Related Experiment Video
Updated: Sep 23, 2026
Home-Based Monitor for Gait and Activity Analysis
Published on: August 8, 2019
Measuring Long-Term Outcomes After Degenerative Spine Surgery: Is It Time for Something New? A Smartphone-Based
Advith Sarikonda1, Harsh Jain1, Logan D Pasquariello2
1Department of Neurological Surgery, Vanderbilt University Medical Center, Nashville, Tennessee, USA.
Background And Objectives:
Although the goal of spine surgery is to improve functionality, conventional patient-reported outcome measures (PROMs) cannot capture nuances of longitudinal ambulation. Therefore, using patient smartphones, we (1) assessed long-term change in mobility and (2) evaluated correlations between objective mobility and subjective PROMs.
Methods:
Patients undergoing degenerative lumbar spine surgery or surgery for cervical myelopathy were enrolled to share iPhone (Apple Inc.) health data. Smartphone metrics included daily step count, walking distance, and flights climbed. Primary outcome was change in mobility from preoperatively to the following: immediate postoperative (0-30 days), 6 months, and last follow-up. Linear mixed-effects models evaluated mobility changes, expressed as SD units relative to baseline. Likewise, correlations between mobility and PROMs were performed, including: Oswestry Disability Index, Neck Disability Index, Visual Analog Scale (VAS) pain, and Patient Health Questionnaire-9.
Results:
Fifty-one patients (38 lumbar, 13 cervical) shared 60 753 patient-days of mobility data. The mean age was 53.2 ± 14.8 years; 51.0% were female. Change in Mobility: All mobility parameters declined during the immediate postoperative period, though patients recovered by approximately 2 to 3 months postoperatively. At last follow-up, lumbar patients demonstrated sustained improvement in all mobility parameters, particularly daily walking distance (β = 0.54 SD). Cervical patients demonstrated significant long-term improvement in steps and walking distance (both β = 0.19 SD). Correlation with PROMs: Among lumbar patients, mobility improvements correlated with lower/better Oswestry Disability Index, VAS-leg pain, and VAS-back pain (all r ≤ -0.40). In cervical patients, improved step count and walking distance correlated with lower/better Neck Disability Index, Patient Health Questionnaire-9, and VAS-neck pain (all r ≤ -0.40).
Conclusion:
In this pilot study using smartphone motion sensors, spine surgery was associated with an early postoperative decline in mobility, followed by recovery at approximately 2 to 3 months postoperatively and sustained long-term improvement. Objective ambulatory improvement correlated with subjective functionality, pain, and mood. Smartphones may therefore assist surgeons in data-driven patient counseling and early identification of atypical recovery trajectories.
