Orthosis Symbiosis: custom versus prefab foot orthoses

[Guest guest]

From BioMechanics May 2005

Orthosis Symbiosis By Cary Groner

Clinicians are finding a middle ground in the debate over custom

versus prefab foot orthoses.

I am my podiatrist's worst nightmare. After I developed plantar

fasciitis last December, he did an exam, took a couple of x-rays, and

prescribed custom orthoses. He's a great doctor, but when my orthoses

came, they frankly hurt like crazy. So after a couple of weeks he

adjusted them. They got worse. A few weeks later we tried again. No

luck.

In an earlier life I'd briefly made custom athletic shoes for a small

clientele, so I knew something about these things. In fact, I'd been

using prefabricated inserts for years because my arches are so high

they inspire architects. And although the prefabs never completely

compensated for my tendency to overpronate, my feet were reasonably

comfortable under most circumstances.

But I'd never had fasciitis before, and the new custom devices were a

different animal altogether. Finally, in desperation, I took them

apart, then got myself some Poron, leather, and barge cement, and

went to work. I'm afraid to tell my podiatrist any of this, of

course, because I don't want him to yell at me.

The good news is that my feet are much more comfortable now, and the

orthoses seem to control my foot motion far better than the prefabs

did. But the whole imbroglio got me wondering about orthotic

treatment, and in particular about the relative merits of custom

orthoses versus prefabricated ones for a variety of conditions.

Advantages of prefab

Prefabricated orthoses, as clinicians know, fall into two main

categories. Accommodative ones are shaped to offload certain areas of

the foot, and are used primarily for patients with arthritis or

diabetes. Functional prefabs, by contrast, alter the foot's

mechanics, as do most custom orthoses.

" There are indications for both prefabricated and custom orthoses,

and there is decent documentation in the literature for both, " said

Scherer, DPM.

Scherer is chair of applied biomechanics and an adjunct clinical

professor at Merritt College in San Francisco; he is also an

owner of ProLab, a maker of custom orthoses, also in San Francisco.

" For prefab, there are three main uses, " Scherer said. " To prevent

overuse injury, to help in diagnosis by determining whether a

patient's pathology is mechanically related, and to provide temporary

relief while a custom orthosis is being made. "

Scherer's own research into custom orthoses suggests that they help

many patients suffering from plantar fasciitis.1

" The art and science of being a doctor is to figure out which one

will work better in which patient, " he said.

Importance of prevention and comfort

Recent studies have supported the use of orthoses for injury

prevention, but the impact of materials and design remains unclear.

For example, a study of 874 recruits in the Israeli military found

that significantly fewer of those given soft prefab orthoses finished

basic training in their assigned devices than did those in the " soft

custom " group (53% vs. 72% respectively), while those with semirigid

custom devices fared slightly worse, meaning they were more likely to

have discontinued device wear by the end of basic training, than

those with semirigid prefabs (75% versus 82%, respectively). Although

both types of soft orthoses were rated more comfortable than either

of the semirigid ones, there were no significant differences in the

rate of overuse injuries between any of the groups. The authors

concluded that soft orthoses-whether prefab or custom-were preferable

to semirigid ones for injury prevention.2

Benno Nigg, Dr ScNat, director of the Human Performance Laboratory at

the University of Calgary, reported a study he'd helped conduct for

the Canadian military.3 Soldiers were given a choice of six

prefabricated inserts and were told to try them out for half an hour

and rank them on comfort. Each subsequently wore the one he or she

liked during four months of training.

" The orthoses were different in certain respects, " Nigg said. " One

had a medial support; one did not; one had elastic material; one had

viscous material; one was hard; one was soft. "

Soldiers chose five of the six devices with about equal frequency and

averaged more than 40% fewer lower extremity injuries than a control

group that did not use insoles, regardless of which design they

chose.

Nigg's previous research has suggested, moreover, that comfort has

clinical relevance. One paper concluded that " evaluations of foot

orthoses using comfort do not only reflect subjective perceptions but

also differences in functional biomechanical variables. " 4

New potential

Beyond prevention, prefabricated orthoses appear to successfully

address several pathologies. Research suggests they are useful in

treating osteoarthritis of the knee5,6 as well as some aspects of

foot or ankle pain associated with rheumatoid arthritis.7,8 In a

condition such as metatarsalgia that sometimes is associated with RA,

a clinician may choose either an accommodative device or a functional

one, depending on the etiology of the problem and the patient's

needs.

