Posterior Tibial Tendon Rupture
One of the most common causes for a
flat foot in the adult is a rupture of the posterior tibial tendon.
The posterior tibial tendon (along with other supportive ligaments)
is responsible for maintaining the arch of the foot. This tendon
passes behind the ankle and winds around one of the bones inside
the ankle called the medial malleolus. There are certain individuals
who seem to be prone to developing a rupture of the posterior tibial
tendon. These include women who are overweight and those people who
have a flat foot that has been present since early adulthood or even
childhood. In these individuals the posterior tibial tendon may be
prone to stretch out and tear. As the tendon tears, its supportive
function is lost. This causes pain and the foot begins to roll inward
and get flat.
 |
 |
This is the typical appearance of the
foot after a rupture of the posterior tibial tendon.
Note that only one foot is flat, a common finding with
this condition. |
|
|
 |
|
These are XR images of
two very different feet. On the left is an XR of a normal
foot, and on the right, a very flat foot. |
|
|
Once the foot begins to flatten, other structures
including supportive ligaments on the inside of foot begin to stretch
and tear and the foot becomes very flat. Frequently, the patient
will note pain which begins on the inside of the foot, just behind
the ankle. This is due to inflammation of the tendon, which is also
associated with partial rupture or tearing of the tendon. One of
two things will happen to the foot at this stage. Either the foot
remains mobile and flexible or it will start to become stiff. If
the condition deteriorates further, the flattening of the foot is
associated with stiffening of the joints of the back of the foot.
This will limit the inward and outward movement of the foot (inversion
and eversion). The stiffer the foot, the more difficult it becomes
to treat the condition. For this reason we try to initiate treatment
as early as possible once the diagnosis of a rupture of the posterior
tibial tendon is made.
 |
With increasing deformity of the foot, the
joints in the foot get very stiff, and little in and outward
movement of the foot is possible. |
Treatment of this condition begins with support of the foot. This
is done with shoe modifications, orthotic arch support and, at times,
a brace that is custom molded to the ankle. The problem with this
deformity is that once the foot becomes flat, there is very little
that can stop it from flattening out further. This occurs as one
stands, since the weight of the body and the mechanical effect of
this weight pushes the foot out further. However, provided the foot
can be maintained in a reasonably straight position, there is never
any urgency to perform any reconstructive surgery. Ultimately, the
decision to perform surgery for this condition depends on the patient’s
symptoms.
There are certain flat foot deformities in which the foot is so very
flat it is not in the patient’s best interest to have orthotic
arch support treatment. In these individuals the foot is so deformed
and under so much stress, severe ankle arthritis develops.
Surgical treatment for the adult’s flat foot deformity is divided
into three different types: 1) tendons are repaired or transferred
2) bones are cut or realigned and 3) joints are fused together. It
is always preferable to avoid a fusion (called arthrodesis) of the
foot if possible, since stiffness of the foot is never ideal. The
extent of the deformity is the key factor in the decision.
For the flat foot where the tendon is ruptured but there is not significant
deformity, a tendon is usually transferred to replace the torn posterior
tibial tendon. It is not possible to repair the torn posterior tibial
tendon, since it will quickly stretch out and tear again. The tendon
transfer uses a tendon which lies behind the back of the ankle, but
which is not a critical tendon, and can be easily used without causing
loss of foot function. The tendon transfer is combined with a cut
on the heel bone (called a calcaneal osteotomy). The heel bone needs
to be shifted to add support to the tendon transfer on the inside
of the ankle. This operation was developed and popularized in the
late 1980’s by Dr. Myerson and is now one of the most common
operations performed around the world to correct this condition.
 |
The heel bone is cut as shown here, and shifted
inwards to improve the arch of the foot and help support the
repaired tendon on the inside of the foot. |
 |
|
The arch of the foot has been very
well restored following the re-constructive flatfoot
surgery for a posterior tibial tendon rupture. The blue
line shows the direction of the arch which in the top
XR is collapsed. The white shadow in the heel is a screw
that is buried in the bone and holds the bone cut in
the corrected position. |
|
|
When the deformity gets a little worse, bone cuts or osteotomies
must be added to reshape the foot. In some of these, a bone
graft has to be used to elongate different parts of the foot.
Dr. Myerson has pioneered the use of graft bone used from the
bone bank rather than using the patient’s bone. The use
of bone from the bone bank significantly reduces the risks
of taking the patient’s own bone from the pelvis. After
the bone is cut, the bone graft is shaped and then inserted
to reshape the arch and contour of the foot.
|
This very severe flatfoot was corrected
by fusing joints of the back of the foot together (called
a triple arthrodesis). In addition to the fusion, however,
a bone graft had to be inserted to straighten the foot.
The bone graft (circled in blue) was taken. from the
bone bank instead of using the patient’s own bone
in order to straighten the foot. |
|
|
 |
|
On the left is an XR showing a very
severe form of flatfoot where the entire foot has shifted
outwards. This was corrected with a triple arthrodesis
(fusion of three joints in the back of the foot) with
screws as seen on the right XR. |
|
|
| |
|
|
|
The foot on the left is severely flat.
Many surgeons would perform a fusion of joints of the
back of the
foot (called a triple arthrodesis) to correct this.
However, it is quite possible to correct even severe
deformity with bone cuts (called an osteotomy), rather
than fusion. This operation was performed for this
patient, and you can see on the right hand XR the marked
improvement in the arch from the osteotomies with screws
to fix the bone. |
|
|
 |
It is easy to see the severe flatfoot on
the XR above, nicely corrected in the XR below. The foot was
not yet terribly stiff and this was corrected using a bone
cut (osteotomy) of the calcaneus to lengthen the heel. A bone
graft was inserted. One of the joints in the middle of the
foot which connects the 1st metatarsal to the middle of the
foot was also fused with screws. |
For the severe
flat foot deformity, the foot becomes quite stiff and a tendon
transfer and bone cut is no longer enough to correct the deformity.
The foot has to be reshaped and realigned and the joints fused
together with screws to maintain the corrected position. Although
the foot is somewhat stiff, the up and down movement of the foot
is fully maintained. The inward and outward (inversion and eversion)
movement is lost.
|
|
