ISO 13485 Certified | ISO9001 Certified Request more information or an in-office demo (267) 483-8081

pedCAT: Visualizing the Sesamoids in a Hallux Valgus Deformity

rotated sesamoids

Dr. Robert Weinstein, DPM,  recently lectured at The International Foot & Ankle Foundation for Education and Research meeting in Maui, Hawaii, and presented an illuminating finding from his clinical practice: the pedCAT can be a useful diagnostic tool for a very common foot condition.

When it comes to Hallux Valgus, or bunions, a 3D scan could make a major difference in the surgical plan.

Valgus, by definition is a three-dimensional problem, since there is a rotational component, Dr. Weinstein explained.

And “sesamoids, in my mind, drive the whole deformity,” Dr. Weinstein said. “You have to be able to look at them very carefully.”

However, the standard positioning for the “sesamoid view” on plain X-Ray places the patient in an abnormal position, and therefore is not clinically relevant, he added.

“Sesamoid condition is just as important as sesamoid position,” Dr. Weinstein said. “If I see sesamoids that are diseased, it doesn’t matter how good I am at reconstructing those MPJs, that I can get that metatarsal back to zero or two degrees, it’s going to be a failure. So it’s very important to look at the crista and the condition of each of those sesamoids.”

Dr. Weinstein practices at the Ankle & Foot Centers of Georgia.

Dr. Matthew Welck, MD, FRCS, of the Royal National Orthopedic Hospital in London, presented on a similar topic at the AOFAS/IFFAS Annual Meeting in Chicago in a lecture titled, “The Metatarsosesamoid ‘The Empty Crista Sign’ – Could This be a Predictor of Deformity Recurrance after Hallux Valgus Surgery?”

Case Study: pedCAT vs. Radiographs

Surgeons often make assumptions based upon plain radiographs.  But plain radiographs often hide or distort significant radiographic findings due to bony superimposition.

Take, for example, the case below:

A patient sought  a second opinion for the cause of her medial foot and ankle pain.  The treating physician used plain radiographs to diagnose her with posterior tibial tendon dysfunction/partial tear and degenerative joint disease of the 1st, 2nd, and 3rd tarsometatarsal joints.  The treating physician also noted a “chip” of bone on the inside of the ankle.

The treating physician planned on performing a flat foot reconstruction, a posterior tibial tendon repair, and a tarsometatarsal joint fusion.

The physician performing the second opinion noted the patient’s discomfort over the medial ankle gutter was much more significant than over the posterior tibial tendon and the spring ligament.  The patient had minimal discomfort through the tarsometatarsal joints. The physician performing the second opinion ordered a weight bearing pedCAT study to assess the midfoot DJD and to better evaluate the midtarsal joint and ankle joint.  The pedCAT study clearly documented a degenerative process in the medial ankle gutter with a bony impingement.  On secondary exam, the majority of the symptoms arose from the medial ankle gutter.

If the flat foot reconstruction was performed as planned, the talus would have been dorsiflexed and the tibio-talar impingement would have been worsened.  The pedCAT images helped prevent an un-necessary surgery, while directing the physician to the appropriate pathology.

tibio talar impingement
The patient was prescribed a pedCAT diagnostic weight bearing CT scan when the patient sought a second opinion.

To learn how more about how the pedCAT could benefit your patients, contact CurveBeam today.