Dynamic instability is associated with worse patient-reported outcome measures after fusion for lumbar degenerative spondylolisthesis: a single-center retrospective cohort study
Year: 2026
Type: article
Study design: Observational Study
Abstract: Background: Dynamic instability is commonly considered when selecting surgical treatment for degenerative spondylolisthesis, which presents with a variety of radiographic morphology and severity. However, the relationship between dynamic instability and patient-reported outcomes (PROs) following fusion has been sparsely explored. This study evaluated if preoperative dynamic instability and other radiographic metrics were associated with PROs and perioperative outcomes following fusion for one-level lumbar degenerative spondylolisthesis. Methods: This retrospective study included adult patients undergoing surgical fusion for single-level lumbar degenerative spondylolisthesis between 2010 and 2024 at a single, academic, urban medical center. Degenerative spondylolisthesis was identified utilizing lateral standing radiographs, and all radiographic metrics were evaluated by a team of six research fellows using standardized methods. Patients were eligible if they received either laminectomy with interbody fusion (IF) or laminectomy with posterior segmental fusion (LPSF). Patients receiving laminectomy alone were excluded, since no structural change can be accomplished. Multiple IF approaches were combined into the composite category due to insufficient subgroup sample sizes. Preoperative index level slip distance, foraminal height, disc height, segmental lordosis, index level facet joint angle and gap, pelvic incidence-lumbar lordosis (PI-LL) mismatch, and dynamic instability greater than 4 mm at the index level based on flexion slip distance minus extension slip distance at the index level were recorded. Primary outcomes included PRO values of the Oswestry Disability Index (ODI) and Visual Analog Scale (VAS) scores collected from the final follow-up appointment in the electronic medical record; all PRO models adjusted for the corresponding baseline preoperative values from the immediate preoperative clinic visit. Other primary outcomes included intraoperative estimated blood loss (EBL), hospital length-of-stay (LOS), and total opioid usage in the hospitalization. Secondary outcomes included any transfusions and complications. Multivariable linear and Firth logistic regression models were used to evaluate predictors of final PROs and clinical outcomes. Results: Four hundred and seventy-three patients qualified for the study; 324 (68.5%) had available dynamic translation measurements and 140 (29.6%) had at least one complete pair of preoperative and final follow-up PROs. The mean follow-up time was approximately 15 months for patients who underwent LPSFs and 8 months for those who underwent IFs. Preoperative dynamic instability was associated with higher ODI [β=+15.14, 95% confidence interval (CI): 7.62 to 22.66, P<0.001] and VAS Back (β=+2.35, 95% CI: 1.16 to 3.54, P<0.001) scores than in patients without dynamic instability at final follow-up. Conclusions: Most radiographic metrics were not associated with perioperative outcomes or PROs at final follow-up in degenerative lumbar spondylolisthesis (DLS), but preoperative dynamic instability was identified as independently associated with worse PROs. However, the retrospective, single-center nature of the study as well as considerable missing follow-up data limit the ability of these findings to provide definitive comparisons of clinical effectiveness between treatment methods.
Source: Journal of Spine Surgery
Language: English
Subfield: Orthopedics and Sports Medicine
Field: Medicine
Domain: Health Sciences
Open Access status: diamond
OpenAlex ID: W7223861939