INTRODUCTION: Lumbar MRI phenotypes, including Modic changes, disc bulging, and high-intensity zones (HIZs) are reported to be related to low back pain (LBP). Platelet-rich plasma (PRP) has recently become a clinical option for treating degenerative disc diseases. A previous randomized clinical trial of the releasate isolated from PRP (PRPr) injection into degenerated discs of patients with discogenic LBP reported that PRPr was safe and maintained improvements in pain and LBP-related disability for 60 weeks [1]. However, whether intradiscal administration of PRPr induces tissue repair and/or regenerative effects, which improve the MRI phenotypes related to discogenic LBP, has not been evaluated. This study aimed to retrospectively evaluate time-dependent changes in MRI phenotypes (Modic changes, disc bulging, and HIZs) after intradiscal injection of PRPr for patients with discogenic LBP in a previous randomized clinical trial.
METHODS: 1. This study retrospectively analyzed a previous randomized, double-blind, active-controlled clinical trial [1]. Patients received an intradiscal injection of either PRPr or corticosteroids (CS). Patients from both the PRPr and CS groups who still experienced pain received PRPr as optional treatment at eight weeks post-injection. The efficacy of PRPr was evaluated for up to 12 months after optional injection (Post 12M). 2. MRI assessment: MRI data at baseline and Post 12M were retrospectively evaluated. a) The extent of IVD degeneration of the targeted discs at baseline and Post 12M was evaluated using a modified Pfirrmann grading system. b) Modic changes adjacent to the endplate were evaluated and classified into three groups (Type I, II, and III). c) Disc bulging was evaluated by discs extending into the spinal canal beyond the edge of the apophyses. e) HIZ was diagnosed as a high-intensity signal identified within the posterior AF. The area of posterior HIZ was determined in the regions of interest (ROI) framing the border of the HIZ.
RESULTS: 1. Patient characteristics: Fifteen patients (mean age: 33.9 years, 11 men, 4 women) were included in this study. A total of 19 discs were used for the analyses. No significant differences in age, sex, number of targeted discs, modified Pfirrmann classification, and prevalence of Modic changes, disc bulging, or posterior HIZs were found between the groups. 2. MRI-graded disc degeneration: No significant time-dependent changes from baseline in the MRI grades were also found in both groups. 3. MRI phenotypes: There were no significant differences in the prevalence of Modic changes, disc bulging, and HIZs between the CS and PRPr groups at baseline. The prevalence of these MRI phenotypes did not show significant changes during the observational period. The area of posterior HIZs in the total targeted discs significantly decreased time-dependently (P<0.05); however, no significant differences were found between the groups.
DISCUSSION: There were no significant changes in the MRI-graded disc degeneration and prevalence of MRI phenotypes. However, the area of posterior HIZs decreased time-dependently, suggesting that the intradiscal injection of PRPr may have the potential to stimulate the tissue repair of posterior AF tears.
REFERENCES: 1. Akeda, K. et al. J. Clin. Med. 2022.