Incidence of Heterotopic Ossification Among NFL Athletes Following Platelet-Rich Plasma (PRP) for Treatment of Core Muscle Injuries (CMI)

OBJECTIVES: Platelet-rich plasma (PRP) therapy is an increasingly-popular treatment to promote healing in damaged tendons, ligaments, cartilage and muscles. Few studies analyze long-term effects of PRP. The authors have a busy practice treating core muscle injuries (CMI) and, in the last several years, have noticed an unusually high incidence of HO among patients with previous PRP injections for these injuries. The purpose of this study is to investigate PRP and heterotopic ossification in core muscle injuries. METHODS: NFL players with core muscle injuries treated at a single institution during the 2015 season filled out questionnaires and were included in retrospective analysis. Heterotopic ossification was observed on MRI and intraoperatively and confirmed pathologically. RESULTS: Five NFL players had previous PRP injections for core muscle injuries and 4/5 (80%)had HO. These were 2 linebackers and 2 cornerbacks. The fifth, a kicker, had no ossification but extensive fibrosis around the distal rectus abdominis and proximal adductors. These results are similar for all athletes with previous PRP injections treated around the same time period, 87% (13/15). The incidence of HO among all athletes without a previous PRP injection was 2/1088 (0.18%). CONCLUSION: Retrospective analysis may be overestimating the true incidence and we have yet to identify patterns related to the variations in PRP technique. But these preliminary results suggest the need for further research and a cautious approach to using PRP in the treatment of CMI.