Radiological and Clinical Outcomes comparing 2-level MIS Lateral and MIS Transforaminal Lumbar Interbody Fusion in Degenerative Lumbar Spinal Stenosis.

STUDY DESIGN: Retrospective Cohort Study. OBJECTIVES: To compare early postoperative radiological and clinical outcomes between 2-level minimally invasive (MIS) trans-psoas lateral lumbar interbody fusion (LLIF) and MIS transforaminal lumbar interbody fusion (TLIF) for degenerative lumbar spinal stenosis. METHODS: Fifty three consecutive patients undergoing 2-level lumbar interbody fusion from L3-L5 for degenerative lumbar spinal stenosis were enrolled. Twenty four patients underwent LLIF and 29 underwent TLIF. RESULTS: Operative time and length of stay were similar between LLIF and TLIF (272.8 ± 82.4 vs 256.1 ± 59.4 minutes; 5.5 ± 2.8 vs 4.7 ± 3.3 days, P > .05), whereas blood loss was lower for LLIF (229.0 ± 125.6 vs 302.4 ± 97.1mls, P = .026). Neurological deficits were more common in LLIF (9 vs 3, P = .025), whereas persistent deficits were rare for both (1 vs 1, P = 1). For both groups, all patient reported outcomes visual analogue scale (VAS back pain, VAS leg pain, ODI, SF-36 physical) improved from preoperative to 2-years postoperative (P < .05), with both groups showing no significant differences in extent of improvement for any outcome. Lateral lumbar interbody fusion demonstrated superior restoration of disc height (L3-L4: 4.1 ± 2.4 vs 1.2 ± 1.9 mm, P < .001; L4-L5: 4.6 ± 2.4 vs .8 ± 2.8 mm, P < .001), foraminal height (FH) (L3-L4: 3.5 ± 3.6 vs 1.0 ± 3.6 mm, P = .014; L4-L5: 3.0 ± 3.5 vs -.1 ± 4.4 mm, P = .0080), segmental lordosis (4.1 ± 6.4 vs -2.1 ± 8.1°, P = .005), lumbar lordosis (LL) (4.1 ± 7.0 vs -2.3 ± 12.6°, P = .026) and pelvic incidence-lumbar lordosis (PI-LL) mismatch (-4.1 ± 7.0 vs 2.3 ± 12.6°, P = .019) at 2-years follow-up. CONCLUSION: The superior radiological outcomes demonstrated by 2-level trans-psoas LLIF did not translate into difference in clinical outcomes compared to 2-level TLIF at the 2-years follow-up, suggesting both approaches are reasonable for 2-level lumbar interbody fusion in degenerative lumbar spinal stenosis.

Smoking Is Associated With Lower Satisfaction in Nondiabetic Patients Undergoing Minimally Invasive Single-level Transforaminal Lumbar Interbody Fusion.

STUDY DESIGN: This was a retrospective review of prospectively collected registry data. OBJECTIVE: The objective of this study was to investigate the effect of smoking on 2 years postoperative functional outcomes, satisfaction, and radiologic fusion in nondiabetic patients undergoing minimally invasive transforaminal lumbar interbody fusion (TLIF) for degenerative spine conditions. SUMMARY OF BACKGROUND DATA: There is conflicting data on the effect of smoking on long-term functional outcomes following lumbar fusion. Moreover, there remains a paucity of literature on the influence of smoking within the field of minimally invasive spine surgery. METHODS: Prospectively collected registry data of nondiabetic patients who underwent primary single-level minimally invasive TLIF in a single institution was reviewed. Patients were stratified based on smoking history. All patients were assessed preoperatively and postoperatively using the Numerical Pain Rating Scale for back pain and leg pain, Oswestry Disability Index, Short-Form 36 Physical and Mental Component Scores. Satisfaction was assessed using the North American Spine Society questionnaire. Radiographic fusion rates were compared. RESULTS: In total, 187 patients were included, of which 162 were nonsmokers, and 25 had a positive smoking history. In our multivariate analysis, smoking history was insignificant in predicting for minimal clinically important difference attainment rates in Physical Component Score and fusion grading outcomes. However, in terms of satisfaction score, positive smoking history remained a significant predictor (odds ratio=4.7, 95% confidence interval: 1.10-20.09, P=0.036). CONCLUSIONS: Nondiabetic patients with a positive smoking history had lower satisfaction scores but comparable functional outcomes and radiologic fusion 2 years after single-level TLIF. Thorough preoperative counseling and smoking cessation advice may help to improve patient satisfaction following minimally invasive spine surgery. LEVEL OF EVIDENCE: Level III-nonrandomized cohort study.

Does Cervical Alignment Matter? The Effect of 2-level Anterior Cervical Discectomy and Fusion on Sagittal Alignment and Patient-reported Outcomes.

