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Tag Archives: CT Imaging

CurveBeam CT Imaging Technology is Right On Point

Ballet is an art of extremes. As such, the risk factors are high among dancers for developing chronic injury and weakened tissues throughout the lower half of their bodies. About 60% of ballet injuries affect the legs, hips, ankles or feet. Lateral ankle sprains and Posterior Ankle Impingement Syndrome, or the pinching sensation felt during repeated floor or barre work as the heel bone comes into contact with the talus bone, are chief among them.

By the age of 12, ballet dancers are generally considered ready to begin learning the en pointe technique which utilizes the unnatural convergence of the tibia, talus, and calcaneus to lock the ankles in place.

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pedCAT weight bearing CT scan of a ballerina en pointe.

While we do know this position may facilitate injury, prior to the advent of advanced CT imaging podiatrists had no method of accurately determining the exact anatomical position of either bones or tissue in this position.

CurveBeam, founded in 2009, designs and manufactures Cone Beam CT imaging equipment for the orthopedic and podiatric specialties. In 2012 CurveBeam’s pedCAT system received official clearance from the FDA, and in 2013, CE Mark approval. With the implementation of tools such as the pedCAT and CubeVue, CurveBeam’s custom visualization software, researchers finally have the capability to help ballet teachers better understand the demands of this position before introducing it to young students.

en pointe sag
pedCAT weight bearing CT scan of a ballerina en pointe

Pointe technique, when examined through an advanced imaging system, reveals the posterior portion of the talus resides beyond its articular surface, while the posterior portion of the tibia’s articular surface leaves the articular surface of the dome to rest on the posterior talus. The three bones converge. According to Dr. Jeffrey A. Russell, Ph.D, A.T., FIADMS:

“Attaining the full en pointe position requires contributions from movements between the bones in the foot. Examples of such movements include sliding between the talus and the navicular, the navicular and the medial cuneiform, and the medial cuneiform and the first metatarsal. These small increments of motion combine to provide approximately 30% of the plantar flexion range.”

pedCAT weight bearing CT ballet
pedCAT weight bearing CT scan of a ballet dancer en releve.

“In addition, it is noteworthy that the talus shifts slightly anterior from under the tibia as the ankle-foot complex moves en pointe. This subtlety arises because the converging tibia, talus, and calcaneus form a fulcrum that applies an anterior force to the talus, somewhat like a watermelon seed being squeezed from between one’s thumb and forefinger.”

Recently, Dr. Russell took to an advanced open MR scanner to review the upright and weight bearing position of uninjured ankles in six university-level dancers who had been dancing for an average of 13 years, and dancing en pointe for an average of seven years.

“All exhibited several traits in their ankle MRIs: the posterior portion of the articular surface of the tibia rested on a nonarticular surface of the posterior talus; the synovial sheaths of the flexor and fibularis tendons collected fluid; Kager’s fat pad was impinged by the posterior tibial plafond; and small ganglion cysts were apparent in one or more spots around the ankle and proximal foot.”

pedCAT weight bearing CT ballet
pedCAT weight bearing CT scan of a ballet dancer en releve

It’s an interesting find, and begs the question: do these conditions increase the likelihood of ballet dancers developing ankle osteochondritis or osteoarthritis?

Not only do advanced imaging systems such as the CurveBeam pedCAT – which was not used in this particular study – reveal the bones’ proper anatomic alignment, but they also enable a close investigation of cartilage quality, which isn’t possible with traditional MR imaging. Bilateral, weight bearing three-dimensional views of the foot and ankle are therefore the most cogent means for specialists to create comprehensive treatment regimens and surgeons to better visualize their surgery plans for better operation outcomes.

Most importantly, however, is Dr. Russell’s recent study confirms the use of orthopedic imaging to examine pointe dancers’ ankles in detail will only continue to offer more insight into the demands placed on the ankle by dancing in this way, ultimately leading to safer instruction, more accurate treatment of injuries, and faster recovery times.

