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Adequacy of deformity correction must be considered in arthroscopic vs open ankle arthrodesis

Issue: July 2018

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The appropriate indications for arthroscopic ankle fusion remain a topic of active debate. Several studies have demonstrated rates of nonunion and other complications with the arthroscopic technique that are low and comparable to traditional open approaches for ankle fusion. Despite this, open approaches continue to be widely used. This Orthopedics Today Round Table provides diverse opinions regarding the potential advantages and limits of arthroscopic fusion with regard to the amount of correction possible for patients with associated deformities.

Participants discuss technical tips for those interested in adopting arthroscopic ankle fusion techniques. Specific emphasis is placed on avoiding potential pitfalls and risks specific to the arthroscopic technique.

Nelson SooHoo, MD
Moderator

Nelson SooHoo, MD: The emerging literature regarding arthroscopic ankle fusion suggests this procedure is associated with high fusion rates and low risks of complications that are at least comparable to traditional, open fusion techniques. Given these results, what are your indications for arthroscopic vs. open fusion? What percentage of fusion cases do you perform arthroscopically?

Richard D. Ferkel, MD: Indications for arthroscopic ankle arthrodesis include moderate to severe unrelenting pain at the tibial-talar joint that does not respond to conservative measures. I try to do all fusions arthroscopically. We can treat patients with up to 30° talar tilt if we can neutralize the ankle under preoperative fluoroscopy in the office to 5° or less, or if we can neutralize it in surgery to a similar extent. For more than 30° talar tilt or a severely stiff ankle that does not distract enough to allow an arthroscopic procedure, open arthrodesis should be performed. If there is malrotation of the ankle, significant bone loss, active infection, previous failed fusion, complex regional pain syndrome or neuropathic destructive process, open fusion should be considered. At present, we perform 10 arthroscopic fusions to every one open fusion case.

Bruce J. Sangeorzan, MD: Ankle arthrodesis is a well-established and effective treatment for end-stage ankle arthritis. It is also used for paralytic conditions and deformity. There are goals achieved in the short-term — pain relief. Its longer-term goals are preservation of gait and surrounding joints by proper positioning. Recently, a relatively new goal emerged: Arthrodesis to reserve structures for potential conversion to total ankle replacement (TAR) when the subtalar or Chopart’s joints degenerate. Arthrodesis should also be done with this long-term goal in mind. The latter requires a neutral ankle position that will have minimum impact on the rest of the ankle’s function. An overly plantar-flexed talus will rapidly wear the subtalar and Chopart’s joints and cause a lurching of the body over the joint during walking. Too much anterior subluxation similarly causes increased torque on hindfoot joints and the lurching-type gait. Similarly, the impact of coronal misalignment will cause early wear and discomfort.

The choice of incision type and location and instruments used is more likely to be based on surgeon experience than any other factor. In my algorithm, the soft-tissue envelope is the most important factor for determining incision type followed by the anatomy of the deformity. I use small incisions when the soft tissue requires it and more traditional open approaches when there is significant deformity, particularly anterior translation or coronal tilt. All ankle arthrodeses are now done as outpatient procedures in the United States, so length of stay is no longer a consideration. The theoretical advantage of arthroscopic arthrodesis is reduction in wound complications. There has not yet been an adequately sized, methodologically sound study that demonstrates a difference in ankle arthrodesis outcomes based on the technique used.

Thomas S. Roukis, DPM, PhD, FACFAS: I perform an equal number of open and arthroscopic ankle arthrodesis procedures. I favor an arthroscopic approach in the following situations:

• Primary or secondary “other” (ie, gouty arthropathy, rheumatoid arthritis, etc.) causes of end-stage degenerative ankle arthrosis with a well-aligned ankle in the sagittal and transverse planes;
• Flaccid drop-foot deformity correctable to neutral with minimal soft-tissue releases;
• A salvage procedure for multiple failed treatment attempts of a talar osteochondral defect or chronic lateral ankle instability; or
• When the fixation of choice is two or three large-diameter compression screws.

