1. The clinical outcome of chronic midportion Achilles tendinopathy, measured via the Victorian Institute of Sport Assessment-Achilles score, did not differ between participants randomized to platelet-rich plasma (PRP) injection or sham injection at 3 months or 6 months. Similarly, quality of life and pain did not significantly differ between the PRP and sham groups at 2 weeks, 3 months, and 6 months.
2. Minor adverse events like discomfort, swelling, and bruising, occurred in both groups, with one serious adverse event of intense pain requiring tendon debridement occurring in the PRP group.
Evidence Rating Level: 1 (Excellent)
Study Rundown: Chronic midportion Achilles tendinopathy is degeneration of the Achilles tendon that causes pain and swelling and is associated with increased risk of tear. It has a prevalence of 5.2 per 1000 people. Therapies currently available include exercise, orthotics, electrotherapy, and injection with an irritant solution, high volume injection, corticosteroids, or platelet-rich plasma (PRP) injection. PRP contains growth factors thought to repair the tendon. This study is a large, single-blind multi-centre randomized clinical trial comparing PRP injection versus sham injection in patients with chronic midportion Achilles tendinopathy using the Victorian Institute of Sport Assessment-Achilles (VISA-A) score, as well as quality of life (QOL) and pain measurements. Adults with chronic midportion Achilles tendinopathy were randomized to PRP treatment or sham injection and encouraged not to seek other treatment while they were followed for 6 months. VISA-A scores, as well as QOL (measured with the 5-level Euroqol questionnaire [EQ-5D-5L]), and pain (measured with visual analog scale) did not significantly differ between the PRP and sham groups at 2 weeks, 3 months, and 6 months. Additionally, there were no differences between subgroups classified by laterality or duration of symptoms. Adverse events occurred, including injection site discomfort at 2 weeks and 6 months, swelling, bruising, and severe pain in both groups. These results suggest no clinical evidence for the use of PRP in treating chronic midportion Achilles tendinopathy. A strength of this study is the choice of sham treatment; dry needling with penetration of the tendon or injection of saline have been associated with therapeutic value due to trauma to the tendon recruiting healing factors and pressure changes, so the choice of dry needling without penetration of the tendon was the most appropriate control. This study is limited in that no method was used to confirm the location of injection into the Achilles for the PRP treatment; however, missing the tendon is unlikely given how superficial and identifiable the tendon is. Finally, the quality of every PRP sample used in this protocol could only be verified by internal and not independent quality assessment.
Relevant Reading: Current Clinical Recommendations for Use of Platelet-Rich Plasma
In-Depth [prospective cohort]: Adults with imaging-confirmed chronic (>3 months) midportion Achilles tendinopathy, who did not have systemic conditions that affect tendons (diabetes or rheumatoid arthritis), pregnancy, prior tendon rupture or ankle injury, lower leg deformity or recent leg bone fracture, or prior treatment with or contraindications to PRP (hemodynamic instability, platelet dysfunction syndrome, cancer, septicemia, anticoagulation therapy) were eligible for this study. Participants were randomized using a minimization algorithm with stratification based on their recruitment center (24 UK hospitals in the National Health Service) and laterality (1 or both Achilles tendons involved). All participants had 9 mL of blood taken, waited 30 mins for “PRP preparation” and received 5 mL of 2% lidocaine; for treatment patients (n=121), 3 mL of PRP (blood centrifuged for 5 minutes at 1200 relative centrifugal force (RCF), had red blood cells removed, and then re-centrifuged for 10 minutes at 1200 RCF) was injected through 1 hole into 5 parts of the tendon, while for sham patients (n=119), a dry injection was performed, where the needle was inserted under the skin but not into the tendon. 92% of participants completed the VISA-A score. 30.6% of participants in the PRP and 33.6% of participants in the sham group received additional treatments against the encouragement of the study protocol, which were similar between groups. Participants had a mean age of 52.2±10.5 years, 58% were women, and a mean prior duration of symptoms of 24 months. VISA-A scores did not differ between the PRP treated group and the sham control group at 6 months (mean difference = -2.7; 95% CI = −8.8 to 3.3) or 3 months (mean difference = −0.4; 95% CI = −5.1 to 4.3). The two groups also did not differ when compared by intention to treat on quality of life measured with the EQ-5D-5L or on pain measured on visual analog scale at 2 weeks, 3 months, and 6 months. These results were the same on per-protocol analysis (3 participants in treatment received sham due to equipment failure), nor imputed analysis correcting for missing data. There were no differences between groups when grouped by laterality (single vs bilateral) or duration of symptoms (≤median vs > median duration). The most common adverse event was discomfort at injection site 2 weeks after the injection (82% of PRP group vs 61% of sham) and at 6 months (7.4% of PRP group vs 0.8% of sham). Other adverse events included swelling at 2 weeks post-injection (47% of treatment group vs 44% of sham) and bruising (40% of PRP group vs 41% of sham). 1 serious event occurred in the PRP group involving intense pain requiring tendon debridement. Overall, these findings suggest potential clinical risk and no significant benefit to a single PRP injection for chronic midportion Achilles tendinopathy, though it remains possible that repeat PRP therapy may have an effect.
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