differences in biomechanical properties. In this model using interference screw fixation, the increases in area and diameter were correlated with an increase in stiffness and a decrease in elasticity. Level of evidence V; biomechanical study.

RESUMEN Introducción: Estudios recientes demostraron que la probabilidad de ruptura de los injertos semitendinoso y gracilis (STG) durante el pos operatorio de reconstrucción de ligamento cruzado anterior (LCA) está inversamente correlacionada a su diámetro. Un injerto puede ser preparado para obtener cuatro o cinco hebras para aumentar su diámetro, pero la superioridad biomecanica de los injertos STG de cinco hebras aún se mantiene en discusión. Objetivo: Evaluar las características biomecánicas de los injertos STG de humanos de cuatro o cinco hebras por pares. Métodos: Fueron evaluados tendones STG de diez cadaveres masculinos y diez cadaveres femeninos frescos, entre los 18 y 60 años. Los injertos de cuatro y cinco hebras fueron fijados en túneles de madera con tornillos de interferencia. Cada injerto fue sometido a una tracción axial de 200mm/min hasta su ruptura; estos tendones fueron separados por pares de acuerdo con sus donadores. Los datos fueron registrados en tiempo real y incluyeron el análisis del área del injerto, diámetro, fuerza, deformación máxima y rigidez. Resultados: Los resultados sobre el diámetro, el área y el tamaño del túnel fueron significativamente mayores en los injertos de cinco hebras que en los de cuatro. No existieron diferencias significativas en las propiedades biomecánicas. El área y el diámetro del injerto fueron correlacionados positivamente con la rigidez e inversamente con la elasticidad. No existió correlación significativa entre el tamaño del injerto y la fuerza máxima al momento de la falla, Máxima deformación o máxima tensión. Conclusión: Los injertos de isquiotibiales de cinco hebras tienen una área, diámetro y tamaño de túnel más grande que los injertos de cuatro hebras. No hubieron diferencias biomecánicas significativas. Los aumentos de área y diámetro en este modelo con la fijación de tornillo de interferencia fueron correlacionados con aumento de en la rigidez y una disminución en la elasticidad. Nivel de evidencia V; estudio biomecánico.

RESUMO Introdução: Estudos recentes demonstraram que a probabilidade de ruptura do enxerto dos tendões do semitendíneo e do grácil (STG) é correlacionada inversamente com seu diâmetro. Um enxerto pode ser preparado de forma quádrupla ou quíntupla para se aumentar o diâmetro. No entanto, a superioridade biomecânica dos enxertos STG quíntuplos ainda está em debate. Objetivo: Este estudo teve como objetivo avaliar as características biomecânicas dos enxertos STG humanos quádruplos ou quíntuplos pareados. Métodos: Foram avaliados tendões STG retirados de dez cadáveres masculinos e femininos frescos, com idades entre 18 e 60 anos. Os enxertos quádruplos ou quíntuplos foram preparados com os tendões e fixados em túneis de madeira com parafusos de interferência. Cada enxerto foi submetido à tração axial a 20 mm/min. até a ruptura; os testes foram pareados de acordo com os doadores. Os dados foram registrados em tempo real e incluíram a análise de área, diâmetro, força, deformação máxima e rigidez dos enxertos. Resultados: O diâmetro, a área e o tamanho do túnel foram significativamente maiores nos enxertos quíntuplos do que nos enxertos quádruplos. Não houve diferenças significativas nas propriedades biomecânicas. A área e o diâmetro do enxerto foram correlacionados positivamente com a rigidez e inversamente com a elasticidade. Não houve correlação significativa entre o tamanho do enxerto e a força máxima na falha, deformação máxima ou tensão máxima. Conclusão: Os enxertos quíntuplos dos músculos isquiotibiais têm maior área, diâmetro e tamanho do túnel do que os enxertos quádruplos. Não houve diferenças significativas nas propriedades biomecânicas. Neste modelo de fixação com parafuso de interferência, aumentos da área e do diâmetro foram correlacionados com o aumento da rigidez e a diminuição na elasticidade. Nível de evidência V; Estudo Biomecânico.

Comparison of a 3-hole 4.5-mm Dynamic Compression Plate and a 7-hole 5.5-mm Y Locking Compression Plate for Arthrodesis of the Proximal Interphalangeal Joint in Horses-an Ex Vivo Biomechanical Study.

