CME OnDemand: 2022 AOFAS Annual Meeting-Paper Session 1A: Ankle Arthritis

Video Transcription

Our first speaker is Dr. Gross and he'll be presenting on severe ankle deformity. Does it affect outcomes of fourth generation total ankle prosthesis?  Hi there.  My name is Christopher Gross. I'm coming to you from the Medical University of South Carolina in Charleston.  And today I'm going to be discussing the results of a prospectively enrolled multi-center  And then we looked at their patient.  our survivorship, our reoperation rate, and a patient reported out.  for stress shielding and aseptic loosening.  Hello, I'm Cody Toger, I'm here today to present research  that I did at my fellowship at the Orthopedic Foot and Ankle Center, investigating stress shielding and aseptic loosening in fully porous coated versus smooth stemmed  tibial implants in total ankle arthroplasty.  Disclosures for all participating authors are up to date on the website for anybody that's interested.  Now we're all well aware of the reported rates of stress shielding in hip arthroplasty literature, there seems to be a lack of studies investigating  the potential for these effects in total ankle arthroplasty, and few studies have actually investigated the incidence of peritibial cystic formation in total ankle arthroplasty.  Therefore, the purpose of this study was to investigate the incidence of tibial cystic formation in a stemmed modular total ankle design,  and secondarily to explore a potential relationship between smooth and fully porous coated stemmed tibial implants, with regards to the rates of periprosthetic cystic formation  as well as their relative risk for reoperation.  And what we're talking about here is a smooth stemmed modular tibial implant, as you can see the base segment does remain porous as does the tibial base plate,  versus a fully or extensively porous coated stemmed tibial implant.  Stress shielding was classically defined in the hip arthroplasty literature as the reduction in bone density as a result of the removal of typical stresses  from the bone by an implant, and we adapted this description in our radiographic definition about the ankle to include new bone trabecular ridging  between the proximal modular stem segments and the cortical shell, coinciding with relative radiolucency and cyst formation about the distal segments and tibial base plate.  This was a retrospective cohort study where we identified a group of patients  who underwent total ankle arthroplasty using only a smooth stemmed design, and then we created a second matched group  We looked at demographic and radiographic information, our biomedical...  That's how we match them. Mean age, kind of similar between all three groups.  There were more revisional cases.  while performing the radiographic review.  to be better visualized with CT.  Again, more well-circumscribed, circular, contained.  And just like the Type I as well, good Osseous interface proximally.  Now it is important to remember that this implant has demonstrated good outcomes with regards to survivorship.  More research is obviously required with regards to  Thank you. The next speaker is going to be Dr. Henry, presenting on risk factors for early mechanical failure in roofing.  Thank you. Good morning. I would like to thank my co-authors, my mentors, and the moderators  for this session. These are our disclosures. We know, and we heard Dr. Kadakia talk this morning, we know that  for failure and we also have to figure out how to choose the optimal implant for each patient.  So the objective for this study was to identify risk factors for early mechanical failure in  modern total ankles and we hypothesized a greater BMI and ipsilateral hindfoot fusion would predict failure while implants with greater tibial fixation would be protective.  This is a review of prospectively collected  We collected basic demographics, operative data, radiographs, and our primary outcome was mechanical failure.  So revision of the tibial and or the tailor component for a non-infectious cause, things like loosening, subsidence, or malalignment.  And the risk factors we analyzed were weight and BMI,  coronal deformity, hindfoot fusion, and tibial fixation type.  From a stats perspective, we performed a Bayesian logistic regression to determine the effect of those risk factors on failure.  And we picked that because it accounts for a small number of failures, but also acknowledges the work that prior studies have released in the literature.  We had 696 patients with a mean clinical follow-up of just over two years. Demographics are there and are quite typical for a total ankle study. In terms of arthritis etiology,  just around three-quarters had a post-traumatic etiology of their arthritis, and 10% had a concomitant hindfoot fusion.  Our mean pre-op coronal deformity was 9.8 degrees, but if you look at the breakdown, just under half of our patients had deformity of greater than 10 degrees,  and 12% had varus or valgus of greater than 20 degrees.  Additional procedures were commonly used to balance the ankle and foot intraoperatively.  And we looked at our revisions. There was a 5.5% rate of all cause revisions, so that includes mechanical and infectious. But broken down, we had 31 patients, or 4.5%,  who had mechanical failures.  We look at what happened with those patients.  