Leukocyte concentration may not impact safety, efficacy of PRP injections for knee OA
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Key takeaways:
- Leukocyte-rich and leukocyte-poor platelet-rich plasma injections yielded similar outcomes for knee osteoarthritis.
- Leukocyte concentration may not impact the safety or efficacy of platelet-rich plasma.
According to published results, leukocyte-rich and leukocyte-poor platelet-rich plasma injections may yield comparable outcomes in the treatment of patients with knee osteoarthritis.
Iacopo Romandini, MD, and colleagues from the Rizzoli Orthopedic Institute in Bologna, Italy, performed a double-blinded, randomized controlled trial of 132 patients with radiographic signs of mild to moderate knee OA, defined by Kellgren Lawrence grades 1, 2 or 3.
Romandini and colleagues randomly assigned 66 patients to receive three weekly intra-articular, leukocyte-rich PRP knee injections (mean 14.4 leukocytes per 106/L of PRP) and 66 patients to receive three weekly intra-articular, leukocyte-poor PRP knee injections (mean 4.7 leukocytes per 106/L of PRP). Outcome measures included IKDC, KOOS, WOMAC and VAS scores at 2-month, 6-month and 1-year follow-ups. Overall, 65 patients (mean age, 56.7 years) from the leukocyte-rich cohort and 63 patients (mean age, 51.9 years) from the leukocyte-poor cohort had complete follow-up at 2 months and were included in the analysis of outcomes.
The researchers found both cohorts had overall improvements in outcomes at final follow-up. Patients in the leukocyte-rich cohort had significantly greater IKDC scores at 2 months and range of motion at 6 months, while patients in the leukocyte-poor cohort had significantly greater quadriceps circumference at 1 year. The researchers found no other significant differences in subjective or objective outcomes between the cohorts at any follow-up.
From baseline to 1-year follow-up, mean IKDC subjective scores improved from 42.5 to 55.6 for the leukocyte-rich cohort and from 45.7 to 55.3 for the leukocyte-poor cohort.
Among the leukocyte-rich cohort, there were 16 mild complications with five patients (7.6%) failing treatment. Among the leukocyte-poor cohort, there were 17 mild complications with two patients (3.2%) failing treatment. Romandini and colleagues noted that the differences were not significant.
“Leukocytes did not influence the clinical effects of PRP in this study, suggesting that the heterogeneous PRP effects documented in the literature may depend on a much more complex interplay of factors rather than the mere presence or absence of white blood cells,” Romandini and colleagues wrote in the study.
Perspective
Back to TopAndrew S. Bi, MD, and Jorge Chahla, MD, PhD
The influence of leukocyte concentration on platelet-rich plasma injections in knee osteoarthritis has been a subject of debate. In a recently published double-blind, randomized controlled trial, Iacopo Romandini, MD, and colleagues compared leukocyte-rich PRP (LR-PRP) and leukocyte-poor PRP (LP-PRP) in 132 patients for the treatment of Kellgren-Lawrence (KL) grade 1 to 3 knee OA. They demonstrated no meaningful differences in clinical outcomes or adverse events (KOOS, WOMAC and complications) with the exception of a higher IKDC score at 2 months in the LR-PRP group, but greater knee range of motion at 6 months in the LP-PRP group. These findings corroborate an earlier randomized controlled trial by Alessandro Di Martino, MD, and colleagues of 192 patients with KL grade 1 to 3 knee OA, as well as a recent network meta-analysis.
In contrast, pre-clinical studies have suggested varying effects of leukocyte concentrations, suggesting LR-PRP have an increased inflammatory role that may better stimulate tenocyte healing in tendinopathies, while LP-PRP has an anti-inflammatory effect for knee OA.
Ultimately, these findings suggest that while there may be different reactions to LP-PRP or LR-PRP at a molecular/cellular level, in the clinical setting PRP formulations may have limited influence on PRP efficacy and safety. In addition, multiple other variables affect PRP therapeutic efficacy, such as total platelet count, red blood cell count, patient donor factors, etc., and comparing LP-PRP to LR-PRP is just the tip of the PRP iceberg. There should remain a requirement for all future PRP studies to adequately define their PRP processing and composition methodology for accurate interpretation, for longer follow-up periods than typical 6 to 12 months and for inclusion of objective outcome variables to patient-reported outcomes, such as imaging MRI follow-up findings.
References:
Abbas A, et al. J Bone Joint Surg Am. 2022;doi:10.2106/JBJS.20.02258.
Di Martino A, et al. Am J Sports Med. 2022;doi:10.1177/03635465211064303.
Jayaram P, et al. Am J Sports Med. 2023;doi:10.1177/03635465231170394.
Lin KY, et al. Orthop J Sports Med. 2022;doi:10.1177/23259671221084706.
Romandini I, et al. Am J Sports Med. 2024;doi:10.1177/03635465241283500.
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