Clinical and Radiographic Factors Affecting the Outcomes of Decompression Surgery in Clinical and Radiographic...

Introduction The optimal surgical strategy for Clinical and Radiographic Degenerative Spondylolisthesis (CARDS) Type C remains controversial, particularly regarding decompression alone versus fusion surgery. Evidence focusing on outcomes after decompression alone in this subgroup is limited. This study evaluated clinical outcomes after decompression in patients with L4 degenerative spondylolisthesis classified as CARDS Type C and identified preoperative factors associated with postoperative walking function. Methods This retrospective analysis of prospectively collected data included 59 patients who underwent decompression surgery for lumbar spinal stenosis associated with L4 degenerative spondylolisthesis between April 2018 and March 2022 and were followed for at least one year. Thirty-four patients classified as CARDS Type C were analyzed. Clinical outcomes were assessed using visual analog scale scores for low back pain and leg pain, the Oswestry Disability Index, and the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ) preoperatively and at six months and one year postoperatively. Preoperative radiographic parameters, including slip distance, segmental motion, and spinopelvic alignment, were evaluated. Factors associated with changes in JOABPEQ walking function were analyzed using correlation analysis, stepwise multiple regression, and receiver operating characteristic (ROC) curve analysis. Results All clinical outcome measures showed significant improvements at six months and one year after surgery. Stepwise multiple regression identified two independent factors associated with poorer improvement in walking function: preoperative change in L4 slip distance and preoperative pelvic tilt (PT). ROC analysis for treatment effectiveness based on the JOABPEQ walking function score showed areas under the curve of 0.65 for slip distance change and 0.76 for PT, with optimal cutoff values of 4 mm and 30 degrees, respectively. Conclusions Decompression surgery provides generally favorable outcomes in CARDS Type C. However, postoperative improvement in walking function may vary depending on preoperative radiographic characteristics. Greater dynamic instability and increased PT were associated with limited functional recovery. These findings suggest that decompression alone may achieve favorable outcomes in selected patients with less dynamic instability and lower PT.