Lateral radiograph showing fusion with cannulated screws and an anterior tension plate. Reprinted from Advanced Reconstruction Foot and Ankle. American Academy of Orthopaedic Surgeons, 2004, page 185.

AAOS Now

Published 10/1/2016
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Robert L. Parisien, MD; Jason P. Tartaglione, MD; Shaun Kink, MD; Michael Aynardi, MD; Lew C. Schon, MD; Christopher W. DiGiovanni, MD

The Fate of the Ailing Ankle: Arthrodesis Versus Arthroplasty

This "Face Off" presents the most compelling arguments in support of both ankle arthrodesis and total ankle replacement (TAR) in the management of end-stage ankle arthritis. Although it seems increasingly clear that both arthrodesis and arthroplasty will have their place in the treatment of ankle arthritis, both procedures come with particular advantages, disadvantages, and associated complications.

POINT
Arthrodesis demonstrates reliably superior outcomes with lower rates of revision surgery.

Robert L. Parisien, MD; Shaun Kink, MD; and Christopher W. DiGiovanni, MD

Arthrodesis has long been the gold standard and mainstay of treatment for end-stage osteoarthritis (OA) of the ankle, and for good reason. It has demonstrated consistent, reproducible, and reliable results over decades of use—enabling both patients and providers to count on significant pain reduction, improved clinical outcomes, and a fairly rare revision requirement—in the vast majority of cases. Even back in 1953, The New England Journal of Medicine reported a study showing good long-term outcomes in 43 primary ankle fusions. The authors declared that arthrodesis of the ankle demonstrated "practically no disability," enabling patients to "stand, walk, and run in a normal fashion."

Today, evolving data appears not only to support the cost-effectiveness of arthrodesis over TAR, but also to suggest that its reliability as a surgical solution may rise in proportion to the degree of disease and deformity affecting the ipsilateral foot and ankle when compared to existing replacement options. As such, few would argue against its being our most predictable "workhorse solution" for difficult cases.

Position and pain reduction
A primary goal of managing end-stage ankle OA is successful and lasting pain relief in a well-aligned ankle. A well-performed ankle fusion reliably obtains and maintains both objectives over time. In a study of the long-term results of 62 ankle arthrodeses from three academic teaching hospitals in Canada during an 11-year period, 100 percent of patients reported "excellent" pain relief. One retrospective investigation of long-term outcomes of patients who underwent primary arthrodesis for end-stage arthritis with progressive severe pain found that all patients had a "solidly fused ankle" at an average of 8 years. None of the patients required pain medication or had pain while walking on level ground, with only 25 percent reporting mild discomfort during "strenuous activities."

Of all the outcome measurements in foot and ankle surgery, the American Orthopaedic Foot & Ankle Society (AOFAS) hindfoot score and the Kofoed score have been the two most frequently quoted to measure pain. A recent systematic review examining the intermediate- and long-term outcomes of ankle arthrodesis versus TAR documented better Kofoed pain scores for arthrodesis as compared to TAR. Further, once alignment and healing have been confirmed following a successful ankle fusion, it is rare to have to perform a revision for malposition, loosening, instability, infection, or subsidence. The same cannot be said for TAR when considering the current body of literature.

Wound complications and revision rates
Compelling evidence supports arthrodesis over TAR with respect to revision risk. In evaluating reoperation rates for 4,705 ankle fusions and 480 arthroplasties over a 10-year period, Soohoo et al found arthroplasty to have a statistically significant "increased risk of device-related infection and major revision procedures" as compared to arthrodesis. The rate of major revision surgery for patients who underwent TAR was 9 percent at 1 year and 23 percent at 5 years—double the rate of revision experienced by patients who had a primary ankle arthrodesis.

Similarly, a systematic review by Haddad et al reported that 1 in 14 patients require revision for TAR, with implant survival rates found to be only 78 percent and 77 percent at 5 and 10 years respectively. A recent multicenter investigation by Daniels et al evaluating intermediate-term outcomes reported a 5.5-year revision rate of 7 percent for ankle arthrodesis versus 17 percent for TAR. Additionally, a retrospective analysis of 41 patients who had TAR for end-stage ankle arthritis found a 39 percent revision rate, with six (38 percent) of those revisions occurring within 1 year of surgery. Not surprisingly, the authors concluded that TAR must be "approached with caution" and emphasized the need for continued research to "elucidate the role of contemporary TAR." In contradistinction, the rate of ankle nonunion after fusion surgery approximates only 10 percent or so across multiple papers in the literature.

