Abstract and Introduction
Abstract
Objective To investigate the effectiveness of ultrasound guided corticosteroid injection in the treatment of plantar fasciitis.
Design Randomised, investigator and participant blinded, placebo controlled trial.
Setting University clinic in Melbourne, Australia.
Participants 82 people with a clinical and ultrasound diagnosis of plantar fasciitis unrelated to systemic inflammatory disease.
Interventions Participants were randomly allocated to ultrasound guided injection of the plantar fascia with either 1 mL of 4 mg/mL dexamethasone sodium phosphate (experimental group) or 1 mL normal saline (placebo). Before injection the participants were given an ultrasound guided posterior tibial nerve block with 2% lidocaine (lignocaine).
Main outcome measures Primary outcomes were pain, as measured by the foot health status questionnaire (0-100 point scale), and plantar fascia thickness, measured by ultrasound at 4, 8, and 12 weeks.
Results Reduction in pain at four weeks favoured the dexamethasone group by 10.9 points (95% confidence interval 1.4 to 20.4, P=0.03). Between group differences for pain scores at eight and 12 weeks were not statistically significant. Plantar fascia thickness measured at four weeks favoured the dexamethasone group by -0.35 mm (95% confidence interval -0.67 to -0.03, P=0.03). At eight and 12 weeks, between group differences for plantar fascia thickness also favoured dexamethasone, at -0.39 mm (-0.73 to -0.05, P=0.02) and -0.43 mm (-0.85 to -0.01, P=0.04), respectively. The number needed to treat with dexamethasone for one successful outcome for pain at four weeks was 2.93 (95% confidence interval 2.76 to 3.12). There were no reported adverse events associated with the intervention.
Conclusion A single ultrasound guided dexamethasone injection is a safe and effective short term treatment for plantar fasciitis. It provides greater pain relief than placebo at four weeks and reduces abnormal swelling of the plantar fascia for up to three months. However, clinicians offering this treatment should also note that significant pain relief did not continue beyond four weeks.
Trial registration Australian New Zealand Clinical Trials Registry ACTRN12610000239066.
Introduction
Plantar fasciitis is the most commonly reported cause of inferior heel pain. The condition is characterised by pain at the calcaneal origin of the plantar fascia, exacerbated by weight bearing after prolonged periods of rest. The prevalence of heel pain in the general population is estimated to range from 3.6% to 7%, and the disorder has been reported to account for about 8% of all running related injuries. An estimated one million visits per year were made to office based physicians and hospital outpatient departments in the United States for the diagnosis and treatment of plantar fasciitis, representing an important economic burden.
The histological features of plantar fasciitis are poorly understood, although studies report a predominance of degenerative changes at the plantar fascia enthesis, including deterioration of collagen fibres, increased secretion of ground substance proteins, focal areas of fibroblast proliferation, and increased vascularity. The presence of biochemical markers of inflammation such as cytokines and prostaglandins have not been well investigated, although, several studies report non-specific evidence of local inflammatory change.
Plantar fasciitis is commonly described in the literature as a self limiting condition. This view is supported by the findings of a systematic review, in which plantar heel pain, on average, resolved after 12 months regardless of treatment type (including placebo). None the less, plantar fasciitis can be a painful and disabling condition, having a negative impact on health related quality of life.
Several interventions are used for the management of plantar fasciitis, and corticosteroid injection is a common choice among clinicians. Surveys of American podiatrists and orthopaedic surgeons reported that about 75% of respondents used or recommended this intervention. Despite the widespread use of corticosteroid injection for plantar fasciitis, only two randomised controlled trials have evaluated the effect of this treatment compared with placebo. One compared the effect of 25 mg prednisolone and lidocaine (lignocaine) with lidocaine alone (placebo) and found a significant difference in pain reduction favouring corticosteroid one month after treatment. No significant differences between groups were detected three or six months after treatment. A large proportion of participants were, however, lost to follow-up, so the authors were unable to make conclusions about the efficacy of corticosteroid in the longer term. An earlier trial compared the effect of 25 mg hydrocortisone with normal saline (placebo) and found no significant difference in pain reduction between the groups two months after treatment. This trial, however, had a small sample size (19 participants) and was therefore statistically underpowered to detect clinically worthwhile differences.
The findings of existing clinical trials provide some support for the use of corticosteroid injection in the short term management of plantar fasciitis. However, a recent systematic review concluded that the effectiveness of this treatment has not been sufficiently established, indicating that further research is required. Therefore, we evaluated the effectiveness of ultrasound guided corticosteroid injection in the treatment of plantar fasciitis.