New Study Discredits Custom Foot Orthotics

There has been a lot of chatter on podiatric websites regarding a recent study published by Rasenberg and coworkers in the British Journal of Sports Medicine (BJSM), which evaluated the efficacy of foot orthoses to treat plantar heel pain.¹ This systematic review of 20 studies of treatment of plantar heel pain showed no superiority of custom orthotic therapy after a meta-analysis of the data.

This week, Med Page Today, a popular website read by those in multiple medical specialties, featured an article and podcast reviewing this recent study.² Here is a key quote from the discussion that appears on this site:

What's at issue is, should we use custom orthotics, which are really expensive and often require a foot impression and so forth, in order to manage (plantar fasciitis)? Is that really helpful? This is a meta-analysis. They took a look at high-quality studies; eight different types of foot orthoses were included in this review. The upshot is they took a look at all of them and said, "Hey, folks. Guess what? Yeah, it's not really that helpful. Save your money."

If a podcast from a respected medical school comes up with such a biased conclusion about a published study, how will third-party insurance payors react?

The conclusions from this BJSM study are not new.¹ However, the methodology of comparing outcomes of treatment with different forms of foot orthotic therapy with other standard interventions using meta-analysis is noteworthy. The authors selected 20 previously published studies for a meta-analysis to see if there was any advantage of foot orthotic therapy over other interventions such as stretching, night splints, physical therapy and corticosteroid injection. The study found all forms of foot orthoses, both custom and prefabricated, provided no additional benefit compared to other interventions in the treatment of plantar heel pain.

I have written previously on this dilemma of published research on foot orthotic therapy, which conflicts with our own day-to-day experience in the clinical setting.³ In particular, I reviewed three prospective randomized clinical trials and essentially came up with the same findings that custom foot orthoses provide no benefit in comparison to prefab and sham devices.^3-6 I also reviewed other studies that showed favorable treatment effects with custom foot orthoses.^3,7-10

All of the studies I discussed in my Podiatry Today article were included in the systematic review conducted by Rasenberg and coworkers in their BJSM article. In fact, out of the 20 studies that were included and had meta-analysis, the majority showed favorable outcomes treating plantar heel pain with various types of foot orthotic devices. There were more studies showing favorable outcomes than not favorable. Thus, one would expect the analysis to show an overall benefit for using foot orthoses to treat plantar heel pain.

Keep in mind that this systematic review and meta-analysis compared treatment outcomes among many standard interventions and did not rate the individual performance of foot orthotic therapy by itself.¹ The goal of the study was to determine if foot orthoses were “superior” to these other interventions rather than measuring the true effectiveness of orthotic therapy alone. When comparing the different interventions with statistical analysis, the researchers pool the data from several studies and look for any significant advantage of one treatment in comparison to another. Therefore, if the statistical power of the “not superior effect” foot orthotic studies is greater than the statistical power of the “superior effect” foot orthotic studies, the overall result will reveal a “not superior” result of a meta-analysis of the pooled data. This is exactly what happened in the study published by Rasenberg and colleagues.

This statistical phenomenon was exhibited in a study by Ferber and colleagues, who evaluated the changes in plantar fascia strain when a foot orthosis was custom molded versus not molded.¹¹ In this kinematic study, over half of the patients showed reduced strain in the plantar fascia when the foot orthosis was heat molded to their foot. However, when researchers added the remaining patients who did not show reduced strain to the data, the overall statistical analysis showed no improvement or overall reduced plantar fascia strain with custom molding of the device.

Another shortcoming of many of these randomized clinical trials is the failure to identify and recognize that certain patients do benefit from custom orthotic therapy while others do not. None of these studies in the BJSM publication evaluated those patients who improved with custom foot orthotic therapy as a subgroup and compared them to the group who did not improve.

These are valid questions to ask when looking at the data from the Pfeffer, Landorf and Wrobel studies, all of which showed no superiority of custom foot orthoses.^4–6 Among these questions: How many patients actually improved with custom foot orthotic therapy? What was unique about those patients in comparison to the other patients who did not improve?

We see this same trend in clinical practice when some patients respond to certain therapies for plantar heel pain while others do not. Is this because there are unique characteristics or foot types that respond differently, or is it because there are various pathologies that cause plantar heel pain?

In the meantime, we are reminded that we conduct our own “clinical trials” in our daily practices and rely on therapies that work best in our own hands. We should never abandon the power of foot orthotic therapy if it provides cost-effective, reliable positive outcomes that we witness firsthand on a regular basis.

References

1. Rasenberg N, Riel H, Rathleff MS, Bierma-Zeinstra SMA, van Middelkoop M. Efficacy of foot orthoses for the treatment of plantar heel pain: a systematic review and meta-analysis. Br J Sports Med. 2018; epub March 19.

2. Lange R, Tracey E. Orthotics and heel pain; bacteria and cancer. Med Page Today. Available at   https://www.medpagetoday.com/orthopedics/orthopedics/71975 . Published March 24, 2018.

3. Richie D. Orthoses for plantar fasciitis: what the evidence reveals. Podiatry Today. 2015; 28(11):40–50.

4. Landorf KB, Keenan AM, Herbert RD. Effectiveness of foot orthoses to treat plantar fasciitis: a randomized trial. Arch Intern Med. 2006; 166(12):1305–1310.

5. Wrobel JS, Fleischer AE, Crews RT, Jarrett B, Najafi B. A randomized controlled trial of custom foot orthoses for the treatment of plantar heel pain. J Am Podiatr Med Assoc. 2015; 105(4):281-94.

6. Pfeffer G, Bacchetti P, Deland J, et al. Comparison of custom and prefabricated orthoses in the initial treatment of proximal plantar fasciitis. Foot Ankle Int. 1999; 20(4):214-21.

7. Turlik MA, Donatelli TJ, Veremis MG. A comparison of shoe inserts in relieving mechanical heel pain. Foot. 1999; 9(1):84.

8. Martin JE, Hosch JC, Goforth WP, et al. Mechanical treatment of plantar fasciitis: a prospective study. J Am Podiatr Med Assoc. 2001; 91(2):55-62.

9. Rome K, Gray J, Stewart F, et al. Evaluating the clinical effectiveness and cost-effectiveness of foot orthoses in the treatment of plantar heel pain: a feasibility study. J Am Podiatr Med Assoc. 2004; 94(3):229–238.

10. Roos E, Engstrom M, Soderberg B. Foot orthoses for the treatment of plantar fasciitis. Foot Ankle Int. 2006; 27(8):606–611.

11. Ferber R, Benson B. Changes in multi-segment foot biomechanics with a heat-moldable semi-custom foot orthotic device. J Foot Ankle Res. 2011; 4(1):18.