Depending on the clinical situation, open approaches are most commonly performed either laterally through a fibular-sparing approach or anterior. I favor an open approach in patients with the following presentations:

• History of traumatic injury treated operatively, especially high-energy open trauma with previous soft-tissue flap coverage;
• Significant retained internal fixation, especially if it is placed in atypical locations or is from unknown manufacturers. This makes mini-incision approaches impractical, time-consuming and often unsafe due to risk of damage to adjacent soft-tissue structures;

• Presence of avascular osteonecrosis of the distal tibial plafond, especially posterolateral, which tends to be severely sclerotic, and of the talar body, especially when associated with collapse or massive cystic changes that may require large volumes of bone graft;
• Significant sagittal-plane malalignment in the where the foot is markedly translated anterior or posterior or when marked internal or external rotational deformities are present. This mandates soft-tissue releases of the adjacent capsule, ligaments and/or tendons and bone resection to achieve neutral alignment;
• Global foot deformity, such as that associated with stage IV posterior tibial tendon dysfunction, rigid cavus foot or prior trauma;
• Chronic infection or concern for infection where soft-tissue and bone biopsy/cultures are required, and a staged approach is commonly performed; or
• When the fixation of choice is plate-and-screw fixation.

Source: Richard D. Ferkel, MD

David I. Pedowitz, MD, MS: The literature is compelling in its support of arthroscopic techniques. I currently perform about 20% of my tibiotalar fusions arthroscopically. The clearest indications for an arthroscopic technique are patients with comorbidities that make them prone to wound problems or patients with a hostile skin flap along the planes of traditional open surgery. I perform 10 TARs for every one fusion I do.

SooHoo: Does the less-invasive nature of arthroscopic fusion make you less likely to recommend TAR in certain patients?

Pedowitz: No. I don’t think a less-invasive ankle fusion provides an advantage over TAR specifically. It may, as the data would suggest, provide advantages over traditional open ankle fusion, but when we add in the idea of comparing a less-invasive ankle fusion to TAR, we are comparing two surgical procedures with vastly different approaches, functional outcomes, patient expectations and indications.

SooHoo: Some authors report an ability to adequately correct even significant varus or valgus deformity with arthroscopic fusion. Do you agree with this or do you limit your indications? What technical tips may help surgeons provide better correction of deformity using the arthroscopic technique?

Ferkel: In our 2005 publication on arthroscopic ankle fusion, we performed arthroscopic arthrodesis in patients with less than 10° talar tilt. However, since we have acquired significantly more experience, we now feel some patients with talar tilt up to 30° can be fused arthroscopically. Technique tips I include having the patient come into the office preoperatively and, using an ankle distraction strap with someone providing counter-force, under fluoroscopy I try to take them out of varus and valgus to within 4° or 5° of neutral. If I can, then I feel comfortable I will be able to do it in surgery and put them in a good position arthroscopically. If patients have severe ankle collapse and I am unclear whether they are too stiff to distract, we use a similar maneuver and, under fluoroscopy, verify how much space can be obtained with distraction. Admittedly, the patients are not as relaxed as they are in surgery, but if we obtain adequate distraction on a preoperative fluoroscopic exam, then obtaining that during surgery should not be a problem.

In surgery, if significant varus or valgus deformity is present and does not correct well, I insert a Steinmann pin into the talus to further reduce its position in the mortise, and then insert the guide pin and screw to hold that position. If there is varus deformity, I insert the medial screw first. If there is valgus deformity, I insert the lateral screw first. I always use two cross screws — one through the medial malleolus and one through the posterior cortex of the fibula and into the tibia and then into the talus. A third screw provides further fixation in patients with lower quality bone stock.

Sangeorzan: With experience, significant correction can be obtained with any technique. A terminally threaded Schanz pin inserted into the talus as a “joystick” combined with sufficient release of the talus can correct a lot of coronal and sagittal deformity. Because the plafond is typically in extended position, shifting the talus posteriorly is more challenging because it requires moving uphill against the slope of the plafond, as well as getting past the fibula. One deformity that cannot be corrected arthroscopically is anterior displacement of the talus with a fibula that blocks posterior translation. My primary reason to not use an arthroscope is a scope is straight and the talar dome is shaped like a sideways saddle. The only way to maintain that curve with a straight instrument is to introduce the instruments from the lateral and medial side. The medial side is inaccessible due to the medial malleolus.

