DOI: 10.1227/neuprac.0000000000000298 ISSN: 2834-4383
Measuring Long-Term Outcomes After Degenerative Spine Surgery: Is It Time for Something New? A Smartphone-Based Analysis of 60 753 Days of Objective Mobility Data
Advith Sarikonda, Harsh Jain, Logan D. Pasquariello, Clayton R. Baker, James F. Bathon, Nick De Oliveira, Raymond J. Gardocki, Bayard R. Wilson, Amir M. Abtahi, Byron F. Stephens, Scott L. Zuckerman
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.