Pilot Evaluation of the Incidence of Preoperative Spinopelvic Malalignment in One- and Two-level Non-deformity Fusion Patients and its Correction following Minimally Invasive Posterior Lumbar Interbody Fusion

Presented at SMISS Annual Forum 2016
By Nitin Khanna MD
With

Disclosures: Nitin Khanna MD B; Nuvasive. C; Nuvasive. D; Globus, Spineology, Nuvasive. F; Nuvasive.

Introduction

There has been increased attention on sagittal alignment and its surgical correction in patients undergoing lumbar spinal surgery, with much of the previous research focused on multilevel deformity correction. There is a paucity of literature, however, assessing the role of alignment in one- and two-level fusions, which make up the vast majority of fusion surgeries performed. The purpose of this study was to evaluate the incidence of preoperative malalignment (PI-LL >10°) in one- and two-level non-deformity fusion patients to assess the incidence of baseline malalignment and then to determine their alignment outcomes following minimally invasive (MIS) posterior lumbar interbody fusion (PLIF). 

Aims/Objectives

Call attention to the importance of measuring spinopelvic parameters in minimally invasive lumbar fusion. 

Methods

Ten (10) consecutive one- and two-level non-deformity patients were treated with MIS PLIF (MAS PLIF®) utilizing clinic- and operating room based alignment analysis software (NuvaMap/NuVaMapOR) to determine preoperative, intraoperative, and postoperative pelvic parameters (pelvic incidence (PI) and lumbar lordosis (LL)) on lumbar spine upright radiographs that included the femoral heads and the entire lumbar spine. 

Results

Half (5/10) of patients were in alignment preoperatively, with PI-LL ≤±10°. In these patients, lordosis increased postoperatively an average of 8.2° (range 7-10 degrees). Overall, Lordosis was improved 6.9 ° (range0-10 degrees). In the five cases where the patients were out of alignment preoperatively (PI-LL > 10 degrees) all patients had their alignment resolved to PI-LL <10 degrees.

Conclusions

In this study, short-segment degenerative fusion patients were able to have their alignment measures made efficiently and implemented into surgical decision making.

Half of patients were malaligned preoperatively with all resolving to within acceptable parameters following treatment with MAS PLIF. MAS PLIF is a procedure that involves bilateral facet and bilateral posterolateral release of the disc space through a minimally invasive approach, with these data demonstrating the potential for this procedure to correct sagittal alignment, even in short-segment cases. The historic approach of simply trying to attain a fusion and ignoring sagittal alignment in one and two level lumbar fusion cases utilizing open or minimally invasive techniques is suboptimal given our growing understanding of the incidence of malalignment in everyday cases. Much further study is required with longer term radiographic and clinical outcomes ideally utilizing a prospective multicenter study.