Significant wound complications have been reported in association with both arthrodesis and TAR but are seemingly more common—and certainly more feared—following replacement. One study reported a 13 percent rate of "postoperative wound problems" following TAR performed by fellowship-trained foot and ankle surgeons.

Functional outcomes and preservation of motion
The preservation of motion with reliable reproduction of functional outcomes, as demonstrated by ankle arthrodesis, has long been an important goal of TAR. Earlier generation cemented and noncemented total ankle implants were quickly abandoned secondary to complications related to hardware loosening, subsidence, and instability.  Although the newest generation designs comprised of both mobile- and fixed-bearing constructs appear to hold great promise, a systematic review of 49 primary studies by Haddad et al reported meta-analytic mean results demonstrating poor overall outcomes in 24 percent of patients who underwent TAR versus just 13 percent in those with ankle arthrodesis (95 percent confidence interval).

Moreover, several studies of major joints having undergone replacement surgery have documented a direct correlation of preoperative range-of-motion (ROM) with ROM at about 1 year. Because the normal ankle exhibits a far less arc of motion (40 to 50 degrees) compared to the native hip, knee, or shoulder, one must consider whether the additional risks and unpredictability inherent to TAR are worth the tradeoffs related to forgoing fusion when patients with diseased ankles have a preoperative ROM that commonly ranges between 0 to 10 degrees. The ankle is also the only joint that effectively cannot be dislocated while being replaced, adding a layer of complexity to the effectiveness of replacement surgery. Therefore, one can make a sound argument that the learning curve for TAR is far steeper than it is for ankle arthrodesis.

A significant amount of attention in recent years has been paid to the fate of the syndesmosis as syndesmotic integrity is vitally important to overall ankle function and, therefore, patient outcomes. In an evaluation of 82 patients (85 ankles) undergoing one version of a TAR, Pyevich et al found that 12 tibial and 9 talar components had migrated, often as a result of syndesmotic malunion or nonunion. At the most recent follow-up (average 4.8 years), only 55 percent of patients reported being pain-free. The authors proposed that longer follow-up be required to "clarify whether delayed union or nonunion of the syndesmosis is associated with an increased rate of clinically important problems."

Adjacent-joint arthritis
Acceleration of adjacent joint arthritis has remained the most often cited argument against performing ankle arthrodesis in patients. Although several papers have highlighted radiographic arthritic change in adjacent foot joints after long-term follow-up of ankle fusion patients, the literature overall has been challenged to demonstrate any direct cause and effect relationship between ankle arthrodesis and adjacent joint disease because many studies failed to report preexisting arthritic changes. Further, although the argument that these patients have elevated levels of arthritic change in adjacent joints has been made using sequential imaging, few studies document any significant need for a return to the operating room based on symptom severity. 

Hallock et al reported progression of preexisting adjacent joint arthritis in 10.4 percent of patients (5 of 48) undergoing ankle arthrodesis at a mean follow-up of 4 years, but the correlation to clinical significance remains unclear. Further, Hendrickx et al failed to find any correlation between degree of radiographic arthritis and visual analog pain scales (VAS) in a similar population. Additionally, moderate-to-severe radiographic arthritis of the adjacent subtalar joint following ankle arthrodesis is reportedly asymptomatic in 44 percent of patients. Interestingly, Morrey and Wiedeman found that up to 82 percent of patients with subsequent radiographic evidence of arthritis of the adjacent Chopart joints after ankle fusion were asymptomatic.

Although some degree of accelerated adjacent joint arthritis seems reasonably well-documented as a potential expectation following ankle arthrodesis, a meta-analysis of four studies evaluating 222 patients revealed that only 12 patients required a subsequent operation secondary to adjacent joint arthrodesis (5.4 percent). Nine required a subtalar arthrodesis, two required a triple arthrodesis, and one patient required a talonavicular arthrodesis. Given the fairly high revision rates associated with TAR and the comparatively low rate of secondary surgery for adjacent joint disease following ankle arthrodesis, the scale does not appear to tip in the direction of arthroplasty.

Cost-effectiveness
A recent National Inpatient Sample database study of 12,000 ankle arthrodesis patients and 3,000 TAR patients found a statistically significant increase in overall hospital expenditures for TAR, with a reported difference of almost $25,000 per patient. This new evidence strongly suggests that, although length-of-stay appears to be similar, TAR may be associated with significantly greater hospital charges and increased healthcare expenditures than arthrodesis.