Accommodative orthoses are also used to offload pressure points in

patients with diabetes, of course. But research by Nigg and others,

suggesting that orthoses may work by other than strictly

biomechanical means, has opened the door to new views of the devices'

potential.

At the University of Virginia, for example, assistant professor of

kinesiology Jay Hertel, PhD, ATC, found that prefab orthoses

heightened activation of subjects' vastus medialis and gluteus medius

muscles during squat and step-down exercises, regardless of posting

or foot type.9

" Traditionally, orthoses have been regarded mostly as motion

restrictors, especially in people who pronate too much, " Hertel

said. " But I'm studying how they affect the sensory motor system. Do

we really need to do all this posting, or do we just want to alter

the sensory information going into the bottom of the foot? If that's

the case, then a prefabricated orthosis makes a lot of sense. "

Hertel acknowledges that this position is harder to support when it

comes to plantar fasciitis, but that it may be very appropriate for

patellofemoral pain, which is characterized by muscular dysfunction,

including quadriceps inhibition.

" We've shown that by simply inserting an orthosis into the shoe, we

can increase quadriceps activation, " he said. " We know that

peripheral sensory information is directly connected to muscular

output, so it may just be a matter of providing different

information. "

Pathology is crucial

Researchers have also found that custom orthoses improve

patellofemoral pain in subjects with excessive pronation.10

Gross, PhD, PT, professor of human movement science at the University

of North Carolina at Chapel Hill, admits that off-the-shelf orthoses

can help some patients, but contends that they're not for everyone.

" You have to look at the condition, duration, and intensity of

symptoms, and the pathology, " he said.

Someone with a pronounced forefoot varus, for example, as shown in

the photo may experience a powerful roll into pronation during stance

phase, overwhelming a prefab orthosis, Gross said.

" In the process of the first metatarsal head reaching the ground

there's this huge collapse of the medial side of the foot, which puts

tensile stress on the plantar fascia and can lead to fasciitis-or to

tendinitis of the tibialis posterior tendon or the Achilles tendon,

or to metatarsalgia, " he added. " For a foot like that, I design a

medial forefoot post so that the foot doesn't go through all that

motion. "

It is nevertheless difficult to make generalizations about prefab

versus custom orthoses, Gross continued.

" If I can't get to a patient for a while, I'll suggest they get

something off-the-shelf to hold them over, and a lot of times they're

helped tremendously, " he said. " They may be so much better that they

cancel their appointment, but even if they're just a little better,

if I can see how the prefab orthosis helped, I can use that

information when I design a custom one. "

Fasciitis issues

The discussion becomes more animated when the subject is plantar

fasciitis. In 1999, Glenn Pfeffer, MD, and several colleagues

published a study concluding that fasciitis patients were more likely

to improve using prefabricated shoe inserts than custom polypropylene

orthoses.11 Patients were randomized into one of several treatment

groups and reevaluated after eight weeks. The percentages improved in

each group are in the table on this page.

The study ignited controversy, but it's important to bear in mind

that it took place in patients who were seeking initial treatment for

fasciitis. Many clinicians now consider off-the-shelf devices a

logical first step, both as a diagnostic aid and as a cost-saving

measure. Gross himself has published a study supporting custom

orthoses for fasciitis treatment,12 but as he acknowledged above,

they aren't the only solution. The question is what happens when they

fail.

An updated clinical practice article in the New England Journal of

Medicine last year noted the frustration practitioners face in

treating plantar fasciitis.13 Although the question of which are the

best methods remains open to debate, roughly 80% of patients see

their symptoms resolve within a year regardless of what they do.

Orthoses, night splints, anti-inflammatory agents, shock-wave

therapy, and surgery have all been tried, but good outcomes data are

in short supply.

A 2003 meta-analysis of plantar fasciitis studies reached similar

conclusions, including that stretching and heel pads are slightly

more effective than custom orthoses.14 However, a 2004 article in

BioMechanics emphasized that custom orthoses have a place in

fasciitis treatment, especially in patients who have failed other

modalities.15

In any case, as Nigg noted drily, " There are few hard facts, and they

are all influenced by who does the study. "

An outdated model?

One aspect of orthotic treatment of plantar fasciitis is that,

regardless of its effectiveness, it has typically been based on the

pioneering podiatric biomechanics work of Merton Root, DPM.16,17

Root, who published his seminal works in the 1970s and died in 2002

at age 80, brought to the field a vocabulary that remains in wide

use: forefoot varus or valgus, rearfoot varus, and the whole notion

of normal foot alignment-including a neutral position for subtalar

joints and excessive motion-that underlies orthosis design today.

