Electronic Thesis and Dissertation Repository

Thesis Format

Integrated Article


Master of Science




Bailey, Chris


Objective: To confirm the importance of sagittal spinal alignment on functional outcome with degenerative lumbar spondylolisthesis (DLS) surgery and to identify the radiographic parameters that predict functional outcomes after DLS surgery.

Methods: Retrospective analysis of the prospectively collected functional and radiographic outcomes of the Canadian Spine Outcomes and Research Network DLS database. All patients underwent either decompression, posterolateral fusion or interbody fusion surgery with a minimum of one-year postoperative follow-up.

Results: Most patients improve or remain unchanged in their sagittal spinal alignment regardless of surgery type with fusion procedures not experiencing statistically significantly improved alignment changes to decompression alone. By multiple linear regression adjusted for baseline patient age, body mass index, gender and preoperative presence of depression, worsening of a patient’s pelvic incidence-lumbar lordosis (LL) mismatch with any technique of DLS surgery was associated with a higher one-year postoperative ODI score R2 0.179 (95% CI 0.080, 0.415, p=0.004), back pain R2 0.152 (95% CI 0.021, 0.070, p 2 0.059 (95% CI 0.008, 0.066, p=0.014) score. Likewise, reduction of LL was associated with a higher ODI score R2 0.168 (-0.387, -0.024, p=0.027) and back pain R2 0.135 (95% CI -0.064, -0.010, p=0.007).

Conclusions: This is the first work to examine DLS patients outside of extrapolated sagittal balance parameters from the adult scoliosis literature. Importantly, we show that any worsening in sagittal spinal alignment parameters with DLS surgery regardless of surgery type leads to poorer functional outcomes even among patients who remain within conventionally held appropriate sagittal balance.

Summary for Lay Audience

Degenerative lumbar spondylolisthesis (DLS) is a commonly encountered clinical issue for adult spinal surgeons and results in painful cramping in the legs with activity. These symptoms can be debilitating in patients and when there are signs of damage to the nerves in the lower legs coming from the lumbar spine, surgery has proven beneficial. It is unclear how best to treat patients surgically with DLS. Multiple surgical options exist with the mainstay being a decompression procedure, whereby bone and soft tissue are removed from the involved level of the lumbar spine to free the nerves providing function to the lower legs. Largely the North American spine surgical practice has moved to include fusion procedures alongside decompressions. With fusions, screws are placed in the pedicles, (the bony connection from the back to the front of the spine), stabilized by instrumentation on both sides of the spinal canal. Additionally, the use of artificial spacers placed in the disc space to reestablish collapsed disc heights, called interbody devices, are commonly utilized in DLS surgery. Without proven benefit of fusion procedures over decompression procedures alone, it is important to establish the effect that instrumentation can have on patients with DLS. Much recent interest in the world of DLS surgery has focused on how surgery for DLS can improve the overall alignment of a patient’s spine. The work of this thesis project provides a comprehensive and informative analysis of 248 DLS patients, the largest available Canadian DLS patient data set. We demonstrate that a similar proportion of patients undergoing decompression, decompression and fusion and decompression and fusion with interbody device use, improve in their overall spinal alignment regardless of the type of surgery. Furthermore, we have demonstrated that patients who have a worsening of their spinal balance one-year after surgery do predictably worse functionally than those patients who remain unchanged or see an improvement in their spinal alignment with surgery. Our work has helped to demonstrate the importance of spinal alignment to DLS surgery in addition to highlighting the tendency to perform too much and too invasive of spinal surgery for the average DLS patient.