In conclusion, the available evidence supporting primary ankle arthrodesis as the ongoing gold standard for end-stage OA remains compelling. Although newer generation TARs appear to post improved outcomes and lower complication rates than their predecessors, long-term comparative data proving superiority with these implants should be required before considering the possibility of TAR unseating arthrodesis as the gold standard treatment for end-stage ankle arthritis. Ankle fusion surgery is a time-tested procedure posting a long track record of low revision rates, superior functional outcomes, reliable pain relief, excellent deformity correction capabilities, and comparatively low healthcare expenditures.

Robert L. Parisien, MD, is an orthopaedic surgical resident at Boston University Medical Center in Boston; Shaun Kink, MD, is a foot and ankle fellow at Massachusetts General Hospital in Boston; Christopher W. DiGiovanni, MD, is chief of foot and ankle surgery at Massachusetts General Hospital and vice chairman of academic affairs at Harvard Medical School.

References:

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  2. Saltzman CL, Salamon ML, Blanchard GM, et al: Epidemiology of ankle arthritis: Report of a consecutive series of 639 patients from a tertiary orthopaedic center. Iowa Orthop J 2005;25:44–46.
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  8. Naal FD, Impellizzeri FM and Rippstein PF: Which are the most frequently used outcome instruments in studies on total ankle arthroplasty? Clin Orthop Relat Res 2010;468(3):815–826.
  9. Haddad SL, Coetzee JC, Estok R, Fahrbach K, Banel D, Nalysnyk L: Intermediate and long-term outcomes of total ankle arthroplasty and ankle arthrodesis: A systematic review of the literature. J Bone Joint Surg Am 2007;89(9):1899–1905.
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Lateral radiograph showing fusion with cannulated screws and an anterior tension plate. Reprinted from Advanced Reconstruction Foot and Ankle. American Academy of Orthopaedic Surgeons, 2004, page 185.
Lateral radiograph of patient who underwent conversion from fusion to TAR. Reprinted from Advanced Reconstruction Foot and Ankle 2. American Academy of Orthopaedic Surgeons, 2015, page 196.

COUNTERPOINT
Arthroplasty preserves functional range of motion while delaying the acceleration of adjacent joint disease.

Jason P. Tartaglione, MD; Michael Aynardi, MD; and Lew C. Schon, MD

Although considered the "gold standard" for treatment of end-stage ankle OA, ankle arthrodesis has many disadvantages, including prolonged postoperative immobilization, progression of arthritis in adjacent hindfoot joints, and gait abnormalities. Arthrodesis patients also risk delayed union, nonunion, and symptomatic pseudoarthrosis. Arthrodesis nonunion rates range from 7 percent to 43 percent, and the risk of adjacent hindfoot joint arthritis has been reported to be as high as 90 percent.

Long-term studies have demonstrated that loss of ankle motion affects patients' functional status, including pain after prolonged activity, trouble walking on uneven ground, and difficulty while ascending and descending stairs. Additionally, the physical and emotional subscales of global functioning scoring measures like the Short Form-36 (SF-36) have demonstrated poor results. One study found a direct relationship between increased ankle range of motion and higher SF-36 scores.

Gait analysis of arthrodesis shows decreased overall ankle motion in the sagittal plane (dorsiflexion and plantarflexion), decreased hindfoot motion in the coronal plane (inversion and eversion), and decreased tibial rotation. The increased compensatory hypermobility of the subtalar joint has been shown to narrow the posterior facet, contributing to the development of degenerative arthritis.

In the literature, the debate of TAR versus arthrodesis for the treatment of end-stage ankle OA has been waged since the first TAR was implanted in 1970. But new surgical techniques and improved instrumentation, combined with clinical experience, have expanded the indications for TAR. Currently, both 3-component mobile-bearing and 2-component fixed-bearing designs are used in the United States.

Modern TAR designs and techniques have demonstrated equivalent pain relief and better function when compared to arthrodesis. As part of a Food and Drug Administration non-inferiority trial, Saltzman et al demonstrated that, compared to patients who underwent arthrodesis, patients receiving TAR had superior outcomes in total functional scores as well as in the subcomponents of stairs, standing, support, and range of motion on the Buechel-Pappas scale. Today, TAR is more popular than ever before. Medicare per capita standardized utilization for TAR has increased by 671 percent while ankle arthrodesis utilization has decreased by 15.6 percent.

