The effect of the retroperitoneal transpsoas minimally invasive lateral interbody fusion on segmental and regional lumbar lordosis

Abstract

Background: The minimally invasive lateral interbody fusion (MIS LIF) in the lumbar spine can correct coronal Cobb angles, but the effect on sagittal plane correction is unclear.

Methods: A retrospective review of thirty-five patients with lumbar degenerative disease who underwent MIS LIF without supplemental posterior instrumentation was undertaken to study the radiographic effect on the restoration of segmental and regional lumbar lordosis using the Cobb angles on pre- and postoperative radiographs. Mean disc height changes were also measured.

Results: The mean follow-up period was 13.3 months. Fifty total levels were fused with a mean of 1.42 levels fused per patient. Mean segmental Cobb angle increased from 11.10° to 13.61° (P < 0.001) or 22.6%. L2-3 had the greatest proportional increase in segmental lordosis. Mean regional Cobb angle increased from 52.47° to 53.45° (P = 0.392). Mean disc height increased from 6.50 mm to 10.04 mm (P < 0.001) or 54.5%.

Conclusions: The MIS LIF improves segmental lordosis and disc height in the lumbar spine but not regional lumbar lordosis. Anterior longitudinal ligament sectioning and/or the addition of a more lordotic implant may be necessary in cases where significant increases in regional lumbar lordosis are desired.

Figure 1

XLP lateral plate. (a) Lateral view. Notice the plate spans across the disc space (DS) and is secured down to the vertebral bodies (VB) with lock nuts. (b) AP view. Lateral plate (white arrow) is seated on two bicortical screws, which are parallel to the adjacent endplates (EP). A cage (C) is depicted in the disc space. (Images used with permission of NuVasive, Inc., San Diego, CA, USA).

Figure 2

Representative lordosis and disc height measurements. Regional Cobb angles are based on the superior endplate of L1 and the superior endplate of S1 to measure regional lumbar lordosis. Segmental Cobb angles are based on the superior endplate of the rostral vertebral body and the inferior endplate of the caudal vertebral body (L4 and L5 in this example). Disc heights are calculated using the average between the anterior and posterior disc heights.

Figure 3

Segmental lumbar lordosis changes after MIS LIF. Statistically significant increases were observed at each measured level as well as in aggregate. (* = P < 0.05,** = P < 0.01,*** = P < 0.001).

Figure 4

: Regional lumbar lordosis changes after MIS LIF. No statistically significant increases were observed.

Figure 5

Disc height changes after MIS LIF. Statistically significant increases were observed at each measured level as well as in aggregate. (* = P < 0.05,** = P < 0.01,*** = P < 0.001).