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Scientific Articles:
Benedict F. Digiovanni, Deborah A. Nawoczenski, Daniel P. Malay, Petra A. Graci, Taryn T. Williams, Gregory E. Wilding, and Judith F. Baumhauer
Plantar Fascia-Specific Stretching Exercise Improves Outcomes in Patients with Chronic Plantar Fasciitis. A Prospective Clinical Trial with Two-Year Follow-Up
J Bone Joint Surg Am 2006; 88: 1775-1781 [Abstract] [Full text] [PDF]
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[Read Letter to the Editor] Stretching for chronic plantar fasciitis: more evidence is needed.
Joel A. Radford, Karl B. Landorf, Senior Lecturer & Research Coordinator, Dept. of Podiatry, La Trobe University, AUSTRALIA   (23 October 2006)

Stretching for chronic plantar fasciitis: more evidence is needed. 23 October 2006
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Joel A. Radford,
PhD candidate
School of Biomedical & Health Sciences, University of Western Sydney, AUSTRALIA,
Karl B. Landorf, Senior Lecturer & Research Coordinator, Dept. of Podiatry, La Trobe University, AUSTRALIA

Send letter to journal:
Re: Stretching for chronic plantar fasciitis: more evidence is needed.

j.radford{at}uws.edu.au Joel A. Radford, et al.

EDITOR'S NOTE: The corresponding author of the article was invited to respond to this letter, but to date has not done so.

To The Editor:

We read with interest the two-year follow up by DiGiovanni et al. (1) comparing plantar fascia and Achilles tendon stretching for plantar fasciitis. We wish to congratulate the authors for attempting to evaluate the effectiveness of such treatments for a condition that has received little rigorous evaluation. However, unfortunately the trial update is plagued by a fundamental methodological flaw - the failure to include a placebo or control group for comparison. Accordingly, the conclusion from the trial that the “long-term benefits of the stretch include a marked decrease in pain and functional limitations and a high rate of satisfaction” is incorrect.

The importance of including a comparison group was highlighted by Buchbinder in her excellent evidence-based review(2). Long-term follow-up data from large case series revealed that the clinical course for most patients with plantar fasciitis is favourable, with resolution of symptoms in more than 80 percent of patients within 12 months. This is a vital factor that must be considered in trials evaluating interventions for plantar fasciitis. A more powerful example of this natural resolution can be found in the results of recent randomised trials that have included a control or placebo group. Such trials report large improvements in pain in control groups over the duration of the intervention period(3-6). Changes over time in a placebo or control group may be due to three important effects: (i) the natural resolution of the condition being studied, (ii) the placebo effect, and (iii) the Hawthorne effect. All can explain some of the magnitude of the effect of an intervention when used for plantar fasciitis.

Because DiGiovanni’s long term trial(1) did not compare those participants that were stretching to a control group, the authors cannot attribute the changes in symptoms to the stretches performed. As previously mentioned, such improvements may have been due to the natural progression of the disorder or to the placebo or Hawthorne effects. Indeed the long-term improvement may even have been a result of the orthotic therapy the participants were encouraged to continue using from the earlier trial(7).

In conclusion, researchers conducting plantar fasciitis intervention trials must include placebo or control groups (i.e. a group or groups to compare the intervention against) if they wish to conclude that an intervention is truly effective.

The author(s) of this letter to the editor did not receive payment or other benefits or a commitment or agreement to provide such benefits from a commercial entity. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, educational institution, or other charitable or nonprofit organization with which the author(s) are affiliated or associated.

References:

1. Digiovanni, B. F.; Nawoczenski, D. A.; Malay, D. P.; Graci, P.; Williams, T. T.; Wilding, G. E.; and Baumhauer, J. F.: Plantar fascia-specific stretching exercise improves outcomes in patients with chronic plantar fasciitis. A prospective clinical trial with two-year follow-up. Journal of Bone and Joint Surgery. American Volume, 88(8): 1775-1781, 2006.

2. Buchbinder, R.: Plantar fasciitis. New England Journal of Medicine, 350(21): 2159-2166, 2004.

3. Landorf, K. B.; Keenan, A.-M.; and Herbert, R. D.: Effectiveness of three foot orthoses for plantar fasciitis: a randomised trial. Archives of Internal Medicine, 166(12): 1305-1310, 2006.

4. Radford, J. A.; Landorf, K. B.; Buchbinder, R.; and Cook, C.: Effectiveness of low-Dye taping for the short-term treatment of plantar heel pain: a randomised trial. BMC Musculoskeletal Disorders, 7(1): 64, 2006.

5. Buchbinder, R.; Forbes, A.; and Ptasznik, R.: Shock wave therapy for treatment of plantar fasciitis. Journal of the American Medical Association, 289(2): 172-178, 2003.

6. Winemiller, M. H.; Billow, R. G.; Laskowski, E. R.; and Harmsen, W. S.: Effect of magnetic vs sham-magnetic insoles on plantar heel pain: A randomized controlled trial. Journal of the American Medical Association, 290(11): 1474-1478, 2003.

7. DiGiovanni, B. F.; Nawoczenski, D. A.; Lintal, M. E.; Moore, E. A.; Murray, J. C.; Wilding, G. E.; and Baumhauer, J. F.: Tissue-specific plantar fascia-stretching exercise enhances outcomes in patients with chronic heel pain. Journal of Bone and Joint Surgery. American Volume, 85(7): 1270-1277, 2003.