Four had tibial...  alignment, a little bit of a mixed bag here. One was converted to a TTC fusion, one was revised, one was converted to a stemmed implant.  We had eight talus only failures, all were converted, or sorry, all were revised using the same implant system. And then our three combined  but it was a weak effect. So 13% greater odds of failure for every 10 kilos a patient was heavier.  We look at hindfoot fusion without controlling for implant type or deformity or weight. The revision rate was higher, although not statistically so,  patients who had higher weights and BMIs, who had hindfoot fusions, who had greater coronal deformity. But even so, the revision rate was significantly lower  among those stem implants. And in our model, there was a 99% probability that stems are associated with 90% lower odds of failure.  So if you put that all together, we have a few scenarios here. So if you take a patient with very few risk factors, 86 kilos, no hindfoot fusion, minimal coronal deformity,  there's really a low risk of failure regardless of the implant choice that you're using. But if you start to add in those additional risk factors,  if they have a concomitant hindfoot fusion, if it's a bigger patient, if there are now 110 kilos, you can see that their risk of failure goes up. Stems can mitigate that risk,  especially in those high-risk patients.  So overall, we can conclude that among modern total angles, short-term survivorship in this study was 95% at two-year follow-up, and that's consistent with existing studies.  In terms of weight, it was a weak risk factor in this analysis. There's mixed data in the literature about the impact of weight on total angles.  We know that higher BMI does increase failures in total hip and knee. It could be that this is a time-dependent variable. It could be that there's a threshold for weight or BMI.  This is a great area for a future study.  In terms of hindfoot fusion, we know from this fantastic article from Dr. Cody and the Duke group, we know the subtalar fusion likely increases the risk of our failure.  We know from the biomechanics studies  that when we fuse the subtalar joint, there's abnormal kinematics across the ankle joint, which probably increases stress of the bone-implant interface.  But again, there's a lot of nuances to this, and we're excited to tease this out in future research.  And then finally, implant type was the most influential factor in this study to predict mechanical failure. Stems were protective, even in patients who had greater weight,  hindfoot fusion, or deformity. It's difficult to know what to make of those keel failures, again, because they all occurred in those size zero patients.  risk factors. Things like how well are you correcting post-operative alignment and other things that might be important. But I will say at our institution we're  trending towards treating patients who are over 100 kilos with stemmed implants, especially if they have additional risk factors. They have severe deformity or  if they have a hind foot fusion. This is a great area for future research from the biomechanical side, from the clinical side, hopefully with  multi-institutional collaboration. So we really look forward to refining and  All right. My name is Jacob Modest, and I come from Brown University. I'll be.  So for some background, I'll go through this very quickly because this is not new to anyone in this room.  But ankle osteoarthritis is a debilitating condition with pain, stiffness, and diminished quality of life. Historically, ankle fusion has been the gold standard.  For the last several decades, total ankle replacement has emerged as a viable alternative with some studies showing improved motion, function, and pain relief.  Several studies have evaluated this. This first study is a meta-analysis of 10 comparative studies from 2007 to 2015.  They found that patient-reported outcomes were equivalent, but there was a higher re-operation and complication rate in arthroplasty.  More recent data has disputed this and found improving outcomes in total ankle arthroplasty. This second study discusses identifying the right procedure for the right patient.  They discuss this as a moving target with evolving implants and improving outcomes. In general, arthroplasty is a better consideration when the patient has a contralateral ankle  fusion or adjacent joint disease in the subtalar or TN joint, and fusion is potentially a better  alternative for patients with neuropathy, younger patients, patients with more deformity,  and then cost analysis does favor fusion. So what have been the prior reported trends? So this first study used the SPARCS database, which is an insurance database in New York  State. They looked in the late 90s to the early 2000s, so they looked in 1997 to 2010, and they found even at this early time window that arthroplasty was increasing.  This second study built on the prior results. They used the same database. They looked from 2005 to 2014.  They found the rate of ankle arthroplasty had increased by 1500% from 11 cases a year to 180 cases a year.  They also found fusion was decreasing by about a third from 900 to 600 cases a year. And finally, this third study is a Pearl Diver database study from 2005 to 2014 also.  