LAUSR

STUDY DESIGN Retrospective Cohort Study. OBJECTIVE The decision to pursue operative intervention for patients with isthmic spondylolisthesis is complex. While steroid injections are a well-accepted therapeutic modality that may delay or obviate surgery, little is known regarding their ability to predict surgical outcomes. SUMMARY OF BACKGROUND DATA Here we examine whether improvement following pre-operative steroid injections can accurately predict clinical outcomes after surgery. MATERIALS AND METHODS A retrospective cohort analysis was performed on adult patients undergoing primary posterolateral lumbar fusion for isthmic spondylolisthesis between 2013 and 2021. Data were stratified into a control (no pre-operative injection) group and an injection group (received a pre-operative diagnostic and therapeutic injection). We collected demographic data, peri-injection VAS pain scores, PROMIS pain interference (PI) and physical function (PF) scores, ODI, and VAS pain (back and leg). Student t test was utilized to compare baseline group characteristics. Linear regression was performed comparing changes in peri-injection VAS pain scores and post-operative measures. RESULTS 73 patients did not receive a pre-operative injection and were included in the control group. 59 patients were included in the injection group. Of patients who received an injection, 73% had greater than 50% relief of their pre-injection VAS pain score. Linear regression revealed a positive interaction between the injection efficacy and post-operative pain relief as measured by VAS leg scores (P<0.05). There was also an association between injection efficacy and back pain relief, though this did not achieve statistical significance (P=0.068). No association was found between injection efficacy and improvement in ODI nor PROMIS measures. CONCLUSIONS Steroid injections are often utilized in the non-operative therapeutic management of patients with lumbar spine disease. Here, we demonstrate the diagnostic value of steroid injections in predicting post-operative leg pain relief in patients undergoing posterolateral fusion for isthmic spondylolisthesis.