THE ROUND LIGAMENT IN DEVELOPMENTAL HIP DYSPLASIA: ARE ITS MECHANICAL AND HISTOLOGICAL PROPERTIES PRESERVED?

Introduction: During open surgical dislocated hip reduction, several anatomical structures, such as the round ligament, are approached. However, there is controversy over both the possibility of preserving the ligament and its functional importance. Materials and Methods: This experimental study used skeletally immature rabbits as a model for congenital hip dislocation. Thirty-six rabbits comprised the sample that was submitted to the round ligament analysis. The sample was stratified for analysis (biomechanics, zymography, histology, and immunohistochemistry). Statistical analysis compared the unstable side to the control side of each rabbit. Results: Biomechanical assays showed that the mean maximal strength of the round ligament on the unstable side was similar to that of the control side (p = 0.594), which was also the case with maximum deformation (p = 0.328). Histologically, there was a statistically significant increase in cellularity on the unstable side (p <0.001). Additionally, there was significantly greater collagen occupancy on the control side (p <0.001). Zymography revealed no significant difference in the amount of active metalloproteinase 2 (MMP-2) (p = 0.068). Conclusions: Although histological analysis found evidence of significant changes in the RL in unstable hips, there were no significant differences in zymography, and no changes were observed in biomechanical tests. Evidence Level V; Experimental study.

Introdução: Durante a redução cirúrgica aberta de luxação de quadril, várias estruturas anatômicas são abordadas, entre elas, o ligamento redondo. No entanto, há controvérsias quanto à possibilidade de preservação desse ligamento, bem como sua importância funcional. Materiais e Métodos: Este estudo experimental usou coelhos esqueleticamente imaturos como modelo de luxação congênita do quadril. Trinta e seis coelhos compuseram a amostra que foi submetida à análise do ligamento redondo. A amostra foi estratificada para análise (biomecânica, zimografia, histologia e imuno-histoquímica). A análise estatística comparou o lado instável com o lado controle de cada coelho. Resultados: Os ensaios biomecânicos mostraram que a força máxima média do ligamento redondo no lado instável era semelhante ao lado controle (p = 0,594), o que também ocorreu com a deformação máxima (p = 0,328). Em termos histológicos, houve um aumento estatisticamente significante da celularidade no lado instável (p < 0,001). Além disso, houve maior ocupação de colágeno no lado controle (p < 0,001). A zimografia não mostrou diferença significativa da quantidade de metaloproteinase 2 ativa (MMP-2) (p = 0,068). Conclusões: Embora a análise histológica tenha encontrado evidências de alterações significativas do LR nos quadris instáveis, não houve diferenças significativas na zimografia e não foram observadas alterações nos testes biomecânicos. Nível de evidência V; Estudo experimental.

The round ligament in developmental hip dysplasia: are its mechanical and histological properties preserved? / O ligamento redondo na displasia do desenvolvimento do quadril: suas propriedades mecânicas e histológicas são preservadas?

ABSTRACT Introduction During open surgical dislocated hip reduction, several anatomical structures, such as the round ligament, are approached. However, there is controversy over both the possibility of preserving the ligament and its functional importance. Materials and Methods This experimental study used skeletally immature rabbits as a model for congenital hip dislocation. Thirty-six rabbits comprised the sample that was submitted to the round ligament analysis. The sample was stratified for analysis (biomechanics, zymography, histology, and immunohistochemistry). Statistical analysis compared the unstable side to the control side of each rabbit. Results Biomechanical assays showed that the mean maximal strength of the round ligament on the unstable side was similar to that of the control side (p = 0.594), which was also the case with maximum deformation (p = 0.328). Histologically, there was a statistically significant increase in cellularity on the unstable side (p <0.001). Additionally, there was significantly greater collagen occupancy on the control side (p <0.001). Zymography revealed no significant difference in the amount of active metalloproteinase 2 (MMP-2) (p = 0.068). Conclusions Although histological analysis found evidence of significant changes in the RL in unstable hips, there were no significant differences in zymography, and no changes were observed in biomechanical tests. Evidence Level V; Experimental study.

RESUMO Introdução Durante a redução cirúrgica aberta de luxação de quadril, várias estruturas anatômicas são abordadas, entre elas, o ligamento redondo. No entanto, há controvérsias quanto à possibilidade de preservação desse ligamento, bem como sua importância funcional. Materiais e Métodos Este estudo experimental usou coelhos esqueleticamente imaturos como modelo de luxação congênita do quadril. Trinta e seis coelhos compuseram a amostra que foi submetida à análise do ligamento redondo. A amostra foi estratificada para análise (biomecânica, zimografia, histologia e imuno-histoquímica). A análise estatística comparou o lado instável com o lado controle de cada coelho. Resultados Os ensaios biomecânicos mostraram que a força máxima média do ligamento redondo no lado instável era semelhante ao lado controle (p = 0,594), o que também ocorreu com a deformação máxima (p = 0,328). Em termos histológicos, houve um aumento estatisticamente significante da celularidade no lado instável (p < 0,001). Além disso, houve maior ocupação de colágeno no lado controle (p < 0,001). A zimografia não mostrou diferença significativa da quantidade de metaloproteinase 2 ativa (MMP-2) (p = 0,068). Conclusões Embora a análise histológica tenha encontrado evidências de alterações significativas do LR nos quadris instáveis, não houve diferenças significativas na zimografia e não foram observadas alterações nos testes biomecânicos. Nível de evidência V; Estudo experimental.

Hyperglycemic condition during puberty increases collagen fibers deposition in the prostatic stroma and reduces MMP-2 activity.

Puberty is an important period for the growth and maturation of the male reproductive system, and is also a critical window for endocrine or environmental interference. The physiological levels of circulating insulin and hyperglycemic control are important factors for a normal prostate growth. Hyperglycemia during puberty is reported to retard the growth of the prostate gland, with remarkable effects on the epithelial compartment. Here, we investigated the impact of hyperglycemia along with a simultaneous or late insulin replacement on the ventral prostate growth in rats during puberty, paying special attention to the deposition of collagen fibers and activities of gelatinase, matrix metalloproteinase-2 (MMP-2), and -9 (MMP-9). Hyperglycemia was induced by streptozotocin (STZ) administration in 40-day-old male Wistar rats. A subset of hyperglycemic rats underwent an early insulin replacement (three days after the STZ administration), and another subset underwent a late insulin replacement (twenty days after the STZ administration). Animals were euthanized at 60 and/or 80 days of age. The ventral prostatic lobe was processed for picrosirius red staining, type I and III collagen immunohistochemistry, and gelatin zymography. Hyperglycemic animals showed an increased area of collagen fibers in the prostate, which was composed both types of collagens. MMP-2 activity was significantly reduced in the hyperglycemic animals, while MMP-9 activity was very low and showed no alteration. The simultaneous and late insulin administration restored collagen content and MMP-2 activity. In conclusion, puberty is a critical window for prostate maturation and type-1 diabetes-induced hyperglycemia affects the ratio of the prostatic parenchymal and stromal growth, leading to fibrotic tissues by also MMP-2 down regulation.