Outcome of one-level posterior lumbar interbody fusion for spondylolisthesis and postoperative intervertebral disc degeneration adjacent to the fusion

Study Design. Review of the clinical and radiologic records of patients who underwent one-level posterior lumbar interbody fusion (PLIF) at L4-L5. Objective. To determine whether adjacent intervertebral disc degeneration a fter PLIF affects the clinical results, and whether preoperative caudal dis c (L5-S1) degeneration affects postoperative clinical results. Summary of Background Data. There is little reliable information in the lit erature regarding clinical results and adjacent disc degeneration after PLI F. Methods. Forty-five patients who underwent L4-L5 PLIF for spondylolisthesis with more than 5 years of postoperative observation were included in this study. PLIF was performed in conjunction with posterior instrumentation. Th e posterior lumbar intervertebral grafting was performed using both autogra ft and a ceramic spacer. Intervertebral disc heights at L2-L3, L3-L4, and L 5-S1 were measured before and after surgery. The patients were divided into two groups based on the presence or absence of the preoperative L5-S1 narr owing. Correlation between clinical status evaluated by the recovery rate o f the Japanese Orthopedic Association (JOA) score and disc heights were det ermined. Results. All intervertebral disc heights adjacent to the fusion decreased a fter surgery (P < 0.05). However, no significant correlation was seen betwe en clinical results estimated by the recovery rate and postoperative disc n arrowing. There was also no significant difference in clinical results betw een patients with or without preoperative L5-S1 narrowing. Conclusions. There is no evidence from the results that postoperative narro wing of the adjacent disc and preoperative narrowing of the L5-S1 disc affe cts the clinical outcome of L4-L5 PLIF.