Corticosteroids and Local Anesthetics Decrease Positive Effects of Platelet-Rich Plasma: An In Vitro Study on Human Tendon Cells

Purpose: To determine the effects of mixing anesthetics or corticosteroids with platelet-rich plasma (PRP) on human tenocytes in vitro. Methods: Two separate protocols (double spin and single spin) were used to obtain homologous PRP from the blood of 8 healthy volunteers. Discarded tendon acquired during biceps tenodesis served as tendon specimens for all experiments. After cell isolation, tenocytes were treated in culture with PRP alone or in combination with corticosteroids and/or anesthetics. Fetal bovine serum in concentrations of 2% and 10% served as controls. Cell exposure times of 5, 10, and 30 minutes were used. Radioactive thymidine and luminescence assays were obtained to examine cell proliferation and viability. Results: The presence of lidocaine, bupivacaine, or methylprednisolone resulted in significantly less proliferation than the negative 2% fetal bovine serum control (P < .05). When we compared groups, both lidocaine and bupivacaine had a greater inhibitory effect than methylprednisolone (P < .05). At all time points, viability was significantly decreased in the presence of lidocaine, bupivacaine, or methylprednisolone compared with the negative control (P < .05). Conclusions: The addition of either anesthetics or corticosteroids to PRP resulted in statistically significant decreases in tenocyte proliferation and cell viability. These results suggest that incorporation of anesthetics or corticosteroids, either alone or in combination, with PRP injection may compromise the potentially beneficial in vitro effects of isolated PRP on tendon cells and compromise cell viability at the site of tendon injury. Clinical Relevance: Anesthetics or corticosteroids either alone or in combination should be used carefully to preserve the proposed positive effects of PRP in the treatment of tendon injury.