Vince v. Hungerford on Correcting Extra-Articular Deformity

Extra-articular deformity? Go intra-articular for the correction, says Kelly Vince. Not so fast, counters David Hungerford…there are many kinds and sources of deformity: congenital, metabolic, traumatic, and surgical, and what is the magnitude of the deformity, and the location from the knee, etc. There are multiple considerations.

This week’s Orthopaedic Crossfire® debate is “Extra-Articular Deformity: Always Correctable Intra-Articularly.” For the proposition was Kelly G. Vince, M.D., F.R.C.S.(C) from the University of Auckland in New Zealand. Against the proposition was David S. Hungerford, M.D. of the Johns Hopkins University in Baltimore; moderating was Steven J. MacDonald, M.D., F.R.C.S.(C) of the University of Western Ontario. 

Dr. Vince: “I like to correct these deformities inside the joint. Extra-articular deformity is a limb deformity with implications for the joint; it should be easy to solve. When it comes to varus-valgus alignment issues it’s the mechanical axes that we must examine. When it comes to flexion-extension problems, we can ignore most of them. The mechanical axis: center of knee, center of hip, center of ankle. And the anatomic axis just drifts and melts away because it is distorted.”

“Sagittal deformities: you get an imposing looking X-ray and you’re not sure what to do. The secret is that this patient bends well and extends well, and we should probably just ignore it—like fracture work, it’s in the plane of the joint. For the next phase of planning, you need full length X-rays.”

“We only need that femur film. We draw the mechanical axis, the bone cut should be at right angles to it, and you can set your IM [intramedullary] guide accordingly. If you have navigation it makes everything simple. It requires a bit more attention to the soft tissue surgery, but results in a postoperative result with a restoration of the angle that you would like.”

“Some of them look intimidating—until you draw that simple angle that goes from the center of the head to the distal femur, and at right angles. When it comes to tibial extra-articular deformities these are straightforward because our extramedullary cutting guides span the joint and tibia, and correspond to the mechanical axis.”

“Surgical technique: the alignment of the new arthroplasty comes simply from the component position and the bone cuts. Then things get a little challenging in that we must do ligament releases and possible constraint…and in very few cases I have done ligament advances and even ligament reconstructions. Consider a gentleman with a midshaft femur fracture. There’s a little more valgus in the distal cut…and requires having to do a little more release of the medial collateral ligament.”

“Another patient with bilateral femur fractures…really impressive malunion that nobody wants to revisit. She was unable to accept blood transfusions, and I didn’t want to do two operations—four because it’s bilateral—and I didn’t want her to have blood loss at one surgery. So we did it all intraoperatively with aggressive releases, and supplemented things with a non-linked constrained device.”

“At times I’ve done ligament advances—Ken Krackow’s technique—which I’ve modified very slightly. At times I’ve done ligament allografts including an Achilles tendon that’s anchored below the tibial component, and goes through a drill hole in the femur.”

“When it comes to the limits of correction, there is a paper from Taiwan which was inspired by John Insall. They say that they can’t do a distal femoral cut if it goes through the attachments in the collaterals—and that makes sense. What I would do is cut a little more distal, and carry on. And then they said they won’t do the correction if it doesn’t correspond to the tibial axis. It wouldn’t bother me to make that cut—center of knee to center of ankle—and then do a rebuilding of the bone.”

“A case I did in Australia: because I wanted to have the options of constraint and fixation, I actually did an osteotomy along with the case so that the stem could go up the canal, and I’d have those options. How simple can it be with intra-articular correction? But if you correct the osteotomy the hip has to get accustomed to a whole new range of motion—and you’re going to have to do some pretty daunting surgery at the knee as a result. In conclusion: keep it simple.”

Dr. Hungerford: “I think the operative word in this discussion is ‘always.’ Kelly already proved my point in that he showed a case in which he did an extra-articular correction. So if we come to the conclusion that there will be cases where an extra-articular deformity should be corrected extra-articularly, the question is, ‘How do you make that decision?’”

“The question is, ‘When do you do intra-articular and when do you do extra-articular?’ In most deformities, the deformity is because of intra-articular bone loss, and it doesn’t make any difference how much that is, it can always be corrected intra-articularly. When you get to extra-articular deformity you have lots of kinds and sources of deformity: congenital, metabolic, traumatic, surgical.”

“The issues: the magnitude of the deformity, the location from the knee—a deformity that is close to the knee has almost a 1-to-1 degree deformity of the knee itself, whereas an extra-articular deformity near the hip or ankle has very little impact. Also, is it medial or lateral? Is the femur involved, or the tibia? The malalignment on the knee when it’s supracondylar is about 20 degrees, whereas when it’s subtrochanteric it’s almost zero. Same with the ankle. If you have a big deformity at the ankle you might want to do something, but it has very low impact on the knee unless it’s close to the knee.”

