A histological study of the augmented reconstruction of the anterior cruciate ligament in rabbits

Abstract

An experimental study was carried out to investigate the histological properties of the anterior cruciate ligament (ACL) reconstructed by the augmentation procedure. After the resection of 42 knees in 42 adult New Zealand white rabbits, 21 of the knees were reconstructed with a patellar tendon alone (nonaugmented group) and 21 with an augmented patellar tendon using a Leeds-Keio artificial ligament (augmented group). The rabbits were destroyed 4, 8, 12, 16 and 24 weeks, respectively, after the operation. After 4 weeks, a remarkable proliferation of fibrous tissue was present in the augmented group ligaments, while tissue necrosis was dominant, with slight granulation, in the nonaugmented group. After 8 weeks, the fibrous tissue was regularly arranged in a longitudinal direction in the augmented group, while this took 12 weeks in the nonaugmented group. Furthermore, 16 weeks postoperatively, the collagen fibers had matured and resembled normal ligaments in the augmented group, but this took 24 weeks in the nonaugmented group. After 16 weeks, columnar formations and some mineralization of the fibrocartilage were observed in the bone-ligament junctions in the nonaugmented group, but not until after 24 weeks in the augmented group. After 24 weeks, there were no histological differences between the two groups, either in the reconstructed ligaments or in the bone-ligament junctions. It is suggested that augmentation had an effect on the early histological maturation of collagen fibers, and an adverse effect on the formation of enthesis.