What’s an Os Trigonum?
An os trigonum is a non-utilitarian piece of bone that usually rests peacefully at the back of some peoples’ feet.
Ordinarily, an os trigonum is a harmless anomaly. However, if you punt a football, kick a soccer ball, swim using a butterfly kick, or go en pointe as a ballet dancer, that little hunk of bone can become a big source of agonizing pain.
There’s a reason it’s called the “Nutcracker Syndrome”.
What is Nutcracker Syndrome?
When a person’s toes point downward (plantar flexion), so the line between toes and knee is suddenly straight, an os trigonum is trapped between the tibia, the talus, and the calcaneal bone in your ankle, like a filbert in a nutcracker.
The syndrome can result from a single isolated trauma. It can also be caused by repetitive vigorous toe pointing, as in soccer, punting a football, ballet and swimming.
The os trigonum bone fragment has early origins
It appears as potential cartilage during the second month of fetal development. Years later, through a process known as enchondral ossification, that loose cartilage turns into a small piece of irregularly shaped bone.
This ossification takes place in girls between the ages of 7 and 11. It happens later in boys, usually between 11 to 13. Within a year after its appearance, the os trigonum bone usually fuses with the large central ankle bone known as the talus. So no problem.
However, in 5 to 15 percent of the population, the os trigonum bone stays unfused and independent. This is potentially a big problem.
Sometimes the rear portion of the talus, where an os trigonum has normally fused gets caught in a “nutcracker” compression. This can result in an os trigonum fracture which leaves a newly independent os trigonum in its wake.
The os trigonum is generally shaped like a three-sided pyramid, and its sides are rarely more than a centimeter long.
Os trigonum syndrome is tricky to diagnose
The symptoms of os trigonum can resemble those of Achilles tendinitis, retrocalcaneal bursitis, or a fractured talus. An MRI is often necessary to differentiate between these conditions.
When an os trigonum is asymptomatic (and that’s almost always the case) it causes no problems and needs no treatment. For athletes and dancers who habitually and strenuously point their toes downward, an os trigonum is problematic. Treatment is often urgently necessary.
What’s the treatment for os trigonum?
Treatment generally depends on the immediate cause of pain and the demands of the patient’s lifestyle. Choice of treatment does not depend on whether the os trigonum is pre-existing or the brand-new result of a talus fracture.
If the causing event is a one-time trauma, with a small likelihood of recurrence, conservative treatment, consisting of rest, ice, compression, and elevation, is usually perfect. A cortisone injection is often helpful.
However, unless a dancer, swimmer, punter, or soccer player with a highly symptomatic os trigonum is ready to give up all activity that requires constant toe pointing, surgery is often the answer.
What’s os trigonum surgery like?
Fortunately, os trigonum surgery is simple, effective, and offers a relatively quick healing. It takes a ballet dancer between two and three months to recover from surgery and return to full activity.
After a spinal block so the patient does not feel any pain, an incision at the rear of the calcaneous starts the procedure. Because of prior imaging, locating the os trigonum or the fracture fragment is usually simple, and removal is equally uncomplicated. The nearby tendons are closely inspected and any defects are surgically repaired.
- Post-surgical protocol generally mandates about a week of non-weightbearing
- Then a couple of weeks of complete weight-bearing while wearing a cast
- Then another week or so in a walking boot will prepare the patient for physical therapy
- Most dancers and athletes can resume full activity six to eight weeks after surgery
Like all surgical procedures, excision of an os trigonum or talus fracture fragment has some risks and potential complications. But the comparatively quick healing time, minimally invasive operation and high success rate, makes it an excelleent option for active and athletic patients.
If you’re experiencing problems with your feet, University Foot and Ankle Institute is here to help. Our nationally recognized foot and ankle experts offer the most advanced podiatric care and highest success rates in the nation.
For more information or to schedule a consultation, please call (877) 736-6001 or visit us at www.footankleinstitute.com.
When not tending to patients at University Foot and Ankle Institute, Dr. Jafary utilizes his surgical expertise assisting those less fortunate. As a member of the Yucatan Crippled Children Foundation, he has traveled to Mexico several times and performed hundreds of limb correction surgeries on children with disabling foot and ankle disorders. Dr. Jafary also participates in Podiatry Overseas, which takes him to underserved countries to treat patients with lower extremity deformities.
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