June 2014

Evidence-based use of metatarsal pads

cover-mainPlantar pressure analysis studies are demonstrating the effectiveness of met pads for forefoot offloading and helping clinicians determine which patients are most likely to benefit from different pad designs and placement strategies.

By Greg Gargiulo

Metatarsal pads, usually referred to simply as met pads, are commonly prescribed shoe modification devices used for relief of pressure on the metatarsal head.1 The met pad is typically employed to shift the load from the metatarsal head to the shaft of the metatarsal and surrounding tissue, decreasing the pressure at the met head and providing relief of symptoms in that area.1,2

“It’s all about the stress transfer, so what you’re trying to do is unload a certain spot on the foot—generally the met head with a met pad—and transfer it to a more proximal region,” said Michael Mueller, PT, PhD, division director of research in physical therapy at the Washington University School of Medicine in St. Louis, MO.

Met pads are commonly used as a simple and inexpensive conservative treatment for a number of conditions.3,4 These include metatarsalgia,1,5,6 diabetic peripheral neuropathy and related foot ulceration,2,7-9 rheumatoid arthritis,10 and pes planus,11 and the literature regarding their effectiveness is generally supportive.1,5,7,11

LER-Resource-Guide-Products-foot-pads

Met pads date back to at least the 1930s, when orthopedist Emil Hauser, MD, would hand-make longitudinal arch met pads out of surgical wool felt and apply them directly to patients’ shoes.12 Since then, increasing utilization of met pads has been accompanied by significant improvements, and a variety of designs are now available.13

Although the wide range of met pad designs offers more options for clinicians, the choices can also be overwhelming and make evidence-based clinical protocols difficult to establish. But, in certain patient populations, plantar pressure analysis studies have led to a better understanding of the optimal usage and placement of the pads.1,14

“I have used them in my practice for more than fifteen years with great success, but not all met pads are created equal, and not all met pads work for everybody, so it really is on a case-by-case basis that we have to evaluate our expected outcomes with respect to their use,” said Ryan Robinson, CPed, former president of the Pedorthic Association of Canada and current president of Walking Mobility Clinics in Ontario.

Photo courtesy of PediFix.

Photo courtesy of PediFix.

Metatarsalgia, or pain on the plantar aspect of the foot in the region of the met heads, is a common problem that usually arises when the pressure tolerance of the focal tissue under the met heads is exceeded.15-17 A 1982 study by Craxford et al found little difference in the outcomes of operative versus nonoperative treatment for metatarsalgia associated with rheumatoid arthritis, which supports the use of met pads as a conservative strategy for the condition.1,18

Studies evaluating met pads for metatarsalgia have been primarily positive. Kang et al found that applying met pads is an effective method for reducing pressure unloading under the met heads and relieving symptoms of metatarsalgia.5 Hsi et al showed not only that met pads decreased pressure, but that optimum pressure decrement is attained when peak pressures of the pad are just proximal to those of the met head.1

Given that the most common cause of diabetic plantar ulcers is excessive plantar pressure in the presence of sensory neuropathy and foot deformity,19 clinicians regularly use met pads to reduce forefoot pressures and skin breakdown in at-risk patients.

In studies of diabetic patients, met pads are often combined with insoles, again with success. Two studies found the combination of a met pad with a total contact insole (TCI) reduced pressures under the met heads, with the greatest reductions occurring when they were placed optimally (ie, with the distal aspect of the pad placed 6.1-10.6 mm proximal to a line identifying the met head).2,7

Photo courtesy of Dr. Jill's Foot Pads.

Photo courtesy of Dr. Jill’s Foot Pads.

Application of met pads for other conditions has also been studied, as two other investigations both found metatarsal domes to be the most effective forefoot pads for reducing peak plantar pressure when treating pes planus and forefoot pain in older adults, respectively.11,20

Although patient pathologies and characteristics may reveal some indications for effectiveness, a system for evidence-based prescription is still lacking. 10,11,20

“It’s a mechanical phenomenon: It’s going to help the person who has too much stress on their met heads, and that’s the clear indication regardless of any other overriding diagnosis,” Mueller said.

But, for Rob Sobel, CPed, vice president of the Pedorthic Footcare Association and owner of Sobel Orthotics & Shoes in New Paltz, NY, certain patient characteristics may play a part, while others do not.

“Age doesn’t seem to be all that relevant in my experience, but I would have to say it’s important to stay away from met pads when dealing with an extremely sensitive foot,” Sobel said. “In those cases the patient may not be able to get used to the pad and other modalities may need to be utilized, like a metatarsal bar on the bottom of the orthotic or the shoe, which I prefer not to utilize as it might present a fall risk.”

