Bone Marrow-Derived Fibrin Clots Stimulate Healing of a Knee Meniscal Defect in a Rabbit Model

Purpose: To determine the in vivo effectiveness of bone marrow aspirate-derived (BMA) fibrin clots for avascular meniscal defect healing in a rabbit model.

Methods: In 42 Japanese white rabbits, a 2.0-mm cylindrical defect was introduced into the avascular zone of the anterior part of the medial meniscus in the bilateral knees. The rabbits were grouped according to implantation of a BMA fibrin clot (BMA group) or a peripheral blood (PB)-derived clot (PB group) into the defect and nonimplantation (control group). Macroscopic and histological assessments were performed using a scoring system at 4 and 12 weeks after surgery. At 12 weeks after surgery, compressive stress was analyzed biomechanically.

Results: The meniscal score in the BMA group (12.1) was greater than that in the PB group (5.5; P = .031) and control group (4.4; P = .013) at 4 weeks. The meniscal score in the BMA group (13.1) was greater than that in the control group (6.4; BMA = 13.1; P = .0046) at 12 weeks. In the biomechanical analysis, the BMA group demonstrated significantly higher compressive strength than the PB group (6.6 MPa) (BMA = 15.4 MPa; P = .0201) and control group (3.6 MPa; BMA = 15.4 MPa; P = .007).

Conclusions: Implantation of BMA fibrin clots into the meniscal defect of the avascular zone in a rabbit model improved the meniscal score at 4 weeks and strengthened the reparative meniscal tissue at 12 weeks compared with the implantation of PB fibrin clots.

Clinical Relevance: Healing in the avascular zone of the meniscus can be problematic. Approaches to improving this healing response have had variable results. This study provides additional information that may help improve the outcomes in patients with these injuries.