Platelet-rich plasma as a treatment for patellar tendinopathy: a double-blind, randomized controlled trial

Abstract

Background: Previous studies have shown improvement in patellar tendinopathy symptoms after platelet-rich plasma (PRP) injections, but no randomized controlled trial has compared PRP with dry needling (DN) for this condition.

Purpose: To compare clinical outcomes in patellar tendinopathy after a single ultrasound-guided, leukocyte-rich PRP injection versus DN.

Study design: Randomized controlled trial; Level of evidence, 1.

Methods: A total of 23 patients with patellar tendinopathy on examination and MRI who had failed nonoperative treatment were enrolled and randomized to receive ultrasound-guided DN alone (DN group; n = 13) or with injection of leukocyte-rich PRP (PRP group; n = 10), along with standardized eccentric exercises. Patients and the physician providing follow-up care were blinded. Participants completed patient-reported outcome surveys before and at 3, 6, 9, 12, and ≥26 weeks after treatment during follow-up visits. The primary outcome measure was the Victorian Institute of Sports Assessment (VISA) score for patellar tendinopathy at 12 weeks, and secondary measures included the visual analog scale (VAS) for pain, Tegner activity scale, Lysholm knee scale, and Short Form (SF-12) questionnaire at 12 and ≥26 weeks. Results were analyzed using 2-tailed paired and unpaired t tests. Patients who were dissatisfied at 12 weeks were allowed to cross over into a separate unblinded arm.

Results: At 12 weeks after treatment, VISA scores improved by a mean ± standard deviation of 5.2 ± 12.5 points (P = .20) in the DN group (n = 12) and by 25.4 ± 23.2 points (P = .01) in the PRP group (n = 9); at ≥26 weeks, the scores improved by 33.2 ± 14.0 points (P = .001) in the DN group (n = 9) and by 28.9 ± 25.2 points (P = .01) in the PRP group (n = 7). The PRP group had improved significantly more than the DN group at 12 weeks (P = .02), but the difference between groups was not significant at ≥26 weeks (P = .66). Lysholm scores were not significantly different between groups at 12 weeks (P = .81), but the DN group had improved significantly more than the PRP group at ≥26 weeks (P = .006). At 12 weeks, 3 patients in the DN group failed treatment and subsequently crossed over into the PRP group. These patients were excluded from the primary ≥26-week analysis. There were no treatment failures in the PRP group. No adverse events were reported. Recruitment was stopped because interim analysis demonstrated statistically significant and clinically important results.

Conclusion: A therapeutic regimen of standardized eccentric exercise and ultrasound-guided leukocyte-rich PRP injection with DN accelerates the recovery from patellar tendinopathy relative to exercise and ultrasound-guided DN alone, but the apparent benefit of PRP dissipates over time.

Keywords: patellar tendon; platelet-rich plasma; randomized controlled trial; symptoms; tendinopathy; tendon injuries.