The results of the study suggest that taping (combined with limited stretching) provides initial short term reduction of both pain and stiffness symptoms in people with PF when used with placebo or acetic acid iontophoresis. In terms of the ability to maintain these changes after an additional two weeks of no intervention, it is clear that this effect was maintained in the acetic acid group, whereas the greatest attenuation of relief—that is, return—of both pain and stiffness symptoms occurred in the placebo group.
The benefits of taping found in this study are consistent with research in which mechanical adaptations—that is, taping, orthoses—are prescribed.8,9
In the clinical setting, LowDye taping results in almost immediate changes in symptoms. It is proposed that, during this short term alleviation of symptoms, the adjunct management options have time to reach therapeutic thresholds.
Continuous taping, however, is difficult as patients become sensitive to the tape. This may lead to skin breakdown. In this study, the two weeks of taping resulted in about 23% of cases in which there were clinically noticeable changes to the skin by the end of the two weeks. This suggests that longer term use of taping may be problematic and any adjunct intervention that prolongs the treatment effect would be of great benefit.
The results for the dexamethasone/taping group showed a different pattern of response. Firstly, this group tended not to show the magnitude of improvement of the other two groups at the end of the initial treatment. Acetic acid produced significantly greater improvements in morning pain than dexamethasone. The change scores of the dexamethasone group failed to reach significance for the worst pain and residual stiffness scores unlike the other two groups.
Secondly, continued resolution of the pain during the no treatment period was only observed in the dexamethasone group. This was observed for all the assessments of pain.
It is unclear why, or if, the LowDye taping affected the effectiveness of the dexamethasone, as it would seem that this combination did not achieve the same early responses as the acetic acid/taping and placebo/taping alone.
Importantly, although the continued improvement in pain symptoms of the dexamethasone group during the no treatment period is clear, the group change scores provide no evidence that it outperformed acetic acid across either domain of pain or stiffness at any assessment point.
One aspect of interest was the different responses to pain and stiffness in the population tested in this study. The greatest clinical response of acetic acid/taping was the alleviation of morning stiffness where the sustained improvements in the dexamethasone group were noted only for pain. These findings may suggest that the symptoms of PF that reduce function are pain and stiffness, and there may be slight differences in the type of symptoms people experience. This may reflect subgroups within the PF population and therefore may have a prognostic value in the choice of intervention. Further research may suggest different combinations of interventions to target the primary symptomatic complaint.
What is already known on this topic
- Two studies have looked at iontophoresis of drugs for the treatment of plantar fasciitis; one is a randomised, placebo controlled trial using dexamethasone that shows good outcomes from this treatment
- The other is an uncontrolled clinical trial of acetic acid with outcomes that are perhaps better than that of dexamethasone
What this study adds
- This study shows that both drugs, when delivered via iontophoresis in combination with LowDye taping, give good short term relief, with acetic acid being at least as good as, if not better than, dexamethasone
- The benefits of taping are reduced when it is stopped; however, when it is combined with iontophoresis, treatment effects are maintained
The timeline of the intervention was relatively short and of a mixed (intervention) mode. Rapid change in the primary symptoms that restrict the activities of daily living was the basis for the research design. This reflects the current clinical practice of many treating physicians.