Differences in Tendon Graft Healing Between the Intra-articular and Extra-articular Ends of a Bone Tunnel

Anterior cruciate ligament (ACL) tear is common in sports and accidents, and accounts for over 50% of all knee injuries. ACL reconstruction (ACLR) is commonly indicated to restore the knee stability, prevent anterior–posterior translation, and reduce the risk of developing post-traumatic osteoarthritis. However, the outcome of biological graft healing is not satisfactory with graft failure after ACLR. Tendon graft-to-bone tunnel healing and graft mid-substance remodeling are two key challenges of biological graft healing after ACLR. Mounting evidence supports excessive inflammation due to ACL injury and ACLR, and tendon graft-to-bone tunnel motion negatively influences these two key processes. To tackle the problem of biological graft healing, we believe that an inductive approach should be adopted, starting from the endpoint that we expected after ACLR, even though the results may not be achievable at present, followed by developing clinically practical strategies to achieve this ultimate goal. We believe that mineralization of tunnel graft and ligamentization of graft mid-substance to restore the ultrastructure and anatomy of the original ACL are the ultimate targets of ACLR. Hence, strategies that are osteoinductive, angiogenic, or anti-inflammatory should drive graft healing toward the targets. This paper reviews pre-clinical and clinical literature supporting this claim and the role of inflammation in negatively influencing graft healing. The practical considerations when developing a biological therapy to promote ACLR for future clinical translation are also discussed.

Download Full-text

Tendon Healing in Bone Tunnel after Human Anterior Cruciate Ligament Reconstruction: A Systematic Review of Histological Results

The Journal of Knee Surgery ◽

10.1055/s-0038-1653964 ◽

2018 ◽

Vol 32 (05) ◽

pp. 454-462 ◽

Cited By ~ 4

Author(s):

Hongbin Lu ◽

Can Chen ◽

Shanshan Xie ◽

Yifu Tang ◽

Jin Qu

Keyword(s):

Systematic Review ◽

Acl Reconstruction ◽

Cruciate Ligament ◽

Healing Process ◽

Tendon Healing ◽

Tendon Graft ◽

Bone Tunnel ◽

Bone Interface ◽

Graft Healing ◽

Anterior Cruciate

AbstractMost studies concerning to tendon healing and incorporation into bone are mainly based on animal studies due to the invasive nature of the biopsy procedure. The evidence considering tendon graft healing to bone in humans is limited in several case series or case reports, and therefore, it is difficult to understand the healing process. A computerized search using relevant search terms was performed in the PubMed, EMBASE, Scopus, and Cochrane Library databases, as well as a manual search of reference lists. Searches were limited to studies that investigated tendon graft healing to bone by histologic examination after anterior cruciate ligament (ACL) reconstruction with hamstring. Ten studies were determined to be eligible for this systematic review. Thirty-seven cases were extracted from the included studies. Most studies showed that a fibrovascular interface would form at the tendon–bone interface at the early stage and a fibrous indirect interface with Sharpey-like fibers would be expected at the later stage. Cartilage-like tissue at tendon graft–bone interface was reported in three studies. Tendon graft failed to integrate with the surrounding bone in 10 of the 37 cases. Unexpectedly, suspensory type of fixation was used for the above failure cases. An indirect type of insertion with Sharpey-like fibers at tendon–bone interface could be expected after ACL reconstruction with hamstring. Regional cartilage-like tissue may form at tendon–bone interface occasionally. The underlying tendon-to-bone healing process is far from understood in the human hamstring ACL reconstruction. Further human studies are highly needed to understand tendon graft healing in bone tunnel after hamstring ACL reconstruction.

Download Full-text