Objective evaluation of postoperative changes in real-life activity levels in the postoperative course of lumbar spinal surgery using wearable trackers

BACKGROUND: Lumbar spinal disease causes disabilities in performing daily activities. Operative treatments are aimed at pain relief and rapid return to routine activity. Patient-based outcome measures are used to evaluate pathologies and therapeutic effects associated with lumbar spinal disease. Nevertheless, it remains unknown as to how much such treatment improves activity levels. The purpose of the current study was to measure changes in activity levels before and after lumbar spinal surgery using a wearable activity tracker and to analyze the differences between results and patient-based outcomes. METHODS: Sixty patients who underwent lumbar surgery were studied. The physical activity of participants was objectively evaluated using a wearable Micro-Motion logger system (Actigraph). We measured the amount of activity before and at 1, 3, 6, and 12 months after the surgery to evaluate postoperative changes. The Japanese Orthopaedic Association Back Pain Evaluation Questionnaire, Oswestry Disability Index, Roland-Morris Disability Questionnaire and visual analog scale were used to assess patient-based outcomes of pain and activities of daily living-related scores; we analyzed the relationships between scores and actual activity levels. RESULTS: The amount of actual activity decreased significantly 1 month after the surgery compared to that during the preoperative period, which then improved after 3 months postoperatively (p < 0.01). Furthermore, there was a significant improvement 6 months after the surgery compared to that during the preoperative period (p < 0.05). The changes in activity for each period were strongly correlated, regardless of the period. In contrast, a significant improvement was observed at 1 month after the surgery in almost all items of the patient-based questionnaires (p < 0.05). CONCLUSIONS: The objective activity tracker demonstrated that lumbar surgery results in the amount of activity decreasing 1 month just after surgery followed by gradual postoperative recovery within 3 months. By contrast, patient-based outcomes showed improvement in 1 month that was significantly different from the change in actual activity, indicating a gap between patient-oriented clinical scores and their actual activities.