Preoperative disc angle is an important predictor of segmental lordosis after degenerative spondylolisthesis fusion — The International Society for the Study of the Lumbar Spine
  1. Schedule
  2. Special Poster Session 2H. DEGENERATIVE LUMBAR DISEASE
  3. Preoperative disc angle is an important predictor of segmental lordosis after degenerative spondylolisthesis fusion

Preoperative disc angle is an important predictor of segmental lordosis after degenerative spondylolisthesis fusion (#134)

Patrick Thornley 1 , Raymond Andrew Glennie 2 , Abdulmajeed Alahmari 1 , Fares Al-Jahdali 2 , Y. Raja Rampersaud 3 , Charles Fisher 4 , Jennifer Urquhart 5 , Chris Bailey 1
  1. London Health Sciences Centre, London, ON, Canada
  2. Department of Surgery, Division of Orthopaedic Surgery, Dalhousie University, Halifax, Nova Scotia, Canada
  3. Department of Surgery, Division of Orthopaedic Surgery, The Schroeder Arthritis Research Institute, Krembil Research Institute, University Health Network, Toronto, ON, Canada
  4. Combined Neurosurgical and Orthopaedic Spine Program, University of British Columbia, Vancouver, British Columbia, Canada
  5. Lawson Health Research Institute, Western University, London, ON, Canada

Introduction:  Maintenance of sagittal balance is largely dependent upon lumbar lordosis, the majority of which is derived from the lower lumbar motion segments and specifically the segmental disc angles. Lumbar degenerative spondylolisthesis (LDS) with associated spinal stenosis is a common indication for spinal surgery, often treated with fusion surgery with or without the use of an interbody. It is important to understand the effects of spinal fusion on the index spinal segment prior to surgery so as not to induce iatrogenic deformity by changing previously lordotic disc spaces to kyphotic or failing to address a preoperatively kyphotic disc space. The objective of this study was to determine the effect of interbody cages inserted via posterior approach on segmental lordosis in the setting of preoperative lordotic versus kyphotic/neutral disc spaces in patients with LDS.

Methods:  Five consecutive years of retrospective data from the Canadian Spine Outcomes and Research Network (CSORN) prospective study on the assessment and management of LDS patients was collected from two contributing centres of consecutively enrolled patients. Patients were analyzed preoperatively and at 12-month follow-up with standing lumbar radiographs. At the spondylolisthesis level, segmental lumbar lordosis (SLL) was measured from the upper end plate of the proximal vertebra to the lower end plate of the distal vertebra. Patients were stratified into four groups based on index level disc angle and the type of procedure performed: preoperative lordotic posterolateral fusion (PLF) (Group 1); preoperative neutral/kyphotic PLF (Group 2); preoperative lordotic interbody fusion (IF) (Group 3); preoperative neutral/kyphotic IF (Group 4).

Results:  A total of 100/111 (90%) patients completed one-year follow-up. Twenty-three patients underwent PLF with 18 (18%) in group 1 and only five (5%) in group 2. Eighty-eight patients underwent IF, with 40 (40%) in group 3 and 48 in group 4 (48%). Among patients with preoperatively lordotic disc angles, group 3 had a greater magnitude of worsening in SLL than group 1 patients, with significant differences persisting at one-year (mean difference 2.30, 95% CI, 0.3, 4.3, P=0.029). Patients in group 4 were more likely to achieve improvement in SLL at one year than group 3 (67% vs. 44%, p=0.046), with similar mean improvement magnitude between groups 3 and 4 (-1.1, 95% CI, -3.7, 1.6, P=0.415).  

Discussion:  In the setting of an index-level preoperative lordotic disc angle, the magnitude of segmental lordosis worsening was more pronounced when an interbody cage was used versus PLF. Patients who have a kyphotic or neutral disc space preoperatively are more likely to gain lordosis when an interbody cage is used.

#ISSLS2022