Evidence-Based Use of Metatarsal Pads | Lower Extremities Review Magazine (2023)

Plantar pressure analysis studies demonstrate the effectiveness of Met pads for forefoot relief and help clinicians determine which patients are most likely to benefit from different pad designs and placement strategies.

Von Greg Gargiulo

Metatarsal pads, commonly referred to simply as metatarsal pads, are commonly prescribed shoe modification devices used to relieve pressure on the metatarsal head.¹The metatarsal pad is typically used to shift load from the metatarsal head to the metatarsal shaft and surrounding tissues, reducing pressure on the metatarsal head and relieving symptoms in that area.^1,2

"It's all about transferring stress, so try picking up a specific point on the foot, usually the ball of the foot, with one paw and trying to transfer it to a more proximal region," said Michael Mueller, PT., PhD, chief from the physical therapy research department 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 variety of conditions.^3,4These include metatarsalgia,^1,5,6diabetic peripheral neuropathy and associated foot ulcers,^2,7-9Rheumatoid arthritis,¹⁰and flat foot,¹¹and the literature on its effectiveness is generally favorable.^1,5,7,11

Met pads date back to at least the 1930s, when orthopedist Dr. physician Emil Hauser made long, curved Met pads from surgical wool felt by hand and applied them directly to patients' shoes.¹²Since then, the increased use of metal inserts has been accompanied by significant improvements, and several designs are now available.¹³

While the wide variety of Met Pad designs offer more options for clinicians, the options can also be overwhelming and make it difficult to create evidence-based clinical protocols. However, in certain patient populations, studies looking at plantar pressure have led to a better understanding of optimal electrode use and placement.^1,14

"I've been using it in my practice for over fifteen years with great success, but not all metal patches are created equal and not all metal patches are right for everyone, so we really have to do a case-by-case assessment of our expected results regarding its use," said Ryan Robinson, CPed, former president of the Pedorthic Association of Canada and current president of Walking Mobility Clinics in Ontario.

Metatarsalgia, or pain on the plantar side of the foot in the area of ​​the metal heads, is a common problem that often occurs when the pressure tolerance of the focal tissue under the metal heads is exceeded.^15-17A study by Craxford et al. of 1982 found little difference in the results of surgical versus non-surgical treatment of metatarsalgia associated with rheumatoid arthritis, supporting the use of Met pads as a conservative strategy for the condition.^1,18

Studies evaluating Met pads for metatarsalgia were mostly positive. Kan et al. found that the application of metal pads is an effective method of reducing pressure discharge under metal heads and relieving symptoms of metatarsalgia.⁵Hsi et al. showed not only that the metal pads reduced pressure, but also that optimal pressure reduction is achieved when the peak pressures of the pads are close to those of the metal head.¹

Since the most common cause of diabetic plantar ulcers is excessive plantar pressure in the presence of sensory neuropathy and foot deformity,¹⁹Methamphetamine pads are regularly used by physicians to reduce forefoot pressure and skin damage in at-risk patients.

Met pads are often combined with pads in studies with diabetics, again with success. Two studies found that combining a Met pad with a full contact insole (TCI) reduced pressure under Met heads, with the greatest reductions occurring with optimal placement (i.e., when the distal aspect of the pad was 6.1 -10, placed 6 mm proximal). 🇧🇷 to a line that identifies the head of the Met).^2,7

The use of Met Pads for other conditions was also explored, as two additional studies found that metatarsal shells are the most effective forefoot pads for reducing peak plantar pressure in the treatment of flat feet and forefoot pain, respectively, in older adults. old.^11,20

Although pathologies and patient characteristics may provide some clues to efficacy, an evidence-based prescribing system is still lacking.^10,11,20

"It's a mechanical phenomenon - it's going to help the person who has a lot of stress in their head, and that's the clear clue, regardless of other prevailing diagnoses," 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 matter and others may not.

"Age doesn't seem to be as relevant in my experience, but I have to say that when you're dealing with an extremely sensitive foot, it's important to stay away from metal pads," Sobel said. “In these cases, the patient may not be able to get used to the pad and other modalities need to be used, as a problem. Fall hazard."

