Robin M. Queen, PhD,

AAOS Now

Published 8/1/2016
|
Jay D. Lenn

When TAA Fails

OREF grant recipient assesses treatment options
End-stage ankle arthritis results in severe pain, deformity, and functional disability. Although both ankle fusion and total ankle arthroplasty (TAA) are effective treatment options for the condition, TAA has become more common because it preserves mobility in the ankle and may protect surrounding joints from increased wear.

Studies have shown that survival rates of ankle implants have improved over the years, yet there is still little to no information about best practices following an implant failure. How do the outcomes of revision ankle arthroplasty compare with primary arthroplasty outcomes? And how do the outcomes of revision arthroplasty compare with ankle fusion for treating a failed total ankle arthroplasty?

assistant professor of orthopaedic surgery at Duke University Medical Center, was awarded a 2014 Orthopaedic Research and Education Foundation (OREF) Research Grant in Revision Related to Total Ankle Arthroplasty to address these questions. The grant, made possible by Wright Medical, provides $100,000 over a 2-year period. Dr. Queen is completing this work as the director of the Kevin P. Granata Biomechanics Lab (Granata Lab) and associate professor of biomedical engineering and mechanics at Virginia Tech.

Dr. Queen's study has two goals: to compare and characterize the outcomes of primary and revision arthroplasty and to assess the economic outcomes of revision ankle arthroplasty and ankle fusion to treat a failed ankle implant. Assembling the data to achieve the first goal requires the use of some innovative technology.

Recording movement
One assessment tool that Dr. Queen and her colleagues are using is three-dimensional (3D) motion-capture technology. A biomedical engineer by training, Dr. Queen noted that this technology provides relevant biomechanical data that helps the researchers evaluate postoperative changes in functional abilities.

Dr. Queen explained, "We used a technology similar to what is used to make video games or movies to look at how somebody moves. We put small reflective markers on the patients and recorded their movement using a large motion-capture system (Fig. 1). With this system, we calculated such things as the amount of force that was being imparted on the patients' bodies and their joint position while walking, sitting, or standing."

According to Dr. Queen, the technology was valuable not only in their investigations but also for patient education. "We showed patients a visual representation of how they were walking before surgery and after. They think it's great when they can see they don't have the same limp or they're not walking as slowly," she said.

Comprehensive assessment of outcomes
Duke University Medical Center already had a comprehensive database of functional and clinical outcomes following primary TAA. The OREF-funded study built upon this work with the outcomes of revision arthroplasty or fusion—either ankle fusion or tibiotalocalcaneal fusion.

The expanded database includes the following information (preoperative and one-year postoperative):

  • motion-capture, biomechanical data
  • physical examination by the treating physician
  • multiple scales for patient-reported functional abilities and pain
  • multiple standard functional assessments, such as timed get-up-and-go, single-leg stance, walking speed, and the Short Physical Performance Battery
Robin M. Queen, PhD,
Fig. 1 TAA patient with reflective markers in place. Markers are used to monitor motion as the patient performs specific activities.
Courtesy of Robin M. Queen, PhD

This will enable researchers to compare and characterize the outcomes of the primary and revision arthroplasty. They started with 20 patients in each treatment group matched by age, sex, and body mass index.

"We anticipate that these findings can be used to refine patient education, to explain what the postoperative course will look like, what their limitations may be, and what their expectations should be," said Dr. Queen.

She hopes that ultimately the research will inform efforts to alter the postoperative course with nonsurgical interventions, such as physical therapy and activity modifications. "That's where my research melds with orthopaedic surgery. After the surgeon has performed this great procedure, what can we do to augment that in an attempt to get the patient back to moving better or to lower the risk for another surgery?"

Cost-effectiveness of treatment options
To assess the economic outcomes of revision ankle arthroplasty and ankle fusion to treat a failed ankle implant, researchers are taking into account both the direct medical costs of the procedures and indirect costs related to treatment outcomes and functional status, such as the ability to work, changes in earnings, number of days missed from work, and disability payments. They will collect data from 30 patients in each of the treatment groups.

Dr. Queen noted that the benefit of this investigation may be two-fold. First, it would lay a foundation for determining best practices in treating failed ankle implants. Second, better outcomes and more cost-effectiveness with revision arthroplasty—if observed—might inform alterations in implant designs and surgical procedures that better accommodate revision surgery.

Benefits of OREF
The value of OREF, according to Dr. Queen, extends beyond funds for conducting investigations and gathering pilot data for grants from the National Institutes of Health (NIH). Another benefit is OREF's grant-writing workshops. "I had the opportunity to sit down with researchers who are highly funded," she stated. "They gave us feedback that has helped us make the strongest proposal we can to secure NIH grants."

Dr. Queen also noted that OREF grants have enabled her to train junior level researchers in her lab. "The students and residents get to understand the importance of doing research and doing it correctly and ethically. OREF has fostered my role in helping them move toward their own goals of becoming surgeons or PhDs in orthopaedic research."

In addition to directing the Granata Lab, Dr. Queen holds affiliated positions in the Edward Via College of Osteopathic Medicine, the Department of Health Sciences at Virginia Tech, and the Department of Orthopaedic Surgery at Virginia Tech–Carilion School of Medicine.

Jay D. Lenn is a contributing writer for OREF. He can be reached at communications@oref.org