Purpose: The study aims to elucidate the effects of single platelet-rich plasma (PRP) injection combined with rehabilitation exercises on growth factor concentrations and muscle strength following hamstring tear injury.
Methods: 17 physically active male athletes (22.3 years; 1.80 m; 74.7 kg; 24.9 kg/m2) with a 2nd-grade acute hamstring tear were randomized to a treatment group (n = 8) or control group (n = 9). Both groups received the same physical rehabilitation program for 8 weeks; however, only the treatment group received an autologous single PRP injection. Growth factor concentrations, hamstring strength (HS), knee flexion range of motion (KFROM), and return time to play (RTP) were collected at baseline, and 4 and 8 weeks.
Results: Athletes in the PRP group demonstrated at 4 weeks a significantly higher concentration in IGF-1, FGF-2, VEGF, and PDGF than that the control group demonstrated (p < 0.004). However, neither HS nor KFROM showed any significant differences between groups at 8 weeks (p > 0.05), but HS was significant at 4 weeks (p > 0.002).
Conclusion: PRP injection combined with physical rehabilitation for hamstring tear was more effective in growth factor concentration and return time to play than the physical rehabilitation alone.