Department of Podiatry, Faculty of Health Sciences, La Trobe University, Melbourne, Victoria 3086, Australia.
Department of Podiatry, Faculty of Health Sciences, La Trobe University, Melbourne, Victoria 3086, Australia ; Lower Extremity and Gait Studies Program, Faculty of Health Sciences, La Trobe University, Melbourne, Victoria 3086, Australia.
J Foot Ankle Res. 2013 May 17;6:19. doi: 10.1186/1757-1146-6-19. eCollection 2013.
The effectiveness of foot orthoses has been evaluated in many clinical trials with sham foot orthoses used as the control intervention in at least 10 clinical trials. However, the mechanical effects and credibility of sham orthoses has been rarely quantified. This study aimed to: (i) compare the effects on plantar pressures of three sham foot orthoses to a customised foot orthosis, and (ii) establish the perceived credibility and the expected benefit of each orthotic condition.
Thirty adults aged between 18 and 51 participated in this study. At 0 and 4 weeks, plantar pressure data were collected for the heel, midfoot and forefoot using the pedar(®)-X in-shoe system for the following five randomly assigned conditions: (i) shoe alone, (ii) customised foot orthosis, (iii) contoured polyethylene sham foot orthosis, (iv) contoured EVA sham foot orthosis, and (v) flat EVA sham foot orthosis. At the initial data collection session, each participant completed a Credibility/Expectancy Questionnaire (CEQ) to determine the credibility and expected benefit of each orthotic condition.
Compared to the shoe alone at week 0, the contoured polyethylene sham orthosis was the only condition to not significantly effect peak pressure at any region of the foot. In contrast, the contoured EVA sham orthosis, the flat EVA sham orthosis and the customised orthosis significantly reduced peak pressure at the heel. At the medial midfoot, all sham orthoses provided the same effect as the shoe alone, which corresponded to effects that were significantly different to the customised orthosis. There were no differences in peak pressure between conditions at the other mask regions, the lateral midfoot and forefoot. When the conditions were compared at week 4, the differences between the conditions were generally similar to the findings observed at week 0. With respect to credibility and expected benefit, all orthotic conditions were considered the same with the exception of the contoured polyethylene sham orthosis, which was perceived as being less credible and less likely to provide benefits.
The findings of this study indicate that all of the sham orthoses tested provided the same effect on plantar pressures at the midfoot and forefoot as a shoe alone. However, the contoured EVA sham orthosis and the flat EVA sham orthosis significantly reduced peak pressure under the heel, which was similar to the customised orthosis. In contrast, the contoured polyethylene sham orthosis had no significant effect on plantar pressure and was comparable to the shoe alone at all regions of the foot. Hence, lower plantar pressures were found under the heel with some sham orthoses, but not with others. Importantly, participants perceived the polyethylene sham orthosis - the sham that had no effect on plantar pressure - to be the least credible orthosis and the least likely to provide benefits. This may be critical for the design of future clinical trials as it may introduce confounding effects that produce inaccurate results. These findings provide some evidence for the mechanical effects, treatment credibility and expected benefit of sham foot orthoses, which should be considered when they are used as a control intervention in a clinical trial.
已有多项临床试验采用假足矫形器作为对照干预措施来评估足部矫形器的有效性，其中至少有 10 项临床试验采用了假足矫形器。然而，假足矫形器的机械效应和可信度很少被量化。本研究旨在：（i）比较三种假足矫形器与定制足矫形器对足底压力的影响；（ii）确定每种矫形器条件的感知可信度和预期获益。
30 名年龄在 18 至 51 岁之间的成年人参与了这项研究。在 0 周和 4 周时，使用 pedar(®)-X 鞋内压力测量系统收集脚跟、中足和前足的足底压力数据，以下五个条件随机分配：（i）仅穿鞋子，（ii）定制足矫形器，（iii） 轮廓聚乙烯假足矫形器，（iv）轮廓乙烯-醋酸乙烯酯（EVA）假足矫形器，（v）平 EVA 假足矫形器。在初始数据收集阶段，每位参与者都完成了可信度/预期问卷（CEQ），以确定每种矫形器条件的可信度和预期获益。
与 0 周时仅穿鞋子相比，只有轮廓聚乙烯假足矫形器在足部任何区域的峰值压力都没有显著变化。相比之下，轮廓 EVA 假足矫形器、平 EVA 假足矫形器和定制矫形器都显著降低了脚跟的峰值压力。在内侧中足，所有假足矫形器的效果都与仅穿鞋子相同，这与定制矫形器的效果明显不同。在其他假足区域、中足外侧和前足，各条件之间的峰值压力没有差异。当在第 4 周比较这些条件时，与第 0 周观察到的结果相比，这些条件之间的差异通常相似。关于可信度和预期获益，除了轮廓聚乙烯假足矫形器之外，所有矫形器条件都被认为是相同的，因为它被认为可信度较低，不太可能提供获益。
本研究的结果表明，所有测试的假足矫形器在中足和前足的足底压力上都与仅穿鞋子一样有效。然而，轮廓 EVA 假足矫形器和平 EVA 假足矫形器显著降低了脚跟处的峰值压力，这与定制矫形器相似。相比之下，轮廓聚乙烯假足矫形器对足底压力没有显著影响，在足部所有区域与仅穿鞋子相当。因此，在一些假足矫形器下，脚跟处的足底压力降低，但在其他假足矫形器下没有。重要的是，参与者认为没有对足底压力产生影响的聚乙烯假足矫形器是最不可信的矫形器，也是最不可能提供获益的矫形器。这可能对未来临床试验的设计至关重要，因为它可能会引入产生不准确结果的混杂效应。这些发现为假足矫形器的机械效应、治疗可信度和预期获益提供了一些证据，在临床试验中使用假足矫形器作为对照干预措施时，应考虑这些证据。