They looked at over 20,000 patients. They found nationwide arthroplasty was increasing from about 700 cases a year to 1800 cases  a year, where fusion was decreasing from about 2500 to 1800 cases a year. So overall the share of arthroplasty had increased from about 22% to nearly half of the procedures  at the end of their time window. They also found ankle arthroplasty had shorter length of stay.  It was more common in the northeastern United States, and fusion was more common in medically comorbid patients. So what is the goal of our study?  So we want to review and update these current trends. We want to see is ankle arthroplasty still increasing? Is ankle fusion still decreasing?  What are the patient factors associated with both? And what are the complications between the two? So for methodology we used the SPARKS database from 2009 to 2018.  It's an insurance database. We analyzed ICD codes for diagnosis and CPT codes for procedure identification.  For variables we looked at procedure type, patient variables including demographics, comorbidities, insurance type, and then for complications we looked at 1, 3, and 12 months.  In terms of results we had over 3,700 cases in the 9-year window we looked at. Arthrodesis ranged from about 2 to 300 cases a year.  Arthroplasty meanwhile increased from about 50 cases a year to over 350 cases a year. So in 2009 arthroplasty made up about 16% of procedures, but by the end of the study  in 2018 it made up a majority of 57%. Figure 1 you can see here shows the rapid increase in arthroplasty particularly from 2013 and onwards.  Here is a point around 2016 where arthroplasty actually became more common than arthrodesis  and overall we found that arthrodesis increased mildly by about 25%, but arthroplasty increased by seven and a half fold. When we looked at inverse outpatient claims...  So the inpatient claims on the left we see that sharp increase in arthroplasty accompanied by a kind of slow steady state decrease in infusion procedures.  On the right we see the outpatient cohorts. We see a kind of symmetric increase in both procedures which is more indicative of the  general trend towards outpatient management, not just of ankle arthritis but throughout orthopedics. For patient demographics we had 1,500 patients.  We found those undergoing arthrodesis tend to be younger, tend to be from areas of higher social deprivation.  They were more likely male, they were more likely African-American, and they were more likely to have more medical comorbidities.  This second table shows a similar interpretation showing the odds ratio from the logistic regression we had.  I also want to emphasize that patients with federal insurance or workers' compensation had increased odds of having ankle arthrodesis.  In terms of complications we found that ankle arthrodesis had a higher rate of readmission, acute renal failure, and cellulitis at all time points 1, 3, and 12 months.  There's also an increased rate of UTI at one month and an increased surgical site infection rate at one year in the arthrodesis group.  For length of stay we found patients with federal insurance stayed on average one day longer, those with more than one comorbidity stayed on average one day longer, and those  undergoing fusion stayed on average 0.8 days longer. This is a nice pictorial representation of the disparities analysis we did.  So on the left you can see the social deprivation index with darker areas being more socially deprived areas. It's based on zip code.  And then on the right is the rate of arthrodesis. This gives a nice schematic where you can see the comparison between the two that the  darker areas with higher social deprivation also had higher rates of arthrodesis. So in terms of discussion, overall we found a slight increase of 25% in the fusion rate  in conjunction with a rapid increase of over 7.5 fold in the arthroplasty group. So given the growth of both these procedures and assuming a relatively steady state of  ankle arthritis in the New York state, we're starting to find that arthroplasty may not be replacing fusion as an option.  It may not be helpful in patients but instead may be indicated for in attracting a different patient of populations.  And I want to emphasize this because compared to the prior studies I talked about, all of those studies showed increasing arthroplasty accompanied with a decreasing arthrodesis.  Ours is the first study showing actually an increase in both. So potentially those patients who are opting for non-operative management are now interested  in emotion-preserving surgery. And then what about disparities? So there's certainly been an increased focus on healthcare disparities and unequitable  access to care and orthopedics. This has ranged from pediatric orthopedics to adult reconstruction.  There's more and more studies documenting this problem in the last couple of years. There really is no easy solution. It's most well-studied in the adult reconstruction literature.  And at the systemic level, insurance status certainly plays a big role. Some studies out of the Kaiser Network have analyzed when patients have insurance controlled  for, a lot of these disparities cease to exist. So improving access to care is of utmost importance and decreasing these barriers is  a large mission statement of most orthopedic societies at this point. And hopefully strides can be made in the next several years.  