The only problem with Root's model is that it now appears to be at

least partly incorrect. A 1995 article by McPoil, PhD, PT,

ATC, and his colleague Hunt, PT, OCS, pointed out the weaknesses

in Root's paradigm,18 including that his definition of neutral

subtalar joint position was based on a misinterpretation of earlier

work.19 When McPoil and his colleagues studied the feet of 58 healthy

young women, for example, they found that only 17% of the 116 feet

had a " normal " alignment by Root's standards.

" There was no validity and poor reliability to that podiatric model, "

McPoil said. " When you look at the published data-for example, at the

prevalence of stress fractures-some say a rigid foot is bad, some say

a mobile foot is bad. That's because of the difficulty of blaming a

multifactorial injury on one component. "

McPoil and his colleagues suggested a new approach they called

the " tissue stress model, " which involves four steps:

- identifying the tissues being excessively stressed based on patient

history and symptoms;

- evaluating stressed tissues with a variety of tests and physical

exams;

- determining whether the complaint is secondary to excessive

mechanical loading; and

- instituting a management protocol that includes tissue stress

reduction via rest, footwear, and orthoses; healing of the tissues;

and restoration of flexibility and muscle strength.

When orthoses are indicated for his own patients, McPoil favors full-

length orthoses that make total contact with the plantar surface of

the foot.

" If someone has plantar fasciitis, I want to give them full contact, "

he said. " Not to lift their arch up and create pain, but to help

reduce the strain on something that's been strained. "

Elaboration with TDT

At the University of Queensland in Australia, Bill Vicenzino, PhD,

has elaborated on McPoil's work with a new approach called

the " treatment direction test " (TDT), which emphasizes, first, the

identification of physical tasks that provoke pain and thereby serve

as patient-specific outcomes measures, and second, the use of

specific corrective interventions as those tasks are performed.20

" I wanted to provide a quick test to see whether an orthosis will

benefit a given person, " Vicenzino said.

In the TDT, the clinician observes the patient's foot motion while

walking and determines his or her pain threshold in terms of distance

walked. The practitioner then applies tape or felt pads as needed to

correct motion problems such as pronation or supination, and the

patient repeats the walk. If the preliminary interventions improve

motion and increase the amount of walking possible before pain onset,

the patient is deemed a good candidate for an orthosis.

Vicenzino doesn't favor prefab or custom; he just wants the orthoses

to be comfortable (like Nigg, he considers that crucial to clinical

success) and to ameliorate patients' symptoms.

" If a patient comes in with a painful custom orthosis and says, 'This

hurts me,' it's the height of arrogance to tell them to tough it

out, " Vicenzino said.

The case for custom

Other clinicians acknowledge that Root's model had limitations, but

find value in aspects of it nonetheless.

" Tom (McPoil) made a good point, " said , MD, a staff

physician at OrthoIndy, one of the country's largest orthopedic

practices. " There is quite a spectrum of what we consider normal, and

even normal gait, so one size does not fit all. But I will very

seldom write a prescription for an orthosis and say, 'Place the foot

in subtalar neutral.' If you use a weight-bearing mold, you totally

throw that out the window. Most of my prescriptions are geared toward

the diagnosis and what I want the device to do. "

, who sees patients with relatively severe pathologies,

generally favors custom orthoses.

" A lot of off-the-shelf products are probably feasible for people

with minimal problems given their foot structure, but for feet with

significant problems, custom devices are head and shoulders above

them, " she said.

A similar position is taken by Irene , PhD, PT, director of

research at Drayer Physical Therapy Institute and a professor of

physical therapy at the University of Delaware. works primarily

with runners and will often suggest prefabs as a first intervention.

" If you have an average arch, they will probably be pretty

comfortable, " she said. " If you have a very high arch or a flat arch,

they may not work as well. "

For athletic patients, favors graphite orthoses because they

are lightweight, firm, and durable.

She sees a new development in the field as offering a happy medium

for most patients, however: semicustom devices that are just now

becoming more widely available.

" They take measurements from the mold of the person's foot and pull a

blank to fit, " explained. " They're more custom than an over-the-

counter device, and considerably less expensive than a fully custom

one. "

Noting that even the fabrication of custom orthoses isn't an exact

science, and her team have studied the semicustom devices

informally and found them only minimally different from full-custom

models.

" I believe that for a large majority of the population, this will be

the way that orthoses go, " she said.

Balance

As for Pfeffer, whose 1999 study favoring prefab orthoses kicked the

whole debate into gear, he admits that his position has softened

somewhat.

