Injections are commonly used to treat knee pain in football. This randomised controlled trial from the American Journal of Sports Medicine compares two of the more common types of injection, platelet rich plasma (PRP) and hyaluronic acid (HA) and found little difference between the two options at five-year follow-up1.
Osteoarthritis (OA) commonly occurs in footballers who have a history of joint trauma or surgery, typically presenting with activity-related pain and swelling, and loss of movement. Playing football at a high level also appears to be an independent risk factor for developing OA. Joint injections are a popular treatment option as they are less invasive than surgery and are reported to give good symptomatic relief. The efficacy of these injections, especially in the longer term, has not been well established.
This randomised controlled, double-blind study of 192 patients compared the efficacy of PRP with HA injections over a longer follow-up period than studies that have been conducted to date (up to five years). Patients with chondral disease or established OA (Kellgren-Lawrence grade 0-3) were included. Patient received a single injection of either PRP or HA. Both treatments had a statistically significant improvement at two months post injection which remained stable at all time points up to two years. From this point the improvement declined (but remained better than baseline) until final follow-up. Those treated with PRP injections were less likely to have a second intervention (either another injection or surgery within the first two years).
Given that chondral disease can be difficult to treat, these findings are potentially encouraging with both PRP and HA providing symptomatic relief (especially in the first two years). The study methodology (a double blind RCT) appears robust. The method used to produce the PRP was also well described. The lack of a true placebo group is a clear limitation of this study as it is unclear whether these treatments are actually better than observation. The fact that both groups did actually improve over the study period is however encouraging. We should remember that an earlier FastFact showed that saline injections can be effective treatments too.
1Di Martino A, Di Matteo B, Papio T, Tentoni F, Selleri F, Cenacchi A, Kon E, Filardo G. Platelet-Rich Plasma Versus Hyaluronic Acid Injections for the Treatment of Knee Osteoarthritis: Results at 5 Years of a Double-Blind, Randomized Controlled Trial. Am J Sports Med. 2019; 47(2): 347-354.