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What is Endoscopic Os Trigonum Excision?

Endoscopic os trigonum excision is a minimally invasive surgical procedure to remove a painful tiny bone at the back of the foot known as the os trigonum.

Endoscopic refers to the surgery being performed using an endoscope - a thin tubular instrument with a camera, light, and a magnifying lens attached at the end - that is used to inspect the internal structures of the rear of the foot.

The surgical procedure involves making two small surgical incisions behind the ankle and passing an endoscope and special instruments through the incisions to remove the bone and soft tissue that is causing the problem.

Anatomy of the Os Trigonum

The os trigonum is a small accessory (extra) bone that develops sometimes behind the talus (ankle bone). It is attached to the ankle bone by a fibrous band. An os trigonum can occur in one or both feet at birth; however, it only becomes obvious during adolescence when one section of the ankle bone does not join with the rest of the bone, creating an accessory bone. Only a small number of individuals have an os trigonum.


Os trigonum syndrome is the main indication for endoscopic os trigonum excision. Os trigonum syndrome is a condition in which the accessory bone becomes trapped between the heel and ankle bones causing significant pain. The condition is usually caused by an injury, such as an ankle sprain. The syndrome is also commonly triggered by repeated downward pointing of the toes as in ballet dancers, soccer players while kicking a football, and other athletes. Following the diagnosis of the condition, non-surgical treatment such as activity modification, rest, and medications is often employed to relieve symptoms. When these remedies fail to provide satisfactory results and the symptoms continue to persist, endoscopic os trigonum excision is recommended due to its advantages over traditional open surgery.

Benefits of Endoscopic Os Trigonum Excision Surgery

Some of the benefits of endoscopic os trigonum excision surgery over traditional open surgery include:

  • Less post-operative pain
  • Less scarring
  • Less blood loss
  • Less damage to the surrounding tissues
  • Shorter hospital stay
  • Smaller incisions
  • Minimal muscle trauma
  • Faster recovery
  • Quick return to normal activities

Preparation for Endoscopic Os Trigonum Excision Surgery

Preoperative preparation for endoscopic os trigonum excision surgery may involve the following steps:

  • A thorough examination is performed by your doctor to check for any medical issues that need to be addressed prior to surgery.
  • Depending on your medical history, social history, and age, you may need to undergo tests such as bloodwork and imaging to help detect any abnormalities that could compromise the safety of the procedure.
  • You will be asked if you have allergies to medications, anesthesia, or latex.
  • You should inform your doctor of any medications, vitamins, or supplements you are taking.
  • You may need to stop taking supplements or medications such as blood thinners or anti-inflammatories for a week or two prior to surgery.
  • You should refrain from alcohol or tobacco at least a few days prior to surgery.
  • You should not consume solids or liquids at least 8 hours prior to surgery.
  • Arrange for someone to drive you home after surgery.
  • A written consent will be obtained from you after the surgical procedure has been explained in detail.

Procedure for Endoscopic Os Trigonum Excision Surgery

The procedure for endoscopic os trigonum excision surgery will involve the following steps:

  • You will lie on the operating table in a face-down position with the foot to be treated hanging over the end to allow access to the back of the ankle.
  • You will be typically administered regional or general anesthesia.
  • Your surgeon makes 2 small incisions on either side of the Achilles tendon at the back of the ankle.
  • Care is taken to avoid any harm to surrounding structures such as nerves and vessels.
  • An endoscope is inserted through one of the incisions. The endoscope is connected to an external monitor and enables your surgeon to visualize the condition of the os trigonum and its surrounding structures on the monitor as the scope is advanced along the treatment area.
  • Your surgeon passes small miniature surgical instruments through the other incision and the abnormal bony prominence (os trigonum) along with any other soft tissue causing impingement are excised while looking at the monitor.
  • After satisfactory repair is confirmed, the scope and the instruments are withdrawn and the incisions are closed and bandaged.
  • Your surgeon will then place your foot in a plaster splint or boot to facilitate healing and protect the treatment area.

Postoperative Care and Recovery

In general, postoperative care instructions and recovery after endoscopic os trigonum excision surgery will involve the following steps:

  • You will be transferred to the recovery area where your nurse will closely observe you for any allergic/anesthetic reactions and monitor your vital signs as you recover.
  • Keep the foot elevated at or above the level of your heart to help minimize swelling and discomfort.
  • You will be prescribed medications for pain relief and for prevention of deep vein thrombosis (DVT) as needed.
  • Antibiotics may also be prescribed as needed to address the risk of surgery-related infection.
  • You will be provided with crutches to ambulate safely as soon as you feel comfortable.
  • The sutures and boot/cast are removed after two weeks, and you are encouraged to begin physical therapy exercises to strengthen ankle/foot muscles and improve range of motion. Full recovery and healing of the foot may take 8 to 12 weeks.
  • Keep the surgical site clean and dry. Instructions on surgical site care and bathing will be provided.
  • Refrain from strenuous activities for the first few months and lifting heavy weights for at least 3 months. A gradual increase in activities over a period of time is recommended.
  • You may return to sports once the leg has regained its normal strength and function, and with your surgeon's approval.
  • A periodic follow-up appointment will be scheduled to monitor your progress.

Risks and Complications

Endoscopic os trigonum excision surgery is a relatively safe procedure; however, as with any surgery, some risks and complications may occur, such as the following:

  • Infection
  • Bleeding
  • Damage to surrounding structures
  • Thromboembolism or blood clots
  • Anesthetic/allergic reactions
  • Persistent pain
  • Muscle weakness

Pathway Foot & ankle center hme
3100 Sam Rayburn Hwy
Melissa, TX 75454
Mon - Thu: (8am - 5pm)
Friday: (8am - 3pm)
Saturday: 9am – 12pm (By Appointment Only)