Hunter Butler M.D.^* and Aamir Ahmad M.D

University of Texas Rio Grande Valley School of Medicine, 1210 W Schunior St Edinburg, TX 78541, USA

^*Corresponding Author: Hunter Butler M.D., University of Texas Rio Grande Valley School of Medicine, 1210 W Schunior St Edinburg, TX 78541, USA.

Received: 24 February 2026; Accepted: 16 March 2026; Published: 01 April 2026

Article Information

Citation: Hunter Butler. Platelet Rich Plasma Injection Treatment Outcomes in Patellar Tendinopathy. Journal of Orthopedics and Sports Medicine. 8 (2026): 126-129.

DOI: 10.26502/josm.511500261

Abstract

Keywords

Platelet rich plasma; Patellar tendinopathy; PRP injection; Knee; Sports

Article Details

1. Introduction

Patellar tendinopathy (PT), also referred to as “jumper’s knee,” is a pathology of the knee which primarily results from microtears in the patellar tendon [1-4]. As implied by “jumper’s knee,” sports that emphasize activity requiring speed and power generation through the leg extensors, such as jumping, puts stress on the patellar tendon. This stress accumulates over time, causing PT [5]. The definition of platelet rich plasma (PRP) is an autologous blood sample which has platelet concentration above an established baseline [1]. Due to the variation in blood samples across a patient population and preparation type, there is variability in the contents of an individual injection of PRP [6]. While other injection options do not contain this drawback, understanding the basis for this variability is essential. Primarily, the preparation of PRP starts with drawing peripheral blood from the patient, followed by a 2 step centrifugation process to separate the red blood cells from the plasma, and then the platelets and white blood cells from the clotting factors [7]. Variables such as the type of collecting tube and centrifuge speed cause differences in the final concentration of platelets and leukocytes in the PRP product [6]. PRP end products are further divided into leukocyte rich or leukocyte poor variations. While leukocytes play an important role in tissue repair and healing, it may also create an unwanted inflammatory effect. Additionally, there is limited evidence on which preparation provides the most benefit [8].

What is known is there are certain components of PRP, including insulin-like growth factor, epidermal growth factor, vascular endothelial growth factor, platelet-derived growth factor, and transforming growth factor, which stimulate healing of tendon and cartilage [9]. This provides additional physiologic benefit due to the naturally low blood supply of these areas [10].

2. Methods

A systematic literature search was conducted using the University of Texas Rio Grande Valley (UTRGV) online database. The search included the terms “patellar tendonitis” and “platelet rich plasma” to identify relevant studies assessing the efficacy of PRP injections in treatment of patellar tendonitis. Upon initial search, 32 articles were relevant. However, after exclusion criteria was applied, 12 total articles were deemed appropriate for analysis. For the article to be considered for analysis it must be a primary article and comparing a PRP and non-PRP treatment strategy, Due to limited article availability, no distinction was made between lymphocyte rich and lymphocyte poor formulations of PRP injections in the analysis.

3. Results

Of the 12 studies that were analyzed, eight of them supported PRP injections as an appropriate treatment strategy that provides clear benefit compared to placebo. Four studies failed to find a difference in long term outcome of PRP (Table 1).

* - Victorian Institute of Sport Assessment for pain (VISA-P), self-reported tendon pain during activity (visual analog scale [VAS]), muscle function by dynamometry, tendon thickness and intratendinous vascularity by ultrasonographic imaging and Doppler signal, ultrasound tissue characterization (UTC) echo type changes, and magnetic resonance imaging (MRI) T2-weighted mapping changes

Table 1: PNT- percutaneous needle tenotomy, BM-MSCs - bone marrow mesenchymal stem cells, GRoC - Global rating of change, LR-PRP - lymphocyte rich platelet rich plasma, LP-PRP - lymphocyte poor platelet rich plasma.

