Abstract
There has recently been growing interest worldwide in biological therapies such as platelet-rich plasma injection for the treatment of knee osteoarthritis. However, predicting the effectiveness of platelet-rich plasma therapy remains uncertain. Therefore, this retrospective cohort study was performed to assess a range of predictors for the effectiveness of platelet-rich plasma therapy in treating knee osteoarthritis. The study included 517 consecutive patients who underwent three injections of leucocyte-poor platelet-rich plasma therapy from 2016 to 2019 at a single institution. The treatment outcomes, including patient-oriented outcomes (visual analogue scale score and Knee Injury and Osteoarthritis Outcome Score), were analyzed and compared according to the severity of knee osteoarthritis based on Kellgren–Lawrence (KL) grading using standing plain radiographs. Fisher’s exact test, univariate regression, and multivariate regression were used for data analysis. Patient-oriented outcomes were significantly improved 6 and 12 months after platelet-rich plasma therapy. The overall responder rate in patients who met the Outcome Measures in Rheumatology (OMERACT)–Osteoarthritis Research Society International (OARSI) responder criteria was 62.1%. The responder rate was significantly lower in patients with severe knee osteoarthritis (KL4, 50.9%) than in those with mild (KL2, 75.2%) and moderate (KL3, 66.5%) knee osteoarthritis. The multivariate logistic regression analysis revealed that deterioration of the knee osteoarthritis grade (increased KL grade) was a significant predictor of a worse clinical outcome (odds ratio, 0.58; 95% confidence interval, 0.45–0.75; p < 0.001). The relative risk for non-responders in severe (KL4) KOA was 2.1 (95% CI, 1.5–3.0) at 6 months and 2.3 (1.6–3.2) at 12 months compared with mild-to-moderate (KL2-3) KOA. The efficacy of platelet-rich plasma therapy was not affected by age, sex, body weight, or platelet count. This study revealed that the effectiveness of platelet-rich plasma therapy for the treatment of knee osteoarthritis is approximately 60% and that the effectiveness depends on the severity of knee osteoarthritis. This observation is useful not only for physicians but also for patients with knee osteoarthritis.
Highlights
Osteoarthritis is a major public health concern worldwide because it is associated with considerable disability
The female sex was dominant in all KL grades, but the ratio of male patients was significantly higher than that of female patients in the group with lower grades of knee osteoarthritis (KOA)
This study demonstrated that the progression of the severity of radiographic KOA was a significant predictor of a poor outcome for a course of platelet-rich plasma (PRP) therapy
Summary
Osteoarthritis is a major public health concern worldwide because it is associated with considerable disability. Orthopedic surgeons usually recommend conservative treatments, such as rehabilitative therapies, non-steroidal anti-inflammatory drugs, steroid injections, and hyaluronic acid (HA) injections before offering surgery [2]. If these conservative therapies fail, surgical treatments such as osteotomy around the knee joint and arthroplasty should be considered. A new category of conservative and regenerative treatments involving cell-based therapies, such as platelet-rich plasma (PRP) therapy, has recently been introduced [3]. A meta-analysis of clinical trials involving intra-articular (IA) PRP injection in patients with KOA demonstrated that PRP has favorable effects on improving pain and functional scores compared with HA, steroid, and saline injections [4,5]. We performed the present retrospective study to confirm whether the clinical outcomes of PRP therapy for KOA are affected by the patients’ characteristics, including age, sex, body mass index, severity of KOA, and platelet concentration
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