Can a Made-for-Consumer Activity Monitor Assess Physical Activity in Adolescents and Young Adults after Lower Extremity Limb Salvage for Osseous Tumors?

Background: The purpose of this study was to test the validity of a consumer-oriented activity monitor in adolescents and young adults undergoing limb salvage for primary bone malignancies. Methods: A cross-sectional population of participants with an average age of 16 (range 12 to 22) years produced 472 days of activity monitoring during 25 evaluations periods alongside patient-reported outcome measures. Results: Average daily steps ranged from 557 to 12,756 (mean=4711) and was moderately associated with the short-form (SF) 36 physical component subscale (r=0.46, P=0.04) as well as the SF6D health state utility measure (r=0.48, P=0.04), but not the SF36 mental component subscale (P=0.66) or Toronto extremity salvage score (P=0.07). Time from surgery was strongly correlated with average daily steps (r=0.7, P<0.001). Conclusions: A made-for-consumer activity monitor provided real-world data regarding the outcome of adolescent and young adult limb salvage, and evidence of validity in this population. Such lower cost, user-friendly devices may facilitate assessment of free-living activity and allow novel comparisons of treatment strategies. Level of Evidence: Level II-diagnostic.