Clinical and Radiologic Predictors of Slower Improvement and Nonimprovement After Surgical Treatment of L4-L5 Degenerative Spondylolisthesis: Preliminary Results.

Study design: Retrospective cohort.

Objective: To identify the predictors of slower and nonimprovement after surgical treatment of L4-5 degenerative lumbar spondylolisthesis (DLS).

Summary of background data: There is limited evidence regarding clinical and radiologic predictors of slower and nonimprovement following surgery for L4-5 DLS.

Methods: Patients who underwent minimally invasive decompression or fusion for L4-5 DLS and had a minimum of 1-year follow-up were included. Outcome measures were: (1) minimal clinically important difference (MCID), (2) patient acceptable symptom state (PASS), and (3) global rating change (GRC). Clinical variables analyzed for predictors were age, gender, body mass index (BMI), surgery type, comorbidities, anxiety, depression, smoking, osteoporosis, and preoperative patient-reported outcome measures (PROMs) (Oswestry disability index, ODI; visual analog scale, VAS back and leg; 12-Item Short Form Survey Physical Component Score, SF-12 PCS). Radiologic variables analyzed were slip percentage, translational and angular motion, facet diastasis/cyst/orientation, laterolisthesis, disc height, scoliosis, main and fractional curve Cobb angles, and spinopelvic parameters.

Results: Two hundred thirty-three patients (37% decompression and 63% fusion) were included. At less than three months, high pelvic tilt (PT) (OR: 0.92, P= 0.02) and depression (OR: 0.28, P= 0.02) were predictors of MCID nonachievement and GRC nonbetterment, respectively. Neither retained significance at above six months and hence, were identified as predictors of slower improvement. At above six months, low preoperative VAS leg (OR: 1.26, P= 0.01) and high facet orientation (OR: 0.95, P= 0.03) were predictors of MCID nonachievement, high L4-5 slip percentage (OR: 0.86, P= 0.03) and L5-S1 angular motion (OR: 0.78, P= 0.01) were predictors of GRC nonbetterment, and high preoperative ODI (OR: 0.96, P= 0.04) was a predictor of PASS nonachievement.

Conclusions: High PT and depression were predictors of slower improvement and low preoperative leg pain, high disability, high facet orientation, high slip percentage, and L5-S1 angular motion were predictors of nonimprovement. However, these are preliminary findings and further studies with homogeneous cohorts are required to establish these findings.