Factors Associated with Pain Intensity and Walking Disability after Lumbar Fusion

Retrospective longitudinal study.To identify the preoperative factors associated with postoperative lumbar fusion recovery in back or leg pain, self-reported walking time and gait speed over a 6-month period.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.The study analysed 232 subjects with mono- or bi-segmental lumbar fusion surgery who underwent standardized assessment preoperatively and at 4, 12, and 24 weeks 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 modelling.At 6months 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 self-reported 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 (aOR = 4.0) and shorter walking time (aOR = 2.7) - but not with slower gait speed (difference = 0.01m/s). Old age and female gender were strongly associated with gait speed but not with self-reported walking time.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 self-reported 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 optimise postoperative outcomes.