4. Discussion

The evidence for platelet-rich plasma (PRP) injections for patellar tendinopathy remains unclear, with outcomes varying per article. Pilot and prospective cohort studies commonly report symptomatic improvement following PRP injection. However, some randomized controlled trials (RCTs), particularly when compared to percutaneous needle tenotomy (PNT), did not show long term improvement of PRP over placebo [11-13].

Several pilot and comparative studies showed improvements in pain and function after PRP injections. In one study, long term improvement in VISA-P scores were reported at 6 months [14].  Gosens et al. [15] similarly showed improved scores in VISA-P and VAS at a mean follow up of 18 months. Long-term symptom improvement was also described in additional pilot studies [16,17]. Collectively, these findings suggest an association between PRP treatment and clinical improvement.

Some placebo-controlled RCTs have shown limited or no long-term benefit of PRP. Scott et al. [11] found no significant differences between leukocyte-rich PRP, leukocyte-poor PRP, and saline injection at either 6 or 12 months. Similarly, Herrero et al. [12] and Kirschner et al. [13] reported no benefit of leukocyte-poor PRP and PNT compared with PNT alone at 26 week and 104 week follow-up, respectively.

However, there may be a positive short term prognosis for PRP injections. Dragoo et al. [18] reported improved pain and function at 12 weeks in patients receiving PRP compared with PNT. Although, this benefit was not sustained at later follow-up intervals. Additionally, one RCT reports improvement following PRP injection at 12 weeks [19].

Studies comparing PRP with other active interventions rather than placebo report mixed results. Superior outcomes with PRP compared with focused shockwave therapy were reported at 6 and 12 months, although the absence of a placebo control limits conclusions regarding true treatment efficacy [20]. Additionally, better clinical outcomes with PRP compared with high-volume injection were observed at 6 months [21]. However, one study found worse clinical outcome at 6 months with leukocyte-poor PRP compared with bone marrow–derived mesenchymal stem cell injection [22].

The lack of standardized primary outcomes available complicates in depth analysis of existing literature. Differences in PRP formulation, injection technique, number of injections, post-procedural rehabilitation protocols, and primary outcome measures likely contribute to inconsistent findings. Additionally, follow-up duration varied widely, with short-term benefits reported more frequently than sustained long-term improvements. Standardization of these variables and additional studies will likely allow for better analysis.

5. Conclusion

While symptomatic improvement in several cohort and pilot studies was reported, PRP injections do not demonstrate consistent superiority over placebo or standard interventions. However, there is durable evidence for the short-term benefits of PRP injections. These findings suggest that PRP should be considered an adjunctive or short-term therapy rather than a first-line treatment for patellar tendinopathy. While PRP is a promising field for the treatment of patellar tendinopathy, a larger body of standardized literature is needed to elucidate a clear long-term benefit.

Conflict of interests

The authors declare that they have no conflict of interests.

Acknowledgements

Not applicable.

