A Canadian Spine Outcomes and Research Network study of radiographic alignment outcomes with different surgery type for degenerative lumbar spondylolisthesis — The International Society for the Study of the Lumbar Spine
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  2. SESSION #6 - SURGERY II: FUSION AND MINIMALLY INVASIVE SURGERY
  3. A Canadian Spine Outcomes and Research Network study of radiographic alignment outcomes with different surgery type for degenerative lumbar spondylolisthesis

A Canadian Spine Outcomes and Research Network study of radiographic alignment outcomes with different surgery type for degenerative lumbar spondylolisthesis (#33)

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

Introduction:  The importance of sagittal balance and pelvic parameters as they pertain to overall spinal balance are well-established for the deformity and isthmic spondylolisthesis population. The overall effect of differing surgical intervention type for patients undergoing interventions for degenerative lumbar spondylolisthesis (DLS) is not known. Furthermore, the magnitude of postoperative alignment effects based on a particular surgical intervention for DLS is not established. The objective of this investigation was to assess the effect of decompression versus posterolateral fusion versus interbody fusion on spinal alignment among patients undergoing surgery for DLS. 

Methods:  Retrospective analysis of the Canadian Spine Outcomes and Research Network (CSORN) prospective study on the assessment and management of DLS was performed. Patients who had decompression alone (D), posterolateral fusion (PLF) or interbody fusion (IB) between 2015 and 2020 and were one-year postoperative were included. Sagittal vertical axis (SVA), lumbar lordosis (LL) and pelvic incidence (PI) were measured preoperatively and one-year postoperatively. Patients were divided into two groups based on whether their one-year postoperative spinal alignment improved/stayed the same or deteriorated by subtracting the one-year measure from baseline. The proportion of patients and the magnitude of the change was compared among surgery types.

Results:  Two-hundred forty-eight patients had LL (D=69, IB=147, PLF=32), 192 patients had SVA (D=52, IB=114, PLF=26) and 243 patients had PI-LL (D=71, IB=137, PLF=32) measures at one-year. The majority of patients saw an improvement in alignment and the proportion of patients that improved was similar among surgery groups (SVA: 50%, 35%, 41%, P=0.148; PI-LL: 64%, 66%, 56%, P=0.617; LL: 62%, 71%, 63% P=0.385 for D, IB and PLF respectively). LL deteriorated an average of 6.1±5.7° and was similar among surgery types. Patients undergoing decompression only saw a smaller improvement in LL compared to IB (P=0.039; D=6.5±6.0°, IB=9.7±7.6°, PLF=9.1±7.0°). SVA deteriorated an average of 14±18 mm and was similar among surgery types. PLF saw the greatest improvement in SVA (48±51 mm vs D, 24±39 mm (P=0.002) vs IB 18.1±23 (P=0.003)). PI-LL deteriorated an average of 7.1±6.0 mm and improved an average of 11.1±9.2 mm and did not differ among surgery types.

Discussion: Overall spinal alignment either remains the same or improves with the vast majority of patients undergoing surgery for DLS regardless of surgical intervention. In this large, longitudinally followed multi-centre patient cohort, more invasive surgical intervention in the form of interbody or posterolateral fusion for DLS was not associated with a statistically significant between group alignment improvement compared to decompression alone. 

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