Foot + Ankle Problems + Treatments

Posterior Impingement / Os Trigonum / Trigonal Process

What is Posterior Impingement?

Os Trigonum causing posterior impingement on X-ray

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Posterior ankle impingement syndrome causes posterior ankle pain. It typically occurs in a position of forced plantar flexion (foot pointing downwards). This form of ankle pain may occur with an acute onset such as a traumatic injury or it may occur in a chronic fashion with gradual onset. The x-ray above shows Os Trigonum causing posterior impingement.

Posterior Impingement: The Causes

The most common cause is pathology of the trigonal process or the os trigonum, but other common causes also include flexor hallucis longus (FHL) tenosynovitis, ankle cartilage lesions, subtalar joint cartilage injuries, and fractures.

Push-off maneuvers, particularly with the ankle in plantarflexion, are typical of this disorder. The diagnosis is made primarily based on physical examination and by patient history, and imaging studies such as MRI, CT scan, and plain x-rays are helpful in making the diagnosis.

Treating Posterior Impingement / Os Trigonum / Trigonal Process

If symptoms do not improve with immobilization and injections, surgical treatment with a minimally invasive posterior arthrosocopic technique may be required.

Arthroscopy is a surgical procedure in which the inside of a joint, such as the foot, is examined and treated using a camera and instrumentation that are inserted through small incisions typically one centimeter in length (called portals). Two or three small portals are typically used to perform the procedure. For more information about ankle arthroscopy is available in the Patient Education of Dr. Carreira’s website.

Video of Posterior Ankle Arthroscopy

The above video of minimally invasive arthroscopy procedure for the treatment of pain in the back of the ankle and foot is performed through two small incisions in the back of the ankle and foot. Excess bone was removed which was causing posterior impingement, which resulted in pain and catching or snapping.

Video of Hindfoot Arthroscopy and Endoscopy

In this video of minimally invasive arthroscopy procedure, posterior impingement is treated through two small incisions, approximately an eyelash in size.

Compared to traditional open incisions, the advantages of arthroscopy include earlier rehabilitation, an accelerated rehabilitation course, less pain and blood loss, and a lower rate of infection. Additional procedures may be performed based on the abnormalities found at surgery.

Posterior Ankle Impingement Video

The above video demonstrates both an outside view and an arthroscopic view simultaneously. The patient is in the prone position and the entire is performed through two arthroscopic portals that are approximately the size of a pencil eraser. The same approach is used for different diagnoses including os trigonum, trigonal process, FHL impingement and other more rare diagnoses of the back of the ankle and foot.

Photos of Posterior impingement / Os Trigonum / Trigonal Process

Posterior impingement/ Os Trigonum/ Trigonal Process photos are shown in the album below.