The effect of intra-articular autogenous bone marrow injection on healing of an acute posterior cruciate ligament injury in rabbits

Purpose: The purpose was to identify the effect of intra-articular autogenous bone marrow injection on the healing of an acute posterior cruciate ligament (PCL) rupture in a rabbit model. The effect of autogenous bone marrow on the healing process was assessed serially by gross inspection, histologic examination, and immunohistochemical study of growth factors. Methods: In both knee joints, the PCL was completely transected surgically near the femoral attachment site in 24 rabbits. Autogenous bone marrow was obtained from both tibias and delivered only to the right knee joint by direct intra-articular injection. Gross inspection, histologic examination, and immunohistochemical study of growth factors were performed at 8, 12, and 16 weeks after severing of the posterior cruciate ligament (PCL) among 8 randomly chosen specimens. The degree of healing in both marrow-stimulated and untreated control ligaments was evaluated by gross inspection using an ordinal scale consisting of 5 grades. The degree of fibroblast and vessel proliferation and alignment of collagen fibers were evaluated by histologic examination. The degree of expression of transforming growth factor β1, epidermal growth factor receptor, and vascular endothelial growth factor was evaluated by immunohistochemical study. Statistical analysis was performed with the Mann-Whitney U test. Results: In the group with marrow-stimulated ligaments, the degree of healing was higher at 8 and 12 weeks by gross examination, whereas there was no significant difference at 16 weeks between the 2 groups. According to histologic examination, the healing process was faster in the bone marrow injection group than in the control group at 8 and 12 weeks because the degree of fibroblast and vessel proliferation significantly declined and collagen fibers were arranged more regularly compared with the control group. Similar to the results of histologic examination, the results of immunohistochemical studies showed that the healing process was faster in the bone marrow injection group. However, the recovery of the PCL was completed at 16 weeks after PCL resection in both the bone marrow injection group and the control group. Conclusions: Intra-articular autogenous bone marrow injection appeared to promote the initiation of healing response in acutely injured PCLs in rabbits. Clinical Relevance: Intra-articular autogenous bone marrow injection can be a viable option for treating acutely injured PCLs.