Yingtai: Intra-articular Injection of PRP for Osteoarthritis Pain (Part II)

Yingtai: Intra-articular Injection of PRP for Osteoarthritis Pain (Part II)

Intra-articular injection of PRP has become a popular choice for treating osteoarthritis (OA) pain due to the limitations of intra-articular corticosteroid and hyaluronic acid injections. Sampson et al. conducted a study on 14 patients with primary and secondary knee OA to understand the efficacy of PRP. Patients received PRP injections into the suprapatellar pouch of the affected knee under ultrasound guidance every 4 weeks, for a total of three treatments. After the treatments, there was a significant reduction in pain and symptoms, with no adverse events observed. VAS scores showed a significant decrease in knee pain during movement and at rest, and the therapeutic effect was still evident 12 months after treatment, indicating that intra-articular PRP injection may alleviate medium-term pain. Another study evaluated the efficacy of intra-articular PRP injection at 6 and 12 months. The study included 100 patients with 115 knees of varying degrees of degenerative changes (Kellgren 0-IV) who underwent PRP injection treatment. The injections were given once every 21 days, for a total of three times, with the first injection administered within 2 hours after PRP preparation. PRP was derived from anticoagulant whole blood, and each injection into the lesion contained about 6.8 million platelets. Similar to previous studies, no serious adverse events related to the injection were observed. In the 6-12 month follow-up, all clinical scores (VAS, IKDC) showed significant improvement compared to before treatment. The study also found that the older the patient and the higher the degree of joint degeneration, the less significant the therapeutic effect. Subsequently, Filardo et al. [38] followed up with 90 OA patients for 2 years and found that patient pain increased over time (12 months vs 24 months), but the degree of pain increase was milder after PRP treatment, indicating that this therapy has clinical advantages in treating OA pain. In short, these early studies suggest that intra-articular injection of PRP has the potential to relieve OA pain, and its exact efficacy requires further validation from randomized clinical trials. In 2015, Laudy et al. conducted a comprehensive and systematic search of randomized or non-randomized controlled trials to analyze the efficacy of intra-articular injection of PRP (or similar products). The study included 10 clinical trials and found that knee pain was still reduced 6 months after a single or double PRP injection (high risk of bias, low level of evidence); compared with hyaluronic acid injection treatment, PRP was more significantly effective in relieving pain (high risk of bias, moderate level of evidence). The study indicated that more large-scale randomized clinical trials with low risk of bias are needed to ultimately determine the efficacy of intra-articular PRP injection. In 2017, Shen et al. conducted a systematic review and meta-analysis to determine the impact of intra-articular PRP injection on pain and joint function, and compared its efficacy with other intra-articular injections (such as saline placebo, hyaluronic acid, ozone, and corticosteroids). The meta-analysis included 14 randomized controlled trials with 1423 participants. Among them, 4 studies were considered to have a moderate risk of bias, and 10 were considered to have a high risk of bias. The authors concluded that compared with the control group, WOMAC pain scores were significantly reduced at 3, 6, and 12 months after intra-articular PRP injection, and the WOMAC function subscores of the PRP group were also significantly improved compared with other groups. Injection of PRP did not significantly increase the incidence of adverse events after injection. The conclusion of this study was supported by a phase I and II clinical trial of mild to moderate knee OA in Japan. The study included 10 patients who received intra-articular injection of leukocyte-poor PRP obtained by centrifugation of anticoagulant whole blood, once a week for a total of three treatments. The study found that at 6 months, 80% of patients had a reduction of more than 50% in VAS scores, indicating that PRP treatment can alleviate OA pain. Similarly, Wu et al. compared the effects of placebo and PRP injection in relieving pain and improving muscle strength in bilateral knee OA. Twenty patients (40 knees) were included in the study and received a single intra-articular PRP or saline injection. The study found that at 1, 3, and 6 months after injection, the WOMAC scores of the PRP group were significantly lower than those of the saline group, and the PRP group showed greater knee strength over a longer follow-up period. However, there was no significant difference in muscle strength between the two groups. In 2019, Chen et al. summarized four level 1 evidence meta-analyses to compare the efficacy of intra-articular injection of PRP, hyaluronic acid, and placebo. The included meta-analyses had quality scores ranging from 14 to 17, and Oxman-Guyatt scores ranging from 4 to 6. The heterogeneity of the included studies included leukocyte-rich PRP (LR-PRP); leukocyte-poor PRP (LP-PRP); single or double centrifugation; whether activated; PRP injection dosage, frequency, and interval; standardized and non-standardized patient outcome indicators. Three meta-analyses showed that compared with hyaluronic acid or placebo treatment, PRP had more advantages in relieving OA pain and improving function, while another study showed no differences between groups. In addition, there was no difference in the incidence of adverse events between groups. The study concluded that intra-articular injection of PRP was more effective in treating pain within 1 year. This study once again suggested that more rigorous randomized controlled trials are needed, focusing on specific issues such as PRP preparation methods, activation methods, platelet concentration, PRP components, and PRP injection frequency, to clearly understand the clinical efficacy of intra-articular PRP injection in order to develop the best treatment plan. In addition, more medium- and long-term follow-up studies are needed to evaluate the efficacy of PRP injection and its potential for long-term pain relief. In 2020, Hohmann et al. conducted a systematic review and meta-analysis that included 12 level 1 and 2 studies, comparing the efficacy of intra-articular injection of PRP (636 cases) and hyaluronic acid (612 cases) in 1248 OA pain patients. The study found that although the PRP group had significantly reduced pain (assessed by VAS and WOMAC pain scales) at 6 and 12 months compared with the hyaluronic acid group, there was no significant improvement in functional outcomes for both groups. In the same year, Chen et al. conducted a meta-analysis comparing the efficacy of PRP and hyaluronic acid intra-articular injection. This meta-analysis included 14 randomized controlled trials involving 1350 patients (714 in the PRP group and 636 in the hyaluronic acid group). The results showed that the PRP group had better VAS scores and long-term WOMAC pain scores at 24 weeks and 54 weeks compared with the hyaluronic acid group, further confirming the efficacy of PRP in relieving OA-related pain. Another systematic review and meta-analysis of randomized controlled trials compared the efficacy and safety of PRP and hyaluronic acid injections. The study included 18 level 1 studies involving 1608 patients (811 in the PRP group and 797 in the hyaluronic acid group), with an average follow-up of 11.1 months. The results showed that compared with hyaluronic acid, the average improvement in WOMAC total scores in the PRP group was significantly higher. Wu et al. conducted a meta-analysis of 10 randomized controlled trials with consistent treatment cycles and injection frequencies, and found that compared with hyaluronic acid, PRP had more advantages in relieving pain and improving function. Filardo et al. conducted a meta-analysis of 34 randomized controlled trials published by January 2020. The study concluded that the efficacy of intra-articular injection of PRP was better than the placebo effect and showed statistically significant improvement in pain scores. The study also found that the benefits of PRP increased over time, and the efficacy was still significant at 6 and 12 months after injection. This evidence suggests that PRP treatment may have a cumulative superimposed effect and long-term benefits. As mentioned earlier, the included studies have problems such as low quality and significant heterogeneity, and further research is necessary. The potential of intra-articular PRP injection in relieving pain in early or moderate OA patients has been confirmed by clinical trials. Some recent studies have explored the potential of intra-articular PRP injection in treating severe knee OA by changing the application mode of PRP. Sanchez et al. improved the conventional PRP treatment method by infiltrating PRP into the subchondral bone of the cartilage while also performing intra-articular PRP injection, making the effect of PRP more in-depth.