Accessory Navicular Syndrome
What is the Accessory Navicular?
What is Accessory Navicular Syndrome?
Signs and Symptoms of Accessory Navicular Syndrome
Diagnosis
Treatment : Non-Surgical Approaches
When is Surgery Needed
What is the
Accessory Navicular?
The accessory navicular (os navicularum or os
tibiale externum) is an extra bone or piece of cartilage located on the inner
side of the foot just above the arch. It is incorporated within the posterior
tibial tendon, which attaches in this area.
An accessory navicular is congenital (present at birth). It
is not part of normal bone structure and therefore is not
present in most people.
What is
Accessory Navicular Syndrome?
People who have an
accessory navicular often are unaware of the condition if it
causes no problems. However, some people with this extra bone
develop a painful condition known as accessory navicular
syndrome when the bone and/or posterior tibial tendon are
aggravated. This can result from any of the following:
- Trauma, as in a foot or ankle sprain
- Chronic irritation from shoes or other footwear rubbing
against the extra bone
- Excessive activity or overuse
Many people with accessory navicular syndrome also have
flat feet (fallen arches). Having a flat foot puts more strain
on the posterior tibial tendon, which can produce inflammation
or irritation of the accessory navicular.
Signs and Symptoms
of Accessory Navicular Syndrome
Adolescence is a common time for the
symptoms to first appear. This is a time when bones are
maturing and cartilage is developing into bone. Sometimes,
however, the symptoms do not occur until adulthood. The signs
and symptoms of accessory navicular syndrome include:
- A visible bony prominence on the midfoot (the inner side
of the foot, just above the arch)
- Redness and swelling of the bony prominence
- Vague pain or throbbing in the midfoot and arch, usually
occurring during or after periods of activity
Diagnosis
To
diagnose accessory navicular syndrome, the foot and ankle
surgeon will ask about symptoms and examine the foot, looking
for skin irritation or swelling. The doctor may press on the
bony prominence to assess the area for discomfort. Foot
structure, muscle strength, joint motion, and the way the
patient walks may also be evaluated.
X-rays are usually ordered to confirm the diagnosis. If
there is ongoing pain or inflammation, an MRI or other
advanced imaging tests may be used to further evaluate the
condition.
Treatment:
Non-Surgical Approaches
The goal of non-surgical
treatment for accessory navicular syndrome is to relieve the
symptoms. The following may be used:
- Immobilization. Placing the foot in a
cast or removable walking boot allows the affected area to
rest and decreases the inflammation.
- Ice. To reduce swelling, a bag of ice
covered with a thin towel is applied to the affected area.
Do not put ice directly on the skin.
- Medications. Oral nonsteroidal
anti-inflammatory drugs (NSAIDs), such as ibuprofen, may be
prescribed. In some cases, oral or injected steroid
medications may be used in combination with immobilization
to reduce pain and inflammation.
- Physical therapy. Physical therapy may
be prescribed, including exercises and treatments to
strengthen the muscles and decrease inflammation. The
exercises may also help prevent recurrence of the symptoms.
- Orthotic devices. Custom orthotic
devices that fit into the shoe provide support for the arch,
and may play a role in preventing future symptoms.
Even after successful treatment, the symptoms of accessory
navicular syndrome sometimes reappear. When this
happens, non-surgical approaches are usually
repeated.
When Is
Surgery Needed?
If non-surgical treatment fails
to relieve the symptoms of accessory navicular syndrome,
surgery may be appropriate. Surgery may involve removing the
accessory bone, reshaping the area, and repairing the
posterior tibial tendon to improve its function. This extra
bone is not needed for normal foot function.