Centre for Rheumatic Diseases, Glasgow Royal Infirmary, 10 Alexandra Parade, Glasgow G31 2ER, UK
SIR, We thank Wong et al. [1] for their interest in our article. Idiopathic plantar fasciitis is a common condition and the long-term prognosis is good, with resolution of symptoms in the majority of patients after 6 weeks. The randomized, controlled trial referred to by the correspondents provides clear and convincing evidence that steroid injection of the heel is useful in managing symptoms in the short term [2]. The benefit of this is clear in allowing a more rapid return to normal activities for most patients.
After 6 weeks, a small number of patients will have persistent or recalcitrant plantar fasciitis and a wide range of treatments, including surgery, is used. Most treatments of recalcitrant plantar fasciitis have not been formally evaluated by a randomized, controlled trial [3]. Despite the absence of controlled evidence, corticosteroid injection is widely used to manage recalcitrant plantar fasciitis and an uncontrolled study using scintigraphy suggests that accurate localization of the inflammatory site may improve the response to heel injection [4]. We undertook to determine the effectiveness of ultrasound-guided injection of the heel. There are considerable difficulties in recruiting patients with chronic heel pain and significant walking dysfunction to a placebo-controlled trial. We elected to compare ultrasonographically guided injection with standard heel injection. In our study we found the two approaches to have a similar response rate and ranked the two treatments as equally effective, though no comparison with placebo could be made. The statistical limitations of this small clinical study are accepted and clearly there is a need for further studies of both injection techniques. The 95% confidence interval for the VAS (visual analogue scale) score at baseline in the ultrasound guided group is incorrect and should be 47.373.7, though the data from which it was calculated are presented in full in the text.
Musculoskeletal ultrasound readily demonstrates superficial tissue inflammation and allows visualization of the plantar fascia [5]. The thickness of the normal plantar fascia has been described and the criteria which we used for the ultrasonographic diagnosis of plantar fasciitis are widely accepted. While patients 6, 11, 16 and 19 did not have a thickened plantar fascia, we noted reduced echogenicity and loss of border definition of the fascia, which are consistent with plantar fasciitis. A significant reduction in the plantar fascia thickness of 1.05 mm was observed, which approximates to the 1 mm thickness difference between heels accepted for the diagnosis of plantar fasciitis.
Steroid injection of the heel remains a common practice employed by rheumatologists and other practitioners in the management of plantar fasciitis. Patients continue to rank corticosteroid injection as a highly effective treatment when compared with other treatments [6]. Wong et al. correctly point out the need for properly designed randomized, controlled trials of steroid injection of the heel in recalcitrant plantar fasciitis. We would suggest that this applies to most treatments of plantar fasciitis currently in practice.
Notes
Correspondence to: D. Kane. E-mail: dk44a{at}clinmed.gla.ac.uk
References