Physical Performance Continues to Improve After Surgery for Sciatica, Exceeding Recovery Periods of Physical Capacity and Patient-Reported Outcomes: Multicenter Prospective Observational Study.

OBJECTIVE

To longitudinally analyze smartphone-based real-life activity data and compare it with established clinical outcome measures in patients undergoing lumbar spine surgery for sciatica, focusing on identifying divergence in recovery trajectories.

METHODS

Fifty patients were assessed preoperatively and at 6 weeks (6W), 3 months (3M), and 6 months (6M). Outcomes included smartphone-derived daily Step Count, objective capacity (6-minute walking test [6WT]), and subjective disability (visual analogue scale [VAS] leg/back, Core Outcome Measures Index [COMI] back, and Oswestry Disability Index [ODI]). All metrics were standardized into z-scores relative to baseline. Piecewise linear mixed-effects (LME) models compared recovery slopes across 2 segments: phase I (early: 0-6 weeks) and phase II (late: 6 weeks-6 months).

RESULTS

The cohort (mean age, 50.7 years; 24 females) included 33 patients with lumbar disc herniation and 17 with lateral recess stenosis. All measures improved significantly during phase I (all p<0.05). However, LME modeling revealed a significant interaction between time segment and measurement type in phase II. Daily Step Count was the only metric maintaining a significant, linear upward recovery slope during the late phase (β=0.31 Z/mo). Conversely, slopes for 6WT, ODI, and COMI were significantly flatter (p<0.001 vs. Step Count), indicating a statistical plateau or "ceiling effect." Spearman correlations between Step Count and traditional metrics weakened from strong at baseline to weak at 6 months.

CONCLUSION

Smartphone-derived real-life activity data detect continuous functional improvement up 6 months postoperatively, whereas conventional objective and subjective measures plateau by 6 weeks. Real-world activity monitoring provides a more sensitive assessment of long-term surgical success.