The Influence of Ruptured Scar Pattern on the Healing Potential of Anterior Cruciate Ligament Remnant Cells

Abstract

Background: Vascular CD34+ cells in anterior cruciate ligament (ACL) tissues have a potential for high proliferation and multilineage differentiation, which can accelerate tendon-bone healing after ACL reconstruction. To predict outcomes of ACL reconstruction with remnant preservation or ruptured tissue incorporation, patient characteristics should be considered. However, the influence of ACL remnant morphologic pattern on healing potential remains unknown. Hypothesis: The healing potential of ACL remnants could differ among their morphologic patterns. Study Design: Descriptive laboratory study. Methods: ACL remnant tissues were harvested from patients aged <35 years who received primary ACL reconstruction within 3 months after injury. The tissues were evaluated according to the Crain classification (4 patterns). The patterns were divided into 2 groups: the reattachment group (Crain I-III) and the nonreattachment group (Crain IV). ACL remnant cells were characterized via fluorescence-activated cell sorting. The potential for proliferation and multilineage differentiation was assessed and compared between the groups. Results: The ratio of CD34+ cells was significantly higher in the nonreattachment group than in the reattachment group. In early passages, the nonreattachment group had a significantly higher expansion potential than the reattachment group. In the evaluation of osteogenic and endothelial differentiation potential, the nonreattachment group showed a higher potential in immunohistochemical/histochemical staining and quantitative real-time polymerase chain reaction analysis as compared with the reattachment group. Conclusion: In the subacute phase, ACL remnant tissue of the nonreattachment group possibly has a higher healing potential than that of the reattachment group. Clinical Relevance: If healing potential differs among the morphologic patterns of ACL remnants, surgeons may expect the healing potential when preserving remnants.