Synovium and blood capillaries at the femoral attachment of anterior cruciate ligament are significantly abundant than those at the tibial attachment / Sinovial y capilares sanguíneos en la inserción femoral del ligamento cruzado anterior son significativamente más abundantes que los de la inserción tibial

SUMMARY: The anterior cruciate ligament (ACL) is a ligament that mainly controls the anterior and rotational mobility of the knee joint, and its surface is covered by a synovial membrane with large number of blood vessels. In general, nutritional supply to the ligament is from many capillaries in the adjacent synovium. However, statistical studies of the capillaries distributed to the ACL are insufficient. In this study, we examined cross-sectional histological images of the femoral attachment (femoral level), middle level of the tendon (middle level), and tibial attachment (tibial level) of the ACL and statistically analyzed blood capillary distribution among the three levels. The ACLs of 10 cadavers were divided into 5 equal sections, and 4mm-thick paraffin sections were made at the femoral level, middle level, and tibial level, and then hematoxylin-eosin (HE) staining were performed. The area of each transverse section was measured using Image-J 1.51n (U. S. National Institutes of Health, Bethesda, MD, USA). Fiber bundles of the ACL were relatively small and sparse in cross-sectional area at the femoral level and became larger and denser toward the tibial level. Many blood levels. The synovium at the attachment of ACL covered the surface of the fiber bundle and also penetrated deeply between the fiber bundles. In particular, the blood capillaries were densely distributed in the synovium at the femoral attachment rather than another two levels. Indeed, the number of capillaries were also most abundant in the femoral level. The cross-sectional ACL area at the femoral level is significantly small, however, the blood capillaries were most abundant. Therefore, when the ACL is injured, its reconstruction with preservation of the femoral ligamentous remnant may be clinically useful for remodeling of the grafted tendon.

El ligamento cruzado anterior (LCA) es un ligamento que controla principalmente la movilidad anterior y rotacional de la articulación de la rodilla, y su superficie está cubierta por una membrana sinovial con gran cantidad de vasos sanguíneos. En general, el suministro de nutrientes al ligamento proviene de muchos capilares en la sinovial adyacente. Sin embargo, los estudios estadísticos de los capilares distribuidos en el LCA son insuficientes. En este estudio, examinamos imágenes histológicas trans- versales de la inserción femoral (nivel femoral), el nivel medio del tendón (nivel medio) y la inserción tibial (nivel tibial) del LCA y analizamos estadísticamente la distribución de los capilares sanguíneos entre los tres niveles. Los LCA de 10 cadáveres se dividieron en 5 secciones iguales y se realizaron cortes en parafina de 4 µm de espesor a nivel femoral, medio y tibial, y luego se realizó tinción con hematoxilina-eosina (HE). El área de cada sección transversal se midió utilizando Image-J 1.51n (Institutos Nacionales de Salud de EE. UU., Bethesda, MD, EE. UU.). Los haces de fibras del LCA eran relativamente pequeños y escasos en el área de la sección transversal a nivel femoral y se hicieron más grandes y más densos hacia el nivel tibial. La membrana sinovial en la unión del LCA cubría la superficie del haz de fibras y también penetraba profundamente entre entre los haces de fibras. En particular, los capilares sanguíneos estaban densamente distribuidos en la unión femoral de la sinovial respecto a los otros dos niveles. De hecho, el número de capilares también fue más abundante a nivel femoral. El área transversal del LCA a nivel femoral era significativamente pequeña, sin embargo, los capilares sanguíneos fueron los más abundantes. Por lo tanto, cuando hay una lesión del LCA su reconstrucción con preservación del ligamento femoral remanente puede ser clínicamente útil para remodelar el tendón injertado.

Quantitative Assessment of Synovial Vascularity Using Contrast-Enhanced Power Doppler Ultrasonography: Correlation with Histologic Findings and MR Imaging Findings in Arthritic Rabbit Knee Model

OBJECTIVE: To validate contrast-enhanced power Doppler ultrasonography (PD US) for the evaluation of synovial vascularity in an arthritic rabbit knee model in correlation with MR and histological findings. MATERIALS AND METHODS: Power Doppler ultrasonography was performed for carrageenin-induced arthritic left knee and control right knee of 13 rabbits, first without and then with sonic contrast agent enhancement (Levovist, Schering, Berlin Germany), followed by gadolinium-enhanced MR imaging. Synovial vascularity was quantitatively assessed by calculating the color pixel area in power Doppler sonography using a computer-aided image analysis program and by grading the enhancement on MR images: grade 1, enhancement of knee joint is less than one-third of the area; grade 2, one-third to two-thirds enhancement; and grade 3, more than two-thirds enhancement. Microvessel density (MVD) was measured on slides stained immunohistochemically for CD31 antigen for histological assessment. RESULTS: The mean area of color pixels in PD US changed from 4.37 to 16.42 mm2 in the arthritic knee after enhancement (p 0.05). CONCLUSION: Sonic contrast-enhanced PD US improves the visualization of synovial vascularity and allows quantitative measurement in experimentally induced rabbit arthritic knees.