Assal M. J Foot Ankle Surg. 2011. doi:10.1016/j.fas.2010.03.006.
While patients had better walking cadence and American Orthopaedic Foot and Ankle Society hindfoot scale scores after total ankle arthroplasty, the procedure did not increase the amount of time they spent walking, according to Swiss researchers.
Mathieu Assal, MD, University Hospitals of Geneva, Switzerland, and colleagues used a dedicated ambulatory activity monitoring device to prospectively review 19 patients who underwent total ankle arthroplasty (TAA). They tested patients 1 month prior to surgery and at least 18 months postoperatively. In addition, they evaluated the American Orthopaedic Foot and Ankle (AOFAS) hindfoot scale. The researchers chose the following ambulatory parameters: number of steps at different cadences and time spent walking at different paces.
The results showed that there was a significant improvement in the number of steps walked at a normal pace and the number of steps walked at low and medium pace decreased. The researchers found no significant difference between the time actually spent walking at any pace after TAA. The mean AOFAS hindfoot scale improved significantly.
The ability of an orthopedic device, such as TAA, to restore or improve locomotion can be evaluated using gait analysis. Data on gait can be used to recommend, modify or discontinue use of a device.
This study reports that following TAA, there was significant improvement in the number of steps walked at normal cadence, while there was no significant difference between the time actually spent walking at any cadence. Walking is, however, a complex combination of muscle forces, joint interactions and physical condition. Although a significant improvement in cadence is noted, the actual time spent walking remains the same and may be a result of overall strength and conditioning, rather than success of the implant.
Gait analysis can be achieved with simple observation or a complex three-dimensional study. A major problem with many dedicated ambulatory activity-monitoring devices is the accuracy of step counting, an important component of this study. Counting steps in a laboratory may not be as accurate as monitoring days or weeks of walking under normal living conditions. Of interest, studies on commonly used pedometers have shown that some may overestimate by 45%, and some underestimate by 20%.
It is important to note that there was a significant improvement in the AOFAS hindfoot score.
— Carol C. Frey, MD
Associate Professor of Orthopedic Surgery
University of California, Manhattan Beach
Manhattan Beach, Calif.
Foot & Ankle Section Editor