Platelet-rich plasma injections did not significantly improve ankle symptoms compared to placebo in patients with ankle osteoarthritis

1. This trial included 100 patients and took place over a 26-week period, ultimately concluding that platelet-rich plasma (PRP) injections were ineffective at improving symptoms (pain, functional limitations) in patients with ankle osteoarthritis.

Evidence Rating Level: 1 (Excellent)

Study Rundown: Osteoarthritis affects millions of patients worldwide and negatively impacts quality of life. It is associated with symptoms of pain, limited mobility and impaired function, particularly in younger patients who may be affected by ankle osteoarthritis (AOA) following an injury. There is no pharmacologic or procedural intervention standard of care to treat OA, although some interest has been generated around the use of PRP injections. PRP has demonstrated some benefit for patients with OA of the knee; it is thought to work by facilitating an anti-inflammatory & analgesic effect. This randomized controlled trial (RCT) sought to determine whether PRP injections would improve symptoms in patients with AOA. 100 patients in total were randomized for participation in this trial, including 48 in the PRP group and 52 in the placebo group. Patients underwent two intra articular injections, six weeks apart. The primary outcome was the American Orthopedic Foot and Ankle Society (AOFAS) score after 26 weeks. The AOFAS measures pain, function and alignment; secondary outcomes included the AOFAS score at 6 weeks, as well as clinically-important scores from subsets of the AOFAS (i.e., pain, symptoms, quality of life, sport/recreation) and other quality of life scoring systems. The mean improvement in score was 10 points in the PRP group compared to 11 points in the placebo group, indicating no difference at 26 weeks. Duration of symptoms of AOA (years) and radiological degree of tilt within the tibiotalar joint were the two baseline variables found to be associated with AOFAS score. No significant differences were found at 6 or 26 weeks for any of the secondary outcomes assessed between the intervention and placebo groups. Paget et al concluded that PRP injections are an ineffective intervention for the management of pain and other symptoms attributed to ankle osteoarthritis. This trial is important because it demonstrates that a relatively well-accepted intervention should not be recommended in the management of AOA. Further research should confirm these findings in a broader population of patients and consider making alterations to the PRP injection formula based on evidence from the management of OA for other joints. A primary limitation of this study is the narrowness of the intervention, i.e., different formulations of PRP may have produced different results, so the findings here cannot necessarily be generalized. Additionally, differences in activity levels and physical rehabilitation were not controlled for between groups. This study additionally demonstrates that management of AOA symptoms is poorly understood and merits further research to improve patient quality of life.

Click to read this study in JAMA.

Relevant Reading: Clinical outcomes following injections of leukocyte-rich platelet-rich plasma in osteoarthritis patients

In-Depth [randomized controlled trial]: This study was a double-blinded RCT conducted at six healthcare centers in the Netherlands. Patients were eligible if they were over the age of 18, had an X-ray-confirmed diagnosis of ankle osteoarthritis (tibiotalar joint) and had a baseline score of at least 40/100 for AOA pain using a visual analogue scale. Exclusion criteria included the receipt of alternate therapy or other injections within 6 months of trial start. Stratified block randomization was used to assign patients to either the PRP group or the saline group. Research assistants had knowledge of which patients received PRP versus placebo, but the coordinating research physician who assessed and treated patients did not. Patients in the intervention group received a leukocyte-poor PRP injection as had been used previously in the literature. All patients received lifestyle/exercise counselling, as is the standard of care for OA management, and were asked to avoid co-interventions if possible. The improvement in AOFAS score after 26 weeks was 10 points in the PRP group (95% confidence interval [95CI] 6-14) and 11 points in the placebo group (95CI 7-15). The adjusted between-group difference in AOFAS score change was -1 point (95CI [-6] to 3; p = 0.56), which was not statistically significant. The mean score difference between groups within the subsets of the AOFAS were as follows: 0 points for pain (95CI [-2] to 2), -2 points for symptoms (95CI [-8] to 4), -1 point for activities of daily living (95CI [-7] to 6), -1 point for quality of life (95CI [-7] to 6), and -1 point for sport and recreation (95CI [-9] to 6). One patient in the placebo group experienced a transient ischemic attack during the study course which was thought to be unrelated to the injection; no other adverse events occurred in this trial.

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