Pedowitz: Whether done through fusion or TAR, deformity correction is paramount to achieving a pain-free, brace-free plantigrade foot. Most deformity can be corrected with concomitant hindfoot and mid-forefoot procedures with either TAR or arthroscopic fusion. Often, these additional procedures need to be done in a staged fashion but, in general, if corrected, data support the idea that fusion and TAR both do well above a well-balanced hindfoot and forefoot. In my experience, varus or valgus deformity that exceeds 25° becomes a challenge and generally requires additional correction that cannot be achieved alone through fusion or TAR. My approach is as follows: I first address any soft tissue contractures (ie, equinus/varus). Even before I think about forefoot and hindfoot deformity correction, I ensure the tibiotalar joint is congruent. Only when the tibial and talar surfaces are parallel can one can fully appreciate the remaining hindfoot deformity and assess its need for correction.

Roukis: It is not so much the absolute degree of frontal plane deformity, but the passive reducibility of the deformity that seems to matter most. I routinely check frontal plane flexibility under mini-C-arm image intensification in the clinic without anesthesia. Intraoperative tips for achieving frontal plane correction are as follows. Once I prepare the tibiotalar surfaces for arthrodesis, if I cannot achieve neutral alignment, I place a small, 4-mm curved osteotome through an accessory portal inferior to the anterolateral one to release the lateral collateral ligaments directly off the fibula in patients with valgus deformities. I have used an accessory anterior-medial portal to release the deltoid ligament complex off the medial malleolus in ankles with varus deformities using the same technique. Long-standing varus deformities often have contracture of the entire deltoid complex. It may be necessary to advance the osteotomy anterior-medially and release the tibio-navicular band of the deltoid complex. I have been deceived by a seemingly flexible frontal plane deformity that corrects to a few degrees of neutral under stress examination in clinic only to find an unrecognized transverse plane deformity exists that is not amenable to correction through an arthroscopic approach.

Editor’s note: See part 2 of this Round Table in the August issue of Orthopedics Today.

• References:
• Ferkel RD. Arthroscopy. 2018;doi:10.1016/j.arthro.2018.01.006.
• Ferkel RD, et al. Foot Ankle Int. 2005;doi:10.1177/107110070502600402.
• Ferkel RD. Foot and Ankle Arthroscopy. 2nd ed. Philadelphia: Wolters Kluwer; 2017.
• Jones CR, et al. Arthroscopy. 2018;doi:10.1016/j.arthro.2017.11.031.
• Park JH, et al. Arthroscopy. 2018; doi: 10.1016/j.arthro.2017.08.284.

• For more information:
• Richard D. Ferkel, MD, can be reached at Southern California Orthopedic Institute, 6815 Noble Ave., Van Nuys, CA 91405; email: eobrien@scoi.com.
• David I. Pedowitz, MD, MS, can be reached at Rothman Institute, 825 Old Lancaster Rd., Suites 100, 140 and 200, Bryn Mawr, PA 19010; email: david.pedowitz@rothmaninstitute.com.
• Thomas S. Roukis, DPM, PhD, FACFAS, can be reached at Gundersen Health System, Orthopaedic Center, 1900 South Ave., La Crosse, WI 54601; email: tsroukis@gundersenhealth.org.
• Bruce J. Sangeorzan, MD, can be reached at Department of Orthopaedics and Sports Medicine, University of Washington, Seattle, WA 98104; email: bsangeor@uw.edu.
• Nelson SooHoo, MD, can be reached at UCLA Department of Orthopedic Surgery, 1250 16th St., Suite 3142, Santa Monica, CA 90404; email: nsoohoo@mednet.ucla.edu.

Disclosures: Ferkel reports he is a consultant for Smith & Nephew. Pedowitz reports he is a paid consultant and paid presenter or speaker for Arthrex; receives IP royalties from, is a paid consultant and paid presenter or speaker for, and receives research support from Integra; is a paid consultant for MiRus; and receives IP royalties from and is a paid consultant and paid presenter or speaker for Zimmer Biomet. Roukis, Sangeorzan and SooHoo report no relevant financial disclosures.