Short Lumbosacral Decompression Plus Fixation Does Not Change the Spinopelvic Balance on Patients With Moderate Degenerative Spondylolisthesis and Associated Spinal Stenosis

Abstract

Study design: A retrospective cohort study.

Objectives: To investigate whether decompression plus short segment lumbosacral fixation changes the sagittal baseline spinopelvic parameters in patients with moderate degenerative spondylolisthesis (DS) and associated degenerative lumbar spinal stenosis (DLSS).

Summary of background data: Spinal decompression and fusion are commonly performed in DS with associated DLSS. Spinopelvic alignment after surgery for DS is an important research topic. The effect of short lumbosacral instrumented fusion on the global sagittal spinal balance has not been sufficiently studied.

Methods: Thirty-four consecutive adult patients (21 women, 13 men) aged 62 ± 11 years with balanced spines [sagittal vertical axis (SVA) ≤ 40 mm] received decompression and two to three vertebrae fixation plus fusion for DS grades I and II, associated with symptomatic DLSS. Age, gender, number of segments fused, posterolateral fusion (PLF) versus PLF plus posterior lumbar interbody fusion (PLIF) and segmental lordosis (SL) in the free segment above instrumentation were studied for a minimum follow-up of 60 months. The roentgenographic variables measured are T12-S1 lumbar lordosis (LL), SVA, sacral slope (SS), pelvic tilt (PT), pelvic incidence (PI), SL, and anterior (ADH) and posterior disc height (PDH) in the suprajacent free lumbar segment. Clinical outcomes were assessed with visual analog scale and Oswestry Disability Index.

Results: SVA significantly (p = .05) decreased postoperatively but returned to the baseline value at the final observation. Younger individuals (≤59 years) stood with greater SS (p = .036) 6 months postoperatively and with less SVA in all 3 periods of observation (p = .013, .046, and .024) than their older (>59 years) counterparts. Patients with monosegmental stenosis showed on baseline less SVA (p = .028), PT (p = .031), and PI (p = .004) than their two-segmental stenosis counterparts. PI preoperatively to the last evaluation was significantly smaller in the patients who received 360° fusion (p<.016).

Conclusions: Short lumbosacral fixation does not significantly change the preoperative sagittal spinopelvic balance in adult patients with preoperatively balanced spines who have DS and DLSS.

Level of evidence: Level III.

Keywords: Compensatory mechanism; Sagittal balance; Short fusion; Spinal stenosis; Spondylolisthesis.