All patients were treated with either arthroplasty (n = 145) or arthrodesis (n = 89). Their step activity was measured with a StepWatch 3 Activity Monitor preoperatively and at 6, 12, 24, and 36 months postoperatively. In both groups combined, step counts during “high activity” (>40 steps per minute) increased by 46% over 36 months. At 6 months, the mean high-activity step improvement was 194 steps in the arthroplasty group, compared with a mean decline of 44 steps for the arthrodesis group. However, by 36 months after surgery, the between-group differences in high-activity steps had disappeared.
The authors also analyzed associations between the objective step results and 3 patient-reported outcomes (the Musculoskeletal Function Assessment and the SF-36 physical function and pain scores). Unlike the patient-reported scores, which improved dramatically in the first 6 months and then plateaued, improvements in step activity increased gradually throughout the 3-year follow-up.
The authors emphasized that during the first 12 postoperative months, the arthrodesis patients had little or no improvement in step activity, but at 3 years there were no significant differences between arthrodesis and arthroplasty patients. These findings suggest that, in this clinical scenario, an individual patient’s expectations with the pace of improvement may be a suitable topic during shared decision making conversations.
This study does not entirely reconcile previously equivocal findings regarding arthroplasty-versus-arthrodesis, but it does emphasize the substantial and sustained activity benefits that patients in both groups receive. Shofer et al. conclude that objective measurements from wearable technology “may complement patient-reported outcomes” in future longitudinal outcome studies of many orthopaedic treatments.