Patients with High Pelvic Tilt Achieve the Same Clinical Success as Those with Low Pelvic Tilt After Minimally Invasive Deformity Surgery

Presented at SMISS Annual Forum 2016
By Juan Uribe MD, FACS
With Behrooz Akbarnia MD, Neel Anand MD, Robert Eastlack MD, Michael Wang MD, Praveen Mummaneni MD, David Okonkwo MD, PhD, Adam Kanter MD, Paul Park MD, International Group , Gregory Mundis Jr. MD, Joseph Zavatsky MD, Pierce Nunley MD, Stacie Nguyen MPH,

Disclosures: Juan Uribe MD, FACS None Behrooz Akbarnia MD A; Depuy Synthes Spine. B; NuVasive, K2M, Ellipse, Kspine. D; Alphatec Spine, NuVasive, Ellipse, Kspine, Nocimed., Neel Anand MD None, Robert Eastlack MD None, Michael Wang MD None, Praveen Mummaneni MD B; Globus, David Okonkwo MD, PhD B; Nuvasive, Zimmer-Biomet. F; Nuvasive, Zimmer-Biomet, Adam Kanter MD None, Paul Park MD None, International Group A; Biomet, Depuy, Innovasis, K2M, Medtronic, Nuvasive, Stryker., Gregory Mundis Jr. MD A; ISSGF, Nuvasive. B; K2M, Medicrea, Misonix, Nuvasive. C; K2M, Nuvasive. F; Nuvasive., Joseph Zavatsky MD B; Amendia, Biomet, Depuy, Stryker. D; Innovative Surgical Solutions, Safe Wire, Vivex. F; Biomet., Pierce Nunley MD None, Stacie Nguyen MPH None,

Introduction

Pelvic tilt (PT) has been shown to correlate with HRQOL. The effect of PT in minimally invasive spine surgery for adult spinal deformity (ASD) has not been well studied. We present a comparison of clinical outcomes among ASD patients with high and low PT. 

Aims/Objectives

To determine if patients with High PT will not achieve clinical or radiographic success as frequently as those
with Low PT. 

Methods

Retrospective review of a multicenter MIS ASD database was performed. The inclusion criteria for the database were: age>18, and one of the following: coronal Cobb angle (CCA)>20, SVA>5 cm, PI-LL>10 or PT>20. Patients undergoing circumferential minimally invasive (cMIS: lateral interbody fusion with MIS screw placement) correction with a minimum 2-year follow-up were included, and stratified into two groups based on the Schwab classification of PT: High PT (>30) and Low PT (<20). 

Results

Among 420 patients in the database, 165 had complete 2-year data. Of the 165 eligible, 43 patients met criteria of the present study for analysis (25 Low, 18 High PT). The High PT group had higher pre-op PI-LL mismatch (32.1 vs. 4.7; p<0.001) (Table 1). At last follow-up, 77% (14) of patients in High PT Group had continued PI-LL mismatch compared to 40% (10) in the Low PT Group (p<0.006). There was a difference in the High and Low PT groups in terms of postop changes of PT (-3.9 v 1.9), LL (8.7 v 0.5) and PI-LL (-9.5 v 0.1). HRQOL were similar preoperatively with the patients in the High PT group having more back and leg pain. Postoperatively, HRQOL (ODI and VAS back/leg) were significantly improved in both groups (p<0.05). 

Conclusions

The degrees of PT seems to be correlated with PI, SVA and PI-LL mismatch. The higher PT, the lower LL, and higher PI and PI-LL mismatch. However, patients with high preoperative PT treated with cMIS techniques had less radiographic success without compromising the clinical outcomes. Further investigation is required to explain the role of PT when treating ASD patients using MIS techniques.