Webinar Summary: Advanced CT Imaging in Foot and Ankle Surgical Considerations

We all know that X-rays and MRIs aren’t the be-all, end-all of diagnostic imagery.

Try determining the frontal plane rotation of the sesamoid and first metatarsal with an X-ray. It isn’t possible. Correction of the hallux valgus rotation in bunion surgery depends largely on the repositioning of the sesamoidal apparatus which is impossible to assess without an axial view, and X-rays fall completely short when it comes to assessing these relational details from the vantage point of a single plane.

Such was the topic of discussion during the latest Curvebeam webinar led by Dr. Bob Baravarian, Director of University Foot and Ankle Institute in Southern California. He explained how weight-bearing 3-dimensional CT scans are changing the game of podiatric diagnostics.

Throughout the webinar, titled “Advanced CT Imaging in Foot and Ankle Surgical Considerations,” Dr. Baravarian offered a very straightforward presentation of the often-not-so-straightforward complexities of foot and ankle deformities and how advanced imaging technology can improve both surgical planning and surgical outcomes. He cited the example of hallux valgus among many others as “impossible to imagine treating without 3-D imaging technology” these days – given the results he’s seen with his patients and scope webinar 3of its applications.

Planning the frontal plane correction of first metatarsal.

“CT scans are very helpful in planning your frontal plane deformity correction of the first metatarsal to get an anatomic position which is really underestimated,” said Dr. Baravarian.

Multi-plane imaging now allows physicians to correct the frontal plane deformity of the metatarsal while simultaneously realigning the sesamoid. The capability is “critical,” said Dr. Baravarian, “for proper outcome with bunion corrections whether you’re doing a LAP or any kind of osteotomy.”

Identifying the cause of hypermobility of the first ray

When you look at a patient who has a significant flat foot deformity and a significant bunion deformity with some level of hyper-mobility of the first ray, 3D CT imaging allows you to locate the exact area in need of correction.

“In patients who have PTTD or even a pediatric flat foot case we really need to decide which planes of correction make the best sense,” said Dr. Baravarian.  “If I correct my first metatarsal, is my hind foot going to realign or is there an outstanding deformity that needs correction?”

webinar captureDetermining the level of arthritis in hallux rigidus and limitus cases. 

“I’m constantly surprised when I go into surgery and I plan a cheilectomy and I open up a joint and there’s significantly more arthritic changes or some kind of osteochondral legion that I couldn’t really see on the X-ray. Or, I plan to do an osteotomy and I go in and the level of arthritis is not as bad as expected,” said Dr. Baravarian.

It’s very difficult to determine the level of arthritis in a hallux rigidus or limitus case based on a radiograph alone. While MRIs are an excellent option for soft tissue imaging and diagnostic ultrasounds still provide accurate, real-time guidance for proper injections –neither of these methods makes sense for treating anatomic alignment and assessing structural deformities.

 

“With a 3D CT I’m able to look a little more in-depth into the joint and make a better decision prior to surgery.”

Identifying major deformities in complex fractures

Weight-bearing imaging systems allow you to place a foot in its anatomic position and adjust its deformity to see what level of correction you can get across multiple planes.

It “doesn’t makes sense,” according to Dr. Baravarian, “to plan the correction of a complex fracture without a sense of what’s going on inside the foot and ankle.”

Our traditional method of two-dimensional x-rays doesn’t provide the highest level of certainty that doctors need in order to administer the best care possible to their patients where deformity planning is essential for proper surgical outcomes.

Now, with the help of tools such as the pedCAT, a compact 3D weight-bearing CT imaging system, podiatrists have everything they need to create comprehensive treatment plans and more effective surgeries. Better outcomes. Less risk. And patients back on their feet faster than they ever expected.

You can access the entire webinar here. A FOOT Innovate membership is required to access the content. Membership is complimentary for foot & ankle specialists.