OS TRIGONUM

The OS Trigonum is an extra bone that sometimes develops behind the ankle bone (talus). It is connected to the talus by a fibrous band. The presence of an OS Trigonum in one or both feet is congenital (present at birth).

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OS Trigonum

The OS Trigonum refers to a small bone that develops behind the talus (ankle bone). Although doctors identify the OS Trigonum at birth, it usually does not cause adverse symptoms until adolescence. Symptoms occur when a small portion of the talus fails to fuse normally with the rest of the ankle bone, isolating a small portion of bone that forms the separate OS Trigonum. The OS Trigonum may become partially fused in a few people, forming a prominence at the back of the ankle. The size and shape of the bone can vary, appearing as a small, flat bone or a larger, rounded prominence. The OS Trigonum can cause no symptoms and go undiagnosed; however, in active adolescents, such as student-athletes and dancers, the accessory bone can irritate the soft tissues that surround it or cause painful impingement (pinching) of other tissues.

A nutcracker injury is caused by the small bone being often squeezed or crunched by the ankle and heel bones on each side of the OS Trigonum. However, this bone is extremely rare, occurring in less than 10% of the population. The majority of the time, OS Trigonum is not noticed by the affected person because it does not cause any symptoms. However, if a person has OS Trigonum and hurts his or her ankle injury, especially athletes who need to use their ankles frequently, symptoms may develop.

Causes of OS Trigonum

OS Trigonum Syndrome can occur when the presence of an unfused bone combines with an ankle injury. The following will cause painful symptons:

Overuse

Caused by repeated plantarflexion (foot pointing downwards). Ballet dancers, runners, and football players frequently suffer from OS Trigonum Syndrome.

Trauma

An ankle injury that forces the foot into excessive plantarflexion.

Either of these can result in a “nutcracker injury,” which occurs when the unfused OS Trigonum bone and surrounding soft tissues become wedged between the ankle and heel bones (tibia, talus, and calcaneus). Inflammation of the soft tissues causes pain and stiffness. OS Trigonum Syndrome occurs when the soft tissues are irritated.

QUESTIONS AND ANSWERS

Define an OS Trigonum, and how will it affect my child's health?

An OS Trigonum refers to a small, additional bone or piece of bone located in the posterior (back) part of the ankle, near the heel. The bone will appear or not appear during birth. In many cases, an OS Trigonum does not cause any symptoms or health issues. However, for some individuals, it can lead to discomfort, pain, or limited ankle motion, particularly when it gets pinched or irritated during activities like running or jumping.

What are the common symptoms of an OS Trigonum in children, and how is it diagnosed?

The symptoms of an OS Trigonum can include:

Pain or discomfort in the back of the ankle, especially during or after physical activities.
Swelling and tenderness around the OS Trigonum.
Difficulty pointing the toes downward. An orthopedic specialist can diagnose an OS Trigonum through a physical examination and imaging studies, such as X-rays or MRI scans. The evaluation helps confirm the presence of the OS Trigonum and assess any associated soft tissue irritation or inflammation.

What treatment options are available for my child with an OS Trigonum?

The appropriate treatment for a child with an OS Trigonum depends on the severity of their symptoms. Common treatment options include:
- Conservative measures: For mild cases, rest, ice, anti-inflammatory medications, and physical therapy may help alleviate pain and discomfort. Doctors may suggest that parents reduce their child’s activity levels.
- Corticosteroid injections: In some cases, corticosteroid injections into the area around the OS Trigonum can reduce inflammation and provide relief.
- Surgical removal (excision): When conservative treatments don’t work, or if the OS Trigonum causes persistent pain and mobility limitations, doctors may recommend surgical removal. This procedure typically involves a small incision and the removal of the accessory bone. After surgery, physical therapy is often recommended to aid in recovery and rehabilitation.

It’s important for parents to consult with a pediatric orthopedic specialist who can assess their child’s specific case and recommend the most suitable treatment option based on the child’s age, health, and severity of symptoms. Early diagnosis and appropriate management can help children with an OS Trigonum lead active and pain-free lives.

The doctors at Medical City Children’s Orthopedics and Spine Specialists, are experts in treating foot codnditions. To ensure your child’s bones heal properly, call us for an appointment

Symptoms of OS Trigonum

Doctors treat OS Trigonum problems in dancers, swimmers, high jumpers, and other athletes who point their toes repeatedly and apply repetitive pressure to the toes, transferring force to the ankle area. When symptoms appear, they may include:

Foot Pain

This usually occurs at the back of the ankle. The pain becomes worse when plantarflexing the foot (pointing the toes) or walking in the push-off phase, and it subsides with rest.

Tenderness

When touching the back and outer side of the ankle, it hurts

Swelling

Swelling can occur as a result of soft tissue inflammation.

Lump

You may occasionally feel a small, hard lump near the Achilles tendon. The unfused bone is felt in this location.

OS Trigonum Diagnosis

The diagnosis of OS Trigonum Syndrome begins with the patient’s description of the pain. To examine the area of pain and tenderness, radiological studies such as an x-ray or an MRI scan may greatly help. Because the symptoms of OS Trigonum Syndrome are very similar to those of other conditions such as Achilles tendonitis, peroneal tendonitis, or even a fracture, radiological studies play a critical role in the diagnosis of OS Trigonum Syndrome. X-rays and MRI scans will clearly show inflammation around the ankle region around the OS Trigonum, and therefore, confirm the diagnosis of OS Trigonum Syndrome.

