Do Prefab Orthoses Have A Place In Treating Plantar Fasciitis?
The world of orthotic therapy and foot biomechanics was somewhat shaken in 2006 when a randomized study found that “customized and prefabricated orthoses used in the trial (had) similar effectiveness in the treatment of plantar fasciitis.”1 Of course, there was a great deal more to this study than the one sentence but it sure stimulated discussion within podiatry and orthopedic surgery concerning the value of custom orthoses in comparison to prefabricated devices.
There are actually four relatively recent trials that compare prefabricated and custom orthoses relative to plantar fasciitis.1-4 It is quite exasperating to experience the huge difference between the successes of custom orthotics versus prefab in clinical practice and then look at the research statistical analysis, which demonstrates a minor difference between the two devices. What could contribute to this dichotomy? Is there a similar positive effect in other pathologies like hallux limitus, over-pronation, adult-acquired flatfoot, neuroma and various sports medicine injuries?
Unfortunately, the studies and data that compare custom foot orthoses (CFOs) to prefabricated foot orthoses (PFOs) are insufficient to draw any legitimate medical conclusion. The research is even more difficult to interpret due to several factors including:
• the variety of casting;
• various imaging and manufacturing techniques for custom orthoses;
• an almost infinite variety of prefabricated devices that are used in these studies; and
• the large selection of materials, shapes and flexibilities of the prefabricated devices.
Accordingly, let us take a closer look at the available literature that evaluates the effect of various prefabricated orthoses on certain foot pathologies. Then we will consider the anecdotal evidence, logical deductions and opinions that might give the clinician some criteria to use when considering the use of prefabricated orthoses. Lastly, we will consider recommendations and opinions in regard to indications, contraindications and desirable characteristics for prefabricated orthoses use, specifically when it comes to plantar fasciitis.
Discussing prefabricated orthoses becomes very complicated because of terminology. What is the difference between an arch support and a prefabricated foot orthosis? Are soft PFOs in the same category and do they have the same indications as semi-rigid devices? How do we separate accommodative PFOs from functional PFO devices?
While an in-depth discussion of soft prefabricated devices is outside of the scope of this article, these soft devices do have a place in patient care, especially when it comes to lowering pressure peaks and helping to avoid potential problems in the diabetic foot. In regard to accommodative versus functional devices, an accommodative PFO is not designed to change the morphology of the weightbearing foot but rather to alter the pressures under the foot without intentionally altering the motion of the foot. A functional device is designed to alter the motion and morphology of the foot by changing either the ground reactive force under the foot or the progression of the center of pressure plot through the foot.
What The Literature Reveals
A study performed at the University of Teesside in England compared the effectiveness and cost of accommodative prefabricated devices to functional prefabricated devices.5 The researchers found the functional semi-rigid prefabricated devices more effective than the soft accommodative PFOs but both were effective to some degree. The authors of the paper intended to consider whether the difference in cost might be important since the more expensive devices were more effective. Interestingly, study participants who wore the less expensive ($12) PFOs had a 69 percent attrition rate from the study, whereas those who wore the more expensive ($45) PFOs had a very low attrition rate in comparison to similar studies. The more expensive device was actually more cost effective.