STUDY DESIGN: Retrospective review of prospectively collected data. OBJECTIVE: This study aimed to determine the change in cervical sagittal balance following 2-level anterior cervical discectomy and fusion (ACDF) and whether the degree of change was associated with improvement in patient-reported outcomes (PROs). SUMMARY OF BACKGROUND DATA: Sagittal balance in cervical spine surgery has been recognized as an important surgical goal. However, its influence on clinical outcomes following anterior decompressive procedures remains debatable. MATERIALS AND METHODS: Patients who underwent primary 2-level ACDF for cervical spondylotic radiculopathy and/or myelopathy were identified from an institutional spine registry. Radiographic measurements were done preoperatively, postoperatively, and at minimum 24 months follow-up. Measurements comprised segmental lordosis (SL), C2-C7 cervical lordosis (CL), C2-C7 sagittal vertical axis, C7 slope (C7S), T1 slope (T1S) and C7 slope minus cervical lordosis (C7S-CL). Disk heights were measured preoperatively and postoperatively. PROs including the Neck Disability Index, Short Form-36, and Visual Analog Scale for neck pain and arm pain were collected preoperatively and at 24 months postoperatively. RESULTS: In total, 90 patients were included. Mean follow-up was 58.6±22.9 months. Significant improvement in all PROs was achieved at 24 months (P<0.05). SL was -1.2±8.2 degrees preoperatively, increased to 5.2±5.9 degrees postoperatively (P<0.001), and decreased to 1.2±6.2 degrees at follow-up (P=0.005). CL was 8.5±12.5 degrees preoperatively, increased to 10.8±12.4 degrees postoperatively (P=0.018), and maintained at 10.9±11.2 degrees at follow-up (P=0.030). Sagittal vertical axis, C7S, T1S, and C7S-CL did not change significantly. Significant increases in disk heights were achieved postoperatively (P<0.001). Fusion rate was 98.9% at follow-up. PROs were not related to radiologic measurements. Maintaining or increasing CL or SL was not related to a greater degree of improvement in PROs. CONCLUSIONS: Two-level ACDF restored segmental and global CL, but changes in cervical sagittal alignment did not correlate with the magnitude of improvement in PROs. Adequate decompression with solid fusion remains fundamental to achieving good clinical outcomes in patients with degenerative cervical disease.

The Relationship Between Cervical Sagittal Balance and Adjacent Segment Disease After Three-level Anterior Cervical Discectomy and Fusion.

STUDY DESIGN: Retrospective review of prospectively collected data. OBJECTIVE: To determine the relationship between cervical sagittal balance and adjacent segment degeneration (ASD) development after 3-level anterior cervical discectomy and fusion (ACDF). SUMMARY OF BACKGROUND DATA: ASD is a common complication after ACDF. Previous studies have shown that sagittal imbalance may be associated with ASD development after 1-level or 2-level ACDF. However, these findings may not be generalizable to 3-level procedures. MATERIALS AND METHODS: We reviewed prospectively collected data of 46 patients who underwent 3-level ACDF at a tertiary institution. Lateral cervical radiographs taken preoperatively, postoperatively, and at last follow-up were reviewed for ASD. The mean follow-up duration was 5 years. Radiographic parameters measured were cervical sagittal alignment (CSA), segmental sagittal alignment, T1 slope (T1S), sagittal vertical axis, and T1S-cervical lordosis. RESULTS: ASD was present in 27 (58.7%) patients, but only 1 patient (2.2%) underwent reoperation at 4.8 years. The CSA, sagittal vertical axis, and T1S were similar preoperatively, but the T1S-cervical lordosis was higher in the ASD group (18.28 vs. 9.82, P =0.016). All 4 parameters were similar postoperatively and at last follow-up. The ASD group had a greater change in CSA over the follow-up period (-6.26 vs. -1.47, P =0.05), but they achieved similar sagittal alignment at last follow-up. There was no difference in clinical outcomes between the 2 groups. CONCLUSIONS: Unlike studies on 1-level and 2-level ACDF, this study found that cervical spinal alignment was not associated with ASD development after 3-level ACDF. ASD development also had no impact on clinical outcomes at 2 years. LEVEL OF EVIDENCE: Level III-nonrandomized cohort study.

Intraoperative Motor Evoked Potential Improvement in Cervical Spondylotic Myelopathy: Comparison of Cortical Stimulation Parameters.

BACKGROUND AND PURPOSE: Intraoperative monitoring of the motor pathways is a routine procedure for ensuring the integrity of descending motor tracts during spinal surgery. Intraoperative motor evoked potential improvement (MEPI) may be associated with a better postsurgical outcome in cervical spondylotic myelopathy (CSM). To compare the efficacy of two cortical stimulation parameters in eliciting MEPI intraoperatively during CSM surgery. METHODS: We studied 69 patients who underwent decompression surgery for CSM over a 9-month period using either 5 (Group 1) or 9 (Group 2) stimuli. MEPI was defined as the increase in the amplitude of MEPs from baseline at the end of CSM surgery just prior to skin closure. RESULTS: An MEPI of 100% from baseline was observed in 10 patients (53%) in Group 1 and 36 patients (72%) in Group 2. Comparisons of the baseline mean MEP amplitudes of muscles bilaterally between Groups 1 and 2 did not reveal any significant differences. Supramaximal stimulation showed that a significantly higher mean intensity was required for Group 1 than for Group 2. CONCLUSIONS: MEPI is observed in a much larger proportion of cervical decompression surgery cases than previously thought. Intraoperative MEPI with longer-train cortical stimulation may reflect adequacy of decompression and provide additional guidance for the surgical procedure.