The objective of this study was to compare the biomechanical properties in a single cycle axial loading test and the types of failures in two constructs (a 3-hole 4.5-mm dynamic compression plate (DCP) and 7-hole 5.5-mm Y locking compression plate (Y-LCP)) in equine proximal interphalangeal joint (PIJ) arthrodesis. One limb in each pair was randomly assigned to PIJ arthrodesis using a 3-hole 4.5-mm DCP combined with two transarticular 5.5-mm cortical screws, whereas the contralateral limb was submitted to PIJ arthrodesis using a 7-hole Y-shaped 5.0-mm LCP in conjunction with one transarticular 4.5-mm cortical screw inserted through the central plate hole. Cortical screws were inserted in lag fashion. Constructs were submitted to a single axial load cycle to failure. Construct stiffness, load, and deformation were analyzed. Dynamic compression plate and Y-LCP arthrodesis constructs did not differ significantly and were equally resistant to axial loading under the conditions studied (DCP and Y-LCP group stiffness, 5685.22 N/mm and 6591.10 N/mm, respectively). Arthrodesis of the PIJ using a DCP and two transarticular 5.5-mm cortical screws or a Y-LCP yielded biomechanically equivalent outcomes under the test conditions considered. However, Y-LCP provides less impact in the palmar/plantar bone. Application of Y-LCP with unicortical screws has equivalent biomechanical characteristics of DCP and may be a safe option for PIJ arthrodesis, where potential trauma secondary to applying bicortical screws in the palmar/plantar aspect of the pastern can be avoided.

Thick Graft Versus Double-Bundle Technique on Posterior Cruciate Ligament Reconstruction: Experimental Biomechanical Study with Cadavers.

Objective To evaluate the biomechanical effect of graft thickness compared with the double-bundle technique on posterior cruciate ligament (PCL) reconstruction in human cadaveric knees. Methods A total of 9 human cadaveric knees were tested in 5 conditions: intact knee (INT); single-bundle reconstruction with a 10-mm quadriceps tendon (SB); double-bundle reconstruction with a 10 mm-quadriceps tendon for the anterolateral bundle and a 7-mm doubled semitendinosus tendon for the posteromedial bundle (DB); single-bundle reconstruction with a 10-mm quadriceps tendon plus a 7-mm doubled semitendinosus tendon (SBT); and PCL-deficient (NoPCL). The posterior tibial translation (PTT) was measured in response to a 134-N posterior tibial load at 0 ∘ , 30 ∘ , 60 ∘ e 90 ∘ of knee flexion. Results The PTT values of the DB and SBT techniques were always significantly lower (better stability) than those of the SB technique. The PTT values of the SBT technique were significantly lower than those of the DB technique at 60 ∘ ( p = 0.005) and 90 ∘ ( p = 0.001). Conclusions Graft enlargement improves knee stability in isolated PCL reconstructions, whereas the graft division in the two-bundle technique worsens this stability at 60 ∘ and 90 ∘ of knee flexion. The findings of the present study suggest that knee stability in PCL reconstructions may be improved with the use of thicker grafts in the SB technique rather than performing the DB technique.

Thick Graft Versus Double-Bundle Technique on Posterior Cruciate Ligament Reconstruction: Experimental Biomechanical Study with Cadavers / Enxerto espesso versus técnica de duplo feixe na reconstrução do ligamento cruzado posterior: Estudo experimental biomecânico com cadáveres

Abstract Objective To evaluate the biomechanical effect of graft thickness compared with the double-bundle technique on posterior cruciate ligament (PCL) reconstruction in human cadaveric knees. Methods A total of 9 human cadaveric knees were tested in 5 conditions: intact knee (INT); single-bundle reconstruction with a 10-mm quadriceps tendon (SB); double-bundle reconstruction with a 10 mm-quadriceps tendon for the anterolateral bundle and a 7-mm doubled semitendinosus tendon for the posteromedial bundle (DB); single-bundle reconstruction with a 10-mm quadriceps tendon plus a 7-mm doubled semitendinosus tendon (SBT); and PCL-deficient (NoPCL). The posterior tibial translation (PTT) was measured in response to a 134-N posterior tibial load at 0º, 30º, 60º e 90º of knee flexion. Results The PTT values of the DB and SBT techniques were always significantly lower (better stability) than those of the SB technique. The PTT values of the SBT technique were significantly lower than those of the DB technique at 60º (p = 0.005) and 90º (p = 0.001). Conclusions Graft enlargement improves knee stability in isolated PCL reconstructions, whereas the graft division in the two-bundle technique worsens this stability at 60º and 90º of knee flexion. The findings of the present study suggest that knee stability in PCL reconstructions may be improved with the use of thicker grafts in the SB technique rather than performing the DB technique.