In terms of future work, again, ours was the first study documenting that there may be a new subset of patients that are interested in arthroplasty who were not as interested  in fusion prior. I'm curious to see in the next couple of years if this is a continued trend and to corroborate these findings.  And certainly, as I mentioned just last slide, there needs to be more analysis on this.  Thank you. Our last talk for this session before questions is Dr. Fletcher on comparison of clinical outcomes and complications of simultaneous versus a staged bilateral...  I completed my residency at Duke University, so I would like to thank my co-authors, Dr. Nunley, Dr. Easley, and Dr. DiOrio for their patient population that they let me study  and as well as their continued mentorship.  So we have BOGO, buy one, get one, bilateral.  study was to evaluate the safety and efficacy of bilateral simultaneous versus staged ankle  arthroplasty. Specifically, we sought to compare patients who underwent bilateral simultaneous  versus staged ankle arthroplasty, including perioperative complications, patient-reported outcome measures. And our hypothesis was that these outcomes, looking at both complications  and patient-reported outcomes, would be similar between the two cohorts. There are four previous  reports studying bilateral simultaneous ankle arthroplasty, but these were limited to case  theories as well as comparisons to unilateral cohort of patients. There have been previously  reports comparing, excuse me, there have been no previous reports comparing bilateral staged versus simultaneous ankle arthroplasty, which was our goal in this study. It's important  to study this patient population because it's a unique population with an overall more debilitating  condition. This data has been extensively studied in the knee and hip arthroplasty literature  with non-inferior and even superior perioperative complication rates and patient-reported outcomes.  Other advantages include cost savings, early rehabilitation, and earlier return to work. In terms of cost reduction, both knee and hip arthroplasty literature summarize about  a 25% reduction in cost using this technique, which translates to about $10,000 for each total knee replacement and around $8,000 for each total hip replacement. Looking at  our methods, this data was obtained from our prospective total ankle database, which was  established in 2007. We performed a comparative cohort study of patients who underwent bilateral  staged versus simultaneous ankle arthroplasty from 2007 to 2019. So the simultaneous patients  underwent surgery by two surgical teams operating at the same time in the same operative setting.  And then the staged patients initially presented with bilateral ankle pathology, but underwent  surgery in two separate operative settings performed at least three months apart. Patient  demographics, comorbidities, perioperative complications, reoperations, and implant failures  were collected, as well as the patient-reported outcomes that you can see here. Here's a clinical  example of a patient positioning for bilateral simultaneous surgery. As a technique tip,  we put an arm board in parallel at the distal end of the operative table to increase operative  space. And here's another clinical photo of the two-surgeon bilateral simultaneous technique.  Post-operatively, the patients are immobilized in short-leg walking casts for three weeks. They're allowed to immediately weight-bear as tolerated. They typically stay overnight  for one night inpatient. And then at three weeks, they follow up, and they're  or 100 ankles, half of those underwent simultaneous surgery and half underwent the stage surgery. The average follow-up time was four and a half years and then the mean time  between the stage procedures was 17 and a half months. Here is our patient demographics. A couple important things to note is that there were no significant preoperative demographic  differences between the two cohorts. And then another significant finding is that the, if you look at all comers with ankle arthritis,  the most common cause is post-traumatic arthritis. But in this cohort of patients with bilateral pathology, the most common etiology was primary osteoarthritis.  And here's another busy slide looking at our patient-reported outcome measures. And so all patients improved from preoperative to final follow-up in their patient-reported outcomes.  And there were no significant  just some more patient-reported outcomes. These are the VAS scores, and you can see that the average VAS score at final follow-up was between zero to two.  And then in terms of perioperative complications, this is another busy slide, but I'll highlight a few important.  This is important because most surgeons have reservations letting their patients weight bearers tolerated following ankle arthroplasty and, you know, typically in light of wanting  to protect the incision and protect the, the wound. But all the patients in the bilateral simultaneous cohort immediately weight-beared as tolerated  and did not have any increased wound complications. For intraoperative complications, the simultaneous cohort had one medial malleolus fracture.  