Maximal Segmental Lordosis Can Be Achieved When Fixating Into One Or Both Vertebral Bodies During Anterior Column Realignment: A Cadaveric Study

Presented at SMISS Annual Forum 2018
By Jay Turner MD, PhD
With Jakub Godzik MD, Bernardo de Andrada Pereira MD, Anna Newcomb MS, Jennifer Lehrman MS, Gregory M. Mundis MD, Juan S. Uribe MD, FACS, Brian Kelly PhD,

Disclosures: Jay Turner MD, PhD A; NuVasive. B; NuVasive, SeaSpine. Jakub Godzik MD None, Bernardo de Andrada Pereira MD None, Anna Newcomb MS None, Jennifer Lehrman MS None, Gregory Mundis MD A; ISSGF, Nuvasive. B; K2M, Medicrea, Misonix, Nuvasive. C; K2M, Nuvasive. F; Nuvasive., Juan Uribe MD, FACS A; Nuvasive. B; Nuvasive. C; Nuvasive. D; Nuvasive. F; Nuvasive, Brian Kelly PhD None,

Introduction:

Anterior column realignment (ACR) is an effective minimally invasive technique for sagittal realignment. Osteotomy grade and extent of anterior fixation may influence ability to achieve desired correction. Many surgeons choose to fixate into only one vertebral body to ensure that corrective capacity is not limited. However, this has not been scientifically evaluated.

Aims/Objectives:

The objective of this study was to investigate the impact of anterior fixation into 1 or 2 vertebral bodies with grade 1 or 2 posterior osteotomy on ACR segmental lordosis.

Methods:

Eight human cadaveric T12-S1 specimens were potted and instrumented. Each cadaver underwent ACR at L3/4 with a hyperlordotic 30° implant, followed by grades 1 (G1) and 2 osteotomies (G2). Anterior fixation was achieved with an integrated plate and either a single screw into L3 vertebral body (S1) or a single screw into both L3 and L4 vertebral bodies (S2). The amount of posterior compressive force (N) required to maximize lordosis was measured for each condition using a compressive instrument. Segmental lordosis at L3/4 interspace was measured with lateral radiographs. T-test and repeat measures ANOVA were used for statistical analysis; significance was defined as p<0.05.

Results:

Mean segmental lordosis achieved with ACR without osteotomy and 1 screw was 16.5±3.3°, with G1 osteotomy was 19.5±2.3°, and with G2 osteotomy was 30.5±2.8°; mean segmental lordosis achieved with ACR without osteotomy and 2 screws was 15.5±1.8°, G1 osteotomy was 19.5±2.3°, and with G2 osteotomy was 28.5±2.3°. There were no significant differences in segmental lordosis between 1 vs 2 screws for no osteotomy, G1, or G2 osteotomies (p>0.148). There was no difference in posterior compressive force required when using two vs one anterior screws (p>0.650); however, significantly less compressive force was required with G2 osteotomy compared with G1 osteotomy (143 vs 183 N, p=0.013) and no osteotomy (143 vs 173 N, p=0.048) regardless of one or two screws.

Conclusions:

Maximal segmental lordosis can be achieved with ACR whether fixating into one or both vertebral bodies when grade 2 osteotomies are performed.