Factors Associated with Pain Intensity and Walking Disability After Lumbar Fusion

Abstract

Study Design. Retrospective longitudinal study. Objective. To identify the preoperative factors associated with postoperative lumbar fusion recovery in back or leg pain, selfreported walking time, and gait speed over a 6-month period. Summary of Background Data. The demand for lumbar fusion surgeries has significantly increased over the years. Yet, some patients report persistent postsurgical pain and poor functional outcomes. Unfortunately, the associated risk factors are not well understood. Methods. The study analyzed 232 subjects with mono-or bisegmental lumbar fusion surgery who underwent standardized assessment preoperatively and at 4, 12, and 24weeks postoperatively. Preoperative variables collected were demographic, clinical, and psychological variables. Back or leg pain was measured by the Numeric Pain Rating Scale. Walking disability was measured by self-reported walking time and performance-based fast gait speed. Risk factors of pain and walking disability over time were identified using ordinal and linear mixed-effects modeling.Results. At 6 months post-surgery, 17% of patients reported having moderate or severe back/leg pain and 24% were unable to walk longer than 30 minutes. Greater preoperative selfreported leg weakness frequency and body-mass-index (BMI) were strongly associated with greater pain and walking disability. Additionally, greater preoperative depression symptoms were associated with greater back/leg pain (adjusted odds ratio ¼ 4.0) and shorter walking time (adjusted odds ratio ¼ 2.7)-but not with slower gait speed (difference ¼ 0.01 m/s). Old age and female gender were strongly associated with gait speed but not with self-reported walking time. Conclusion. A sizable proportion of patients had poor pain and walking outcomes even at 6 months post-surgery. Preoperative leg weakness and BMI were consistent risk factors and patients with greater depression symptoms may have poorer selfreported outcomes. Although requiring validation, our study has identified potentially modifiable risk factors which may give clinicians an opportunity to provide early (preoperative) and targeted intervention strategies to optimize postoperative outcomes.