© 2024 HMP Global. All Rights Reserved.
Any views and opinions expressed are those of the author(s) and/or participants and do not necessarily reflect the views, policy, or position of the Foot and Ankle Surgery Institute or HMP Global, their employees, and affiliates.

Kristian Buedts, MD, and Casey J. Humbyrd, MD, MBE moderated this session at the American Orthopaedic Foot and Ankle Society Annual Meeting, which touched on important concepts to consider throughout the perioperative period. Timothy R. Daniels, MD, kicked off the track by focusing on preventing wound healing complications by incorporating the concept of using angiosome borders into incisional planning. He explained that the traditional straight anterior incision does not honor the angiosomal borders and could be a reason for wound healing complications noted with the anterior approach.

Dr. Daniels reminded the audience that angiosomes are a 3-dimensional tissue block fed by a source artery and connected by choke vessels. These choke vessels are very consistent in their location and create a unified network among the arteries. He then reviewed key arterial and angiosome anatomy relevant to total ankle replacement, pointing out crucial areas where the tissue relies on retrograde flow. These areas, he said, are then more likely to have wound healing complications. Incorporating a medial based incision that utilizes the border between the anterior and posteromedial angiosomes thus decreases wound healing complications while still allowing for adequate exposure of the ankle joint. Dr. Daniels ended by as he sharing several case examples with an extensile anteromedial approach.

Balance Considerations in Varus, Valgus, and Other Deformities

Jesse F. Doty, MD, then spoke on varus deformities, for which he stated it is important for surgeons to understand the causes. Breaking it up into intra- and extra-articular sources, he noted that within the joint there can be malalignment, erosion from instability, post-traumatic changes, or inflammatory arthropathy. Outside of the ankle, however, there can be anatomic or functional issues proximal or distal to the joint.

He then reviewed Frank Alvine, MD’s classification system relative to varus ankles in TAR.¹ In stage I one can note medial erosion but attempt balance of the mechanical axis via the coronal plane cut, he said. In stage II the surgeon can see remodeling, contractures, and impingement. But in these cases, medial releases and other interventions like ligament reconstruction or tendon transfer may be indicated, especially when there is greater than 10 degrees of laxity upon trialing.¹ Dr. Doty stressed that the ankle must be aligned and the foot in a plantigrade position. To stage or not to stage the interventions is also an important consideration. As a whole he urged the audience to delve into the causes of the varus deformity in order to most properly address them.

Natalie S. Mesnier, MD, addressed valgus deformities on TAR, commenting that this deformity has a negative influence on implant survival. The associated laxity, she noted, does not usually change with arthroplasty, adjunct procedures may not hold, and there is a higher risk of progressive deformity. Varus deformities, she pointed out, generally involve more stiffness than laxity. In cases of TAR in patients with valgus deformities, she shared that surgeons don’t have the luxury of thinking about congruency alone. There are many points to consider including the containment of the talus, response of the subtalar joint, compensatory medial column instability, skew deformities, and stage IV posterior tibial tendon dysfunction. Ultimately, she agreed that the foot needs to be plantigrade, and that ancillary procedures are a vital part of the process. Angles are important, she added, but there is much more to consider than just angles in these deformities. She then shared some decision trees applicable in these cases.

Ariel Palanca, MD, continued the conversation by addressing rotation and tensioning in TAR. She reinforced that a balanced ankle is important for implant longevity, including edge loading, poly wear or fracture, and overall failure. Surgeons should not rely on patient-specific implants (PSI) or any implant alone for deformity correction, she said. Instead, it is the surgeon’s responsibility to achieve this, as PSI cannot account for incongruent deformities and non-weight-bearing computed tomography (CT) creates the PSI. A deep understanding of the deformity at hand preoperatively is vital, she agreed, including varus versus valgus, congruent versus incongruent, foot deformity, and sagittal alignment.

Traditional techniques to address rotation have significant variability, pointed out Dr. Palanca, as ankle rotation is complex, and not just a hinge. The primary axis is externally rotated an average of 23 degrees, and is not fixed, but changes throughout ankle motion.² In ankle dorsiflexion, the primary axis rotates externally, and everts, with converse motion in plantarflexion.² PSI can help tackle rotational issues to some extent, but she recommended assessing rotation with the foot in neutral flexion if the surgeon does not have access to those tools. Lastly, she encouraged surgeons to consider whether to address these issues concomitant to the TAR versus in a staged fashion.

Mobile Bearing Versus Non-Mobile Bearing: Current Debates

Matthew Tomlinson, FRCS(Orth) first reviewed the various generation of TAR implants, pointing out that a 2021 commentary summarizes this well.³ He cited allowance of some rotational motion simulating expected normal ankle motion as one pro of mobile bearing devices, along with self-centering features, motion at both segments, and possible reduction in contact stresses. However, he acknowledged that subluxation is still possible, and two bearing surfaces can increase wear. Additionally, fixed bearing devices may provide more implant stability, he said, with less likelihood for subluxation, impingement, and edge loading. Conversely, though, increased stress at the bone implant interface could contribute to loosening, he added.

After presenting some relevant research findings, he concluded by saying that recent data suggests that mobile bearing TARs may be failing more quickly than fixed bearing. However, there is a distinct need for more studies, as existing ones may be too narrow in focus, and there is not enough consideration of poly size and conformity. Overall, he feels we are not yet at a stage where firm conclusions are possible.

Overcoming Disparities in Utilization and Access to Care in TAR

Richard M. Smith, MD, shared clear data that disparities exist in access to and utilization of many common foot and ankle surgical procedures, including TAR. He encouraged surgeons to learn about the drivers of these disparities and be part of the solution in addressing them. He added that he has observed similar literature related to total knee and total hip arthroplasties. Recent changes in insurance reporting to address social determinant of health domains, he said, may seem an increase in work, but this indeed can potentially hold important insights related to differences in outcomes, and in adherence to treatment regimens.

Identifying potential barriers to access or utilization is one suggested way to improve, per Dr. Smith. Investing in translator services or having multilingual patient education materials may help. Being aware of implicit bias in patient selection and increasing cultural competency in oneself and amongst all staff are also important.

Faculty disclosures are available here.

References
1.        Coetzee JC. Management of varus or valgus ankle deformity with ankle replacement. Foot Ankle Clin. 2008 Sep;13(3):509-20, x. doi: 10.1016/j.fcl.2008.04.004. PMID: 18692013.
2.        Najefi AA, Ghani Y, Goldberg A. Role of Rotation in Total Ankle Replacement. Foot Ankle Int. 2019;40(12):1358-1367. doi: 10.1177/1071100719867068. Epub 2019 Aug 12. PMID: 31402689.
3.        Coetzee, JC. Inching Closer to the End of the Debate Between Fixed Versus Mobile-Bearing Total Ankle Arthroplasty: Commentary on an article by M. Assal, MD, et al.: “Three-Year Rates of Reoperation and Revision Following Mobile Versus Fixed-Bearing Total Ankle Arthroplasty. A Cohort of 302 Patients Treated with 2 Implants of Similar Design”. J Bone Joint Surg. 2021;103(22):e93, DOI: 10.2106/JBJS.21.00739