Platelet-rich plasma as a treatment for chronic patellar tendinopathy: comparison of a single versus two consecutive injections

Background: platelet-rich-plasma is increasingly used in chronic patellar tendinopathy. Ideal number of PRP injections needed is not yet established. This study compares the clinical outcomes of a single versus two consecutive PRP injections. Method: between December 2009 and January 2012, 40 athletes with proximal patellar tendinopathy were treated by PRP injection. Patients received single (20 patients) or two PRP injections 2 weeks apart (20 patients). All patients underwent prospective clinical evaluation, including Victorian Institute of Sport Assessment-Patella (VISA-P) score, visual analog scale (VAS) for pain, and Tegner scale before PRP and after a minimum of 2 year follow-up. Results: 9 patients failed PRP treatment and needed surgery. 1 patient was lost to follow-up. For the remaining patients, the VISA-P, VAS, and Tegner scores all significantly improved from 35.2 to 78.5 (p = 0.0001), 6.6 to 2.4 (p = 0.0001), and 4.8 to 6.9 (p = 0.0003). Patients who received two injections had better scores than those who received single injection with VAS of 1.07 versus 3.7 (p = 0.0005), Tegner score of 8.1 versus 5.9 (p = 0.0003) and VISA-P of 93.2 versus 65.7 (p = 0.0001). Conclusions: two consecutive PRP injections in chronic patellar tendinopathy showed better improvement in outcomes when compared to single injection. Level of evidence: randomized prospective consecutive series, Level 2.