Outcomes Comparison between Unilateral and Bilateral Minimally Invasive Transforaminal Lumbar Interbody Fusion

Presented at SMISS Annual Forum 2014
By Abbas Naqvi BS
With Kern Singh MD, Sreeharsha V. Nandyala BA, Alejandro Marquez-Lara MD, Islam Elboghdady , Eric Sundberg MD, Hamid Hassanzadeh MD, Anton Jorgensen MD, Khaled Aboushaala MD, Blaine Manning BS,

Disclosures: Abbas Naqvi BS None Kern Singh MD A; CSRS Resident Grant. B; DePuy, Zimmer, Stryker, CSRS, ISASS, AAOS, SRS, Vertebral Column - ISASS. D; Avaz Surgical, LLC, Vital 5, LLC. F; Zimmer, Stryker, Pioneer, Lippincott Williams & Wilkins, Th, Sreeharsha Nandyala BA None, Alejandro Marquez-Lara MD None, Islam Elboghdady None, Eric Sundberg MD None, Hamid Hassanzadeh MD None, Anton Jorgensen MD None, Khaled Aboushaala MD None, Blaine Manning BS None,

Introduction:
Emerging literature suggests comparable clinical outcomes between the unilateral and bilateral instrumentation for the open transforaminal lumbar interbody fusion (TLIF). Few studies to date have addressed such a difference in the setting of a minimally invasive (MIS) TLIF.

Aims/Objectives:
The purpose of the study was to determine the differences in the perioperative parameters and clinical outcomes associated with the unilateral vs. bilateral instrumentation techniques for a single level MIS TLIF.

Methods:
Two hundred thirteen consecutive patients who underwent a primary single-level MIS TLIF for degenerative pathology were analyzed (143 unilateral, 70 bilateral) retrospectively using a prospectively collected registry. Patients with either a dynamic or isthmic spondylolisthesis were enrolled in the bilateral instrumentation cohort. Patient demographics, comorbidity burden (Charlson Comorbidity index CCI), operative time (minutes), length of stay (LOS, days), estimated blood loss (EBL, mL), fusion rates, Visual Analog Scale (VAS) scores, and complication rates were assessed. SPSS (version 22) was utilized for statistical analysis with χ 2 test for categorical data and independent-samples T test for continuous data. A value of p ≤ 0.05 denoted statistical significance.

Results:
No differences were observed between the two groups with respect to demographic data (age, gender, and race), smoking status, CCI, and preoperative VAS scores. The unilateral cohort demonstrated decreased mean operative time (104 mins vs. 138 mins; p<0.05), and estimated blood loss (55.6±20.7 ml vs. 67.2±35.3 ml; p<0.05). Both cohorts experienced decreased post-operative VAS scores. Compared to the bilateral cohort, the unilateral cohort experienced significantly lower VAS scores at 6-week (3.9±2.1 vs. 4.5±2.6; p<0.05) and 12-week (3.6±2.5 vs. 4.5±2.6; p<0.05) postoperatively. Both cohorts demonstrated comparable arthrodesis rates of 87.8% (n= 134/143) and 86.0% (n=60/70) for the unilateral and bilateral cohorts, respectively. There were no significant differences in the incidence of postoperative complications, pseudoarthrosis, or revision surgeries between the two surgical cohorts.

Conclusions:
Unilaterally instrumented Single-Level MIS TLIF demonstrated significant reduction of operative times, VAS scores, and EBL compared with the bilateral procedure. The unilateral procedure also provided comparable fusion rates with no increase in the short and long term complications. Improvement in pain scores may increase patient satisfaction, and the shorter surgical times associated with the unilateral technique can provide opportunities for hospitals to reduce utilization of resources and increase surgical case volume.