Outcomes and Predictors of Failure to Improve Following Unilateral Laminotomy With Bilateral Decompression

Presented at SMISS Annual Forum 2019
By Tadhg O'Gara MD
With Michael Schallmo BS, Ziyad Knio BS, Wesley Hsu MD, Benjamin Corona PhD, Justin Lackey BS, Alejandro Marquez-Lara MD, T. David Luo MD, Suman Medda MD, Bradley Wham MD,

Disclosures: Tadhg O'Gara MD None Michael Schallmo BS None., Ziyad Knio BS None, Wesley Hsu MD None, Benjamin Corona PhD None, Justin Lackey BS None, Alejandro Marquez-Lara MD None, T. Luo MD None, Suman Medda MD None, Bradley Wham MD None,


With the emergence of tubular retractor systems, less invasive techniques that minimize trauma to paraspinal musculoligamentous structures, such as unilateral laminotomy with bilateral decompression (ULBD), have become increasingly used for the management of recalcitrant lumbar spinal stenosis (LSS). However, there is a paucity in the evidence-based literature regarding trends in and predictors of clinical outcomes over time following ULBD.


The purpose of this study was to assess factors that may predict failure to improve at 12- and 24-months following ULBD for the management of LSS.


A database of 255 consecutive microdecompression surgeries performed by a single surgeon between 2014-2018 was queried. Inclusion criteria were patients at least 18 years of age with symptomatic LSS who failed non-operative management and subsequently underwent primary, single-level ULBD. Outcomes included visual analog scale (VAS) for back pain and leg pain, and Oswestry Disability Index (ODI), which were collected preoperatively and at 12- and 24-months postoperative. Patient characteristics, radiographic findings, operative factors, and intraoperative findings were assessed for associations with failure to improve. The threshold for clinically important improvement was defined as reaching or surpassing the previously established minimum clinically important difference for ODI (12.8) and not requiring revision.


A total of 68 patients were included. Preoperative values for back pain, leg pain, and ODI (7.32, 7.53, and 51.22, respectively) showed significant improvements upon follow-up at 12-months (2.89, 2.23, 22.40, respectively; p<0.001) and 24-months (2.80, 2.11, 20.32, respectively; p<0.001). A total of 50 patients (73.5%) demonstrated clinically important improvement after ULBD based on the defined criteria. Of the 18 patients who failed to improve, 12 required revision (6 fusions, 6 tubular decompressions). Independent predictors of failure to improve included female sex (adjusted odds ratio=5.06, 95% confidence interval [1.49-21.12]; p=0.014) and current smoker status (adjusted odds ratio=5.39, 95% confidence interval [1.39-23.97]; p=0.018).


Patients in this study who underwent ULBD demonstrated clinically important improvement that was maintained over a 24-month follow-up period. Poorer outcomes were associated with female sex and current tobacco smoker status.