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Kane and colleagues rightly emphasise the increasing importance of diagnostic ultrasound in rheumatological practice.1 New equipment with small transducers and greatly magnified images, albeit more expensive, make the case for its routine use in clinics stronger all the time. As Kane points out, plantar fasciitis is an excellent example of this, both for diagnosis and ensuring correct placement of injection therapy. We entirely agree that it is altogether better than using bone scintigraphy in this condition.
As Kane et al suggest, plantar fasciitis can be difficult to treat. They claim that clinical results are improved by using an ultrasound guided injection. Even accounting for the sample size, their results are difficult to interpret. For the majority of patients appropriate advice on footwear, weight reduction, stretching exercises, non-steroidal anti-inflammatory drugs, and insoles are successful. In addition night splints may offer 59 to 88% success without injection.2 3 It is not clear whether all or some of these were used before patients were termed “recalcitrant”. Were they used at or after ultrasound guided injection? Finally the dose of triamcinolone used when guided by ultrasound was twice that used before and in twice the volume of lignocaine. These factors make it difficult to interpret the “improved response” suggested by this open study.
As the authors conclude, a properly controlled randomised study is needed to clarify the patients that require injecting and when. It should be remembered that corticosteroid injection is not without risk (particularly triamcinolone). Significant side effects such as fat pad atrophy, plantar fascia rupture, and osteomyelitis of the calcaneus may occur. Furthermore a prospective randomised study found no significant difference between corticosteroid and lignocaine injection or lignocaine alone.4
Drs Quinn and Gough make a number of valid points concerning ultrasound, corticosteroid injection of the heel and plantar fasciitis. The development of portable ultrasound machines with 7.5–12.5 MHz transducer frequency and improved image processing and quality is an exciting new development in rheumatology. Our report was intended to highlight a potential application of this new technology and to outline the advantages ultrasonography might offer over bone scintigraphy in guided injection of the heel and other regions. In our report we freely accepted the criticisms that the numbers are small and that the study was open. Over the past 18 months we have been trying to resolve this by prospectively randomising patients with plantar fasciitis to a trial of ultrasound guided injection as compared with palpation guided injection.
We agree that in the majority of patients conservative measures will lead to a satisfactory outcome.1-1 Despite this many patients are still undergoing surgery for plantar fasciitis.1-2 1-3 Night splinting, corticosteroid injection, radiofrequency neurolysis, dexamethasone iontophoresis, open and endoscopic plantar fasciotomy, and surgical neurolysis have all been reported as having variable success in chronic plantar fasciitis. It is difficult to compare these reports as patient selection and measures of outcome vary. We agree that night splints are very effective but they require fitting and good patient compliance for at least 4 to 8 weeks. We believe that corticosteroid injection also has a role in the management of plantar fasciitis that is unresponsive to conservative treatment and that it produces a more rapid amelioration of symptoms than splinting. The patients in our report fall into this category and were all recalcitrant to orthotics, non-steroidal anti-inflammatory drugs, stretching exercises, and palpation guided injection.
The prospective randomised trial of hydrocortisone acetate and lignocaine versus lignocaine alone, which is referred to, did show a greater rate of cure in patients who received hydrocortisone (10 of 13 v 5 of 9), though this did not reach statistical significance. In a retrospective study of 411 patients with plantar fasciitis corticosteroid injection was regarded by patients as a highly effective treatment.1-4 In addition scintigraphic guided injection produced an 80% cure rate in patients with recalcitrant plantar fasciitis.1-5 As we have stated in our report a properly controlled randomised study is required to establish the exact role of corticosteroid injection in plantar fasciitis.