Resumo Objetivo Avaliar o efeito biomecânico da espessura do enxerto em comparação com a técnica do duplo feixe na reconstrução do ligamento cruzado posterior (LCP) em joelhos de cadáveres humanos. Métodos Um total de 9 joelhos de cadáveres humanos foram testados em 5 condições: joelho intacto (INT); reconstrução com um único feixe com tendão de quadríceps de 10 mm (Rec 1); reconstrução com duplo feixe com um tendão de quadríceps de 10 mm para o feixe anterolateral e um tendão duplo do semitendíneo de 7 mm para o feixe póstero-medial (Rec 2); reconstrução com um único feixe mais espesso, usando um tendão de quadríceps de 10 mm mais o tendão duplo do semitendíneo de 7 mm (Rec M); e joelho com lesão isolada do LCP (Lesionado). O limite do deslocamento posterior da tíbia (LDPT) foi medido em resposta a uma carga tibial posterior de 134 N a 0º, 30º, 60º e 90º de flexão do joelho. Resultados O LDPT das técnicas Rec 2 e Rec M foi sempre significativamente menor (melhor estabilidade) do que o LDPT da Rec 1. O LDPT da Rec M foi significativamente menor do que o LDPT da Rec 2 a 60º (p = 0,005) e a 90º (p = 0,001). Conclusões O aumento da espessura do enxerto na reconstrução das lesões isoladas do LCP melhora significativamente a estabilidade, enquanto a divisão do enxerto para reconstruir os dois feixes piora a estabilidade da reconstrução a 60º e 90º de flexão do joelho. As descobertas do presente estudo sugerem que a estabilidade da reconstrução do LCP pode ser melhorada com o uso de enxertos mais espessos em uma técnica de feixe único, em lugar da reconstrução de duplo feixe.

Laparoscopic Insertion of Various Shaped Trocars in a Porcine Model.

BACKGROUND AND OBJECTIVE: The number of laparoscopic procedures increases annually with an estimated 3% of complications, one third of them linked to Verres' needle or trocar insertion. The safety and efficacy of ports insertion during laparoscopic surgery may be related the technique but also to trocar design. This study aims to compare physical parameters of abdominal wall penetration for 5 different trocars. METHODS: Eleven pigs were studied. Five different commercially available trocars were randomically inserted at the midline. Real-time video recording of the insertions was achieved to measure the excursion of the abdominal wall and the time and distance the cutting surface of the bladed trocars was exposed inside the abdominal cavity. An especially designed hand sensor was developed and placed between the trocar and the hand of the surgeon to record force required for abdominal wall perforation. RESULTS: Greater deformations and forces occurred in nonbladed as compared to bladed trocars, and in conical trocars as compared to pyramidal pointed ones, except for peritoneum perforation. Greater distance and time of blade exposure occurred in pyramidal laminae as compared to conical. CONCLUSION: The bladed trocars have lower forces and deformations in their introduction, and should be those that cause less injury and are more suitable for first entry. Conical and pyramidal trocars with the same blade size showed similar force, deformation, time, and distance of exposed blade.

Novel animal model for Achilles tendinopathy: Controlled experimental study of serial injections of collagenase in rabbits.

