Although immobilizing
subtalar neutral ankle foot orthoses (AFOs) is commonly used
and believed to be the posture of greatest stability, the data to confirm this
notion are lacking.
“The evidence points very strongly to the fact that immobilization
in subtalar neutral, no matter the AFO design, does not stand up to
well-established scientific principles that are being applied to other relevant
areas of orthopedic surgery and rehabilitation,” said Robert Meier, CO,
BOCO, director of education at Allard USA.
“Academia is sometimes slow to change what has been ‘common
practice,’ and change for any profession is difficult,” he told
O&P Business News.
Immobilizing subtalar neutral AFOs makes walking difficult, and in
addition, distal immobilization may lead to proximal instabilities. However,
the evidence does point to a “controlled stress” environment to
enhance healing and function, according to Meier.
Meier conducted a Medline search and reviewed about 500 articles
published within the last 15 years to determine the level of support for the
concept that subtalar neutral AFOs are stable.
Although there were numerous studies available on this topic, results
showed that no published data support this concept. Additionally, the research
lacks consistency in terminology, according to Meier.
“There is no consistent definition of the functional status of the
patients being studied and no consistent measurement of outcomes,” he
said. “It’s hard to find two studies that actually correlate to each
other to reach an evidence-based conclusion.”
Meier believes that because the data are so inconsistent, practitioners
are forced to study principles instead of methods. When principles are studied,
then practice becomes a “game changer,” he said.
“There are no data to support subtalar neutral in literature, and
when gait models are studied, one finds that we never function in subtalar
neutral,” Meier said. “The calcaneous is either inverted during swing
or everted during stance. Subtalar neutral is a ‘posture’ through
which we pass, but we are never in that posture.”
Twenty years ago, managing soft tissue injuries or dysfunction through
immobilization was discredited, according to Meier. He believes that most
therapists do not like plastic immobilizing AFOs and that this method is often
the intervention of last resort.
“Taking away motion of the subtalar joint takes away the
neuromuscular rehabilitation they’re attempting to accomplish, so they see
subtalar neutral AFOs as counterproductive,” he said.
Despite the results of this analysis, Meier said that many references
did commonly recommend that a “controlled motion” AFO environment may
enhance joint modeling and neuromuscular development and at the same time
enhance functional outcomes during gait.
In addition, a “controlled stress” orthotic environment may be
more appropriate for attempting to avoid atrophy secondary to immobilization
and to encourage the developmental process.
“The data have been out there for about 30 years: Immobilization
leads to disuse atrophy of all anatomical systems and also leads to the
formation of hypotrophic scaring — the same brittle fragile scarring
associated with burn patients,” Meier said. “In most other areas of
orthopedics, the rule is early motion and early ambulation to avoid the
negative impact of disuse atrophy.” — by Tara Grassia
For more information:
- Meier R. Medical evidence relating to subtalar neutral in AFOs.
Presented at the
American Academy of Orthotists and Prosthetists 37th Annual
Meeting and Scientific Symposium. March 16-19, 2011. Orlando, Fla.- Disclosure: Meier is a consultant to Allard USA, the
manufacturer and distributor of the ToeOFF carbon composite AFO system.
