Do postoperative changes in physical function affect patient-reported outcomes in patients with lumbar spinal stenosis undergoing rehabilitation? A secondary analysis of a randomized controlled trial.

PURPOSE

To investigate the relationships between changes in objective physical function and changes in patient-reported outcome measurements (PROMs) in patients with lumbar spinal stenosis (LSS) undergoing lumbar surgery.

METHODS

This study was a secondary analysis of a randomized controlled trial, in which patients with LSS undergoing lumbar surgery received an inpatient postoperative rehabilitation program. Objective physical assessments included gait speed, a Timed Up and Go test (TUG), handgrip and knee muscle strength, and bioelectrical impedance analysis for skeletal muscle at 3 months. PROMs included the Zurich Claudication Questionnaire (ZCQ), a numerical rating scale for back pain, leg pain, and leg numbness, the Japanese Orthopedic Association Back Pain Evaluation Questionnaire, and the 36-item Short-Form survey (SF-36) at 3 and 12 months.

RESULTS

A total of 80 patients (40 males and 40 females, average age 70.4 years) were included. At 3 and 12 months, changes in gait speed, TUG, and knee extensor strength showed some small but significant correlations with changes in the ZCQ and SF-36 physical functioning subscales (r = 0.23-0.42). Multivariable linear regression analyses revealed some significant associations between changes in objective physical assessments (gait speed, TUG, hand grip, and knee muscle strength) and PROMs (ZCQ, NRS, and SF-36 physical functioning subscale). However, these associations were limited in strength (standardized β = |0.24-0.34|, adjusted R² = 0.03-0.13).

CONCLUSION

The findings of this study showed limited associations between changes in objective physical assessments and changes in PROMs in patients with LSS who underwent lumbar surgery and postoperative rehabilitation.

TRIAL REGISTRATION

UMIN000030881.