By Kirsty Oswald
The efficacy of a single steroid injection for plantar fasciitis has been proven over placebo in one of the few controlled trials of the treatment.
Researchers found that visual analog scale (VAS) pain scores were significantly lower after 12 weeks with both ultrasound-guided and unguided injection of methylprednisolone 20 mg compared with placebo. However, there was no difference in treatment outcomes between the two active treatment groups.
The study included 65 patients with mechanistic pain - the most common pattern of heel pain - who had failed to improve after at least 8 weeks of conventional treatment. Mean VAS scores, on a scale of 0-100, at 12 weeks' follow up were 28.4 in the ultrasound-guided injection group and 28.2 in the unguided group, compared with 53.8 in the placebo group. In comparison, at baseline, scores for all three groups were in the range 56-66.
Improvements in physician-assessed heel tenderness scores and plantar fascia thickness were also significantly greater in the active treatment groups compared with placebo.
"This is the first placebo controlled study to show a sustained benefit from steroid injection of the heel pad over a 12-week period in the treatment of inferior heel pain," say Elisabeth Ball (Musgrave Park Hospital, Belfast, UK) and colleagues.
As well as comparing active treatment with placebo, the study, published in the Annals of Rheumatic Diseases, assessed the potential benefits of ultrasound-guided injection. However, the researchers failed to find any difference in clinical outcome over unguided injection. They suggest that diffusion within the tissue or systemic effects of corticosteroids may negate the need for the injection to be in a precise location.
In comparison, the benefits of steroid treatment over placebo were sustained throughout the trial, with both heel pain VAS and plantar fascia thickness significantly greater in the treatment groups compared with placebo at 6 weeks. At this timepoint, only heel tenderness in the ultrasound-guided treatment group did not significantly differ from placebo.
The authors say their results indicate that, while ultrasound can provide useful information for clinical decisions, it may be of limited benefit during treatment. They also believe that the study provides important information about the treatment of patients who fail to respond to analgesics and rest, and who may experience considerable pain and disability while they wait for symptoms to resolve.
The researchers conclude that "it is important to know that steroid injection (whether guided or unguided) can have significant benefits in the short and medium term."
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