“The varus deformity requires a lateral resection, so in this case you have a laterally based wedge…and this becomes an issue in making this decision. With a valgus deformity you’ll have a medial based wedge intra-articularly to correct the deformity.”

“Femoral and tibial intra-articular corrections are not equal. The femur affects stability only in extension, meaning that you produce instability on the medial side in extension, but not in flexion, therefore the ligamentous alignment that you need to do becomes quite a bit more complex. The tibia deformity that you create intra-articularly to correct an extra-articular deformity affects stability in both flexion and extension, and in those cases ligamentous releases and ligamentous reconstructions are more straightforward.”

“All you really need to do is to template…you’re going to determine the cut that is required, so this automatically takes in account the level of deformity. Lateral over-resection is better tolerated by the simple fact that the lateral side of the joint is dynamically stabilized. So you can tolerate, functionally, lateral instability of a modest degree…where the same degree of instability on the medial side is not well tolerated.”

“Some deformities which are multifactorial—lateral translation, anterior rotation, and severe deformity—are much better taken care of by an osteotomy. In one patient who had a high tibial osteotomy for varus disease, where it’s vastly overcorrected, had good joint space. I decided to do an extra-articular correction back to neutral as the first step. After 15 years she has not yet had a total knee replacement.”

“So you have a decision tree of whether to correct intra-articularly or extra-articularly, and whether it’s a separate procedure or a combined procedure…and then, whether residual deformity is acceptable (and I think that’s not).”

Moderator MacDonald: “Kelly, not everyone is set up with navigation, so you can’t use an IM alignment rod for your femoral resection…take us through how you do that in the OR…an extra-medullary referencing for a standard femoral cut.”

Dr. Vince: “Whether you decide to do an intra-articular correction or the kinds of osteotomies that David has described, get a long film. From that, draw the mechanical axis from the center of the femoral head to the center of the femur (if the deformity is in the femur), and then draw the right angle at the distal part of it. Before navigation, I would draw that line, and if the malunion or deformity was proximal to where the IM guide would go, you would also draw the IM guide on the X-ray and measure that angle. If the deformity precludes the use of IM guides then I’ve gone to intraoperative X-rays to confirm the cut.”

Moderator MacDonald: “Any of you used a technique where you are looking under fluoro with the femoral head and marking the femoral head using that as your guide with a long rod intraoperatively?”

Dr. Vince: “That would be a variation of an intraoperative X-ray.”

Dr. Hungerford: “I would agree with what he said about if you’re going to do this correction and you’ve done your templating and made your mark you can put your distal femoral cutting guide on as to where you think that line ends up, take an intraoperative X-ray and it’s the equivalent of a postoperative X-ray. Most instrumentation systems have the ability to make small corrections if you wanted to.”

Dr. Vince: “Add a spacer block that the alignment rod goes through and stick it in the joint parallel to your new cut on the femur, and look at where that rod hits the femoral head.”

Moderator MacDonald: “David, if you must do a corrective osteotomy, how do you determine when you’re able to incorporate that into your total knee construct or when you’re going to have to do a separate procedure? Or do you get a custom stem?”

Dr. Hungerford: “You don’t have to make a corrective osteotomy at the site of the deformity. You could have a 45-degree malunion of the femur in the midshaft and you could make about a 22-degree supracondylar osteotomy that you could do at the same time as a total knee replacement. In most cases I would like to not subject the patient to two separate surgeries, but I’ve done four or five in which I thought that the patient might well get a significant improvement functionally by having their malalignment corrected to neutral. In all but one of those cases that proved to be true. I had a patient with a segmental fracture with about a 20-degree varus deformity of her tibia at several levels and she looked like she’d be a good candidate for a valgus osteotomy…and that worked for almost 10 years. Ten years later it was a neutral total knee replacement.”

Moderator MacDonald: “Sometimes when you plan these cuts out the soft tissue balancing is a little wonky—not so predictable. Any tips there?”

Dr. Vince: “Look at the patient with a big varus bow in the femur, so you may not be tuned into the fact that they have a big deformity. If you correct that appropriately you’re going to have to do a large medial release or leave them malaligned, overloading the medial side. We want to get the cuts where they should be, do the releases and not be fearful of over-releasing in these cases because we should have planned to have constraint available (or some other plan).”

Please visit www.CCJR.com to register for the 2012 CCJR Winter Meeting, December 12 – 15 in Orlando, Florida.

“You may now view content from the CCJR Meetings on the CCJR Mobile™ App. Please scan the QR code to download the CCJR Mobile App to your Android or iOS mobile device, or visit www.ccjrmobile.com.”