Our goal was to develop a novel technique for inducing Achilles tendinopathy in animal models which more accurately represents the progressive histological and biomechanical characteristic of chronic Achilles tendinopathy in humans. In this animal research study, forty-five rabbits were randomly assigned to three groups and given bilateral Achilles injections. Low dose (LD group) (n = 18) underwent a novel technique with three low-dose (0.1mg) injections of collagenase that were separated by two weeks, the high dose group (HD) (n = 18) underwent traditional single high-dose (0.3mg) injections, and the third group were controls (n = 9). Six rabbits were sacrificed from each experimental group (LD and HD) at 10, 12 and 16 weeks. Control animals were sacrificed after 16 weeks. Histological and biomechanical properties were then compared in all three groups. At 10 weeks, Bonar score and tendon cross sectional area was highest in HD group, with impaired biomechanical properties compared to LD group. At 12 weeks, Bonar score was higher in LD group, with similar biomechanical findings when compared to HD group. After 16 weeks, Bonar score was significantly increased for both LD group (11,8±2,28) and HD group (5,6±2,51), when compared to controls (2±0,76). LD group showed more pronounced histological and biomechanical findings, including cross sectional area of the tendon, Young's modulus, yield stress and ultimate tensile strength. In conclusion, Achilles tendinopathy in animal models that were induced by serial injections of low-dose collagenase showed more pronounced histological and biomechanical findings after 16 weeks than traditional techniques, mimicking better the progressive and chronic characteristic of the tendinopathy in humans.

Early versus late repair of rotator cuff tears in rats.

BACKGROUND: In the event of a traumatic rotator cuff tear, patients are routinely advised that early surgical intervention produces an optimal repair, despite a lack of direct evidence to support this recommendation. To address this knowledge gap, massive rotator cuff tears in rats were assessed by biomechanical and bone morphometric analyses after early or late repair. METHODS: Combined supraspinatus and infraspinatus tendon tears of the left shoulder were created in 21 adult Wistar rats, which were divided into 2 groups. The tendons of the injured shoulder in the animals in group I were surgically repaired 8 weeks after the injury. Under the same anesthesia, the same injury was created on the right shoulder, which was immediately repaired. The rats from group I were euthanized 8 weeks after the repairs. No repair was performed in the rats from group II, which were euthanized 8 weeks after the injury. Tissues from both groups were harvested and biomechanically tested for supraspinatus tendon and bone morphometry analysis of the humeral head. RESULTS: All biomechanical properties were significantly increased in the early repair group compared with the late repair group. No significant differences were observed in bone morphometry of the humeral head when early and late repair groups were compared. CONCLUSION: Early surgical repair of a massive rotator cuff tear leads to improved biomechanical properties of the tissue after healing. Proximal humerus bone morphometry was unaffected by surgical repair timing.

Axial compressive strength of human vertebrae trabecular bones classified as normal, osteopenic and osteoporotic by quantitative ultrasonometry of calcaneus

Abstract Introduction Biomechanical assessment of trabecular bone microarchitecture contributes to the evaluation of fractures risk associated with osteoporosis and plays a crucial role in planning preventive strategies. One of the most widely clinical technics used for osteoporosis diagnosis by health professionals is bone dual-energy X-ray absorptiometry (DEXA). However, doubts about its accuracy motivate the introduction of congruent technical analysis such as calcaneal ultrasonometry (Quantitative Ultrasonometry - QUS). Methods Correlations between Bone Quality Index (BQI), determined by calcaneal ultrasonometry of thirty (30) individuals classified as normal, osteopenic and osteoporotic, and elastic modulus (E) and ultimate compressive strength (UCS) from axial compression tests of ninety (90) proof bodies from human vertebrae trabecular bone, which were extracted from cadavers in the twelfth thoracic region (T12), first and fourth lumbar (L1 and L4). Results Analysis of variance (ANOVA) showed significant differences for E (p = 0.001), for UCS (p = 0.0001) and BQI. Spearman's rank correlation coefficient (rho) between BQI and E (r = 0.499) and BQI and UCS (r = 0.508) were moderate. Discussion Calcaneal ultrasonometry technique allowed a moderate estimate of bone mechanical strength and fracture risk associated with osteoporosis in human vertebrae.

The biomechanical effects of graft rotation on ACL reconstruction tunnel mismatch.

