Topics discussed on this page:
Posterior Tibial Tendon (PTT)
Tibialis Posterior Tendon
Posterior Tibial Tendon Dysfunction (PTTD)
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The Posterior Tibial Tendon (PTT), also known as the Tibialis Posterior Tendon, is a major muscle on the back of the tibia and fibula, (the lower leg bones). It comes down the back of the leg, passing behind the medial malleolus (the bump on the inside of the ankle), and attaches to the foot at the Navicular Bone on the medial (inside) border of the foot. The tendon is very strong and very important in gait. The tendon's primary function is to supinate the foot--to raise the arch, lock bones into a stable position and help push you off from the ground. |
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Because it is used so much in gait, the PTT undergoes a great deal of stress. For this reason, the tendon is vulnerable to injury, particularly when certain other conditions are present.
When the Posterior Tibial Tendon is injured, several things may occur. First, if the injury is not severe, the tendon may simply become inflamed, a condition known as tendinitis. If the injury is chronic, the tendon may be gradually become attenuated, or stretched out. In this case, the tendon no longer able to function as it once did, and the foot becomes non-functional. This is known as "Posterior Tibial Tendon Dysfunction" or PTTD. Finally, if the injury is severe enough, the tendon may completely rupture, a problem that usually requires surgical intervention.
What conditions predispose someone towards PTTD?
There are many predisposing factors to developing posterior tibial tendon problems:
Excessive weight (It's obvious, perhaps, but the more force applied to the tendon, the more stress it's under, and the more likely it is to fail.)
Aging (Except for acute tendon rupture, which is usually seen in younger patients), most PTTD patients are over 60.)
Gender (Females get problems more than males.)
Menopause (There is a hormonal link to this condition. In fact this appears to be the single most common factor in patients with PTTD.)
Steroid use (Steroids weaken tendon, and this is one reason why steroids like cortisone should not be used to treat this condition.)
Smoking (Smoking disrupts circulation and weakens the tendon.)
Rheumatological (arthritic) conditions (Certain types of arthritis tend to also weaken the tendon and may create crystalline deposition within the tendon)
A history of injury (This may mean sudden trauma or chronic, reptetitive, low-grade trauma.)
A fracture of the navicular (This is the bone where the tendon attaches.)
Biomechanical abnormalities such as:
A pronated Foot type (A pronated foot is one that flattens too much).
A leg-length difference.
Calcaneal Valgus (This is a condition where the heel bone is no longer straight, but rolls inwards relative to the leg).
Forefoot Varus (This is a condition where the front of the foot--the metatarsals and toes, e.g.--is positioned inverted relative to the heel).
The presence of an Os Tibiale Externum, or OTE. (The OTE is an extra bone near the navicular.
What kind of problems does the patient experience with PTTD?
Stage One describes the condition when the patient has some sort of biomechanical or predisposing factor before symptoms develop.
Stage Two is the point when the tendon begins to develop some symptoms (tendinitis) along the course of the tendon or in the calf (shin splints). There may be a mild weakness of the tendon.
Stage Three is the stage when the tendon begins to become attenuated or stretched out (tendinosis) and functions poorly. It may be hard for the patient to stand on his toes.
Stage Four describes the point where the foot begins to collapse, causing instability in the foot and arthritis in the joints of the foot.
Arthritis develops, and the pain usually worsens. To the left is a good example of a foot where the arch has collapsed as a result of posterior tibial tendon dysfunction.
How is PTTD diagnosed?
While it's not usually hard to diagnose PTTD once you know to look for it, the condition is very much under-diagnosed and overlooked. The condition is also fairly common. Our office sees the condition once every week or so.
In most cases the diagnosis can be made by history and physical alone. Pain along the course of the tendon, muscle weakness on one side over the other, and a collapsing arch are all possible indicators.
Tendons don't typically show up on x-ray, but radiographs may be of some use when calcification of the tendon, a fractured navicular, a collapsing arch or degenerative changes in the join are suspected clinically. A physician with a good biomechanical background will also be able to see many associated biomechanical abnormalities on film.
Bone scans and CT may also be of some use, but MRI is generally more useful, as it images tendons and other soft tissues better, and it is highly sensitive and specific for this injury. A tenogram, (a test where dye is injected into the tendon sheath) is still another alternative, though its invasive nature means other diagnostic tests are more frequently considered.
How is PTT treated?
This condition may be rapidly progressing, so treatment should be aggressive.
In the acute cases, the primary direction of treatment is based upon stabilizing the joint and calming the tissue.
To stabilize the joint, treatment may range from taping and padding for mild injuries to complete immobilization with a soft or hard cast.
The tissues may be calmed down with conservative care like ice, compression, anti-inflammatories, and ultrasound. Steroid injections are not suggested, as they tend to weaken tendons.
In chronic cases, aggressive functional orthoses is useful for most patients, even many severe ones. New advances in orthotic therapy, such as inverted orthoses, are particularly helpful and may frequently postpone surgery. In fact, with the newer types of orthotic therapy, we find that less than 10% of PTTD patients end up requiring surgery.
If orthoses do not adequately resolve the complaint, surgical intervention may be indicated. Procedures range from repair of the degenerative portions of the tendon and performing tendon transfers to stabilizing or fusing one or a combination of joints in the mid and rearfoot. The procedure chosen is variable from patient to patient.