Feasibility of Smartphone-Derived Short-Interval Walking Tests for Monitoring Functional Recovery After Spine Surgery

Area of Science:

• Orthopedics
• Rehabilitation Medicine
• Digital Health

Background:

• Traditional patient-reported outcomes for spine surgery recovery are subjective and prone to bias.
• Objective monitoring via wearables or smartphones is limited by continuous device use.
• Capacity-oriented measures like the 1-minute walk test (1MWT) and 6-minute walk test (6MWT) offer potential for reliable assessment.

Purpose of the Study:

• To evaluate the reliability and feasibility of smartphone-derived interval metrics for monitoring functional recovery after lumbar spine surgery.
• To compare smartphone-derived walk test data with traditional activity metrics.

Main Methods:

• Retrospective analysis of iPhone Health data from 41 lumbar spine surgery patients.
• A sliding-window algorithm simulated 1MWT and 6MWT from daily distance data.
• Extracted step counts and active time, comparing activity across baseline, preoperative, early postoperative, and late postoperative intervals.
• Statistical analysis included paired t-tests/Wilcoxon signed-rank tests with Simes-Hochberg adjustment and coefficient of variation (CV) for stability.

Main Results:

• Smartphone-derived 1MWT and 6MWT significantly improved from the immediate preoperative period to late recovery (2-6 weeks post-surgery).
• These walk tests demonstrated lower day-to-day variability (CV) compared to step counts.
• 1MWT and 6MWT metrics showed strong correlation with each other.

Conclusions:

• Smartphone-derived 1MWT and 6MWT are feasible and reliable objective measures for assessing functional recovery post-lumbar spine surgery.
• These digital metrics provide a valuable alternative to subjective patient-reported outcomes.
• The findings support the integration of smartphone data into routine surgical recovery monitoring.