The staged had a intraoperative burn with the cautery. So again, with two teams operating in parallel, this could be presumed to be disorganized  with potential safety concerns, but we did not find any increased intraoperative complications in this study.  And then in terms of total complications, the total complication rate was 22 percent for the simultaneous cohort, 20 for the staged cohort, um, which is similar.  And then in terms of, um, in terms of reoperation, it was 12 percent in the simultaneous and 10 percent in the staged.  There was only one, um, failure, um, one implant failure, and that was in the simultaneous cohort and the patient who had, um, AVN.  The two-year re-operation free survival was 96% in the staged cohort, 94% in the simultaneous. Five years, it was 90% in stage, 88% in the simultaneous.  Both cohorts had 100% failure-free survival up to eight years post-operatively until the one patient at eight years had that total talus conversion.  So here's a patient that underwent simultaneous total ankle arthroplasty with a VNR.  review, although the data is prospectively collected, which minimizes selection bias. It is a unique setting where it's a high-volume academic institution that specializes in ankle  arthroplasty, so this may limit the generalizability, as well as the difficulty to reproduce the two-surgeon setting in some institutions.  And then given the limited sample size, this cohort was not matched, and with the  unique population with a higher incidence of primary osteoarthritis. All patients undergoing bilateral ankle arthroplasty showed a significant improvement in pain,  patient reported outcome measures, as well as all other outcomes we looked at, including perioperative complications, reoperation free survival, as well as component revisions,  component failure and survival. So in conclusion, when performed under surgeon expertise and appropriately selective patients,  we advocate that simultaneous bilateral ankle arthroplasty.  And the other question would be, that's 2018.  but just kind of looking at the past.  I've got a question for Dr. Gross.  You had preoperative x-rays defining your two populations. Were there any postoperative x-rays performed looking at the correction in the cohorts?  Or were... Great question  I think that that is  of it, and you might have to think about what other ways can I mitigate failure?  Do I have to use a stem implant?  Do I have to think about my deformity correction? And so I don't think it should be a no-go.  Dr. Topher, could you talk to us a little bit about the height of the stem? Should we be making it more than four, or is two enough? And the other question is, what about fitness?  Good questions. With regards to the length of the stem, we typically, where I trained and the study came out of, we're looking almost 100% actually are all three stemmed implants.  Obviously the base stem segment has to be porous. That's the only option with this company. So I don't have good advice to give you if it should be greater than two or it should  be four just because my sample size and my experiences in all of them have been three  stemmed implants. With regards to fill, we, the way that almost all these implants, there was a preoperative CT and a preoperative CT plan.  We didn't, almost never do we use the patient specific.  Would it be more appropriate to do more of a fit-and-fit?  thinking about how does that early design, because there is some convergence of design features, how does that ultimately affect stability and early success or failure?  So it could be something that we look at.  I think the discussion of weight and BMI is fascinating. So I think that there's a lot of very interesting studies and data out right now that shows that BMI is perhaps not  as scientifically rigorous and not the best cutoff that it should be where it can prejudice against patients just because of how that number was created.  So I actually think if we're talking about load across an implant, I think probably weight is a better and that's what our sensitivity analysis showed.  I don't think BMI is a good surrogate for comorbidity or health status. I really think it should be abandoned and I think that if we want to talk about load over an ankle,  weight is what we mean. I mean, so I think that there probably should not be a BMI cutoff. I think that weight is a good surrogate for co-morbidity  I have a question for Dr. Fletcher, what's the standard of care at Duke now, what's best for the patient?  I tell my patients that and they say no, they'll do one at a time.  Yeah, so they have done okay, there hasn't been any falls or any complications with the cast. The patients do have the opportunity in the discussion to go to preoperative care.  They're bilateral short-leg casts and they're a little shorter than typical short-leg casts  and they've done well.  And is the initial, is it initial cast?  Yeah, I think the question becomes, how many of you would like two separate surgeries if this...  I don't encourage...  BMI was not significant in your analysis. Was the stem dim...  even if you don't control for every other risk factor.  and we're trying to put in stems in those high-risk.  In our prelim analysis, we looked for any co-morbidities or potential risk factors that would...  Any other questions from the audience? I'd like to thank the speakers for staying on time and for excellent presentations.  So I think this is it for the session.

