Effectiveness of Interbody Lordotic Cages to Restore Disc Angle and Lumbar Lordosis Through Completely Mini-invasive Trans-psoas and Hybrid Approach

Presented at SMISS Annual Forum 2016
By Giuseppe Barone MD
With

Disclosures: Giuseppe Barone MD None

Introduction

While it seems to be demonstrated that interbody cage application produces significant increase in average posterior disk height, foraminal and canal area, the degree of correction achieved on segmental and lumbar lordosis by lordotic cages is not well defined. 

Aims/Objectives

Evaluating and quantifying the effectiveness of interbody lordotic cages to improve disc angle and lumbar lordosis and showing the differences between a completely mini-invasive and hybrid approach. 

Methods

We selected patients treated at our Institution by minimally invasive transpsoas approach with a minimal of one-level lateral lumbar interbody fusion or anterior column resection (ACR) with anterior longitudinal ligament release. Patients were divided in 2 groups: completely minimally invasive surgery (cMIS), in which patients underwent lateral retroperitoneal transpsoas approach to the lumbar spine according to standard XLIF procedure, combined with percutaneous posterior fixation; hybrid surgery group, in which patients received supplementary open posterior approach. In this last group, patients underwent ACR procedure were distinguished. Radiographic measurements included pre and post-op (3 months) disc angle (DA) at each level of cage application, lumbar lordosis (LL), sacral slope (SS), pelvic tilt (PT), pelvic incidence (PI), PI-LL mismatch. We also measured DA variation (DAv). 

Results

41 patients had a complete and good quality data set. cMIS approach was performed in 27 patients (65,8%), while 14 patients (34,2%) underwent hybrid surgery. A total number of 78 cages was implanted. In Hybrid group, 4 patients (9,7%) underwent ACR procedure. Mean radiographic data in cMIS group changed as follow: LL from 44,1° pre-op to 51,6° post-op (p < 0,01), PI-LL mismatch from 9,2° to 7,1°. In Hybrid group LL improved from 30,7° pre-op to 49,6° (p < 0,001), PI-LL mismatch from 15,8° to 4,6° (p < 0,001). In cMIS group, DA at each level of cage application changed from a mean value of -2° to -5,8° post-op (p = 0,06), with mean DAv of -3,8°; in Hybrid group, DA changed from -0,5° to -6° (p < 0,01), with mean DAv of -5,5°. In the subgroup underwent ACR procedure, DA changed from a mean pre-op value of +1° to -13,2° post-op (p < 0,001), with mean DAv of -14,2°. LL improved from a mean value of 22,6° pre-op to 45,9° post-op (p < 0,001). 

Conclusions

Minimally-invasive lateral lumbar interbody fusion is an effective technique in improving sagittal parameters. When combined with posterior open approach and/or application of ACR procedure with 20° cages, greater corrections are possible.