“Ankle arthritis is unlike arthritis in other joints,” said James W. Brodsky, MD. “In the ankle, the loss of motion may not be proportional to the severity of the arthritis, nor is there necessarily contracture or extreme loss of motion.”

But stiffness can, indeed, pose a problem for a significant number of people with ankle arthritis. Recent studies suggest these patients benefit from total ankle arthroplasty (TAA) and may even experience increased range of motion (ROM) after undergoing the procedure.

Dr. Brodsky examined the latest research on patient outcomes after TAA and compared outcomes of TAA and ankle arthrodesis during a symposium at the American Orthopaedic Foot & Ankle Society annual meeting.

Longitudinal gait analysis
According to Dr. Brodsky, conventional wisdom has held that TAA preserves, but does not increase, joint ROM.

“Thus, in patients with stiff ankles, the presumption has been that patients’ ROM does not change after TAA,” he said.

In a study published in 2011, Dr. Brodsky and his colleagues at the Human Motion and Performance Laboratory at Baylor University Medical Center in Dallas analyzed the functional outcomes of 50 consecutive patients who underwent TAA using a mobile-bearing, three-component prosthesis. Outcomes were measured on an annual basis using gait analysis and comparison to preoperative function.

“In those 50 patients prospectively studied at a mean of 4.5 years, and now some as long as 15 years, we identified an approximate 20 percent mean increase in ROM,” said Dr. Brodsky.

“For the first time,” he continued, “we were able to use very accurate techniques to document that TAA increased ROM.”

Dr. Brodsky pointed out, however, that the increase in ROM was statistically significant, but was not necessarily clinically meaningful.

“An increase in a small number is still a small number,” he said. He also noted that in the 2011 study, most of the postoperative increase in these TAA patients’ ROM occurred in plantar flexion.

Another study by Dr. Brodsky and colleagues identified an increase in ROM in patients who received a two-component ankle prosthesis.

“We conducted a prospective study on the effects of gait in approximately 30 patients who received a two-component fixed bearing ankle prosthesis,” he said. “These patients also showed an increased ROM—primarily in dorsiflexion—with a completely different prosthesis than the one used in our 2011 study.”

TAA vs. arthrodesis
There are various ways of measuring whether a stiff ankle is still stiff after TAA—and, if stiffness remains, multiple methods can be used to measure ankle function, despite the reduced ROM.

“As orthopaedists, many of us see patients who report satisfactory outcomes after TAA, even though their ROM is nowhere near restored to normal,” Dr. Brodsky said. “And patients who have the ultimate stiff ankle—a result of undergoing ankle arthrodesis—can have excellent clinical outcomes, as well.”

Traditionally, TAA has been thought of as the appropriate treatment for ankle arthritis in patients with flexible ankles, while some have presumed that arthrodesis is the most appropriate treatment for stiff ankles, noted Dr. Brodsky.

“Sometimes we think about it this way: If an ankle is flexible, we replace it, but if it is stiff, we will make it stiffer,” he said.

Comparing TAA to arthrodesis, however, is like “comparing apples to oranges,” with “neither being entirely superior in all parameters of gait,” cautioned Dr. Brodsky.

“There’s no calculus to compare the advantages and disadvantages of stiffness and flexibility because they have different effects, and each has its advantages, depending on the work and lifestyle of the patient,” he said.

Dr. Brodsky cited recent research that compared outcomes after TAA vs. arthrodesis.

“Our group compared functional outcomes of TAA and ankle arthrodesis patients at 1 year,” he said. Using gait analysis to identify patients’ ROM within 1 degree of accuracy, they found that neither treatment was entirely superior to the other.

He also noted a 2012 study performed by Michael E. Hahn, PhD, Bruce Sangeorzan, MD, and colleagues that examined functional outcomes in 18 patients with end-stage ankle arthritis, half of whom underwent TAA, and half of whom underwent arthrodesis. Both groups benefited from reduced pain and improved gait function 1 year after surgery. However, TAA patients had greater ROM.

Another study comparing outcomes between TAA and ankle arthrodesis found a 4-degree increase in ROM in TAA patients, roughly a 20 percent to 25 percent increase. This is about the same increase in ROM found in the 2011 study cited earlier. Arthro­desis patients, who had about 15 degrees of motion before surgery, still had 15 degrees of motion afterward, with no decrease in ROM at 1 year, “strongly suggesting that most of the preoperative sagittal plane ROM was occurring at the talo-navicular joint,” said Dr. Brodsky.

Asking questions, drawing conclusions
“Patients with ankle arthritis don’t have normal motion preoperatively, and they don’t end up with normal motion postoperatively,” said Dr. Brodsky. “So, the question is: How much motion does a patient need to have to have a successful TAA?”

Yet another important question to study, he noted, is whether preoperative ROM predicts function after TAA. According to data from his institution’s gait laboratory, “performing TAA in patients with a very stiff ankle, or a stiffer ankle, does not necessarily lead to a worse outcome,” said Dr. Brodsky.

Overall, he concluded that “stiffness—of which arthrodesis is the extreme example—can produce good function, as long as it is accompanied by pain relief.

“In addition,” he continued, “data analysis shows that patients, even those with diminished motion, still have function that is as good as patients who start out with a higher ROM preoperatively. Thus, these data corroborate clinical experience that has shown that patients with stiff ankles can still have satisfactory outcomes after TAA.”

Disclosure information: Dr. Brodsky—Integra Life Sciences, Small Bone Innovations, Synthes, and Arthrex, Inc.

Jennie McKee is a senior science writer for AAOS Now. She can be reached at mckee@aaos.org

Bottom Line

• Ankle arthritis is not necessarily linked to contracture or extreme loss of motion; however, a significant number of ankle arthritis patients do experience stiffness.
• Recent studies suggest that patients with ankle arthritis who have reduced joint range of motion (ROM) still benefit from total ankle arthroplasty (TAA) and may even experience increased ROM after undergoing the procedure.
• Data in the literature, as well as clinical experience, suggest that patients with stiff ankles who undergo TAA or arthrodesis and experience postoperative stiffness can still have good outcomes, as long as surgery provides pain relief.

References

1. Flavin R, Coleman SC, Tenenbaum S, et al: Comparison of gait after total ankle arthroplasty and ankle arthrodesis. Foot Ankle Int 2013 Oct; 34(10):1340-8.
2. Hahn ME, Wright ES, Segal AD, et al: Comparative gait analysis of ankle arthrodesis and arthroplasty: initial findings of a prospective study. Foot Ankle Int 2012 Apr; 33(4):282-9.
3. Brodsky JW, Polo FE, Coleman SC, et al: Changes in gait following the Scandinavian total ankle replacement. J Bone Joint Surg Am 2011 Oct 19;93(20):1890-6.
4. Choi JH, Coleman SC, Tenenbaum S, et al: Prospective study of the effect on gait of a two-component total ankle replacement. Foot Ankle Int 2013 Nov;34(11):1472-8.