> Sesamoid Disorders
What are Sesamoid Disorders?
Your sesamoids are two small
bones under the base of your big toe that help provide
leverage for toe movement. Every time the ball of your
foot strikes the ground, weight is transferred through
your sesamoids. Functioning like your kneecap, your
sesamoids enable your toe joint to bend with more strength
and stability. Both sesamoid bones rest side by side
inside a tendon called the flexor hallucis brevis. The
bones are a key part of the muscle and tendon mechanism
that bends your big toe’s joint, called the first
metatarsophalangeal joint. Sesamoid disorders typically
are overuse injuries with slowly worsening symptoms
of pain and discomfort in the ball of your foot. Traumatic
injuries, such as sesamoid fractures, are less common.
Ordinarily, only one of your two sesamoids is injured,
but you may suffer damage in both of them. Sesamoids
generally can suffer three types of injury:
– An inflammation of the tissues surrounding your
sesamoid bones. It is a common overuse injury seen in
runners and cyclists. The sesamoids and surrounding
tissue become inflamed and pain results during activity.
– Rare traumatic injury that happens when too
much force cracks the bone. It can occur when someone
falls on a bent big toe.
of blood supply – Called avascular necrosis. Injury
to the sesamoids can cut off the blood vessels that
keep the bones healthy. Bone tissue cannot regenerate
and it can die or collapse.
Overuse of your big toe typically
causes a sesamoid disorder. Runners, cyclists, and people
who abruptly increase their training regimen are at
an increased risk of suffering a sesamoid disorder if
they overuse the muscles and tendons that bend their
big toes. In rare cases, a large force may bend your
toe too far, called a dorsiflexion injury, and tear
tissue around your sesamoid. This type of injury is
called acute, meaning that you typically can recall
the moment when your big toe was bent too far and the
pain began. A fracture can occur in your sesamoid due
to a hard fall on the ball of your foot or someone falling
on your foot when your big toe is bent. Loss of blood
supply in your sesamoids is rare, but it can be caused
whenever damage in the tissue surrounding the sesamoids
decreases their blood supply.
If left untreated, sesamoid disorders
typically continue to hurt and your big toe’s
motion and strength may decrease. A lesion can develop
beneath the ball of your foot that makes walking difficult.
Arthritis may eventually develop and you can lose cartilage
in your big toe’s joint with your foot. Most sesamoid
disorders can be treated without surgery. A combination
of treatments, including rest, orthotic shoe inserts,
and immobilization may be needed to treat your sesamoid
disorder. Surgery may be required if conservative treatment
does not ease your pain after a few months. Surgery
also is commonly prescribed if you have lost blood supply
to your sesamoids. Surgery typically involves removing
one or both of your sesamoid bones.
There usually are three parts to an
orthopedic evaluation: medical history, a physical examination,
and tests that your doctor may order.
Your physician likely will ask about
your activities, which may have caused your sesamoid
disorder. You will be asked when the pain began and
to describe your pain’s duration and severity.
If you have had previous foot injuries, your physician
will ask about the treatments you have tried in the
past. Your physicians may suspect an overuse injury
when you describe a long history of slowly developing
pain in the joint of your big toe. Physicians suspect
a fracture when you describe direct contact to your
foot followed by pain and limited motion in your big
toe. Descriptions of swelling and increasing pain in
the joint at the base of your big toe over a span of
weeks also could be a sign of a fracture. Physicians
typically ask about other conditions, such as diabetes
and allergies, and medications currently being taken.
You may also be asked about your physical and athletic
goals – information that will help your physician
decide what treatment might be best for you in achieving
our physician usually checks for certain
signs of sesamoid dysfunction during a physical exam:
in the joint that connects your big toe with your foot.
in your big toe and the ball of your foot when your
physician presses upon those areas.
when your big toe is bent in different directions.
bending your big toe up and down.
to push with your big toe against pressure applied by
X-rays are the standard test used to diagnose sesamoid
disorders. X-rays can show if the bone has been fractured
or if it has lost its blood supply. Bone scans or MRI
(magnetic resonance imaging) may be needed to properly
see the damaged tissue. Roughly 20 percent of people
have a harmless condition called a bipartite sesamoid.
This means that the sesamoid has a natural split in
it because it did not completely form as one bone. A
bone scan or MRI can help differentiate between a bipartite
sesamoid and actual damage, such as a fracture or loss
of blood supply.