References

1. Everts P, Onishi K, Jayaram P, et al. Platelet-Rich Plasma: New Performance Understandings and Therapeutic Considerations in 2020. Int J Mol Sci 21 (2020): 7794.
2. Andriolo L, Altamura SA, Reale D, et al. Nonsurgical Treatments of Patellar Tendinopathy: Multiple Injections of Platelet-Rich Plasma Are a Suitable Option: A Systematic Review and Meta-analysis. Am J Sports Med 47 (2018): 1001-1018.
3. Bowman KFJ, Muller B, Middleton K, et al. Progression of Patellar Tendinitis Following Treatment with Platelet-Rich Plasma: Case Reports. Knee Surg Sports Traumatol Arthrosc 21 (2013): 2035-2039.
4. Santana JA, Mabrouk A, Sherman AL. Jumper's Knee. StatPearls (2025).
5. Lian OB, Engebretsen L, Bahr R. Prevalence of Jumper's Knee Among Elite Athletes from Different Sports: A Cross-sectional Study. Am J Sports Med 33 (2005): 561-567.
6. Mazzocca AD, McCarthy MB, Chowaniec DM, et al. Platelet-Rich Plasma Differs According to Preparation Method and Human Variability. J Bone Joint Surg Am 94 (2012): 308-316.
7. Marx RE. Platelet-Rich Plasma (PRP): What Is PRP and What Is Not PRP? Implant Dent 10 (2001): 225-228.
8. Zimmermann R, Arnold D, Strasser E, et al. Sample Preparation Technique and White Cell Content Influence the Detectable Levels of Growth Factors in Platelet Concentrates. Vox Sang 85 (2003): 283-289.
9. Kia C, Baldino J, Bell R, et al. Platelet-Rich Plasma: Review of Current Literature on its Use for Tendon and Ligament Pathology. Curr Rev Musculoskelet Med 11 (2018): 566-572.
10. Boswell SG, Cole BJ, Sundman EA, et al. Platelet-Rich Plasma: A Milieu of Bioactive Factors. Arthroscopy 28 (2012): 429-439.
11. 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 47 (2019): 1654-1661.
12. Herrero C, Wasterlain A, Bloom DA, et al. Leukocyte-Poor Platelet-Rich Plasma as a Treatment for Patellar Tendinopathy: A Multicenter, Randomized Controlled Trial. Bull Hosp Jt Dis 82 (2024): 266-272.
13. Kirschner JS, et al. Ultrasound-guided Percutaneous Needle Tenotomy (PNT) Alone versus PNT plus Platelet-Rich Plasma Injection for the Treatment of Chronic Tendinosis: A Randomized Controlled Trial. PM R 13 (2021): 1340-1349.
14. Filardo G, Kon E, Della Villa S, et al. Use of Platelet-Rich Plasma for the Treatment of Refractory Jumper's Knee. Int Orthop 34 (2010): 909-915.
15. Gosens T, Den Oudsten BL, Fievez E, et al. Pain and Activity Levels Before and After Platelet-Rich Plasma Injection Treatment of Patellar Tendinopathy: A Prospective Cohort Study and the Influence of Previous Treatments. Int Orthop 36 (2012): 1941-1946.
16. Dallaudière B, Pesquer L, Meyer P, et al. Intratendinous Injection of Platelet-Rich Plasma Under US Guidance to Treat Tendinopathy: A Long-term Pilot Study. J Vasc Interv Radiol 25 (2014): 717-723.
17. Kon E, et al. Platelet-Rich Plasma: New Clinical Application – A Pilot Study for Treatment of Jumper’s Knee. Injury 40 (2009): 598-603.
18. Dragoo JL, Wasterlain AS, Braun HJ, et al. Platelet-Rich Plasma as a Treatment for Patellar Tendinopathy: A Double-Blind, Randomized Controlled Trial. Am J Sports Med 42 (2014): 610-618.
19. Wasterlain AS, et al. Platelet-Rich Plasma as a Treatment for Patellar Tendinopathy: A Double-Blind Randomized Controlled Trial (SS-60). Arthroscopy 28 (2012): e31-e32.
20. Vetrano M, Castorina A, Vulpiani MC, et al. Platelet-Rich Plasma versus Focused Shock Waves in the Treatment of Jumper's Knee in Athletes. Am J Sports Med 41 (2013): 795-803.
21. Abdelbary MH, Bassiouny A. Ultrasound Guided Injection in Patellar Tendinopathy: Clinical Outcomes of Platelet-Rich Plasma Compared to High-Volume Injection. Egypt J Radiol Nucl Med 49 (2018): 1159-1162.
22. Rodas G, et al. Effect of Autologous Expanded Bone Marrow Mesenchymal Stem Cells or Leukocyte-Poor Platelet-Rich Plasma in Chronic Patellar Tendinopathy (With Gap >3 mm): Preliminary Outcomes After 6 Months of a Double-Blind, Randomized, Prospective Study. Am J Sports Med 49 (2021): 1492-1504.