Objectives: To explore the potential clinical benefits of PRGF injections for the treatment of OA in a retrospective observational study and to characterize the PRGF treatment in OA patients.
Methods: A total of 62 patients with symptomatic OA (Knee OA, 41 patients; hip OA, 21 patients) were treated with a series of three weekly intra-articular injections of PRGF and studied retrospectively. ELISA assays were used to determine the levels of VEGF-A, HGF, PDGF, TGF-β1 and IGF-I in PRGF. The patients completed the WOMAC questionnaires prior to PRGF treatment at two and six months after its instauration. The primary efficacy criteria were mean change from baseline through two and six months in the WOMAC index pain and physical function scores. Change scores for the Harris hip scores were calculated for 6 months post-treatment. Age and BMI were included in the models.
results The mean age and BMI of the participants with hip and knee OA were 59 and 60 years and 27.8 and 28.5 kg/m2 respectively. In knee OA the differences between pain scores at baseline and two or six months were highly significant (−1.766, 95% CI: −1.073 to −2.458, p=0.000, and −2.320, CI: −3.838 to −0.803, p=0.011) The observed success rates for the pain sub-scale reached 37% by two months and 31.7% by six months. After two months, WOMAC physical function scores decreased significantly (−4.772, 95% CI: −6.864 to −2.681, p=0.000). The changes at six months were not statistically significant (n=41). The success rates for the physical function subscale were 31.4% by two months and 31.7% by six months (n=41). In hip OA the differences between WOMAC pain and Harris hip core scores at baseline and six months were significant. The success rate for the pain subscale and Harris hip score reached 58% and 85% by six months
PRGF resulted in a moderate enrichment in platelet number, 2.0 ± 0.5-fold increase compared to peripheral blood. The levels of the main platelet secretory growth factors were 27.28 ± 10.90 ng/cc for TGF-β1 and 15.66 ± 8.02 ng/cc for PDGF. VEGF was also secreted from platelets but was less abundant, 437± 446 pg/cc. Other GFs present in PRGF refiect mainly plasma levels; among these growth factors are IGF-I (55.53 ± 20.87 ng/cc) and the less concentrated HGF (472 ± 221 pg/cc).
Discussion: Due to the localized nature of OA, the possibility of intra-articular administration of PRGF, along with its biocompatibility and non-immunogenicity, may make this unique molecular mixture an attractive treatment for OA. PRGF may have therapeutic effects in OA joints via multiple biologic mechanisms. The results of this study will give a first impression of potential effectiveness of PRGF for the local treatment of hip and knee OA.
