Clinical Question

Are platelet-rich plasma injections effective in patients with patellar tendinopathy?

Bottom Line

In this study, platelet-rich plasma injections were no better than saline injections in improving pain or activity in patients with patellar tendinopathy. It did not matter whether the plasma was leukocyte rich or leukocyte poor. The study was too small to detect potential harms of the intervention. (Level of Evidence = 2b)

Synopsis

In this multicenter (Seattle, Oslo, Bologna) trial, the authors enrolled 61 adults, 18 to 50 years of age, with at least six months of clinically diagnosed patellar tendinopathy confirmed by ultrasonography with persistent symptoms in spite of a minimum of six weeks of exercise-based rehabilitation. The authors randomized patients to receive ultrasound-guided injections of either leukocyte-rich platelet-rich plasma, leukocyte-poor platelet-rich plasma, or saline. One week later, all patients engaged in a supervised gym-based rehabilitation program three times weekly for six weeks. Using standardized scales, the researchers evaluated each patient's pain, function, and activity limitations at baseline, and at 12, 24, and 52 weeks after the injections. They asked the patients for their own overall rating of change at the subsequent assessments. They had nearly complete (93%) follow-up at 12 weeks but only 79% at the end of a year. At no point in the study did the authors find any differences in the three groups as to any of the outcomes or patient global assessment of improvement. Six weeks after the intervention, five patients, none of whom received saline, reported overall worsening compared with their baseline. The authors report one patient experienced localized patellar tendon pain following the injection, enough to prevent activity. No other harms are reported, possibly because of the small sample size. The study was large enough to detect clinically meaningful differences in pain and functional limitations.

Study design: Randomized controlled trial (single-blinded)

Funding source: Foundation

Allocation: Concealed

Setting: Outpatient (specialty)

Reference: Scott A, LaPrade RF, Harmon KG, et al. Platelet-rich plasma for patellar tendinopathy: a randomized controlled trial of leukocyte-rich PRP or leukocyte-poor PRP versus saline. Am J Sports Med. 2019;47(7):1654–1661.