Anterior Cruciate Ligament Reconstruction with Autologous Ruptured Tissue: Pilot Clinical Trial

Introduction: Most surgical procedures for anterior cruciate ligament reconstruction (ACLR) involve the healing of tendon grafts in a surgically created bone tunnel; however, the attachment between the tendon and the bone is the weakest part of the reconstruction in the early post-transplantation period. Secure fixation of the tendon graft to the bone is thus a significant factor in allowing earlier and more aggressive rehabilitation and earlier return to sports and work. Current treatment with hamstring grafts achieves satisfactory anteroposterior and rotatory stability but causes significant tunnel enlargement.Tissue engineering using stem cells has recently been explored to achieve early healing and better tendon-bone integration. Blood vessels have a richer supply of stem/progenitor cells with characteristic expression of CD34 surface markers, and Matsumoto T et al. demonstrated the presence in sub-acutely ruptured ACL tissues of CD34-expressing vascular cells with potential for multi-lineage differentiation that can be recruited to the ACL rupture site to support healing [1]. In addition, Mifune Y et al. demonstrated that human ACL-derived CD34+ cells contributed to tendon-bone healing via angiogenesis/vasculogenesis and osteogenesis in an immunodeficient rat model of ACLR [2]. Based on the abundance of CD34+ cells in ruptured (44.3%) vs. intact (8.3%) ACL tissue [1] and the contributions of non-selected cells as well as CD34+ cells to tendon-bone healing in a rat model of ACLR [2], Matsumoto T et al. confirmed the effectiveness of ruptured tissue for early tendon-bone healing in a preclinical study using a canine ACL reconstruction model [3]. Given this background, we hypothesized that the use of autologous ruptured tissue in ACLR would improve clinical results over conventional ACLR by reducing tunnel enlargement. This study aimed to compare the clinical results of double-bundle (DB) ACLR with and without suturing of the autologous ruptured tissue to the grafts in patients with sub-acute ACL injury.