Osteoarthritis of the ankle is associated with disability, pain, and a worsened quality of life. Currently, there are no effective nonsurgical treatments for this condition. While autologous platelet-rich plasma (PRP) has been used for the management of knee osteoarthritis despite no clear evidence of efficacy, there is even less evidence regarding its efficacy for the treatment of osteoarthritis of the ankle. It is hypothesized that intra-articular injection of PRP, prepared by centrifugation of a blood sample collected from the same patient, might exert a beneficial anti-inflammatory and reparative response in the joint through the release of growth factors from the platelets.
The newly published, double-blinded, PRIMA trial conducted in the Netherlands is the first randomized trial to investigate the efficacy of PRP in patients with osteoarthritis of the ankle. Before PRIMA, only four small observational studies had evaluated PRP in this population –– all of them reporting an improvement in symptoms and function.
PRIMA enrolled 100 adults (mean age 56) with tibiotalar joint space narrowing. All the patients had a score of at least 40 points for pain severity on a 100-point visual analog scale (VAS), with higher scores indicating more pain. Patients were randomized to receive two ultrasound-guided intra-articular injections of either autologous PRP or placebo six weeks apart. In addition, both groups received standard care with lifestyle and exercise counseling. Pain and function of the ankle were assessed using the American Orthopedic Foot and Ankle Society (AOFAS) scale. This scale ranges from zero to 100 points, with a 12-point difference considered clinically important. The mean AOFAS score before the intervention was 63 points in the PRP group and 64 points in the placebo group.
All patients completed the 26-week follow-up. Although both groups exhibited a slight improvement in AOFAS scores compared to baseline, there was no significant difference between the patients treated with PRP and those receiving placebo (mean increase in AOFAS score of 10 points vs. 11 points, p = 0.56). There were also no significant differences among all the investigated secondary outcomes, with both groups reporting similar scores for instruments evaluating pain, symptoms and function, and quality of life. Complications included muscle soreness in both groups (26% vs. 15%) and ipsilateral knee pain, which was only reported in four percent of the patients who received PRP.
This moderate-sized but otherwise well-executed trial failed to find a clinically significant benefit with the addition of PRP to usual care compared to placebo. While several smaller studies previously found benefit of this treatment for ankle osteoarthritis, this trial is another example of how enthusiasm for new ideas may warp our observations in smaller, observational studies. It highlights the importance of blinded controlled trials, so we don't fool ourselves and our patients. For now, the benefits of PRP for ankle osteoarthritis remain unproven.
For more information, see the topic Osteoarthritis (OA) of the Ankle in DynaMed®.