Video Summary

The video consisted of multiple presentations on different topics related to ankle deformity and ankle arthroplasty. The first presenter, Dr. Gross, discussed the outcomes of fourth-generation total ankle prosthesis in patients with severe ankle deformity. The second presenter, Dr. Toger, discussed stress shielding and aseptic loosening in fully porous coated versus smooth stemmed tibial implants in total ankle arthroplasty. The third presenter, Dr. Henry, presented on risk factors for early mechanical failure in ankle arthroplasty, focusing on BMI, coronal deformity, hindfoot fusion, and tibial fixation type. The fourth presenter, Dr. Modest, discussed the trends in ankle arthroplasty and ankle fusion procedures, showing an increasing trend in ankle arthroplasty. The fifth presenter, Dr. Fletcher, compared the outcomes and complications of simultaneous versus staged bilateral ankle arthroplasty. The video provided insights into the research and advancements in the field of ankle deformity and ankle arthroplasty.

Asset Subtitle

Moderators: Loretta B. Chou, MD, and Johnny T.C. Lau, MD, MSc

Does Severe Ankle Deformity Aﬀect the Outcomes of a 4th Generation Total Ankle Prosthesis? A 2-year Follow-up
Christopher E. Gross, MD; David A. Friscia, MD; Jesse F. Doty, MD; Anand M. Vora, MD; Nicholas L. Strasser, MD

Stress Shielding and Aseptic Loosening in Fully Porous-Coated Versus Smooth Stemmed Tibial Implants in Total Ankle Arthroplasty
Cody J. Togher; Jacob M. Perkins; John M. Thompson; Christopher F. Hyer, DPM; Gregory C. Berlet, MD

Risk Factors for Early Mechanical Failure and Revision in Modern Total Ankle Replacements
Jensen K. Henry, MD; Lavan Rajan, BA; Robert Fuller; Jiaqi Zhu, MS; Elizabeth Cody, MD; Scott J. Ellis, MD; Jonathan T. Deland, MD; Constantine A. Demetracopoulos, MD

Trends and Utilization of Ankle Arthroplasty versus Arthrodesis in the State of New York, 2009-2018
Peter G. Brodeur, BS; Jacob M. Modest; Devin F. Walsh; Davis A. Hartnett, MD; Joseph A. Gil, MD; Aristides Cruz; Raymond Y. Hsu, MD

Comparison of the Clinical Outcomes and Complications of Simultaneous versus Staged Bilateral Total Ankle Arthroplasty: A Single-Center Comparative Cohort Study
Amanda N. Fletcher, MD, MS; Lindsey G. Johnson, MBA; Mark E. Easley, MD; James A. Nunley II, MD; James K. DeOrio, MD

Discussion

Keywords

ankle deformity

ankle arthroplasty

total ankle prosthesis

severe ankle deformity

stress shielding

aseptic loosening

porous coated tibial implants

smooth stemmed tibial implants