More research may be needed to better define which patients are most likely to benefit from metabolic pads, but pad design has been studied in a little more depth. Some pods are molded from a recipe template, while others are separate pre-made devices made from a variety of materials including felt,²¹Polyurethane foam,⁵silicone,⁸cap,²and latex foam¹⁰– in various shapes and sizes.¹⁰

"Prescribing forefoot pads should depend on the condition being treated," said Dr. Karl Landorf, senior lecturer and research coordinator in the Department of Podiatry at La Trobe University in Melbourne, Australia. "For example, a patient with rheumatoid arthritis with extensive synovitis of the metatarsophalangeal joints may need different cushioning in the forefoot than someone with extensive metatarsalgia below the medial metatarsal heads."

Nordsiden et al. evaluated three different shapes of metallic pads made of self-adhesive orthopedic felt (metal dome, U-shaped pad, and donut-shaped pad) in patients with flat feet during walking. The researchers found that the metal domes were the most effective option for reducing peak and midplantar pressure, while the U-shaped pad was close behind; The donut-shaped pad did not cause significant changes in plantar pressure. Furthermore, 70% of patients reported that the metal cup was the most comfortable of the three; However, the researchers cautioned that clinicians should consider other factors when selecting or designing the appropriate pad, such as: B. Location and intensity of pain, type of footwear and comfort, and pad materials.¹¹

Jackson and others. also found that 70% of patients preferred the dome design insole over the bar design, although the bar is more effective in reducing mean peak pressure and therefore the researchers recommend it as the first choice of treatment. 🇧🇷¹⁰

Another study by Symeonidis et al. compared prefabricated metal pads (made from urethane foam) with metal rods (outer shoe modifications made from high-density rubber) in healthy subjects.²²They found that both thrusts under the second metatarsal head were significantly reduced compared with the shoes alone, although the reduction was significantly greater with the Met rods than with the Met pads.

In contrast, Landorf et al.²⁰found that in older adults with forefoot pain, a metal cup (from the PPT) placed 5 mm distal to the metatarsal head was associated with a significantly greater reduction in plantar pressure than a metal rod or metal cup placed 10 mm distal. However, the researchers caution that these results are difficult to compare with other studies due to differences in pad placement protocol and elderly patient population.²⁰

Based on his findings, which he believes are robust, Landor said, "Patients with relatively mild forefoot pain generally benefit more from a metabolic cup. In particular, anyone with pain below the medial metatarsal heads, and that includes adults young and old.”

While weather domes seem to outperform other designs overall, it is still difficult to draw definitive conclusions based on the literature on the most effective form or material for weather protection panels.^10,11,20

"I don't think there's a lot of evidence for the specific shape, but clinically and intuitively it should be tapered distally for the stress gradient to be smooth," Mueller said. "So I think the key is that the stiffness of the material has to be greater than the soft tissue of the foot,
because you're trying to transfer stress from the metal heads to the soft tissue, so you have to compress the soft tissue from the metabolic pads."

More work is needed to further investigate the role of form and material, but current research highlights the essential role of proper metal pad placement, which some believe is more important than the design itself.^1,2,4,20,21

"I would say location is the most important thing to get a positive or negative response," said Müller.

Hastings et al placed a prefabricated cork pad at multiple locations on the foot, all covering the three central metatarsals, and found that the optimal placement distance for the most consistent pressure reduction is 6.1 to 10.6 mm proximal to a line that identifies the metatarsal. Head.²Hsi et al. also found that Metonic foam pads resulted in the greatest pressure reductions when placed directly near the peak pressure of the Metonic head, which they found to be the ideal position for pressure relief.¹

Landorfet al.²⁰found that distal placement of a Met pad was effective in relieving forefoot plantar pressure, and Hayda et al.²¹found that felt pads placed 5 mm distal to the Met heads resulted in a greater pressure drop than pads placed 5 mm proximal. However, most authors currently agree that the ideal position for the met pads is in line with Hsi's recommendations.^5,11,22

However, despite all the evidence, some clinicians still have difficulty getting Met Pads into their intended position, while others may avoid them altogether due to ignorance or concerns about initial patient discomfort.^2,23Improper placement may also partially explain the variability in patient responses in some studies.^1,2,7

"Because it takes time and effort to educate patients about the possibility of intolerance to metabolic pads and how to treat it, and effort to get patients to come back when there is a problem, clinicians often avoid the problem altogether," said Robert. Ferrari, MD, Clinical Professor, Department of Medicine, University of Alberta Hospital in Edmonton, Canada.

