Yoshihiko Saito; Shinichi Kawata; Takuya Omotehara; Zhong-Lian Li; Tomiko Yakura; Miyuki Kuramasu; Yuki Ogawa; Philipp Pieroh; Hanno Steinke & Masahiro Itoh

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.

KEY WORDS: Anterior cruciate ligament; Blood capillary; Synovium; ACL reconstruction; Remodeling.

SAITO, Y.; KAWATA, S.; OMOTEHARA, T.; LI, Z. L.; YAKURA, T.; KURAMASU, M.; OGAWA, Y.; PIEROH, P.; STEINKE, H. & ITOH, M. Synovium and blood capillaries at the femoral attachment of anterior cruciate ligament are significantly abundant than those at the tibial attachment. Int. J. Morphol., 41(2):527-534, 2023.