Purpose: the aim of this study was to describe the clinical results obtained after intra-articular injection of a leukocyte-poor platelet-rich plasma (PRP) preparation for the treatment of knee osteoarthritis (OA).
Methods: forty-five patients (mean age: 59 years, mean BMI: 27) were included and treated with a cycle of three weekly injections of autologous conditioned plasma. Six patients were affected by bilateral symptomatic OA, therefore 51 knees in total were treated. The patients were divided into two groups: those affected by early/moderate OA and those affected by severe OA. The patients were submitted to baseline evaluation and evaluation after a mean follow-up of 14.5 months (range: 6-24 months), performed using the following outcome measures: IKDC-subjective, EQ-VAS, Tegner, and KOOS scores. Adverse events and patient satisfaction were also recorded. The results in the two groups of patients ("early/moderate" vs "severe OA") were analyzed separately.
Results: the overall clinical outcome was positive and the treatment proved to be safe. In the "early/moderate OA" group, the IKDC-subjective score increased from 36.4 at the baseline evaluation to 57.3 at the follow-up (p<0.0005) and a similar trend was shown by the EQ-VAS, Tegner, and KOOS scores. Although an improvement was also recorded in the "severe OA" group, the clinical outcome of the patients in this group was significantly poorer and they reported less benefit. In the "early/moderate OA" group, BMI and longer symptom duration before treatment were found to be correlated with clinical outcome.
Conclusions: PRP injections are capable of reducing pain and improving knee functional status at short-term follow-up. The patients with a lower degree of joint degeneration were the best responders, whereas in severe osteoarthritic knees this biological treatment, used as a "salvage procedure", produced a less favorable outcome.
Level of evidence: level IV; therapeutic case series.
Keywords: PRP; growth factors; injections; knee; osteoarthritis.