PURPOSE: Bone block protrusion out of the tibial tunnel due to a relatively long graft is a common complication in anterior cruciate ligament surgical reconstruction with a patellar tendon. One possible solution is to shorten the patellar tendon graft already fixed in the femur by applying external rotation. This study aimed to evaluate the degree of shortening and biomechanical changes in porcine patellar grafts subjected to relatively higher degrees of rotation. Data obtained with rotations of 0°, 540°, 720°, and 900° were compared. METHODS: Forty patellar porcine ligaments were subjected to biomechanical tests of degree of shortening, modulus of elasticity and maximum tension in the tendon before rupture. Tests were conducted using a universal mechanical testing machine and a computerized system for acquiring strength and deformation data. RESULTS: Progressive shortening of the patellar ligament occurred with rotations of 0°, 540° and 720°. However, the degree of shortening showed no statistically significant difference as rotation increased from 720° to 900°. Decreased modulus of elasticity was observed compared with the graft rotation at 0° in all groups tested, but no statistically significant differences were observed among 540°, 720° and 900°. The maximum tension of the patellar tendon showed no change before rupture, regardless of the degree of rotation. CONCLUSIONS: Rotating the patellar tendon is an efficient method for shortening a relatively long graft; however, more biomechanical studies are necessary to recommend this technique in clinical practice owing to the resulting decrease in graft stiffness that could compromise knee stability.

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.

Biomechanical study of strength and stiffness of the knee anterolateral ligament.

BACKGROUND: Recent studies clearly characterize the anatomical parameters of the knee anterolateral ligament (ALL). The potential clinical importance of this ligament is exemplified by some patients with possible combined Anterior Cruciate Ligament (ACL) and ALL rupture who do not progress satisfactorily following isolated ACL reconstruction. Previous biomechanical studies have assessed the resistance parameters of the ALL in order to address potential reconstruction strategies; however, these have reported conflicting results. Thus, this study aimed to evaluate the linear resistance of the ALL by means of a biomechanical study in cadaveric knees. METHODS: Fourteen cadaveric knees were used. The ALL was dissected, and all structures that connect the femur and the tibia, except for the ALL, were sectioned. The ALL was subjected to a tensile test with the knee around 30 to 40 degrees, in a way that the ALL was aligned with the machine. The strength at the maximum resistance limit, deformation and stiffness of the ALL were evaluated. RESULTS: The mean maximum strength of the ALL was 204.8 +/- 114.9 N. The stiffness was 41.9 +/- 25.7 N/mm and the deformation 10.3 +/- 3.5 mm. CONCLUSION: The ALL has a mean ultimate tensile strength of 204.8 N. This suggests that simple bands of all autologous or homologous grafts commonly used in clinical practice for ligament reconstruction around the knee possess the required biomechanical resistance characteristics for ALL reconstruction.

Description of an evaluation system for knee kinematics in ligament lesions, by means of optical tracking and 3D tomography.

OBJECTIVE: To describe and demonstrate the viability of a method for evaluating knee kinematics, by means of a continuous passive motion (CPM) machine, before and after anterior cruciate ligament (ACL) injury. METHODS: This study was conducted on a knee from a cadaver, in a mechanical pivot-shift simulator, with evaluations using optical tracking, and also using computed tomography. RESULTS: This study demonstrated the viability of a protocol for measuring the rotation and translation of the knee, using reproducible and objective tools (error < 0.2 mm). The mechanized provocation system of the pivot-shift test was independent of the examiner and always allowed the same angular velocity and traction of 20 N throughout the movement. CONCLUSION: The clinical relevance of this method lies in making inferences about the in vivo behavior of a knee with an ACL injury and providing greater methodological quality in future studies for measuring surgical techniques with grafts in relatively close positions.

OBJETIVO: Descrever e demonstrar a viabilidade de um método de avaliação da cinemática do joelho, por meio de um aparelho de CPM (continuous passive motion), antes e após a lesão do ligamento cruzado anterior (LCA). MÉTODOS: O estudo foi feito em joelho de cadáver, em um simulador mecânico de pivot-shift avaliado a partir de rastreamento óptico associado à tomografia computadorizada. RESULTADOS: Este estudo demonstra a viabilidade de um protocolo de mensuração de rotação e translação do joelho com ferramentas reprodutíveis e objetivas (erro < 0,2 mm). O sistema mecanizado de provocação do teste do pivot-shift é independente do examinador e permite sempre a mesma velocidade angular e tração de 20 N por todo o movimento. CONCLUSÃO: Sua relevância clínica está em fazer inferências sobre o comportamento in vivo de um joelho com lesão do LCA e proporcionar aos estudos futuros maior qualidade metodológica para a aferição de técnicas cirúrgicas com enxertos em posições relativamente próximas.

