An injection into the ankle joint with Platelet Rich Plasma (PRP) does not work better in ankle osteoarthritis than an injection with saline. This is the main conclusion from a multicenter RCT initiated and coordinated at the Amsterdam UMC. The results were published Oct. 26th 2021, in the Journal of the American Medical Association (JAMA).
Injecting PRP has been a popular therapy for joint, muscle and tendon disorders. The idea is that injecting your blood plasma with a high concentration of platelets has a beneficial effect on the healing process because growth factors are released from the platelets.
Hesitant
Sports physician and lead researcher Hans Tol, who conducted the PRP study with researchers from Bergman Clinics, Erasmus MC, Flevoziekenhuis, OLVG and Spaarne Gasthuis, says that they were initially reluctant to start a study into the use of PRP in ankle osteoarthritis. "Eleven years ago, we were the first to investigate the effect of PRP in Achilles tendon injury in an RCT. We found no effect at the time, and those results were also published in the JAMA. But due to clinical experience and, in particular, the recurring question from patients with ankle osteoarthritis, we started to have doubts. And when other research showed that PRP injections lead to less pain and disability patients with knee osteoarthritis, we decided to conduct this. Financial support from ReumaNederland made this possible."
Advanced osteoarthritis
In osteoarthritis, the layer of cartilage in the joint has become thin and irregular. This causes pain and prevents the joint from moving smoothly. In contrast to knee and hip osteoarthritis, ankle osteoarthritis is more common at a younger age. This is because it is secondary to trauma in 70-80% of cases, such as a broken bone or frequent ankle sprains. "The initial trauma causes very local damage to the cartilage," explains co-researcher and head of Orthopedics Gino Kerkhoffs. "We can treat this well surgically, which in many cases prevents progression to osteoarthritis. In advanced osteoarthritis, the cartilage in the entire joint is affected, and we can fixate the ankle joint or place an ankle prosthesis. These are major operations that we do not prefer at a young age." "However, there is not yet a good non-operative therapy in advanced osteoarthritis, continues orthopaedics physician-researcher Liam Paget, who coordinated the research in all hospitals. "Only interventions, such as strengthening the muscles around the affected joint – in this case, foot and calf muscles – and losing weight are of added value. That is why we did this research on a non-surgical alternative."
No difference
100 adult patients with ankle osteoarthritis were included in the six centres for the study. They were required to have a mean pain score of at least 40 on a scale of 100 and X-ray evidence of ankle osteoarthritis. Blood was taken, and PRP was prepared in all patients. Half of them received a PRP injection based on a lottery, the other a saline solution injection (placebo). After six weeks, the injection was repeated. In addition, the patients completed questionnaires at baseline and after 6, 12 and 26 weeks. Physical examinations were also performed three times during this period.
The results showed that there was no difference between the two groups. Tol: "Because we included patients from academic, peripheral, top clinical and independent centres, the results of our study can be generalized well."
Do not administer anymore
"Of course, we had hoped that the PRP injections would offer a solution for people with ankle osteoarthritis, but unfortunately, we have to conclude the opposite," says Paget. "Our advice to practitioners is to stop administering PRP injections in these patients. They don't work. Moreover, it is an expensive therapy that belongs to non-insured care. Patients, therefore, have to pay for it out of their pocket."
Future research
For Kerkhoffs, the study results focus future research on other biological injectables and an injectable gel cushion. "We are a centre of expertise of the Dutch Federation of University Medical Centers (NFU) in the field of cartilage and underlying bone defects of the ankle. It is our mission to have appropriate treatment for all phases of cartilage damage. In the upcoming studies, we will focus on the phase just after trauma to repair the initial, local cartilage trauma and ultimately prevent progression to ankle osteoarthritis. In this way, we hope to solve the problem eventually."
The full paper can be accessed here (paid access)
Paget LDA, Reurink G, de Vos R, et al. Effect of Platelet-Rich Plasma Injections vs Placebo on Ankle Symptoms and Function in Patients With Ankle Osteoarthritis: A Randomized Clinical Trial. JAMA.2021;326(16):1595–1605. doi:10.1001/jama.2021.16602