Step Activity After Surgical Treatment of Ankle Arthritis

• Published in: Journal of bone and joint surgery. American volume Vol. 101; no. 13; p. 1177
• Main Authors: Shofer, Jane B, Ledoux, William R, Orendurff, Michael S, Hansen, Sigvard T, Davitt, James, Anderson, John G, Bohay, Donald, Coetzee, J Chris, Houghton, Michael, Norvell, Daniel C, Sangeorzan, Bruce J
• Format: Journal Article
• Language: English
• Published: United States 03.07.2019
• Subjects: Ankle Joint - physiopathology; Ankle Joint - surgery; Arthrodesis; Arthroplasty, Replacement, Ankle; Disability Evaluation; Female; Humans; Male; Middle Aged; Monitoring, Ambulatory; Osteoarthritis - physiopathology; Osteoarthritis - surgery; Pain Measurement; Patient Reported Outcome Measures; Prospective Studies; Walking
• ISSN: 1535-1386
• DOI: 10.2106/JBJS.18.00511

Ambulatory activity is reduced in patients with ankle arthritis. In this study, we measured step activity over time in 2 treatment groups and secondarily compared step activity with results of patient-reported outcome measures (PROMs). Patients who were treated with either ankle arthrodesis or ankle arthroplasty wore a step activity monitor preoperatively and at 6, 12, 24, and 36 months postoperatively. Changes from preoperative baseline in total steps per day and per-day metrics of low, medium, and high-activity step counts were measured in both treatment groups. Step activity was compared with each subject's PROM scores as reported on the Musculoskeletal Function Assessment (MFA) and the Short Form-36 (SF-36) physical function and bodily pain subscales. Of the 3 activity levels, combined group high-activity step counts showed the greatest increase (mean of 278 steps [95% confidence interval (CI), 150 to 407 steps], a 46% improvement from preoperatively). At 6 months, the mean high-activity step improvement for the arthroplasty group was 194 steps compared with a mean decline of 44 steps for the arthrodesis group (mean 238-step difference [95% CI, -60 to 536 steps]). By 36 months postoperatively, the greater improvement in high-activity steps for the arthroplasty versus the arthrodesis group was no longer present. There were no significant pairwise differences in improvement based on surgical treatment method at any individual follow-up time point. For a within-patient increase of 1,000 total steps, there was a mean change in the MFA, SF-36 physical function, and SF-36 bodily pain scores of -1.8 (95% CI, -2.4 to -1.2), 3.8 (95% CI, 2.8 to 4.8), and 2.8 (95% CI, 1.8 to 3.9), respectively (p < 0.0001 for all associations). There was no evidence that the association differed by study visit, or by study visit and surgical procedure interaction (p > 0.10). Surgical treatment of ankle arthritis significantly improves ambulatory activity, with greater change occurring at high activity levels. Improvement may occur more quickly following arthroplasty than arthrodesis, but at 3 years, we detected no significant difference between the 2 procedures. Step counts, while associated with PROMs, do not parallel them, and thus may be a useful supplementary measure, particularly in longitudinal studies. Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.