Posterior Tibial Tendon Dysfunction
Posterior tibial tendon dysfunction is one of several terms to
describe a painful, progressive flatfoot deformity in adults. Other
terms include posterior tibial tendon insufficiency and adult acquired
flatfoot. The term adult acquired flatfoot
is more appropriate because it allows a broader recognition of
causative factors, not only limited to the posterior tibial tendon, an
event where the posterior tibial tendon looses strength and function. The
adult acquired flatfoot is a progressive, symptomatic (painful)
deformity resulting from gradual stretch (attenuation) of the tibialis
posterior tendon as well as the ligaments that support the arch of the
foot. Most flat feet are not painful,
particularly those flat feet seen in children. In the adult acquired
flatfoot, pain occurs because soft tissues (tendons and ligaments) have
been torn. The deformity progresses or worsens because once the vital
ligaments and posterior tibial tendon are lost, nothing can take their
place to hold up the arch of the foot. The
painful, progressive adult acquired flatfoot affects women four times
as frequently as men. It occurs in middle to older age people with a
mean age of 60 years. Most people who develop the condition already
have flat feet. A change occurs in one foot where the arch begins to
flatten more than before, with pain and swelling developing on the
inside of the ankle. Why this event occurs in some people (female more
than male) and only in one foot remains poorly understood. Contributing
factors increasing the risk of adult acquired flatfoot are diabetes, hypertension, and obesity. The following scheme of events is thought to cause the adult acquired flatfoot: A
person with flat feet has greater load placed on the posterior tibial
tendon which is the main tendon unit supporting up the arch of the
foot. Throughout life, aging leads to decreased strength of muscles,
tendons and ligaments. The blood supply diminishes to tendons with
aging as arteries narrow. Heavier, obese patients have more weight on
the arch and have greater narrowing of arteries due to atherosclerosis.
In some people, the posterior tibial tendon finally gives out or tears.
This is not a sudden event in most cases. Rather, it is a slow, gradual
stretching followed by inflammation and degeneration of the tendon.
Once the posterior tibial tendon stretches, the ligaments of the arch
stretch and tear. The bones of the arch then move out of position with
body weight pressing down from above. The foot rotates inward at the
ankle in a movement called pronation. The arch appears
collapsed, and the heel bone is tilted to the inside. The deformity can
progress until the foot literally dislocates outward from under the
ankle joint. There are three stages of the adult acquired flatfoot: Stage I: Inflammation and swelling of the posterior tibial tendon around the inside of the ankle. Stage
II: Visible deformity comparing one foot to the other, as the
symptomatic foot becomes flatter and more deformed. The deformity is
movable and correctable in this stage. Stage
III:The foot progresses to a rigid, non-movable flat foot deformity
that is painful, primarily on the outside of the ankle. Diagnosis The
adult acquired flatfoot, secondary to posterior tibial tendon
dysfunction, is diagnosed in a number of ways with no single test
proven to be totally reliable. The most
accurate diagnosis is made by a skilled clinician utilizing observation
and hands on evaluation of the foot and ankle. Observation of the foot
in a walking examination is most reliable. The affected foot appears
more pronated and deformed compared to the unaffected foot. Muscle
testing will show a strength deficit. An easy test to perform in the
office is the single foot raise: A
patient is asked to step with full body weight on the symptomatic foot,
keeping the unaffected foot off the ground. The patient is then
instructed to "raise up on the tip toes" of the affected foot. If the
posterior tibial tendon has been attenuated or ruptured, the patient
will be unable to lift the heel off the floor and rise onto the toes.
In less severe cases, the patient will be able to rise on the toes, but
the heel will not be noted to invert as it normally does when we rise
onto the toes. X-rays can be helpful but
are not diagnostic of the adult acquired flatfoot. Both feet - the
symptomatic and asymptomatic - will demonstrate a flatfoot deformity on
x-ray. Careful observation may show a greater severity of deformity on
the affected side. Magnetic Resonance Imaging (MRI)
can show tendon injury and inflammation but cannot be relied on with
100% accuracy and confidence. The technique and skill of the
radiologist in properly positioning the foot with the MRI beam are
critical in demonstrating the sometimes obscure findings of tendon
injury around the ankle. Magnetic Resonance Imaging (MRI) is expensive
and is not necessary in most cases to diagnose posterior tibial tendon
injury. Ultrasound
has also been used in some cases to diagnose tendon injury, but this
test again is usually not required to make the initial diagnosis. Treatment The
adult acquired flatfoot is best treated early. There is no recommended
home treatment other than the general avoidance of prolonged
weightbearing in non-supportive footwear until the patient can be seen
in the office of the foot and ankle specialist. In
Stage I, the inflammation and tendon injury will respond to rest,
protected ambulation in a cast, as well as anti-inflammatory therapy.
Follow-up treatment with custom-molded foot orthoses
and properly designed athletic or orthopedic footwear are critical to
maintain stability of the foot and ankle after initial symptoms have
been calmed. Once the tendon has been
stretched, the foot will become deformed and visibly rolled into a
pronated position at the ankle. Non-surgical treatment has a
significantly lower chance of success. Total immobilization in a cast
or Camwalker may calm down symptoms and arrest progression of the
deformity in a smaller percentage of patients. Usually, long-term use
of a brace known as an ankle foot orthosis is required to stop
progression of the deformity without surgery. A new ankle foot orthosis known as the Richie Brace
has proven to show significant success in treating Stage II posterior
tibial dysfunction and the adult acquired flatfoot. This is a
sport-style brace connected to a custom corrected foot orthotic device
that fits well into most forms of lace-up footwear, including athletic
shoes. The brace is light weight and far more cosmetically appealing
than the traditional ankle foot orthosis previously prescribed. Other
types of braces are the Arizona brace, the California brace or the
gauntlet brace. The decision on which type of brace to use is based
upon the patients overall needs. In cases
where cast immobilization, orthoses and shoe therapy have failed,
surgery is the next alternative. The goal of surgery and non-surgical
treatment is to eliminate pain, stop progression of the deformity and
improve mobility of the patient. Opinions vary as to the best surgical
treatment for adult acquired flatfoot. Procedures commonly used to
correct the condition include tendon debridement, tendon transfers,
osteotomies (cutting and repositioning of bone) and joint fusions. (See
surgical correction of adult acquired flatfoot) Patients
with adult acquired flatfoot are advised to discuss thoroughly the
benefits vs. risks of all surgical options. Most procedures have
long-term recovery mandating that the correct procedure be utilized to
give the best long-term benefit. Most flatfoot surgical procedures
require six to twelve weeks of cast immobilization. Joint fusion
procedures require eight weeks of non-weightbearing on the operated
foot - meaning you will be on crutches for two months. The
bottom line is: Make sure all of your non-surgical options have been
covered before considering surgery. Your primary goals with any
treatment are to eliminate pain and improve mobility. In many cases,
with the properly designed foot orthosis or ankle brace, these goals
can be achieved without surgical intervention.
Back to Top
|