Método de ensaio biomecânico para análise da isometricidade na reconstrução do ligamento patelofemoral medial / Biomechanical access method for analyzing isometricity in reconstructing the medial patellofemoral ligament

OBJETIVO: Apresentar um dispositivo biomecânico para o estudo da reconstrução do ligamento patelofemoral medial (LPFM) e sua isometricidade. MÉTODOS: Foi desenvolvido um sistema biomecânico acessível, que permite a aplicação de forças fisiológicas e não fisiológicas no joelho, através de um braço mecânico e aplicação de pesos e contrapesos, possibilitando a execução de diferentes estudos, além de ter um sistema de medidas bastante preciso de aferição de distâncias entre diferentes estruturas para análise dos experimentos. Este artigo descreve a montagem deste sistema, além de sugerir algumas aplicações práticas. Foram estudados seis joelhos de cadáveres. Os joelhos foram preparados em uma máquina de ensaios desenvolvida no Laboratório de Biomecânica do IOT HC FMUSP, que permitiu a avaliação dinâmica do comportamento patelar, quantificando a sua lateralização entre 0 e 120 graus. A diferença entre as distâncias encontradas, com e sem carga, aplicada na patela foram agrupadas segundo o ângulo de fixação do enxerto (0°, 30°, 60° e 90°) e situação do joelho (íntegro, reconstruído e lesado). RESULTADOS: Houve uma tendência em ocorrer menor desvio lateral em ângulos de fixação acima de 30 graus de flexão, principalmente entre os ângulos entre 45° e 60° graus de flexão, após a reconstrução. Para os demais ângulos não houve significância estatística. CONCLUSÃO: O método desenvolvido é uma ferramenta útil para os estudos da articulação patelofemoral, além de ter um sistema de medidas bastante preciso de aferição de distâncias entre diferentes estruturas e permitir a sua utilização em instituições com menos recursos disponíveis.

OBJECTIVE: To present a biomechanical device for evaluating medial patellofemoral ligament (MPFL) reconstruction and its isometricity. METHODS: An accessible biomechanical method that allowed application of physiological and non-physiological forces to the knee using a mechanical arm and application of weights and counterweights was developed, so as to enable many different evaluations and have a very accurate measurement system for distances between different structures, for analysis on experiments. This article describes the assembly of this system, and suggests some practical applications. Six cadaver knees were studied. The knees were prepared in a testing machine developed at the Biomechanics Laboratory of IOT-HCFMUSP, which allowed dynamic evaluation of patellar behavior, with quantification of patellar lateralization between 0° and 120°. The differences between the distances found with and without load applied to the patella were grouped according to the graft fixation angle (0°, 30°, 60° or 90°) and knee position (intact, damaged or reconstructed). RESULTS: There was a tendency for smaller lateral displacement to occur at fixation angles greater than 30 degrees of flexion, especially between the angles of 45° and 60° degrees of flexion, after the reconstruction. For the other angles, there was no statistical significance. CONCLUSION: The method developed is a useful tool for studies on the patellofemoral joint and the MPFL, and has a very accurate measurement system for distances between different structures. It can be used in institutions with fewer resources available.

BIOMECHANICAL ACCESS METHOD FOR ANALYZING ISOMETRICITY IN RECONSTRUCTING THE MEDIAL PATELLOFEMORAL LIGAMENT.

OBJECTIVE: To present a biomechanical device for evaluating medial patellofemoral ligament (MPFL) reconstruction and its isometricity. METHODS: An accessible biomechanical method that allowed application of physiological and non-physiological forces to the knee using a mechanical arm and application of weights and counterweights was developed, so as to enable many different evaluations and have a very accurate measurement system for distances between different structures, for analysis on experiments. This article describes the assembly of this system, and suggests some practical applications. Six cadaver knees were studied. The knees were prepared in a testing machine developed at the Biomechanics Laboratory of IOT-HCFMUSP, which allowed dynamic evaluation of patellar behavior, with quantification of patellar lateralization between 0° and 120°. The differences between the distances found with and without load applied to the patella were grouped according to the graft fixation angle (0°, 30°, 60° or 90°) and knee position (intact, damaged or reconstructed). RESULTS: There was a tendency for smaller lateral displacement to occur at fixation angles greater than 30 degrees of flexion, especially between the angles of 45° and 60° degrees of flexion, after the reconstruction. For the other angles, there was no statistical significance. CONCLUSION: The method developed is a useful tool for studies on the patellofemoral joint and the MPFL, and has a very accurate measurement system for distances between different structures. It can be used in institutions with fewer resources available.