" The place to start is off-the-shelf, " said Pfeffer, a San Francisco

orthopedic surgeon and immediate past president of the American

Orthopedic Foot and Ankle Society. " There is a critical role for

custom orthoses; it's just that in my practice, it usually comes a

visit or two later than in some other practices. "

Pfeffer believes in incremental change, and considers the progression-

from a pad and shoe modification to a prefab device, then to a custom

orthosis-the appropriate approach to the majority of problems. This

conservative approach has the added benefit of disappointing patients

less often, he believes.

" Everyone who has made a custom orthosis knows that they don't always

help, " he said. " It's one thing when a $40 off-the-shelf device

doesn't work; it's another thing when a $700 custom device doesn't.

Those who fail treatment with prefabs, or those who have more complex

deformities or more advanced pathologies, may benefit from immediate

prescription of a custom device. "

The home front

As for me, my fasciitis is getting better by the week; in fact, I'm

almost out of pain.

Whether I'll ever have the guts to tell my podiatrist what I did is

another question altogether.

Cary Groner is a freelance writer based in Northern California.

References

1. Scherer P. Heel spur syndrome: pathomechanics and nonsurgical

treatment. J Am Podiatr Med Assoc 1991;81(2):68-72.

2. Finestone A, Novak V, Farfel A, et al. A prospective study of the

effect of foot orthoses composition and fabrication on comfort and

the incidence of overuse injuries. Foot Ankle Int 2004;25(7):462-466.

3. Unpublished data, personal communication.

4. Mundermann A, Nigg BM, Humble RN, Stefanyshyn DJ. Orthotic comfort

is related to kinematics, kinetics, and EMG in recreational runners.

Med Sci Sports Exerc 2003;35(10):1710-1719.

5. Marks R. Orthoses wedge their way into OA treatment. BioMechanics

2004;11(8):49-54.

6. Marks R, Penton L. Are foot orthotics efficacious for treating

painful medial compartment knee osteoarthritis? A review of the

literature. Int J Clin Pract 2004;58(1):49-57.

7. Hodge M, Bach T, G. Orthotic management of plantar pressure

and pain in rheumatoid arthritis. Clin Biomech 1999;14(8):567-575.

8. Woodburn J, Helliwell P, Barker S. Changes in 3D joint kinematics

support the continuous use of orthoses in the management of painful

rearfoot deformity in rheumatoid arthritis. J Rheumatol 2003;30

(11):2356-2364.

9. Hertel J, Sloss BR, Earle JE. Effect of foot orthotics on

quadriceps and gluteus medius electromyographic activity during

selected exercises. Arch Phys Med Rehabil 2005;(86):26-30.

10. ston L, Gross M. Effects of foot orthoses on quality of life

for individuals with patellofemoral pain syndrome. J Orthop Sports

Ther 2004;34(8):440-448.

11. 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):214-221.

12. Gross MT, Byers JM, Krafft JL, et al. The impact of custom

semirigid foot orthotics on pain and disability for individuals with

plantar fasciitis. J Orthop Sports Phys Ther 2002;32(4):149-157.

13. Buchbinder R. Clinical practice. Plantar fasciitis. N Engl J Med

2004;350(21):2159-2166.

14. Crawford F, Thomson C. Interventions for treating plantar heel

pain. Cochrane Database Syst Rev 2003;(3):CD000416.

15. Seligman D. Plantar fasciitis pain responds to custom orthoses.

BioMechanics 2004;11(9):55-60.

16. Root ML, Orien WP, Weed JH. Biomechanical examination of the

foot. Los Angeles: Clinical Biomechanics, 1971.

17. Root ML, Orien WP, Weed JH. Normal and abnormal function of the

foot. Los Angeles: Clinical Biomechanics, 1977.

18. McPoil T, Hunt G. Evaluation and management of foot and ankle

disorders: present problems and future directions. J Orthop Sports

Phys Ther 1995;21(6):381-388.

19. D, Desai S, W. Action of the subtalar and ankle-

joint complex during the stance phase of walking. J Bone Joint Surg

1964;46-A:361-382.

20. Vicenzino B. Foot orthotics in the treatment of lower limb

conditions: a muskuloskeletal physiotherapy perspective. Man Ther

2004;9(4):185-196.

IMPROVEMENTS IN PLANTAR FASCIITIS PAIN BY TREATMENT REPORTED BY

PFEFFER ET AL

Silicone heel insert 95%

Rubber heel cup 88%

Felt pad 81%

Stretching only 72%

Custom orthosis 68%

Source: Reference #11