We appreciate the trial performed by McMillan and colleagues, that was published in May 2012 (1), for the nicely performed randomized trial. The authors conclude that an injection with dexamethasone is safe, and effective for the short term treatment of plantar fasciitis. However, after reading the author’s conclusion some questions remained.
The authors state in the limitations section that a factor that limits the generalizability of the results, is the large proportion of men in the patient group. However, we think that other patient characteristics are also limiting the generalizability of the results. For instance, the studied population had an average BMI of 31 and a relatively long duration of complaints. Therefore, one should take into account that the group of patients examined in this study is a specific group of patients, and does not represent the young and active group of patients in which plantar fasciitis also often occurs.
In addition, one of the inclusion criteria was a minimum thickness of the plantar fascia of 4.0 mm. The authors conclude that the treatment significantly reduces abnormal swelling after four weeks. However, after 12 weeks of follow-up none of the participants had a fascia thickness of 4.0 mm or less and the mean decrease was only 0.93 mm. The authors do however suggest that a dexamethasone injection decreases the fascia thickness. The differences found might be the result of a measurement error and do not seem to be clinically relevant.
Finally, as stated in the first part of discussion, no clinical relevant difference was found for pain relief. Consequently, the authors dichotomized the pain data, and choose for the cut-off point of 19.5. Unfortunately, the chosen cut-off point is not further explained. According to this cut-off value the number needed to treat was 2.93. The conclusion of the authors that treatment with dexamethasone is effective in the short term treatment of fasciitis plantaris is based on this finding. However, in the protocol(2), a difference of 13 points was described as clinically relevant only a difference of 11 points was found in the current study.
Therefore, we believe that this additional information is necessary to interpret the conclusion in a right way.
1. McMillan AM, Landorf KB, Gilheany MF, Bird AR, Morrow AD, Menz HB. Ultrasound guided corticosteroid injection for plantar fasciitis: randomised controlled trial. BMJ 2012;344:e3260.
2. McMillan AM, Landorf KB, Gilheany MF, Bird AR, Morrow AD, Menz HB. Ultrasound guided injection of dexamethasone versus placebo for treatment of plantar fasciitis: protocol for a randomised controlled trial. J Foot Ankle Res 2010;3:15.
Rapid Response:
Re: Ultrasound guided corticosteroid injection for plantar fasciitis: randomised controlled trial
We appreciate the trial performed by McMillan and colleagues, that was published in May 2012 (1), for the nicely performed randomized trial. The authors conclude that an injection with dexamethasone is safe, and effective for the short term treatment of plantar fasciitis. However, after reading the author’s conclusion some questions remained.
The authors state in the limitations section that a factor that limits the generalizability of the results, is the large proportion of men in the patient group. However, we think that other patient characteristics are also limiting the generalizability of the results. For instance, the studied population had an average BMI of 31 and a relatively long duration of complaints. Therefore, one should take into account that the group of patients examined in this study is a specific group of patients, and does not represent the young and active group of patients in which plantar fasciitis also often occurs.
In addition, one of the inclusion criteria was a minimum thickness of the plantar fascia of 4.0 mm. The authors conclude that the treatment significantly reduces abnormal swelling after four weeks. However, after 12 weeks of follow-up none of the participants had a fascia thickness of 4.0 mm or less and the mean decrease was only 0.93 mm. The authors do however suggest that a dexamethasone injection decreases the fascia thickness. The differences found might be the result of a measurement error and do not seem to be clinically relevant.
Finally, as stated in the first part of discussion, no clinical relevant difference was found for pain relief. Consequently, the authors dichotomized the pain data, and choose for the cut-off point of 19.5. Unfortunately, the chosen cut-off point is not further explained. According to this cut-off value the number needed to treat was 2.93. The conclusion of the authors that treatment with dexamethasone is effective in the short term treatment of fasciitis plantaris is based on this finding. However, in the protocol(2), a difference of 13 points was described as clinically relevant only a difference of 11 points was found in the current study.
Therefore, we believe that this additional information is necessary to interpret the conclusion in a right way.
1. McMillan AM, Landorf KB, Gilheany MF, Bird AR, Morrow AD, Menz HB. Ultrasound guided corticosteroid injection for plantar fasciitis: randomised controlled trial. BMJ 2012;344:e3260.
2. McMillan AM, Landorf KB, Gilheany MF, Bird AR, Morrow AD, Menz HB. Ultrasound guided injection of dexamethasone versus placebo for treatment of plantar fasciitis: protocol for a randomised controlled trial. J Foot Ankle Res 2010;3:15.
Competing interests: No competing interests