Additional research may be needed to better define which patients are most likely to benefit from met pads, but pad design has been studied in slightly more depth. Some pads are molded into a prescription insole, while others are separate prefabricated devices manufactured from a variety of materials—including felt,21 polyurethane foam,5 silicone,8 cork,2 and latex foam10—in various shapes and sizes.10

“The prescription of forefoot pads should depend on the condition being treated,” said Karl Landorf, PhD, a senior lecturer and research coordinator in the Podiatry Department at La Trobe University in Melbourne, Australia. “For example, a patient with rheumatoid arthritis with widespread synovitis of the metatarsophalangeal joints may require different forefoot padding than someone with generalized metatarsalgia under the middle metatarsal heads.”

Photo courtesy of Hapad

Photo courtesy of Hapad

Nordsiden et al evaluated three different met pad shapes made of self-adhesive orthopedic felt—met dome, a U-shaped pad, and a donut-shaped pad—in pes planus patients while running. Researchers found met domes were the most effective option for reducing both peak and mean plantar pressures, while the U-shaped pad was close behind; the donut-shaped pad did not result in any significant changes in plantar pressures. In addition, 70% of patients said the met dome was the most comfortable of the three; however, researchers cautioned that practitioners must consider other factors, such as location and intensity of pain, shoe type, and comfort and materials of the pad, when choosing or constructing the proper pad.11

Jackson et al also found that 70% of patients preferred the insole with the dome pad design over the bar pad design, despite the fact that the bar pad is more effective for reducing mean peak pressure and therefore recommended as the first line of treatment by researchers.10

Another study by Symeonidis et al compared prefabricated met pads (made of urethane foam) to met bars (external shoe modifications made of high-density rubber) in healthy volunteers.22 They found both significantly reduced impulse under the second metatarsal head compared with shoes only, though the reduction with met bars was significantly greater than with met pads.

In contrast, Landorf et al20 found that, in older people with forefoot pain, a met dome (made of PPT) positioned 5 mm distal to the metatarsal head was associated with significantly more plantar pressure reduction than either a met bar or a met dome positioned 10 mm distal. However, researchers warn that these results are difficult to compare with other studies due to differences in their protocol for pad placement and older patient population.20

Based on his findings, which he considers robust, Landorf said: “Patients with relatively uncomplicated forefoot pain will generally benefit the most from a met dome. In particular, anyone with pain under the middle metatarsal heads, and that includes both younger and older adults.”

Photo courtesy of Powerstep.

Photo courtesy of Powerstep.

Although it seems met domes may fare better overall than other designs, it’s still difficult to reach any definitive conclusions on the most effective shape or material for met pads based on the literature.10,11,20

“I don’t think there’s a whole lot of evidence on the particular shape, but clinically and intuitively, it absolutely has to have a beveled edge shape distally to allow the stress gradient to be smooth,” Mueller said. “Then I think the key thing is the stiffness of the material has to be greater than the soft tissue of the foot,
because you’re trying to transfer the stress off the met heads to the soft tissues, so you need compression of the soft tissues from the met pads.”

More work is needed to further investigate the role of shape and material, but current research clarifies the essential role of proper met pad placement, which some believe may be more important than the design itself.1,2,4,20,21

“I would say that the placement is the most important thing in regard to getting a positive or negative response,” Mueller said.

Hastings et al placed a fabricated cork met pad at various locations on the foot, all of which covered the three central metatarsals, and found that the ideal placement distance for the most consistent pressure reductions is 6.1 to 10.6 mm proximal to a line identifying the met head.2 Hsi et al also found that foam rubber met pads led to the greatest pressure reductions when placed just proximal to the peak pressure of the met head, and consider it to be the optimum positioning for pressure relief.1

Landorf et al20 found that distal positioning of a met pad effectively relieved forefoot plantar pressure, and Hayda et al21 determined that felt pads placed 5 mm distal to the met heads resulted in greater decreases in pressure than pads positioned 5 mm proximally. But most authors currently agree that the optimal position for met pads is in line with the Hsi recommendations.5,11,22

Despite all the evidence, though, some clinicians still experience difficulty placing met pads in the intended position, while others may avoid them entirely due to lack of awareness or concerns about initial patient discomfort.2,23 Improper placement may also partially account for the variability of patient responses in some studies.1,2,7

“Since it takes time and effort to educate patients about the possibility of met pad intolerance and how to deal with it, and it takes effort to have patients come back if there are any problems, practitioners often just avoid the problem altogether,” said Robert Ferrari, MD, clinical professor in the Department of Medicine at the University of Alberta Hospital in Edmonton, Canada.

