Summary
Evaluation of the relationship between cellular content, growth factors, inflammatory cytokines in autologous platelet-rich plasma and clinical efficacy 6 months after its injection into the lateral epicondyle region of patients with Tennis Elbow.
Abstract
Background
Tennis Elbow (TE) is a commonly used term to describe tendinopathy of proximal attachment of extensor muscles to the lateral humeral epicondyle. In cases where severe pain limits daily functioning for a longer period, patients desperately seek for effective solutions. Many treatments have been developed, the effectiveness of which is highly controversial. One of such methods is the injection of autologous platelet-rich plasma (PRP). Its action is based on the local administration of high concentrations of platelet-derived growth factors, which are supposed to stimulate healing and regeneration of tissues. The aim of the study was to assess the relationship between the cellular composition and cytokine content in PRP and the clinical effectiveness of injection therapy in patients with TE.
Material And Methods
Thirty patients diagnosed with TE were recruited for the study and received one injection of 2 ml of leukocyte-rich PRP to the lateral epicondyle region. All PRP samples were analyzed for cellular content and the content of several inflammatory cytokines and selected growth factors including Transforming growth factor-ß1, Epidermal growth factor (EGF), Fibroblast growth factor-basic, Vascular endothelial growth factor, Hepatocyte growth factor, Platelet-derived growth factor. The clinical efficacy of the treatment, before the injection and after 6 months was assessed in terms of the mean daily pain intensity measured by Visual Analog Scale (VAS), pain intensity during provocation tests, the pressure pain threshold (PPT), Subjected Elbow Value (SEV), strength of the grip and the muscle groups during wrist extension and supination, and by the Disability of Arm, Shoulder and Hand (DASH) questionnaire. A statistical analysis of the correlations between biologically active components in PRP and the size of improvement in each parameter, was performed.
Results
After six months all measured outcomes significantly improved. Twenty-five (83%) patients reached a minimal clinically important difference in decrease in pain intensity, and 23 (76%) in functional improvement measured by DASH. At the final end point symptoms completely disappeared in 10 patients. One patient resigned from the study after 3 months, due to dissatisfaction with the results of the treatment. The positive low significant Pearson’s correlation was found between PLT concentration in PRP and the size of improvement measured by SEV (r = 0.40). Significant low positive Spearman’s correlation between EGF concentration and pain decrease (r = 0.42) was found. Significant low negative Spearman’s correlations between functional improvement measured by DASH and several inflammatory cytokines were found: Interferon-a2 (r = -0.39), Interferon-? (r = -0.46), Monocyte Chemoattractant Protein-1 (r = -0.39), Interleukin-17A (r = -0.46), and Interleukin-33 (r = -0.43).
Conclusion
The study showed significant correlations between the content of biologically active components in PRP and the clinical outcomes of TE treatment after 6 months. The obtained results suggest the need for further research aimed at reducing the content of inflammatory cytokines and increasing the growth factors in PRP.