Platelet-rich plasma did not improve early healing of medial collateral ligament in rats

Background: The medial collateral ligament (MCL) is the most frequently injured ligament of the knee. Platelet-rich plasma (PRP) is a relatively new treatment option developed to enhance the healing response after injury to different tissue types. This study aimed at investigating whether the addition of PRP to MCL tears in rats would alter healing both biomechanically and histologically. Methods: Bilateral full-thickness tears of the MCL were surgically induced in the knees of 32 rats. Right ligament was saturated with PRP (n = 32, study group), and the left ligament was saturated with saline (n = 32, control group). The animals were killed 3 weeks later and the surgical sites were evaluated by gross inspection, biomechanically and histologically. Results: There was no gross difference in the mass of granulation tissue, load to failure, stiffness and displacement between the study and control groups. Histological examination by means of maturity score revealed no significant differences between the study and control groups. Conclusion: The addition of PRP to a healing MCL did not improve any of the outcome measures in this model.