The anterior cruciate ligament (ACL) usually fails to heal after rupture mainly due to the inability of the cells within the ACL tissue to establish an adequate healing process, making graft reconstruction surgery a necessity. However, some reports have shown that there is a healing potential of ACL with primary suture repair. Although some reports showed the existence of mesenchymal stem cell-like cells in human ACL tissues, their origin still remains unclear. Recently, blood vessels have been reported to represent a rich supply of stem/ progenitor cells with a characteristic expression of CD34 and CD146. In this study, we attempted to validate the hypothesis that CD34-and CD146-expressing vascular cells exist in hACL tissues, have a potential for multilineage differentiation, and are recruited to the rupture site to participate in the intrinsic healing of injured ACL. Immunohistochemistry and flow cytometry analysis of hACL tissues demonstrated that it contains significantly more CD34 and CD146-positive cells in the ACL ruptured site compared with the noninjured midsubstance. CD34 + CD45 -cells isolated from ACL ruptured site showed higher expansionary potentials than CD146 + CD45 -and CD34 -CD146 -CD45 -cells, and displayed higher differentiation potentials into osteogenic, adipogenic, and angiogenic lineages than the other cell populations. Immunohistochemistry of fetal and adult hACL tissues demonstrated a higher number of CD34 and CD146-positive cells in the ACL septum region compared with the midsubstance. In conclusion, our findings suggest that the ACL septum region contains a population of vascular-derived stem cells that may contribute to ligament regeneration and repair at the site of rupture.

Introductionnatomy is the basis of orthopaedic surgery. Our approach to anterior cruciate ligament reconstruction surgery is governed by this principle. In this article, we describe the concept of anatomic anterior cruciate ligament reconstruction as well as its application to single and double-bundle anterior cruciate ligament reconstruction, revision anterior cruciate ligament surgery, and anteromedial and posterolateral-bundle anterior cruciate ligament augmentation surgery.Traditional single-bundle anterior cruciate ligament reconstruction has been shown to achieve good-to-excellent results in only 60% of patients 1 . As many as 20% to 30% of athletes fail to achieve their previous level of performance, suggesting that there is room for improvement. Because of this high failure rate, we have been driven to explore alternative reconstruction techniques. Our goal is to restore the native anatomy, which we believe will result in superior outcomes and performance levels.Double-bundle anterior cruciate ligament reconstruction is an application of the concept of anatomic reconstruction. Since the native anterior cruciate ligament is composed of two functional bundles, we believe that it is crucial to restore the function of both. The anteromedial bundle is the main contributor to anterior-posterior stability, while the posterolateral bundle mainly controls rotational stability, especially in deep knee flexion 2,3 . Cadaver biomechanical studies demonstrate that single-bundle reconstruction fails to restore the rotational stability of the knee 4 , whereas double-bundle anterior cruciate ligament reconstruction effectively restores rotational stability 5 . Recent Level-I and II short-term studies 6-11 also suggest that double-bundle anterior cruciate ligament reconstruction results in superior clinical outcomes.

Anatomic posterolateral corner reconstruction reproduces 3 main structures: the lateral collateral ligament, the popliteofibular ligament, and the popliteus tendon. The LaPrade technique reproduces all 3 main stabilizers. However, it requires a long graft, limiting its indication to clinical settings in which allograft tissue is available. We propose a surgical procedure that is a modification of the LaPrade technique using the same tunnel placement, hamstring autografts, and biceps augmentation when necessary. It relies on artificial graft lengthening provided by the loop of the suspensory fixation device fixed at the anterior tibial cortex. The final reconstruction reproduces the popliteus tendon with the bulkiest end of the semitendinosus; the popliteofibular ligament with a strand of the semitendinosus and a strand of the gracilis; and the lateral collateral ligament with a strand of the semitendinosus and a strand of the gracilis, which can also be augmented with a biceps strip.