To assess intolerance, Ferrari followed 60 patients with nonspecific low back pain wearing custom foot orthoses with large metal pads for six weeks and informed them of possible initial discomfort in the first week. After the necessary adjustments, almost all patients ended up tolerating the pads; only one still reported pain or discomfort at the end of the study.²³

"If each physician simply informs the patient in advance that initial discomfort is normal, which devices should be used, and which ones to return if there is any concern, this electrode mismatch issue can be resolved," Ferrari said.

For some clinicians, it's always a work in progress and making the necessary changes for each patient based on their personal response.

"You have to accept that you might have to adapt," Robinson said. "Your mods and tweaks are part of the game when it comes to Metonic pads, and sometimes you have to rip them off and try something different to get the best fit."

George Holmes Jr, MD, associate professor and director of the Foot and Ankle Department at Rush University Medical Center in Chicago, believes that control should be placed in the hands of patients.

"I think if they just get a few instructions and a few key tips, they can take care of the pads from there and they don't need me or any of my assistants to help them put them back in," he said.

One way to monitor careful electrode placement and assess effectiveness is to use real-time plantar pressure measurements before and after placement.⁵

"I don't think there's anything on the market that helps you judge the success or failure of a custom foot orthosis like the shoe pressure test," said Bruce Williams, DPM, director of the gait laboratory at Weil Foot. & Ankle Institute. in Chicago and founder of Breakthrough Podiatry in Merrillville, IN. "With the system, I immediately get quantitative information about the function of the insoles and the patient's reaction to them."

Numerous studies highlight the value of pressure measurement systems for determining changes in plantar pressure; however, its use in the clinical setting is limited by its cost.^{2,5,7,8,11,20}

"Shoe-mounted pressure measurement systems are very useful, but they are still too expensive for most physicians to have in their practice," Landorf said.

Met pads are just one of the many types of orthopedic modification equipment available today. Several studies have evaluated metallic pads together or independently of TCI and other orthoses, and the results have been mixed regarding the association of metallic pads to an orthosis with additional benefits.^2,7-9,24

For some physicians, the distinction is irrelevant.

"I use a mix of functional and adaptive devices, and I don't think there's much that differentiates them," Williams said. "Furthermore, there is very little literature on the use of metatarsal pads with orthoses."

Others see great potential for metal pads and other orthopedic devices when combined sensibly.

"I think it's ideal to have some type of TCI first, because you can easily increase the contact area of ​​the entire foot and get significant pressure relief," Mueller said. "Placement of the met pad offers an added benefit, but it's a bit trickier as you need to position it optimally."

Many questions about metal pads remain unanswered.

Which metal pad materials are most effective for discharging? What patient characteristics, in addition to hypersensitivity and a few selected disorders, help determine whether they are good candidates? Should metal pads be used instead of or in conjunction with other orthotics?^1,2,7,21

"It's clear that we now need to take our mechanistic understanding of these pads [i.e., that they can reduce peak pressure under the forefoot] and back up these findings with randomized trials evaluating patient-reported outcomes, including comfort." Landorf said. "Patients with forefoot pain, clinicians and policymakers will greatly benefit from this additional evidence."

While metabolic pads may seem like a key ingredient, they are really just one piece of the puzzle that needs to be seen in the context of the big picture.

"It's part of a broader intervention that needs to happen," Mueller said. “I don't think there will be a magic bullet from a footwear perspective; The Met shoe and insole are part of the treatment, but approaching the patient as a whole and addressing the problem as a whole is very important. So I think we need more research on how to make the brace more effective, but also how to get patients to wear it."

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