What Do We Know About Weight-Bearing CT and Surgical Decision-Making?

I'm Doug Richie. I'm a semi-retired podiatrist now. I actually retired from clinical practice 3 years ago. I am a Fellow of the American Academy of Pediatric Sports Medicine, and a Fellow of the American College of Foot and Ankle Surgeons. I practiced for 38 years in Seal Beach, California.

What can podiatrists learn in general from recent research on weight-bearing computed tomography (CT)?

So, weight-bearing CT has opened up a whole horizon for us, not only biomechanists, but surgeons. and apply, enabling us to get a three-dimensional view of the bones of the foot, and relate the relationship of these bones to certain pathologies that we commonly treat. There's been a plethora of new research, using weight-bearing CT. That has challenged many long-held notions and principles that we apply in the surgical setting every day. And so, it's caused us to take pause and reevaluate the results of research. giving us this new insight. That's actually very exciting.

What role do you feel that weight-bearing CT might play in one’s diagnostic and treatment planning process?

That's a very good question. Because I'm not necessarily advocating screening all patients with weight-bearing CT. What I'm suggesting is we take the knowledge gained from recent research, using weight-bearing CT. And then take that knowledge and still rely on our traditional diagnostic methods, but maybe be a little more cautious about how we interpret plain radiographs, or maybe change some of the plain radiographic imaging studies we do to get the same insight we might gain in the case of a weight-bearing CT.

What has the research revealed with respect to hallux valgus deformities and how surgeons choose their procedures?

Yes, I think that's really the most exciting and interesting area for weight-bearing CT. Because a new and very popular trend in hallux valgus surgery is approaching hallux valgus deformity as a 3-dimensional deformity, most notably looking at the frontal plane positioning of the bones of the first ray and the hallux. This awakening, so to speak, or a modifying surgical approach, was really based on so on modified or simulated weight-bearing CT studies that now have been somewhat refuted by true weight-bearing CT studies. And so, while a lot of surgeons jumped on this 3 dimensional, so-called rotational correction of hallux valgus deformity, we need to pause and really look carefully at the most recent research, and by that I mean over the past 2 years about where the frontal plane deformity of hallux valgus, particularly in the first metatarsal, occurs, and how we might address that surgically, or how we may not address it surgically.

What has this research revealed with respect to flatfoot deformities and procedure selection?

Well, the second area of interest, of a large group of researchers using weight-bearing CT is on the adult-acquired flatfoot, actually leading these researchers to rename the deformity, the progressive collapsing foot deformity. And it's actually, in my opinion, given us really interesting insight into perhaps the importance of treating the pediatric flatfoot deformity.

In short, we're learning that the collapse of the medial longitudinal arch is really revolving around the middle facet of what we used to call the subtalar joint.And what's really happening are changes in the talo-calcaneal-navicular joint complex around the sustentaculum tali.

And we're starting to realize we can evaluate children perhaps early on and see what's different. anatomically, with them that may actually lead them to be at higher risk for the adult acquired flatfoot. And so we're seeing some great insights into where the flat foot deformity occurs, and even the changes that occur after some of the more commonly employed surgical procedures.

What might the future hold when it comes to weight-bearing CT in foot and ankle medicine and surgery?

You know, we're really just scratching the surface with what the weight-bearing CT imaging can provide. We're gonna be able to really look at the way the bones of the foot move in 3 dimensions. And I'm really excited to be part of a research team at Kent State University, where we have a large number of images of patients who had hallux valgus deformity, and we took images of their feet in a fully supinated position, and then a fully pronated position, and we can compare the difference between a supinated foot and a pronated foot, and see how the bones shift or change, and actually for the first time using CT, actually measure motion measure motion at key joints. And this is something that we've long wanted to be able to do. And from this I think we're going to get much better insight into the path of mechanics of many different foot disorders.