A Histological Comparison Between Anterior Cruciate Ligament Remnant Tissue, Anatomically Reconstructed Graft, and Non-Anatomically Reconstructed Graft

Abstract

Introduction: To our knowledge, no studies have investigated the histological comparison between primary injured anterior cruciate ligament (ACL), initially anatomically reconstructed grafts and non-anatomically reconstructed grafts at the time of revision ACL reconstruction. The purpose of this study was to histologically clarify the differences between ACL remnant tissue, reconstructed graft after anatomic double-bundle ACL reconstruction, and reconstructed graft after non-anatomic single-bundle ACL reconstruction. Methods: This histological study included five patients after anatomic double-bundle ACL reconstruction, three patients after non-anatomic single-bundle ACL reconstruction performed who injured their operated knees again, and five patients who injured their ACL for the first time and agreed to participate. All of the grafts and ACL remnant tissue were harvested, stained with hematoxylin and eosin, S-100, and alpha smooth muscle actin and evaluated using light microscopy. Results: There was no area of necrosis in the reconstructed graft after an anatomic double-bundle ACL reconstruction. However, there were obvious areas of necrosis in the reconstructed graft after non-anatomic single-bundle ACL reconstruction. Additionally, the collagen fibers were more longitudinally oriented, and most cells were spindle shaped like those in ACL remnant tissue after an anatomic double-bundle ACL reconstruction in contrast with the finding of the grafts after non-anatomic single-bundle ACL reconstruction. Conclusion: Initially reconstructed graft after an anatomic double-bundle ACL reconstruction may be beneficial if preserved at the time of the revision surgery.

Histological Evaluation of Harvested Specimen of a Patient Who Underwent Unicompartmental Knee Arthroplasty Two Years and Six Months After Medial Meniscus Posterior Root Tear Transtibial Pull-Out Repair

“…Sutures on the meniscus were found intact in the bone tunnel, and there were Sharpey's fiber-like tissues in the tibial bone tunnel [13]. The medial meniscus posterior attachment showed a four-layer structure of ligaments, uncalcified fibrocartilage, calcified fibrocartilage, and subchondral bone zone.…”

“…Since sparse Sharpey's fiber-like tissue was found in the bone tunnel, firm adhesion between medial meniscus pulled into the bone tunnel and cancellous bone was observed to be a well-reconstructed ACL [13]. In addition, the structure of the fibrocartilaginous entheses was observed 2,000 ㎛ medially from the bone tunnel.…”