OA of the tibiotalar joint significantly alters gait mechanics secondary to the distal translation of the ankle joint's center of rotation. This phenomenon causes pain, stiffness, and decreased range of motion, and increases the forces experienced by joints distal to the ankle joint. The progression of arthritis in neighboring hindfoot joints has been well-documented at long-term follow-up after arthrodesis.

By preserving tibiotalar motion, TAR is believed to decrease the mobility and stress experienced by joints distal to the ankle joint, ultimately delaying the progression of arthritis in the adjacent hindfoot joints. Modern TAR designs, especially ones that most closely replicate normal anatomy, can reproduce near normal ankle kinematics.

Multiple studies have demonstrated improved foot and ankle clinical scores, temporospatial parameters, and kinematic and kinetic function following TAR. In a study by Piriou et al, the TAR group had greater symmetrical timing of gait and restoration of normal ground reaction forces than the fusion group.

In a prospective study, Flavin et al examined the effects on gait of TAR versus fusion, using three-dimensional gait analysis with a 12-camera digital-motion capture system. The study found that patients who underwent TAR had higher walking velocity (increased stride length and cadence) as well as more normalized first and second rockers of the gait cycle. Furthermore, patients who underwent TAR had more symmetrical vertical ground reaction force curves that more closely matched those of controls than did the curves of patients receiving ankle fusion.

Studies have established that patients who undergo TAR experience significant improvements in pain, function, and quality of life, as well as favorable patient-reported outcomes. A study by Adams et al found a significant improvement in the visual analog scale (VAS) pain score, AOFAS hindfoot score, the Short Musculoskeletal Functional Assessment (SMFA), and SF-36 scores compared to preoperative values in 194 primary TAR patients, after a mean of 3.7 years.

Similarly, Jastifer and Coughlin found that reported average VAS scores improved from 8.1 preoperatively to 2.1 postoperatively, Buechel-Pappas Scale scores improved from 32.8 preoperatively to 82.1 postoperatively, and AOFAS scores improved from 32.8 preoperatively to 78.1 postoperatively among 41 TAR patients. In addition, they reported a 94.4 percent implant survival rate, and all patients reported their outcome as good-to-excellent.

Oliver et al also examined patient-reported outcomes and patients' perception of their result after receiving a TAR. They found improvements in AOFAS scores, the physical component of the Veterans Rand 12-Item Health Survey (VR-12), and Ankle Osteoarthritis Scale (AOS) pain and disability scores.  In addition, 94 percent of patients in their cohort would "probably" or "definitely" have a TAR on their contralateral ankle.

Jastifer et al studied patients' functional outcomes by examining the performance of TAR and fusion on uneven surfaces, stairs, and an inclined ramp. This study concluded that patients with TAR outperformed ankle fusion patients while walking upstairs, downstairs, and uphill.

Critics of replacement often cite high early failure rates and unacceptably high rates of secondary procedures as major reasons to choose ankle fusion over TAR. However, long-term implant survival is possible, as newer designs aim to recreate ankle kinematics as well as improve clinical experience.

As with most orthopaedic surgeries, patient selection plays a crucial role in successful outcomes. Traditionally, the indications for ankle replacements included older, lower demand patients, often with rheumatoid arthritis, and typically with minimal deformity. However, recent literature has broadened these indications, showing that younger patients and patients with deformity who undergo concomitant procedures addressing the deformity can have successful outcomes.

The debate between ankle replacement and arthrodesis as the best surgical treatment for end-stage ankle arthritis will certainly continue. The recent increase in TAR highlights the generalized excitement, both from physicians and patients alike, about the procedure. As interest continues to grow and indications expand, TAR will inevitably be used for younger, more active patients, and patients with more deformity than ever before. Surgeons and patients who want to preserve motion, improve pain, restore normal gait and ankle kinematics, and delay the acceleration of arthritis in the hindfoot joints should consider joint replacement over arthrodesis as the preferred technique to treat end-stage ankle arthritis.

Jason P. Tartaglione, MD, is an orthopaedic surgical resident at Albany Medical Center, Albany, N.Y. Michael Aynardi, MD, is a foot and ankle fellow at MedStar Union Memorial Hospital in Baltimore. Lew C. Schon, MD, is a past president of the AOFAS, and chief of foot & ankle surgery at MedStar Union Memorial Hospital in Baltimore.

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