Extremity Reconstruction’s Game Changer: Weight-Bearing CT Imaging

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New CT extremity system has the potential to refine clinical skills, create new surgical techniques, and offer greater intelligence for more predictable outcomes.

By Dr. Lew Schon, M.D. FACS, The Johns Hopkins University School of Medicine and at  Georgetown School of Medicine.

Editor’s note: Dr. Schon’s cases were acquired during the research phase for our OnSight solution under IRB. Now that the system is for commercial sale, many customers are using OnSight for similar diagnostic purposes.

As a foot and ankle specialist in practice for 28 years, I’ve been involved in a lot of innovation and technology changes.  At AAOS earlier this year, I had the opportunity to present one of the most exciting innovations for extremity reconstruction in the last 20 years – the CARESTREAM OnSight 3D Extremity Imaging System.

I am eager to share what this technology for capturing weight-bearing CT images means for foot and ankle surgeons, and what the clinical world will look like in 5 or 10 years as a result. I believe it is the wave of the future. Which is why, with fellows across the country, I’ve been researching the CARESTREAM OnSight’s role in the clinical landscape.

Here are just four of the orthopaedic advantages:

1. A full dedicated and portable platform for a broad range of MSK / ortho / rheum imaging
2. Weight-bearing imaging with an open, comfortable bore
3. Artifact correction lets you see around fixation techniques better than a conventional MRI
4. Improved soft-tissue resolution of ligaments and tendons than a conventional CT lessens the need for an MRI to assess bone morphology, density, and alignment

How can these advantages change technique?

Just one example is joint space morphology. We typically don’t look at this because we can’t see the exact mapping of cartilage and bone on the X-rays or MRI.  Where is it thin?  Where is it most dense? Where has the cartilage eroded? Weight-bearing CT with improved soft-tissue resolution will give us a detailed map to allow us to refine techniques for knees and ankles in the future.

Flat foot evaluation

3D imaging helps determine the axes of the flat foot.

In research projects, we’ve also studied flat foot and syndesmotic measurements. Currently, the standards we’ve built for our pre-op and post-op cases are less than ideal. To determine the angles we need to look at in a flat foot, we draw lines on a 2D representation of a 3D structure of weight-bearing X-rays.

But now with the OnSight System, we have 3D information to determine the axes of the flat foot. This allows us to generate reproducible and reliable measurements, and compare what we see happening clinically on the foot with what we know is happening on the CT. We can now track the mal-alignment and correlate the image that best matches the clinical observer alignment. You can see clinical images for this evaluation technique for flat foot in this video.

Syndesmotic measurements

X-rays are insufficient to detect syndesmotic injury. It is difficult to tell if it is truly reduced when you’re taking a 2D image of something that has a lot of variability in terms of rotational and translational dimensions. This can leave a patient with a mal-reduced syndemosis.

We found that weight-bearing CT can produce reliable and accurate measurements to help orthopedic clinicians consistently assess the outcomes of surgery. The measurements include diastasis, rotational mal-alignment, translational mal-alignment, coronal measurement, and talus related measurements. Watch this video to see five syndesmotic cases presented at AAOS.

Weight-bearing extremity imaging can produce reliable and accurate measurements.

I believe that weight-bearing CT technology will have a path similar to MRI. Twenty years ago when MRI was introduced as a tool in orthopedics, no one imagined it would now dominate as an imaging technique in foot and ankle, but it completely changed our clinical approach.

Now as our specialty explores weight-bearing CT, we will learn more clinically, refine our skills, create new surgical techniques and look at outcomes in a more predictable fashion. As a result, weight-bearing CT technology will be a game changer for extremity reconstruction.

#extremityreconstruction #OnSight #orthopedic See Dr. Schon’s full AAOS presentation here.

Dr. Lew Schon, MD FACS, is an orthopedic surgeon, fellowship trained in foot and ankle reconstruction, from Medstar Union Memorial Hospital in Maryland. He is an internationally recognized expert and innovative designer of new surgical techniques and orthopedic devices. Dr. Schon also serves as an Associate  Professor of Orthopaedic Surgery at The Johns Hopkins University School of Medicine and at  Georgetown School of Medicine. In addition to his clinical practice, Dr. Schon is an award-winning researcher and investigator. He founded the Orthobiologic Laboratory, supported by the Innovation Fund, where he and his team work together toward the singular goal of improving patient care and outcomes through research, education, and discovery.  Dr. Schon’s special interests include tendon disorders, deformities, fractures and ligament injuries, sports injuries and dance medicine.

Read the related blog by Dr. Bryan D. DenHartog, M.D., orthopedic surgeon to learn how 3D extremity CT imaging has changed the way he treats and evaluates patients.

And learn more about the CARESTREAM OnSight 3D Extremity System!