Step activity monitoring to assess ambulation before and after total ankle arthroplasty

Decreased physical activity in patients with ankle osteoarthritis. A case-control study comparing daily step counts

BACKGROUND

The purpose of this study was to compare physical activity levels and the proportion of patients who met physical activity recommendations in patients with ankle osteoarthritis and controls.

METHODS

Ankle osteoarthritis patients (n = 50) and controls (n = 50) were recruited. physical activity was measured using an accelerometer-based monitor. Physical activity parameters, including the step count/day, the proportion of patients who met physical activity recommendations of ≥7000 steps/day, and moderate to vigorous physical activity minutes/day, were compared between the patient groups.

RESULTS

The patients with ankle osteoarthritis walked 3998 steps/day, while the controls walked 6531 steps/day (P < .001). Only 7 (14%) ankle osteoarthritis patients and 17 (34%) controls met the physical activity recommendations of ≥7000 steps/day (P =  .01). Time spent performing moderate to vigorous physical activity was 58 and 78 min/day in the ankle osteoarthritis and controls, respectively.

CONCLUSIONS

The physical activity level of ankle osteoarthritis patients was lower than that of controls. Only a limited proportion of ankle osteoarthritis patients met the physical activity recommendation.

Step Activity After Surgical Treatment of Ankle Arthritis

BACKGROUND

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).

METHODS

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.

RESULTS

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).

CONCLUSIONS

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.

LEVEL OF EVIDENCE

Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.