Os Trigonum: Should You Treat It Surgically?

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Christopher Corwin, DPM, MS and John Sekel, DPM

   Perform deep blunt dissection, following the superior aspect of the calcaneus as a guide. Moving anteriorly along the calcaneus, it is relatively easy to find the os trigonum or avulsion of the posterolateral process of the talus. Remove the fracture fragment with careful dissection, which one can usually perform by pushing osteotomes by hand. Take great care on the medial side of the fragment as the flexor hallucis longus (FHL) tendon lies just medial to the fragment. The tibial nerve is also located on the medial aspect of the FHL tendon. Be aware that moving too medially with the dissection may inadvertently injure the tibial nerve.

   After removing the fragment, one can easily examine the FHL tendon by putting the hallux through range of motion. The surgeon can repair defects in the tendon and one can also examine the tendon for a low lying muscle belly, which may also cause posterior ankle impingement. Intraoperative imaging is valuable in determining that one has removed the proper amount of bone. Physicians should also assess the ankle’s range of motion in order to evaluate for any remaining bony impingement.

   Using a rasp, smooth the rough edges of the posterior aspect. Irrigate the area and then close the subcutaneous tissue with an absorbable suture followed by a running subcuticular absorbable suture to close the skin.

   Apply dressings and a posterior splint with ice. Our protocol includes five to seven days of non-weightbearing followed by 10 to 14 days of full weightbearing in a cast. This allows for adequate healing of the incision curving around the posterior aspect of the ankle. Then progress the patient to a removable walking boot for another seven to 10 days. He or she can remove the boot to do range of motion exercises and aggressive physical therapy. Most athletes resume running four to six weeks after the surgery.

Examining The Advantages Of Surgical Excision

   There are many benefits to surgical intervention. Recovery is relatively quick with a full return to activity. By removing the painful bone via surgical excision, there is a low risk of regrowth or recurrence. Removal of the offending bone addresses the cause of the pain as opposed to just treating the symptoms. Surgeons can also perform the procedure successfully across a wide age range of patients.

   One can minimize the risk of possible complications with careful dissection and appropriate incision placement. Protection of the sural nerve in the subcutaneous fat and avoidance of the FHL tendon help decrease the risk of the most common postoperative complications.

   Active individuals benefit from the surgery as they are able to return to pre-injury activity without pain. Athletes have had no trouble returning to play at high levels of competition. The removal of the excess bone reduces the risk of additional injury or re-injury to the posterior ankle. Patients will be able to perform kicking, dancing, gymnastics and any other activity that requires plantarflexion of the ankle without discomfort.

In Conclusion

   Surgical excision of the fractured posterolateral process of the talus or the symptomatic os trigonum is a safe, effective option for patients with pain and limitations of activities. The relatively quick healing time frame, the limited surgical exposure required, the ability to treat the cause of the problem and the high success rate of the procedure make surgical excision an effective alternative to conservative treatments.

Dr. Corwin is an Associate of the American College of Foot and Ankle Surgeons. He is in private practice specializing in sports medicine in Media and Phoenixville, Pa.
For related articles, please visit the archives at www.podiatrytoday.com

No. John Sekel, DPM, says surgery is a last resort as the majority of patients can attain relief from symptoms with conservative therapy such as offloading and orthoses.

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Anonymoussays: February 10, 2010 at 4:03 pm

I have a patient that I am treating for Os Trigonum Syndrome except the Os Trigonum appears to be fused to the calcaneus just posterior to the lateral process of the talus, is this still considered an Os Trigonum? B/L views show a similar presentation on the opposite foot. This patient also has significant peroneal subluxation with audible popping and there is Talo-navicular joint spurring and DJD are these findings linked to the chronic effects of a lack of plantarflextion secondary to the Os Trigonum?

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