Simple suture and anchor in rabbit hips.

OBJECTIVE: USING BIOMECHANICAL STUDIES, THIS RESEARCH AIMS TO COMPARE HIP CAPSULORRHAPHY IN RABBITS, CARRIED OUT WITH TWO DIFFERENT TECHNIQUES: capsulorrhaphy with simple sutures and with anchors. METHOD: Thirteen New Zealand Albino (Oryctolaguscuniculus) male rabbits, twenty-six hip joints, were used. First, a pilot project was performed with three rabbits (six hip joints). This experiment consisted of ten rabbits divided into two groups: group 1 underwent capsulorrhaphy on both right and left hips with simple suture using polyglycolic acid absorbable thread, and group 2 underwent capsulorrhaphy with titanium anchors. After a four-week postoperative period, the animals were euthanized and the hip joints were frozen. On the same day of the biomechanical studies, after the hip joints were previously unfrozen, the following parameters were evaluated: rigidity, maximum force, maximum deformity and energy. RESULTS: There was no relevant statistical difference in rigidity, maximum force, maximum deformity and energy between the simple suture and anchor groups. CONCLUSION: Through biomechanical analyses, using parameters of rigidity, maximum force, maximum deformity and energy, it has been shown that capsulorrhaphy with simple suture and with anchors has similar results in rabbit hip joints. Level of Evidence II, Prospective Comparative Study .

Sutura simples e âncora em quadris de coelhos / Simple suture and anchor in rabbit hips

OBJETIVO: Por meio de ensaios biomecânicos, comparar as capsulorrafias com sutura simples e com âncoras, em quadris de coelhos. MÉTODO: Foram utilizados 13 coelhos, 26 quadris, todos machos da raça Nova Zelândia albinos (Oryctolaguscuniculus). Inicialmente, realizamos um projeto piloto em três coelhos (seis quadris). Este experimento constou de 10 coelhos, divididos em 2 grupos: o Grupo 1 submetido à capsulorrafia (quadris direito e esquerdo) com sutura simples utilizando fio absorvível de ácido poliglicólico e o Grupo 2 submetido a capsulorrafia (quadris direito e esquerdo) com âncora de titânio. Após o período de quatro semanas de operados, todos animais foram submetidos à eutanásia e seus quadris congelados. Após um descongelamento prévio das peças, no mesmo dia das análises biomecânicas, foram avaliados os parâmetros de rigidez, força máxima, deformidade máxima e energia. RESULTADOS: Não houve diferença estatisticamente significante em relação à força no limite de proporcionalidade, rigidez e força máxima entre os grupos com sutura simples e com âncora. CONCLUSÃO: Por meio dos ensaios biomecânicos, tendo como parâmetro a rigidez, a força máxima, a deformidade máxima e a energia, ficou demonstrado que as capsulorrafias em quadris de coelhos com sutura simples e com âncora são semelhantes entre si. Nível de Evidência II, Estudo Prospectivo Comparativo.

OBJECTIVE: Using biomechanical studies, this research aims to compare hip capsulorrhaphy in rabbits, carried out with two different techniques: capsulorrhaphy with simple sutures and with anchors. METHOD: Thirteen New Zealand Albino (Oryctolaguscuniculus) male rabbits, twenty-six hip joints, were used. First, a pilot project was performed with three rabbits (six hip joints). This experiment consisted of ten rabbits divided into two groups: group 1 underwent capsulorrhaphy on both right and left hips with simple suture using polyglycolic acid absorbable thread, and group 2 underwent capsulorrhaphy with titanium anchors. After a four-week postoperative period, the animals were euthanized and the hip joints were frozen. On the same day of the biomechanical studies, after the hip joints were previously unfrozen, the following parameters were evaluated: rigidity, maximum force, maximum deformity and energy. RESULTS: There was no relevant statistical difference in rigidity, maximum force, maximum deformity and energy between the simple suture and anchor groups. CONCLUSION: Through biomechanical analyses, using parameters of rigidity, maximum force, maximum deformity and energy, it has been shown that capsulorrhaphy with simple suture and with anchors has similar results in rabbit hip joints. Level of Evidence II, Prospective Comparative Study.