Treatment Options

OS Trigonum syndrome is a well-known cause of pain in the foot and ankle. The symptoms and physical findings, on the other hand, are frequently nonspecific and difficult to separate from other causes of posterior ankle pain. The doctor’s first line of treatment focuses on healing the soft tissues so that the inflammation can settle. These methods include a mix of:

Rest: complete rest from all activities that aggravate the condition for four to six weeks.
Ice: Applying ice to the back of the ankle on a regular basis helps reduce swelling and inflammation. Visit the ice section to learn how to use ice therapy safely and effectively.
Medication: In addition, the treating physician will prescribe NSAIDs such as ibuprofen or Motrin for pain relief and inflammation reduction. To avoid worsening the condition, the doctor may also advise complete immobilization of the affected foot with a brace.
Immobilization: Conservative treatment includes rest and the use of a boot to immobilize the ankle. This keeps the foot from pointing down and allows the pain in the back of the ankle to heal. Anti-inflammatories aid in the reduction of inflammation. For severe pain from an ankle fracture, the child may require a cast for 4-6 weeks. Rest in the boot if the pain is acute and moderate to severe.
Corticosteroid injections: Corticosteroid injections are sometimes used to treat pain and inflammation. In the injections section of our sister site, you can learn more about how they work and the most common side effects.
Exercises: Working with a physiotherapist on a rehab program of stretching and strengthening exercises can also help. Strengthening the ankle and foot muscles allows the talus to glide forward slightly during plantarflexion, reducing pressure on the OS Trigonum and preventing soft tissue irritation.

Surgical Treatment

If the symptoms of OS Trigonum Syndrome persist or recur, doctors may suggest surgery to remove the extra piece of bone as a mode of treatment for OS Trigonum Syndrome. After this type of treatment, the overall prognosis of OS Trigonum Syndrome is usually excellent, with complete resolution of symptoms and return to activities of daily living and sports-related activities within six to eight weeks.

Chronic pain in the back of the ankle is a common reason for surgery in athletes and dancers. Meanwhile, arthroscopy with a posterior or lateral approach can easily remove any scar tissue and painful Os Trigonum if present in soft tissue or bony injuries. If a talus tubercle is enlarged, it can be debrided arthroscopically or endoscopically. Consequently, patients should start to move their ankles within 24 hours of surgery to avoid the recurrence of scar tissue and pain in the back of the ankle. Around 10-14 days, a progressive return to dance and sports begins. Full recovery can take ten weeks or more.

In our hands, open surgical treatment via a lateral approach has also been extremely successful. Moreover, a small incision of 3-4 cm is made on the outside of the ankle between the fibula and the Achilles tendon. Overall, the Os Trigonum is simple to remove. Following surgery, the patient is immobilized for 3-4 days to allow the skin to heal before allowing an early range of motion to prevent scar tissue formation. In as little as 10-14 days, you can resume sports and dance. A complete return can take ten weeks or more.

Arthroscopic Technique

Arthroscopy is a surgical procedure that examines and treats the inside of a joint, such as the foot, using a camera and instrumentation inserted through small incisions typically one centimeter in length (called portals). The procedure is typically carried out through two small portals.

The advantages of arthroscopy over traditional open incisions include.
Prompt rehabilitation.
An accelerated rehabilitation program.
Less pain and bleeding.
Lower infection rate.

Following surgery, doctors will place a splint or boot on the foot/ankle that was operated on. You don’t put weight on the foot/ankle that was operated on until your surgeon says you can. Athletes typically return to play eight to twelve weeks after posterior ankle arthroscopy and OS Trigonum excision, but this time can certainly vary.

Recovery and Complications of OS Trigonum Surgery

Finally, all surgeries have the risk of complications. These can occur as anesthesia risks, infection, nerve, and blood vessel damage, and bleeding or blood clots. In addition, two major sensory nerves on either side of the back of the ankle are at risk. Our Experts will ensure that there are no problems. Healing typically takes 4-6 weeks, but depending on their activity level, some people may experience discomfort for several months. Patients who have surgery usually wear a surgical boot for 2-4 weeks to allow the tissues to heal. Activities can be resumed as symptoms allow, though it may take 3-6 months to be able to run and jump comfortably.

Conclusion

A child’s foot requires treatment by a pediatric orthopedic doctor or surgeon who understands the complex workings of the bones, tendons, ligaments, and muscles of the foot or ankle. Medical City Children’s Orthopedics and Spine Specialists with offices in Arlington, Dallas, Flower Mound, Frisco, and McKinney, TX are familiar with the latest surgical techniques for even the most difficult fractures to treat, including OS Trigonum problems. Our orthopedic specialists provide individualized treatment programs that cover every aspect of your care, including diagnosis, treatment, rehabilitation, and aftercare. The type of condition your child has and the location of the injury will determine the course of treatment.

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Footnote:

Foot Health Facts: OS Trigonum Syndrome

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