To evaluate intolerance, Ferrari monitored 60 patients with nonspecific low back pain who wore customized foot orthoses with large met pads for six weeks, informing them of possible initial discomfort in the first week. After necessary adjustments were made, nearly all patients eventually tolerated the pads; only one still reported pain or discomfort at the conclusion of the study.23

“If every practitioner simply tells the patient in advance that initial discomfort is normal, that the orthotics must be worn in, and to return if there are any concerns, this problem of met pad intolerance could be dealt with,” Ferrari said.

For some clinicians, it’s always a work in progress and a matter of making necessary changes for each patient based on his or her personal response.

“You have to accept that you may need to adjust,” Robinson said. “Your modifications and adjustments are part of the game when dealing with met pads, and sometimes you need to rip them off and try something different for the best fit.”

George Holmes Jr, MD, an associate professor and director of the Foot & Ankle Section at Rush University Medical Center in Chicago, believes in putting control in patients’ hands.

“I think if they’re given just a few directions and a few key pointers, then from that point on, they can take care of the pads themselves, and they don’t need me or one of my assistants to help them with the placement again,” he said.

One way to monitor proper met pad positioning and assess effectiveness is by using real-time plantar pressure measurements before and after placement.5

“I find that there is nothing on the market that will help you to evaluate the success or failure of a custom foot orthotic like in-shoe pressure evaluation,” said Bruce Williams, DPM, director of the gait lab at Weil Foot & Ankle Institute in Chicago and founder of Breakthrough Podiatry in Merrill­ville, IN. “With the use of the system I can immediately get quantitative feedback on the function of the foot orthotics and the patient’s reaction to them.”

Numerous studies highlight the value of pressure measurement systems in determining plantar pressure changes; however, their usage in the clinical setting is limited by their cost.2,5,7,8,11,20

“In-shoe plantar pressure measurement systems are very useful, but they are still generally too expensive for most clinicians to own in their practice,” Landorf said.

Met pads represent just one of many types of orthotic modification devices currently available. A number of studies have evaluated met pads either in conjunction with or independently against TCIs and other orthoses, and the results have been mixed as to whether adding met pads to an orthosis is associated with an added benefit. 2,7-9,24

To some clinicians, the distinction is irrelevant.

“I use a combination of functional and accommodative devices and, in my opinion, there is little to differentiate them,” Williams said. “There is also very little literature regarding the use of metatarsal pads with orthotics.”

Others see a strong potential for met pads and other orthotic devices if they are judiciously combined.

“I do think that it’s optimal to have some kind of a TCI first, since you can increase the contact area of the entire foot fairly easily and will get substantial pressure relief,” Mueller said. “Placing the met pad gives you additional benefit, but that’s a little trickier, since you have to get it placed optimally.”

Many questions about met pads remain unanswered.

Which met pad materials are most effective for offloading? What patient characteristics—other than hypersensitivity and a few select conditions—will help determine if they are good candidates? Should met pads be used instead of or in conjunction with other orthotic devices?1,2,7,21

“It is clear that we now need to take our mechanism-based understanding of these pads [ie, that they can reduce peak pressure under the forefoot] and back these findings up with randomized trials that evaluate patient-reported outcomes, including comfort,” Landorf said. “Patients with forefoot pain, clinicians, and policymakers will benefit greatly from this additional evidence.”

In addition, though met pads appear to be a key ingredient, they are really just one piece of the puzzle that must be considered in the context of the bigger picture.

“It’s one part of a comprehensive intervention that needs to happen,” Mueller said. “I don’t think there’s going to be any magic bullet from a footwear standpoint; the footwear and the met pad are a piece of the treatment, but it’s really important to approach the patient as a whole and approach the whole problem. So I think we need more research on how to make the most effective orthotic device, but also how to get patients to wear them.”

Greg Gargiulo is a freelance medical writer based in the San Francisco Bay Area.