Biomechanical evaluation on tendon reinsertion by comparing trans-osseous suture and suture anchor at different stages of healing: experimental study on rabbits.

BACKGROUND: Through an experimental biomechanical study on rabbits, tendon reinsertion by means of trans-osseous suture on a spongy bone bed and suture anchor were evaluated comparatively at different phases of healing. METHODS: Twenty-four New Zealand White rabbits were used: 2 as pilots, 4 as the control group, and 18 as the experimental group. These 18 animals underwent sectioning and reinsertion of the Achilles tendon bilaterally, using the technique of trans-osseous suture on 1 side and suture anchor on the other. All the pelvic limbs that underwent the procedure were then immobilized for 3 weeks. The experimental group was divided into 3 groups that were sacrificed, respectively, 3, 6, and 12 weeks later. The tendon-bone complex was subjected to biomechanical tests to evaluate the parameters of maximum strength, stiffness, and yield strength. RESULTS: There was no statistically significant difference between the suture anchor group and the trans-osseous suture group, in relation to yield strength (3 weeks, P = .222; 6 weeks, P = .465; and 12 weeks, P = .200) or maximum strength (3 weeks, P = .222; 6 weeks, P = .076; and 12 weeks, P = .078). In relation to stiffness, the suture anchor group showed a statistically significant difference only at 3 weeks of healing (P = .032) over the trans-osseous suture group. CONCLUSION: The technique of suturing with an anchor was shown to be similar to the technique of trans-osseous suture for the studied parameters.

Estudo biomecânico da rigidez da osteossíntese com placas em ponte em tíbias de cadáveres humanos / Biomechanical study of the osteosynthesis stiffness with bridging plates in cadaveric tibial models

OBJETIVO: comparar a rigidez de três diferentes montagens de placa em ponte com a da haste intramedular bloqueada, em tíbias de cadáveres com fratura tipo C. MATERIAIS E MÉTODOS: vinte tíbias humanas captadas de cadáveres, submetidas à fratura do tipo C; quinze fixadas com placas em ponte, divididas em 03 grupos, de acordo com o tamanho das placas (10, 14 e 18 furos) e 05 fixadas com hastes intramedulares bloqueadas. Todas as tíbias foram expostas a cargas progressivas e semelhantes. Foram medidos os deslocamentos de ambos fragmentos (proximal e distal), nos planos sagital, coronal e axial do espaço, conforme incremento gradual de carga. RESULTADOS: tíbias fixadas com placas em ponte de 18 furos apresentam um comportamento biomecânico semelhante às fixadas com haste intramedular bloqueada. CONCLUSÕES: Em fraturas do tipo C em tíbias há maior mobilidade do segmento ósseo distal no plano coronal, quando a fratura é fixada com placas em ponte de 14 e 18 furos que quando fixada com haste intramedular bloqueada sem fresagem. Apesar dessa maior mobilidade, os movimentos relativos entre os fragmentos fraturários nos GHB e GP18 tendem a ser semelhantes entre si.

OBJECTIVE: To compare the stiffness of three different assemblies of bridging plates with intramedullary locking nails in cadaveric models of tibial fractures type C. MATERIALS AND METHODS: Twenty cadaveric tibias subjected to type C fractures; fifteen were fixed with the bridging plate technique and divided into three groups, according to the plate size (10, 14 and 18 holes), and five were fixed with intramedullary nail. All the tibias were exposed to similar and progressive loads. Dislocation of both fragments (proximal and distal) was measured on three planes (sagittal, coronal and axial), as the load was increased. RESULTS: tibias fixed with the 18 hole bridging plate have the same biomechanical behavior of tibias fixed with intramedullary locking nails. CONCLUSIONS: In type C tibial fractures, there is more mobility at the distal segment on the coronal plane when the fracture is fixed with 14 and 18 holes bridging plates as compared to fractures fixed with non-reamed intramedullary locking nails. Even with this mobility, the relative movements between the fragments at GHB and GP18 seem to be similar.