Applying Biomechanics in Key Surgical Scenarios

Jayson Atves, DPM:

I'm Dr. Jayson Atves. I am a board certified foot and ankle surgeon. I practice out of Georgetown University Hospital in Washington, DC.

For any type of a joint fusion, or effectively bone work in any way, shape or form, really it's the severity and location of their deformity. And perhaps the stereotypical example of that is somebody with Charcot in the various stages we tend to see it, as well as in various locations. But effectively a Charcot patient is someone who has gross or severe instability, severe deformity that is of an osseous nature. Certainly they also have soft tissue contracture and other deformities as well, but primarily looking at the actual deformity and its nature. With a physical exam, with imaging, and perhaps supplemented with a gait exam, depending on the patient, is extraordinarily important.

But on top of that, some of the primary things that I'm looking at are their labs. So drawing their A1C, their vitamin D, PTH, calcium, those things give me an idea of what their bone physiology is. Which for myself is something that we may delay surgery before we can actually correct those things and get them to a better point in time, so that we can more predictably expect that the bone work that we're going to do, especially a fusion, is actually going to work out for them in the end of the day.

Tendon transfer is something that I do quite a lot of. It is based largely in the soft tissues. Again, we're looking for deformity of some nature, whether it is based off of the location or the plane of deformity. A perfect example is patients who have some type of either insufficiency, for instance in their peroneus brevis tendon. They can develop more of a varus type of a foot, where we're seeing overloading of the lateral column. Or individuals who have lost their peroneus brevis, and basically the agonist and antagonist nature of the tendons that we have in our foot. I find that the posterior tibial tendon tends to be more of a deforming force when we've lost the peroneus brevis tendon.

So in those instances we tend to either lengthen or eliminate the posterior tibial tendon in order to correct our varus deformity. And we do that with an anterior tibial tendon transfer. So long and short of it, they have to have mobile joints, they have to have a tendon or tendon complex that's actually functioning, which at the end of the day, with people with neuropathy or more complex patients, we absolutely need to confirm so that we know that our tendon transfer is going to work for them.

Perhaps the most pervasive deformity that we're going to see, or any foot and ankle surgeon is going to see, whether it's in isolation or part of another pathology, is really ankle equinus. Our physical exam can certainly tell us a lot about that. The Silfverskiold test is basically the gold standard, but supplementarily with a gait exam just seeing how the presence of ankle equinus can affect locally the foot and the ankle, as well as perpetuate itself up through the rest of the leg, the rest of the body. Evaluating an individual in both straight ahead or more of a frontal plane view, as well as a side or sagittal plane view, gives me a lot of information for how their foot and ankle complex is functioning, how the rest of their body is perhaps compensating. And again, that can just really tell us an enormous amount of information for whether or not we actually have to do some type of surgery, or if we can make accommodations with shoe gear.

But to be honest with you a lot of these types of things, especially ankle equinus, can be very subtle. So these are changes that are not necessarily jumping out at us and screaming, oh my gosh, this is exactly what it is. And I think that that's the crux of all of it, especially for ourselves, is that in the absence of a huge or grand deformity or gait abnormality, we really have to play detective here and really seek out these very subtle deformities, so that we can correct them and expect that a patient may either heal or not go on to forming some type of a wound or complexity.