REFERENCES
  1. Hsi WL, Kang JH, Lee XX. Optimum position of metatarsal pad in metatarsalgia for pressure relief. Am J Phys Med Rehabil 2005;84(7):514-520.
  2. Hastings MK, Mueller MJ, Pilgram TK, et al. Effect of metatarsal pad placement on plantar pressure in people with diabetes mellitus and peripheral neuropathy. Foot Ankle Int 2007;28(1):84-88.
  3. Hunter S, Dolan M, Davis M. Foot orthotics in therapy and sports. Champaign, Il: Human Kinetics; 1996.
  4. Holmes GB Jr, Timmerman L. A quantitative assessment of the effect of metatarsal pads in plantar pressures. Foot Ankle 1990;11(3):141-145.
  5. Kang JH, Chen MD, Chen SC, Hsi WL. Correlations between subjective treatment responses and plantar pressure parameters of metatarsal pad treatment in metatarsalgia: a prospective study. BMC Musculoskelet Disord 2006;7:95.
  6. Koenraadt KL, Stolwijk NM, van den Wildenberg D, et al. Effect of metatarsal pad on the forefoot during gait. J Am Podiatr Med Assoc 2012;102(1):18-24.
  7. Mueller MJ, Lott DJ, Hastings MK, et al. Efficacy and mechanism of orthotic devices to unload metatarsal heads in people with diabetes and history of plantar ulcers. Phys Ther 2006;86(6):833-842.
  8. Ibrahim M, El Hilaly R, Taher M, Morsy A. A pilot study to assess the effectiveness of orthotic insoles on the reduction of plantar soft tissue strain. Clin Biomech 2013;28(1):68-72.
  9. Ashry HR, Lavery LA, Murdoch DP, et al. Effectiveness of diabetic insoles to reduce foot pressures. J Foot Ankle Surg 1997;36(4):268-271.
  10. Jackson L, Binning J, Potter J. Plantar pressures in rheumatoid arthritis using prefabricated metatarsal padding. J Am Podiatr Med Assoc 2004;94(3):239-245.
  11. Nordsiden L, Van Lunen BL, Walker ML, et al. The effect of 3 foot pads on plantar pressure of pes planus foot type. J Sport Rehabil 2010;19(1):71-85.
  12. Hauser EDW. Diseases of the foot. W.B. Saunders Company: Philadelphia, PA; 1941: 311-314.
  13. Curran M. Mechanical therapeutics in the clinic. Clinical Skills in Treating the Foot. 2nd edition. Edinburgh: Elsevier Churchill Livingstone; 2005: 231-264
  14. Pratt DJ. A critical review of the literature on foot orthoses. J Am Podiatr Med Assoc 2000;90(7):339-341.
  15. Fann AV. Metatarsalgia. In Frontera WR, Silver JK, eds. Essentials of Physical Medicine and Rehabilitation. Philadelphia, PA: Hanley and Belfus; 2002: 435-438.
  16. Wu KK. Morton neuroma and metatarsalgia. Curr Opin Rheumatol 2000;12(2):131-142.
  17. Scranton PE. Metatarsalgia: diagnosis and treatment. J Bone Joint Surg Am 1980;62(5):723-732.
  18. Craxford AD, Stevens J, Park C. Management of the deformed rheumatoid forefoot: a comparison of conservative and surgical methods. Clin Orthop Relat Res 1982;(166):121-126.
  19. Boulton AJ, Hardisty CA, Betts RP, et al. Dynamic foot pressure and other studies as diagnostic and management aids in diabetic neuropathy. Diabetes Care 1983;6(1):26-33.
  20. Landorf KB, Lee PY, Bonanno DR, Menz HB. Comparison of the pressure-relieving properties of various types of forefoot pads in older people with forefoot pain. Foot Ankle Res 2014;7(1):18.
  21. Hayda R, Tremaine MD, Tremaine K, et al. Effect of metatarsal pads and their positioning: a quantitative assessment. Foot Ankle Int 1994;15(10):561-566.
  22. Symeonidis PD, Deshaies A, Roy P, et al. Metatarsal bars more effective than metatarsal pads in reducing impulse on the second metatarsal head. Foot 2011;21(4):172-175.
  23. Ferrari R. Report of metatarsal pad intolerance in a cohort of 60 patients treated with customized foot orthotics. J Chiropr Med 2011;10(1):25-28.
  24. de Morais Barbosa C, Barros Bértolo M, Marques Neto JF, et al. The effect of foot orthoses on balance, foot pain and disability in elderly women with osteoporosis: a randomized clinical trial. Rheumatology 2013;52(3):515-522.
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3 Responses to Evidence-based use of metatarsal pads

  1. Teri Green says:

    Great article on the benefits of metatarsal pads. We have been using metatarsal pads as our number one treatment option for all patients with Morton’s neuroma. It makes a huge difference when the metatarsal pad off loads the met heads and allows the nerve to not be pinched. Thanks again for a great article.

    Teri Green
    Atlas Biomechanics

  2. Keith Rome says:

    This is an excellent resource for podiatric students. We try to endorse an evidence based approach within our curriculum. Thanks again for a great article

  3. Jordana Bieze Foster says:

    Thanks for the positive feedback. We really appreciate it!

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