Dispelling The Misconceptions About Subtalar Arthroereisis

Michael E. Graham, DPM, FACFAS

   As time progressed, foot surgeons continued to push the envelope to include more active adults with further success. Adults need this procedure as much as any other age group. The problem with instability of the subtalar joint complex is that even though the pathologic condition is present, it may take decades before there are symptoms in the hindfoot.

   Myth: Surgeons should not perform subtalar arthroereisis in pediatric patients. In contrast, many foot physicians believe one should only perform this procedure in patients once they have achieved skeletal maturity. The thinking is that the device could lead to stunted osseous growth, leading to more damage as the child grows.

   This is simply not true. The sooner the subtalar joint complex stabilizes, the sooner the excessive forces on the musculoskeletal tissues are eliminated. This prevents the cumulative trauma disorders inflicted on these tissues with every step taken.

Clarifying The Long-Term Effects Of Arthroereisis

Myth: Subtalar arthroereisis stents will lead to arthritis within the sinus tarsi later in life. The sinus tarsi is devoid of cartilage and is instead filled with ligamentous tissue, the function of which is to limit the amount of excessive motion of the talus on the calcaneus. Since arthritis is the chronic inflammation within a joint and the sinus tarsi is not a joint, a sinus tarsi stent cannot lead to arthritis within the sinus tarsi.

   A subtalar arthroereisis procedure is not joint destructive since it is completely extra-articular. After a thorough search of peer-reviewed literature on subtalar arthroereisis, I could not find one article on the development of “arthritis” within the sinus tarsi after the use of a sinus tarsi implant.

   Myth: After the child grows to skeletal maturity, one can remove the sinus tarsi device and maintain osseous correction. This has never been proven as a stand-alone procedure. Many times after removal of the devices, the foot maintains correction. However, some overlook the fact that these patient also underwent other adjunctive osseous and/or soft tissue procedures. Any time I have removed the sinus tarsi device, over time the talus once again ended up slipping out of alignment. One needs to leave these devices in place so they can perform their function.

   Myth: As children age, they will need a larger device since the bones will have grown larger. There are no pediatric or adult-sized sinus tarsi devices. According to GraMedica, the manufacturer of the HyProCure sinus tarsi stent, the most common size of the HyProCure sinus tarsi device in the adult foot is size 7. This is followed by size 6.

   These two sizes account for more than 70 percent of sinus tarsi stents used all over the world.1 Therefore, if a child receives a size 6 or 7, he or she already has the most common adult sized stent.

   We know that by the age of 3, the surrounding osseous chambers of the sinus tarsi have developed yet the growth plates of the talus and calcaneus are still open. This means that the overall dimensions of the sinus tarsi will stay the same yet the bones themselves will continue to grow. Most likely, once the surgeon places the stent into the pediatric foot, the stent size should not change.

Distinguishing Among Sinus Tarsi Stent Designs

Myth: All sinus tarsi stents are the same. There have been many different designs throughout the past decades and for good reason. The sinus tarsi is angulated in an oblique fashion. There are two sections to the sinus tarsi: the outer, more open area referred to as the sinus portion of the sinus tarsi and the deeper, narrower portion called the canalis.

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